https://microbewiki.kenyon.edu/api.php?action=feedcontributions&user=Dmcdonne1274&feedformat=atommicrobewiki - User contributions [en]2024-03-29T12:53:29ZUser contributionsMediaWiki 1.39.6https://microbewiki.kenyon.edu/index.php?title=Keck_Science_Class_Pages&diff=99250Keck Science Class Pages2014-04-15T16:38:10Z<p>Dmcdonne1274: </p>
<hr />
<div>= Spring 2014: Microbiology (Biology 168L) Student Pages=<br />
== Title and Author ==<br />
<br> <br />
<br> [[ ... ]] by Eric Benjamins - sent as word document<br />
<br> [[MicrobeWiki:Yersinia Pestis: Origin and Resistance]] by Shravani Bobde<br />
<br> [[Poliovirus and its three serotypes]] by Rachael Crooke<br />
<br> [[Necrotizing fasciitis induced by Vibrio vulnificus]] by Elana Goldstein<br />
<br> [[Antimicrobial Effects of Honey]] by Celina Hayashi<br />
<br> [[The role of Bifidobacterium on the Immune System]] by Christina Kang<br />
<br> [[Bat Influenza A]] by Erin Mackey<br />
<br> [[Unique structures found in hyperthermophilic archaea, specifically those in Pyrolobus fumarii]] by Libby Mannucci<br />
<br> [[Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose]] by Diana McDonnell<br />
<br> [[Anti-Helicobacter Pylori Activity From Natural Products]] by Amie Patel<br />
<br> [[West Nile Virus in Birds]] by Leah Pomernatz<br />
<br> [[Treatments against Pseudomonas aeruginosa Biofilms in Cystic Fibrosis Patient Lungs]] by Megan Richman<br />
<br> [[Tea Tree Oil and its Effectiveness in Treating Acne Vulgaris]] by Alex Sheridan<br />
<br> [[Canine parvovirus type 2 (CPV2)]] by Casey Sprague<br />
<br> [[ Persister Cells in E. coli ]] by Michelle Suarez<br />
<br> [[Tuberculosis and HIV]] by Inna Tounkel<br />
<br> [[Sovaldi and Olysio: Novel Antiviral Treatment for Hepatitis C]] by Vicki Wong<br />
<br> [[ Synechococcus and Biofuel]] by Caitlyn Young<br />
<br />
=Spring 2013: Microbial Life (Biology 187S) Student Pages=<br />
<br />
== Title and Author ==<br />
<br> <br />
<br> [[Medical Bioremediation]] by Sebastian Aguiar<br />
<br> [[West Nile Virus]] Lyndsay Bergus<br />
<br> [[Plasmodium Falcuparum Control Strategies]] by Lydia dePillis-Lindheim<br />
<br> [[Batrachochytrium dendrobatidis]] by Claire Forster<br />
<br> [[Ebola Transmission]] by Victoria Gawlik<br />
<br> [[Efficacy of vaccines against Streptococcus pneumoniae]] Mehar Kaur<br />
<br> [[Xylitol in Dental Decay Prevention]] by Zoe Kiklis<br />
<br> [[Coral bleaching and climate change]] by Kendall Kritzik<br />
<br> [[Bacillus anthracis as a Bioterrorism Agent]] Alison Lerner<br />
<br> [[Tea Tree Oil Treatment of MRSA]] by Karen Leung <br />
<br> [[Spiroplasma poulsonii]] by Jennifer Martin<br />
<br> [[Dengue virus envelope proteins]] by Claire Mazahery<br />
<br> [[Chlamydophila pneumoniae in Atherosclerosis]] by Tara McIntyre<br />
<br> [[Thermophiles in Astrobiology and Biotechnology]] by Paloma Medina<br />
<br> [[Chronic Salmonella Typhi Infection and Gallbladder Cancer]] by Hannah Moore<br />
<br> [[Acanthamoeba polyphaga]] by Alexa Moy<br />
<br> [[Virus Selection for Lithium Ion Battery Formation]] by Justine Oesterle<br />
<br> [[Cellulose Degradation in the Rumen]] Katie Pruett<br />
<br> [[Microbial production of recombinant chymosin]] by Enrique Rodriguez Rubio<br />
<br> [[Calicivirius Norovirus]] Oliver Smith<br />
<br> [[Pseudoalteromonas]] by Jaclyn Smrecek<br />
<br> [[SARS-CoV: nsp7 and nsp8]] by Amy Tran<br />
<br> [[Microalgal symbionts: Evolution of the coral - dinoflagellate relationship]] by Breanna Walker<br />
<br> [[Lactobacillus rhamnosus GG (ATCC 53103) and its Probiotic Use]] by Hannah Whittemore</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98951Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-15T00:15:30Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|500px|right|Figure 3. Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9) Green lines correlate to genes more abundant in A. wheleri, and red to N. corniger. This diagram demonstrates how different metagenomes, metatranscriptomes, and metabolic and enzymatic activity in general can be between two higher termites, not to mention lower termites.]]<br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. (Fig. 3) Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98950Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-15T00:14:47Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|500px|right|Figure 3. Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9) Green lines correlate to genes more abundant in A. wheleri, and red to N. corniger. This diagram demonstrates how different metagenomes, metatranscriptomes, and metabolic and enzymatic activity in general can be between two higher termites, not to mention lower termites.]]<br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. (Fig 3.) Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98947Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-15T00:06:01Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|500px|right|Figure 3. Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. (Fig 3.) Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98940Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T23:04:08Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|500px|right|Figure 3. Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98939Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T23:02:35Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|600px|right|Figure 3. Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98937Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T23:01:23Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. (Figure 2)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2. The effect of a higher pH or alkalinity on the amount of cellulase activity from Sethi et. al’s study on optimizing cellulase production from these four bacteria isolated from soil. Their results described maximum enzyme activity correlated with a pH between 9.0 and 11.0 (12). ]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98936Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T22:45:29Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
