Trichophyton rubrum: Difference between revisions

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===Species===
===Species===
[[Image:Thermotogapetrophila.jpeg|frame|right|150px|Electron micrograph of T. petrophila from Takahata et al., 2001.<sup>1</sup> Toga (t) and cell wall (cw) are labled. The scale bar measures 1 μm.]]


''Genus: Trichophyton; Species: T. rubrum''
[[Image:Trichophytonjpegg.jpg‎|frame|right|150px|Microscopic view of microconidia and macroconidia in ''T. rubrum''. Credit: CDC/Dr. Libero Ajello]]
 
Genus: ''Trichophyton''; Species: ''T. rubrum''


==Description and significance==
==Description and significance==
T. petrophila is a rod-shaped, gram negative, hyperthermophilic bacterium.  These microbes are free-living and motile, using multiple lateral flagella for propulsion.  T. petrophila bacterium possess a sheath-like outer membrane structure called a toga.<sup>1</sup>
''Trichophyton rubrum'', is the most common causitive agent of dermatophytosis worldwide, mainly occupying the humans’ feet, skin, and between fingernails [3].  ''T. rubrum'' is known to be one of the most prominent anthrophilic species of dermatophtyes [1], a fungus commonly causing skin diseases, appearing in various shades of white, yellow, brown, and red.  It may also be found in various textures, being waxy, cottony, or smooth.  Even though it is commonly observed, ''T. rubrum'' infections are incredibly hard to diagnose, and difficult to differentiate from other dermatophytes.  Because this fungal pathogen is poorly understood, the discovery of its genomic structure may significantly reduce the health costs of those who suffer various forms of dermatophytosis caused by ''T. rubrum''.  Through validated information of what is known on its genome sequence, ''T. rubrum'' is a keratinophilic filamentous fungus.
 
The temperature range in which this species grows is between 47-88˚C with an optimal growth occurring at 80˚C. The species exhibits growth in pH conditions between 5.2-9.0 with optimal growth at 8.0.  The organism also exhibits growth in NaCl concentration from 0.1-5.5% with optimal conditions being 1.0%.  Doubling time was measured at 54 minutes with glucose as a carbon and energy source.<sup>1</sup> 
 
Like other hyperthermophiles, T. petrophila has garnered interest in the last decade for its thermostable enzymes that act to degrade organic materials.  Thermostable enzymatic activity has been the subject of research as it has practical application in the production of biofuels, pharmaceuticals and feedstock chemicals. Pertaining to biofuels, as industries seek energy production methods as alternatives to fossil fuels, enzymes in hyperthermphilic bacteria and archae have shown promising results.<sup>5</sup> One such hyperthermophilic laminarinase found in T. petrophila (TpLam) effectively cleaved the β-1,3-glucosidic bonds in its degradation of substrate, producing glucose, laminaribiose and laminaritriose. The purified TpLam was found to act effectively with a pH of 6.0 at high temperatures of 78˚C and 95˚C.<sup>6</sup>  This is promising in that these enzymes do not lose their stability when exposed to high temperatures.


==Genome structure==
==Genome structure==
Thermotoga petrophila RKU-1 was sequenced on September 1, 2007 at the DOE Joint Genome Institute. The genome is composed 1823511 DNA bases making up 1865 total genes, with the majority of genes (1810) being proteins.  Fifty-five genes are associated with RNA.  The single chromosome of T. petrophila is double stranded and circular.<sup>2</sup> 
In the absence of complete m-RNA-based evidence, the complexity of  filamentous fungi gene structures make gene interpretations challenging [1].  Due to the lack of biochemical identification techniques available, pleomorphism, and cultural variability of Dermatophytes, the current knowledge of the ''T. rubrum'' genomic sequencing is limited but is in progress.
Thus far, the cloning of cDNAs have enabled the generation of expressed sequence tags (ESTs) and have been found to effectively attribute to the identification processes undertaken [4].  The ''T. rubrum'' genome has now been organized into five chromosomes.  Altogether, estimated to be 22Mb in which 5 to 10% of the genome are repetitive DNA subunits of 8 and 50% AT content [4]. To date, 43 unique nuclear-encoded genes have been analyzed, and approximately more than half are proteases [3].


