Dehalococcoides ethenogenes: Difference between revisions
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==Description and significance== | ==Description and significance== | ||
''Dehalococcoides ethenogenes'' has many cellular features. This bacteria is Gram-positive, which generally means it has a very thick cell wall and a single membrane layer. From a three-dimensional prospective, it appears to have an irregular, spherical shape. The species moves spontaneously and independently. It is most suitable in moderate temperature environment around 25 and 40°C with an optimal temperature of 35°C. In the bacteria, there does not exist the following electron acceptors: oxygen, nitrate or sulfate (formally known as anaerobic). It can live in multiple habitats because it has a living temperature similar to soil, the human body, animals, etc. Thankfully, it is not pathogenic, which means it doesn't spread diseases or illnesses its host. | ''Dehalococcoides ethenogenes'' has many cellular features. This bacteria is Gram-positive, which generally means it has a very thick cell wall and a single membrane layer. From a three-dimensional prospective, it appears to have an irregular, spherical shape. The species moves spontaneously and independently. It is most suitable in moderate temperature environment around 25 and 40°C with an optimal temperature of 35°C. In the bacteria, there does not exist the following electron acceptors: oxygen, nitrate or sulfate (formally known as anaerobic). It can live in multiple habitats because it has a living temperature similar to soil, the human body, animals, etc. Thankfully, it is not pathogenic, which means it doesn't spread diseases or illnesses its host. | ||
Revision as of 16:59, 5 June 2007
A Microbial Biorealm page on the genus Dehalococcoides ethenogenes
Classification
Higher order taxa
Domain: Bacteria; Phylum: Chloroflexi; Class: Dehalococcoidetes; Order: Dehalococcoides
Species
Dehalococcoides ethenogenes
Description and significance
Dehalococcoides ethenogenes has many cellular features. This bacteria is Gram-positive, which generally means it has a very thick cell wall and a single membrane layer. From a three-dimensional prospective, it appears to have an irregular, spherical shape. The species moves spontaneously and independently. It is most suitable in moderate temperature environment around 25 and 40°C with an optimal temperature of 35°C. In the bacteria, there does not exist the following electron acceptors: oxygen, nitrate or sulfate (formally known as anaerobic). It can live in multiple habitats because it has a living temperature similar to soil, the human body, animals, etc. Thankfully, it is not pathogenic, which means it doesn't spread diseases or illnesses its host.
This specific strand of genome was sequenced, and it was discovered to help decontaminate toxic chemicals in many industries. Specifically, this species reduces chlorinated hydrocarbons in contaminated environments. Chlorinated hydrocarbons are significantly toxic to humans. Also, it can cause irreparable damage in groundwater areas when the chemical is not handled properly.
This organism can be isolated from environments polluted with chemicals such as PCE and trichloroethane (TCE).
Genome structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?
Dehalococcoides ethenogenes has many features in its genome. The total nucleotide base pairs in this genome is around 1,469,720 or 1.5 Mb. It has one chromosome referring to strain 195. The species has a circular shape, although not perfectly circular (irregular coccus). It is the only known bacterium which completely dechlorinates tetrachloroethene (PCE) and trichloroethene, to ethylene. This is important because PCE and trichlorothene are common chemical groundwater pollutants featured in many commercial industry cleaners.
Apparently, Dehalococcoides ethenogenes has plasmids called pUA969, pUA970, pUA971. These plasmids work to bind D. ethenogenes LexA gene to Bacillus subtilis. This is significant because it makes the first Gram-negative bacterium sharing LexA binding site like that of B. subtilis.
Cell structure and metabolism
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
PCE, carriers of D. ethenogenes, can be metabolize for energy by at least 15 different organisms such as acetogens and methanogens. Acetogens can use PCE to produce energy and carbon. The most common energy and carbon produced are carbon dioxide and hydrogen, respectively. Methanogens also produce energy and carbon of the same kind. Where they differ is some carbon dioxide will react with hydrogen to produce methane, which creates a gradient that generates ATP. Basically, these organisms benefit from PCE, which halococcoides ethenogenes stems. Some organisms in this category produce energy from tetrachloroethene. These organisms are able to react with hydrogen (carbon source) as the electron donor, indicating that hydrogen and PCE serve as electron donors or acceptors for energy growth. The exchange of electrons are responsible for the generation of energy through PCE.
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Dehalococcoides ethenogenes most common use is for cleaning toxic messes by PCE. PCE is a suspected human carcinogen. Basically without this bacterium, PCE cancer spread to the human bodies and animals. The symptoms of short-term exposure to PCE cause dizziness, headaches, and problems with balance, while long-term exposure of PCE has been linked to cancers of the esophagus, bladder, and blood. Therefore, D. ethenogenes is used to manipulate PCE and to minimize its symptoms. Not only does D. ethenogenes stop the spread of cancer to humans, but protect the groundwater that are PCE exposed.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
This organism can be known as pathogen-free. It does not produce disease or illness to its host.
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Dehalococcoides ethenogenes is only known bacteria that can breakdown PCE, a dangerous and toxic carcinogen in chemical working environments. This organism converts PCE and hydrogen to chlorine and ethene, which render the toxin completely harmless.
Current Research
Enter summaries of the most recent research here--at least three required
1) The solvents tetrachloroethene (PCE) and trichloroethene(TCE) are among the most pollutants at contaminated groundwater sites. Under aerobic conditions, PCE is considered can't be reduced, while TCE can be broken down to mainly nontoxic products by certain nonspecific oxygenases. Under anaerobic conditions, PCE and TCE have been reductively dechlorinated to less-chlorinated ethenes.
2) The anaerobic bacterium Dehalococcoides ethenogenes is the only known organism that can completely dechlorinate tetrachloroethene or trichloroethene (TCE) to ethene. One of two enzymes responsible for this pathway, TCE reductive dehalogenase (TCE-RDase) catalyzes the dechlorination of TCE to ethene. This info about the substrates of TCE-RDase may be used to predict the reactivity and the products of other environmental or industrial significance. Some of the compounds that were examined are pollutants.
3) Today, in the United States, the bacteria have been used to clean up chlorinated solvents in ten states at 17 sites including Kelly Air Force Base in Texas and Caldwell Trucking Superfund Site in New Jersey. For SiREM, business has been good; 13 of the sites were done in the past 18 months.
References
[Real reference] Seshadri R et al., "Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes.", Science, 2005 Jan 7;307(5706):105-8
Edited by Tim Hou of Rachel Larsen and Kit Pogliano