[[Image:Correlation between alkalinity and cellulase.jpeg|thumb|300px|right|Figure 2.]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=File:Correlation_between_alkalinity_and_cellulase.jpeg&diff=98935File:Correlation between alkalinity and cellulase.jpeg2014-04-14T22:44:24Z<p>Dmcdonne1274: </p>
<hr />
<div></div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98922Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T18:36:05Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Both higher and lower termites have microbes and enzymes in their hindgut, and this is therefore where the most symbiosis occurs. (Fig. 1) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98921Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T18:32:23Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf ab only.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=File:Scharf_ab_only.png&diff=98920File:Scharf ab only.png2014-04-14T18:31:27Z<p>Dmcdonne1274: </p>
<hr />
<div></div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98918Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T18:30:38Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Figure 1. Collaboration of the host and the symbionts in lignocellulose digestion demonstrated by image of R. flavipes (A) and drawing (B) provided by Scharf et al. (11) In part B, the different components of the digestive tract are labeled: esophagus (E), salivary glands (SG), foregut (FG), midgut (MG), Malpighian tubules (MT), and hindgut (HG).]]<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98908Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T18:02:08Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) Their results suggest these enzymes were important to the symbiotic relationship between the hindgut microbes and the termite host. He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98904Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T17:51:57Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98901Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-14T17:44:49Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but [http://en.wikipedia.org/wiki/Carboxymethylcellulose carboxymethyl-cellulose] can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of [http://en.wikipedia.org/wiki/Microcrystalline_cellulose crystalline cellulose] in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98620Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-09T05:38:57Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and [http://en.wikipedia.org/wiki/Glycoside_hydrolase glycoside hydrolases] to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98619Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-09T05:37:09Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing [http://en.wikipedia.org/wiki/Cellulosome 'cellulosome'] complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98618Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-09T05:28:54Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity (more basic pH level) in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98525Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:22:56Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion (11)]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
(11) Scharf, Michael E, Zachary J Karl, Amit Sethi, and Drion G Boucias. “Multiple Levels of Synergistic Collaboration in Termite Lignocellulose Digestion.” PloS One 6, no. 7 (2011): e21709. doi:10.1371/journal.pone.0021709.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98524Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:21:04Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
[[Image:Scharf symbiosis.png|thumb|300px|right|Collaboration of the host and the symbionts in lignocellulose digestion]]<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=File:Scharf_symbiosis.png&diff=98521File:Scharf symbiosis.png2014-04-08T18:18:30Z<p>Dmcdonne1274: </p>
<hr />
<div></div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98520Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:16:49Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al. (9)]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98519Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:16:18Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br> <br><br />
<br />
<br><b>Metabolism</b><br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98517Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:14:17Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br> <br><br />
<br />