Species of the Thermotoga genus represent a deep lineage back to early bacteria.  Gene sequence analysis for another species in this genus (Thermotoga maritima) shows that 24% of the genes translate back to an archaeal common ancestor.<sup>8</sup> Through structural gene analysis, studies indicate lateral gene transfer between archaea and bacteria occurring sometime during the divergence of Thermotogales.<sup>8,11</sup> Further studies suggest a link between a special archaeal specific reverse gyrase which has been found in many thermophilic bacteria.  This special enzyme is thought to protect DNA from being denatured when cells are exposed to high temperatures by introducing positive supercoiling to the DNA.<sup>11</sup> The exact mechanism by which this occurs is still the subject of debate, however, as other studies have shown that some hyperthermophiles use only negative supercoiling.<sup>12</sup>  Nonetheless, the fact that reverse gyrase is present in all known hyperthermophiles but absent in non-herperthermophiles suggest that is does play some role in the thermostability of these microbes.  
==Cell and colony structure==
Due to pleomorphism, many strains and varieties of ''T. rubrum'' have been described.  ''T. rubrum'' colonies typically produce a white to cream color pigmentation on its surface and have a reverse side that ranges from yellow-brown to wine-red [7].  Textures vary among the diverse strains of ''T. rubrum'' in which colony structures can appear flat to slightly raised [7].  Most cultures have been identified to be granular strains, grain-shaped [7].  Granular strains include abundant numbers of clavate (oblong with thick ends) to pyriform (pear-shaped) microconidia, small spores produced via asexual reproduction.  On the contrary, the production of macroconidia (large spores produced via asexual reproduction) are scanty to moderate, have thin walled septa, and are bacillus-shaped [7].


More comprehensive and specific genomic information can be found at http://img.jgi.doe.gov/cgi-bin/w/main.cgi?section=TaxonDetail&page=taxonDetail&taxon_oid=640427150<sup>3</sup> 
==Metabolism==
''T. rubrum's'' metabolism is highly influenced and responsive to environmental pH conditions that is sensed.  Based on recent studies and annotations, more than half of the ''T. rubrum'' genome sequence is composed of proteases, mostly keritinases[3]. The production of these proteases depend on the pH content of keratins secreted [6] and is optimal in acidic conditions [4], thus determining ''T. rubrum's'' virulence factors (i.e. ability to ingest keratin for growth and strength) [3].


The entire genome sequence can be found at ftp://ftp.jgi-psf.org/pub/JGI_data/Microbial/thermotoga_petrophila_RKU-1/Finished2007/4002277.finished.fsa<sup>4</sup> 
==Ecology==
''T. rubrum'' is an anthrophilic dermatophyte, known to inhabit moist areas of the human skin, where skin folds, or even nails, where keratin is abundant for its growth and survival [1].  ''T. rubrum'' may also contaminate items such as clothing or bedding.  Though much about ''T. rubrum'' is still unknown, through the identification processes of its genome sequence that have been undertaken it appears that some of its gene expression had been linked to the presence of cytotoxic drugs [5]. For the time being, ''T. rubrum'' may not be making any direct contributions to the environment, but the studies of it may lead to many technological advances and methodologies to diagnose other forms of dermatophytosis [1].


The sequenced chromosome can be found at http://img.jgi.doe.gov/cgi-bin/w/main.cgi?section=TaxonCircMaps&page=circMaps&taxon_oid=640427150&pidt=2637.1332089303<sup>2</sup>
==Pathology==


==Cell and colony structure==
[[Image:FeetFungal.JPG|frame|right|150px| Severe case of athlete's foot. Credit: James Heilman, MD]]
T. petrophila cells are rod-shaped and cell dimensions measure 2–7 μm long by 0.7–1 μm wide.  This thermophilic species is motile, utilizing several lateral flagella for movement.  The cell wall is typical of other gram negative bacteria with a thin layer of peptidoglycan with minimal cross-linking. Unlike other gram negative bacteria, species in the Thermotoga genus possess a peptidoglycan layer that does contain D-lysine and L-lysine.<sup>7</sup>