Metabolism <br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
(8) Brune, Andreas. “Symbiotic Digestion of Lignocellulose in Termite Guts.” Nature Reviews. Microbiology 12, no. 3 (March 2014): 168–80. doi:10.1038/nrmicro3182.<br />
<br />
(9) He, Shaomei, Natalia Ivanova, Edward Kirton, Martin Allgaier, Claudia Bergin, Rudolf H Scheffrahn, Nikos C Kyrpides, Falk Warnecke, Susannah G Tringe, and Philip Hugenholtz. “Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-feeding Higher Termites.” PloS One 8, no. 4 (2013): e61126. doi:10.1371/journal.pone.0061126.<br />
<br />
(10) Sethi, Amit, Elena S Kovaleva, Jeffrey M Slack, Susan Brown, George W Buchman, and Michael E Scharf. “A GHF7 Cellulase from the Protist Symbiont Community of Reticulitermes Flavipes Enables More Efficient Lignocellulose Processing by Host Enzymes.” Archives of Insect Biochemistry and Physiology 84, no. 4 (December 2013): 175–93. doi:10.1002/arch.21135.<br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98515Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:13:33Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br> <br><br />
<br />
Metabolism <br />
<br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
Lignocellulose digestion requires efficient cellulases and glycoside hydrolases to degrade the the cellulose and hemicellulose of the cell wall, but additionally a mechanism to handle the lignin barrier. This is accomplished through the combined effort of the host termite and its symbionts. (8) Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. (3) Hydrolysis of cellulose begins with endoglucanases released by the host: in lower termites the endoglucanases are secreted by the salivary glands, while they are secreted in the midgut epithelium in higher termites. (8) The flagellates in lower termites produce numerous exoglucanases, exoglucanases, B-glucosidases, and numerous other glycoside hydrolases. In higher termites, there are also many cellulases, xylanases and other glycoside hydrolases. Burnum et al. used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7) He et al. studied Nasutitermes corniger as well as Amitermes wheeleri with the comparison of metaproteomic and metatranscriptomic analysis. Both N. corniger and A. wheeleri are higher termites, but they have different diets and habitats. (9) He et al. found different abundances of certain bacteria in the guts of the two termites, catering to their varied diets - cow dung for A. wheeleri and wood for N. corniger. In both, however, many glycoside hydrolases were found (similar to the observations of Burnum et al.) to assist in cellulose degradation. He et al. notes that there were no lignin degradation genes identified in either species’ hindguts. (9)<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98514Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:12:22Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Termites degrade lignocellulose with the combination of their own “mechanical and enzymatic contributions” and the catalytic contribution of their symbiotic microbes. (8) Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4)<br />
<br />
<br> <br><br />
<br />
Metabolism <br />
In lower termites, metabolic fermentation processes are credited to the flagellates, but similar to lignin degradation, less is known about the fermentation processes of higher termites. (9) The termite gut, in general, is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) For most lower and all higher termites, there is an accumulation of hydrogen in the hindgut paunches, suggesting it is a key metabolite. (8) Most of this hydrogen is used in homoacetogenesis and methanogenesis. (8) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) <br />
From what has been studied so far, formate is formed in the hindguts of many termites, which then either accumulates, oxidizes to carbon dioxide, or reduced to acetate. (8) <br />
<br />
==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98513Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:10:43Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also due to the challenge of growing them outside of the termite gut. Additionally many of the bacterial species are exclusively found in termite guts. (2) Termite digestion of lignocellulose is assisted by the microbes in their gut, and allows them to greatly contribute to the carbon cycle. (8)<br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria and a more elaborate anatomy while lacking the protozoa. (3) Bacteria and archaea are present in both types of termites, but cellulolytic flagellates are only found in lower termites. (8) The evolution of these flagellates has provided the termites with the ability to digest wood, and experiments have demonstrated that without these protists, lower termites starve. The dominant microbiota in lower termite hindguts are spirochaetes. (8)<br />
Higher termites do not have the protozoa that lower termites have in their hindguts that make cellulose digestion possible, so higher termites have evolved with different gut components and diets. (3) Some higher termites have a symbiosis with a fungus, Termitomyces, and Bacteroidetes and Firmicutes which thrive with a fungus-rich diet. Other higher termites that have cellulose-rich diets, have many spirochaetes and Fibrobacteres in their gut, as well as an anatomically evolved gut that has increased compartmentalization in the hindgut and increased alkalinity in anterior compartments. (8,9) It is possible that this high alkalinity could be the key to the mystery of how higher termites handle the degradation of lignin. <br />
<br />
==Cellulase Activity==<br />
<br />
Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4) <br />
<br />
<br> <br><br />
<br />
Acetogenesis and Methanogenesis<br />
The termite gut is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) The connection between the wood feeding termites and acetogenesis is still unknown. <br />
<br />
==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research== <br />
It is still unclear how higher termites deal with lignin but He et al. suggest it could be the host’s own components, such as higher alkalinity in a certain part of the gut, or possibly unidentified microbes in a more aerobic component of the gut. This hole in the understanding of lignin degradation has not stopped people from researching termite gut symbiosis and how this could be used to convert lignified plant cell walls into soluble sugars. Brune et al. suggest that more knowledge on lignocellulose digestion in termites could inspire a more efficient production of biofuels in the future (8). Sethi et al. looked at three specific GHF7 (glucoside hydrolase) cellulases in the termite gut using cDNA sequences, PCR, and cellobiohydrolase activity assays. They found different levels of activity (GHF7-3 being the most active) which could be important for pursuing cellulases for biofuel production. (10)<br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98512Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T18:04:19Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also because of how hard it is to grow them outside of the termite gut. Additionally many of the bacterial species are exclusively grown in termite guts. (2) <br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria population. (3) The protozoa in the hindguts of the lower termites are important for cellulose digestion, but the termites also can produce cellulase components themselves, as suggested by the existence of higher termite. Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. This suggests the importance of the microbes in the hindgut producing actetate in their process of lignocellulose breakdown. (3)<br />
<br />
==Cellulase Activity==<br />
<br />
Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4) <br />
<br />
<br> <br><br />
<br />
Acetogenesis and Methanogenesis<br />
The termite gut is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) The connection between the wood feeding termites and acetogenesis is still unknown. <br />
<br />
==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
<br />
<br />
[[Image:He et al metabolic higher termites.png|thumb|300px|right|Key metabolic differences between two higher termites from the metagenomic study done by He et al.]]<br />
<br />
<br />
==Further Research==<br />
Efforts to identify more of the bacteria in the termite guts would be helpful, and genomics seem to be a good route in that it is impossible to culture some of these bacterias outside of the unique environment of the termite gut. This will still be difficult as many of the species are specific to termite guts. There is also room for more research on degradation of lignin and cellulose, and the differences between lower and higher termites in the way that they perform these actions, as well as the differences in preferences for acetogenesis and methanogenesis. <br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=File:He_et_al_metabolic_higher_termites.png&diff=98508File:He et al metabolic higher termites.png2014-04-08T17:51:03Z<p>Dmcdonne1274: </p>
<hr />
<div></div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98491Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-04-08T17:32:37Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The [https://microbewiki.kenyon.edu/index.php/Termite_gut termite gut] contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also because of how hard it is to grow them outside of the termite gut. Additionally many of the bacterial species are exclusively grown in termite guts. (2) <br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria population. (3) The protozoa in the hindguts of the lower termites are important for cellulose digestion, but the termites also can produce cellulase components themselves, as suggested by the existence of higher termite. Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. This suggests the importance of the microbes in the hindgut producing actetate in their process of lignocellulose breakdown. (3)<br />
<br />
==Cellulase Activity==<br />
<br />
Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4) <br />
<br />
<br> <br><br />
<br />
Acetogenesis and Methanogenesis<br />
The termite gut is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) The connection between the wood feeding termites and acetogenesis is still unknown. <br />
<br />
==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
<br />
==Further Research==<br />