Unique to thermophiles in the Thermotoga genus, T. petrophila bacterium have a sheath-like outer membrane structure called a toga.<sup>1</sup> The toga can form balloon-like protrusions on the ends of the rod shaped cells and this action creates a periplasmic space. The volume of this space can actually exceed the volume of the cytoplasm.<sup>7</sup> The toga can be seen in the figure provided above.<sup>1</sup>
''T. rubrum'' is the most common infectious, anthrophilic species of dermatophytes [1].  Very little is known about the mechanism of its invasion and pathogenicity [5]. Though it is usually not life-threatening, infections are long-lasting, recurring, and incredibly difficult to cure.  The fungal pathogen’s ability to produce and secrete proteolytic enzymes is a major virulence factor [6]. ''T. rubrum'' attacks the human skin and nails via keratin degradation [1]. Keratin, a fibrous protein, is a major structural component of the human skin and nails; thus ''T. rubrum'' invades through the stratum corneum, the outermost layer of the epidermis, to obtain keratin.  This invasion causes dermatophytosis infections such as athlete’s foot, fungal infections between fingernails,  jock itch, and may be painful.  The infections may be transmitted from person to person.  Anti-fungal medications are available to prevent infections, however infections typically reoccur.


==Metabolism==
==References==
T. petrophila are heterotrophic obligate anaerobes and can grow in the presence of a variety of substrates.  Growth has been detected when exposing the bacterium to medium including glucose, galactose, fructose, ribose, sucrose, arabinose, lactose, starch, maltose, peptone, yeast extract and also cellulose.  This species can use these organic molecules as the sole source of energy as well as carbon through fermentation metabolism. One study reported lactate, acetate, H<sub>2</sub> and CO<sub>2</sub> as byproducts resulting from glucose fermentation.<sup>1</sup>  The cells can reduce elemental sulfur or thiosulfate to H<sub>2</sub>S, however, it was found that their cellular yields actually decreased when exposed to these electron acceptors.<sup>1</sup>
1. White, T., Henn, M., et al., Genomic Determinants of Infection in Dermatophyte Fungi. The Fungal Genome Initiative, Mar. 2012
http://www.genome.gov/Pages/Research/Sequencing/SeqProposals/Dermatophyte_WP_seq.pdf


Mentioned above was the biofuel industry’s interest in hyperthermophilic enzymes involved in the catalytic breakdown of organic substrates.  The major step in biofuel production is the degradation of an organic substrate such as cellulose into simpler sugars. It can take considerable energy to fuel reactions in order to break down cellulose and it is often done at high temperatures with varying pH levels. Using enzymes from thermophilic bacteria and archae which can tolerate these extreme conditions make them especially valuable.  These thermostable enzymes can improve the efficiency of large scale reactions for biofuel production.<sup>9</sup>  Studies have indicated that specific purified enzymes from T. petrophila, along with enzymes from other bacterium in the Thermotoga genus, have effectively been able to function in the presence of harsh conditions, although the mechanism by which they are able to do so is still not well understood.<sup>9</sup>
2.  De Biervre, C. and Dujon, B. Organisation of the mitochondrial genome of ''Trichophyton rubrum''. Current Genetics, Volume 26, Issue 6: 553-559.


More specific information regarding metabolic pathways can be found at the Joint Genome Institute’s website: http://img.jgi.doe.gov/cgi-bin/w/main.cgi?section=TaxonDetail&page=taxonDetail&taxon_oid=640427150  <sup>3</sup>
3. Yang, J., Chen, L., Wang, L., et al., TrED: the ''Trichophyton rubrum'' Expression Database. BMC Genomics, Volume 8: 250.


==Ecology==
4. Silveira, H.C.S., Gras D.E., Cazzaniga, R.A., et al. “Transcriptional profiling reveals genes in the human pathogen...”. Microbial Pathogenesis, Volume 48, Issue 2, 2010: 91-96.
Given their need for high temperatures and anaerobic environments, T. petrophila have been found to inhabit production waters on oil reservoirs. These oil stratifications reach high temperatures and are largely devoid of oxygen, making them ideal for this species of bacterium.<sup>1</sup>  Although T. petrophila has not been found to grow in geothermal areas such as volcanic hot springs, other species of the Thermotoga genus have been discovered in these regions, leading to the possibility that such regions could sustain life.<sup>10</sup>


==Pathology==
5. Maranhao, F.C.A., Paniao, F.G., Martinez-Rossi, N.M.. “Isolation of transcripts over-expressed in human pathogen...”. Microbial Pathogenesis, Volume 43, Issue 4, 2007: 166- 172.
T. petrophila is non-pathogenic as the species has only been found free living in oil reservoirs.<sup>1,3</sup>  One study showed they exhibit some sensitivity when exposed to the antibiotics rifampicin, streptomycin, vancomycin or chloramphenicol. In fact, growth of T. petrophila was completely suppressed when exposed to these compounds.<sup>1</sup>
 
==References==


1. White, T., Henn, M., et al., Genomic Determinants of Infection in Dermatophyte Fungi. The Fungal Genome Initiative, Mar. 2012
6. Chen, J., Yi, Jinling, Liu, Li, et al. “Substrate adaptation of ''Trichophyton rubrum''...”. Microbial Pathogenesis, Volume 48, Issue 2, 2010: 57-61.