Efforts to identify more of the bacteria in the termite guts would be helpful, and genomics seem to be a good route in that it is impossible to culture some of these bacterias outside of the unique environment of the termite gut. This will still be difficult as many of the species are specific to termite guts. There is also room for more research on degradation of lignin and cellulose, and the differences between lower and higher termites in the way that they perform these actions, as well as the differences in preferences for acetogenesis and methanogenesis. <br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98195Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-03-31T16:41:54Z<p>Dmcdonne1274: </p>
<hr />
<div>{{Uncurated}}<br />
The termite gut contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also because of how hard it is to grow them outside of the termite gut. Additionally many of the bacterial species are exclusively grown in termite guts. (2) <br />
<br />
==Lower Termites versus Higher Termites==<br />
<br />
There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria population. (3) The protozoa in the hindguts of the lower termites are important for cellulose digestion, but the termites also can produce cellulase components themselves, as suggested by the existence of higher termite. Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. This suggests the importance of the microbes in the hindgut producing actetate in their process of lignocellulose breakdown. (3)<br />
<br />
==Cellulase Activity==<br />
<br />
Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4) <br />
<br />
<br> <br><br />
<br />
Acetogenesis and Methanogenesis<br />
The termite gut is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) The connection between the wood feeding termites and acetogenesis is still unknown. <br />
<br />
==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
<br />
==Further Research==<br />
Efforts to identify more of the bacteria in the termite guts would be helpful, and genomics seem to be a good route in that it is impossible to culture some of these bacterias outside of the unique environment of the termite gut. This will still be difficult as many of the species are specific to termite guts. There is also room for more research on degradation of lignin and cellulose, and the differences between lower and higher termites in the way that they perform these actions, as well as the differences in preferences for acetogenesis and methanogenesis. <br />
<br />
==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
<br />
(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
<br />
(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
<br />
(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
<br />
(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
<br />
(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
<br />
(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
<br />
<!--Do not remove this line--><br />
Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
<br />
<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274https://microbewiki.kenyon.edu/index.php?title=Symbiosis_of_Termites_and_the_Microbes_in_their_Gut:_Digestion_of_Lignocellulose&diff=98194Symbiosis of Termites and the Microbes in their Gut: Digestion of Lignocellulose2014-03-31T16:41:03Z<p>Dmcdonne1274: Created page with "{{Uncurated}} The termite gut contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut,..."</p>
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The termite gut contains organisms from all three domains of life, Bacteria, Eukarya, and Archaea. (1) There is a great diversity of microbes in the termite gut, many of which are unidentified because of the tiny size of termites and also because of how hard it is to grow them outside of the termite gut. Additionally many of the bacterial species are exclusively grown in termite guts. (2) <br />
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==Lower Termites versus Higher Termites==<br />
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There is a distinction between lower termites and higher termites, mentioned throughout many studies of termite guts. Lower termites have many species of bacteria along with protozoa, while higher termites usually just have the bacteria population. (3) The protozoa in the hindguts of the lower termites are important for cellulose digestion, but the termites also can produce cellulase components themselves, as suggested by the existence of higher termite. Both higher and lower termites have the enzymes needed for the first stage of the TCA cycle, but they lack an enzyme capable to convert pyruvate to acetyl CoA or acetate. This suggests the importance of the microbes in the hindgut producing actetate in their process of lignocellulose breakdown. (3)<br />
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==Cellulase Activity==<br />
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Many studies on termite gut cellulose digestion have been conducted using carboxymethyl-cellulose as the substrate to measure cellulase activity in termites, but carboxymethyl-cellulose can be hydrolyzed in ways that aren’t specific to digestion in the gut, such as activity in salivary glands. Therefore, Tokuda et. al looked at the digestion of crystalline cellulose in termites and compared the different types of cellulase activity. (4) Their investigation found that most cellulose digestion occurs in the hindgut for termites that have flagellates, and the midgut for termites without the presence of flagellates in their gut. They also describe evidence of hingdgut bacteria containing ‘cellulosome’ complexes, explaining how they digest the food substrates with their cell wall by surrounding the food substrates. (4) <br />
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Acetogenesis and Methanogenesis<br />
The termite gut is not a simple anoxic environment, as it actually has a complex structure of different microenivronments. (5) As opposed to the bovine rumen and human colon, which only have anaerobic bacteria, the termite gut has the presence of oxygen and this effects the processes that occur. (6) Part of what makes certain termite guts so interesting is the preference the bacteria have for acetogenesis over methanogenesis. (3) Termites that have fungi in their gut and feed on soil seem to perform methanogenesis more often than acetogenesis, but the higher termites that just feed on wood are the ones that prefer acetogenesis. (6) The connection between the wood feeding termites and acetogenesis is still unknown. <br />
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==Lignocellulose Digestion==<br />
It is also unclear how higher termites are able to degrade the lignin and get to the cellulose, as lower termites do this with the fungi in their gut. It is suggested that higher termites loosen the lignin in their salivary glands (2). Additionally, the mechanisms of these symbioses are still mysterious, but research is turning to techniques such as genomics and metaproteomics in order to try to understand it better. The diversity of the bacterial species still creates difficulty in analysis. Nevertheless, Treponema from the phylum Spirochaetes has been identified as the predominant bacterial group in both higher and lower termites, and an uncultured lineage from the phylum Fibrobaceres has also been identified as a dominant group in higher termites. Both these bacterial groups are generally considered to be very important to lignocellulose hydrolysis and therefore digestion in termites (2). Burnum et. al used metaproteomics to examine the hindgut of Nasutitermes corniger, a higher termite, and found almost a quarter of the 886 proteins they identified were enzymes and 36 were glycoside hydrolases. (7)<br />
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==Further Resarch==<br />
Efforts to identify more of the bacteria in the termite guts would be helpful, and genomics seem to be a good route in that it is impossible to culture some of these bacterias outside of the unique environment of the termite gut. This will still be difficult as many of the species are specific to termite guts. There is also room for more research on degradation of lignin and cellulose, and the differences between lower and higher termites in the way that they perform these actions, as well as the differences in preferences for acetogenesis and methanogenesis. <br />
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==References==<br />
(1) https://microbewiki.kenyon.edu/index.php/Termite_gut<br />
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(2) Hongoh, Yuichi. “Toward the Functional Analysis of Uncultivable, Symbiotic Microorganisms in the Termite Gut.” Cellular and Molecular Life Sciences 68, no. 8 (April 2011): 1311–1325. doi:10.1007/s00018-011-0648-z.<br />
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(3) Breznak, Ja, and A. Brune. “Role of Microorganisms in the Digestion of Lignocellulose by Termites.” Annual Review of Entomology 39 (1994): 453–487. doi:10.1146/annurev.en.39.010194.002321.<br />
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(4) Tokuda, G., N. Lo, and H. Watanabe. “Marked Variations in Patterns of Cellulase Activity Against Crystalline- Vs. Carboxymethyl-cellulose in the Digestive Systems of Diverse, Wood-feeding Termites.” Physiological Entomology 30, no. 4 (December 2005): 372–380. doi:10.1111/j.1365-3032.2005.00473.x.<br />
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(5) Ohkuma, M. “Termite Symbiotic Systems: Efficient Bio-recycling of Lignocellulose.” Applied Microbiology and Biotechnology 61, no. 1 (March 2003): 1–9. doi:10.1007/s00253-002-1189-z.<br />
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(6) Brune, A. “Termite Guts: The World’s Smallest Bioreactors.” Trends in Biotechnology 16, no. 1 (January 1998): 16–21. doi:10.1016/S0167-7799(97)01151-7.<br />
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(7) Burnum KE, Callister SJ, Nicora CD, Purvine SO, Hugenholtz P, Warnecke F, Scheffrahn RH, Smith RD, Lipton MS (2011) Proteome insights into the symbiotic relationship between a captive colony of Nasutitermes corniger and its hindgut microbiome. ISME J 5:161–164. <br />
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Edited by Diana McDonnell, a student of [http://www.jsd.claremont.edu/faculty/profile.asp?FacultyID=254 Nora Sullivan] in BIOL168L (Microbiology) in [http://www.jsd.claremont.edu/ The Keck Science Department of the Claremont Colleges] Spring 2014.<br />
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<!--Do not edit or remove this line-->[[Category:Pages edited by students of Nora Sullivan at the Claremont Colleges]]</div>Dmcdonne1274