2. De Biervre, C. and Dujon, B., Organisation of the mitochondrial genome of Trichophyton rubrum. Current Genetics, Volume 26, Issue 6: 553-559.
7. Ellis, D., ''Trichophyton rubrum'' granular strain. Mycology Online, Apr. 2012
http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/rubrum.html




Edited by Melinda Dao of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio
Edited by Melinda Dao of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio

Latest revision as of 03:51, 7 May 2012

This student page has not been curated.

A Microbial Biorealm page on the genus Trichophyton rubrum

Classification

Higher order taxa

Domain: Eukaryota; Kingdom: Fungi; Phylum: Ascomycota; Class: Eurotiomycetes; Order: Onygenales; Family: Arthrodermactaceae

Species

Microscopic view of microconidia and macroconidia in T. rubrum. Credit: CDC/Dr. Libero Ajello

Genus: Trichophyton; Species: T. rubrum

Description and significance

Trichophyton rubrum, is the most common causitive agent of dermatophytosis worldwide, mainly occupying the humans’ feet, skin, and between fingernails [3]. T. rubrum is known to be one of the most prominent anthrophilic species of dermatophtyes [1], a fungus commonly causing skin diseases, appearing in various shades of white, yellow, brown, and red. It may also be found in various textures, being waxy, cottony, or smooth. Even though it is commonly observed, T. rubrum infections are incredibly hard to diagnose, and difficult to differentiate from other dermatophytes. Because this fungal pathogen is poorly understood, the discovery of its genomic structure may significantly reduce the health costs of those who suffer various forms of dermatophytosis caused by T. rubrum. Through validated information of what is known on its genome sequence, T. rubrum is a keratinophilic filamentous fungus.

Genome structure

In the absence of complete m-RNA-based evidence, the complexity of filamentous fungi gene structures make gene interpretations challenging [1]. Due to the lack of biochemical identification techniques available, pleomorphism, and cultural variability of Dermatophytes, the current knowledge of the T. rubrum genomic sequencing is limited but is in progress. Thus far, the cloning of cDNAs have enabled the generation of expressed sequence tags (ESTs) and have been found to effectively attribute to the identification processes undertaken [4]. The T. rubrum genome has now been organized into five chromosomes. Altogether, estimated to be 22Mb in which 5 to 10% of the genome are repetitive DNA subunits of 8 and 50% AT content [4]. To date, 43 unique nuclear-encoded genes have been analyzed, and approximately more than half are proteases [3].

Cell and colony structure

Due to pleomorphism, many strains and varieties of T. rubrum have been described. T. rubrum colonies typically produce a white to cream color pigmentation on its surface and have a reverse side that ranges from yellow-brown to wine-red [7]. Textures vary among the diverse strains of T. rubrum in which colony structures can appear flat to slightly raised [7]. Most cultures have been identified to be granular strains, grain-shaped [7]. Granular strains include abundant numbers of clavate (oblong with thick ends) to pyriform (pear-shaped) microconidia, small spores produced via asexual reproduction. On the contrary, the production of macroconidia (large spores produced via asexual reproduction) are scanty to moderate, have thin walled septa, and are bacillus-shaped [7].

Metabolism

T. rubrum's metabolism is highly influenced and responsive to environmental pH conditions that is sensed. Based on recent studies and annotations, more than half of the T. rubrum genome sequence is composed of proteases, mostly keritinases[3]. The production of these proteases depend on the pH content of keratins secreted [6] and is optimal in acidic conditions [4], thus determining T. rubrum's virulence factors (i.e. ability to ingest keratin for growth and strength) [3].

Ecology

T. rubrum is an anthrophilic dermatophyte, known to inhabit moist areas of the human skin, where skin folds, or even nails, where keratin is abundant for its growth and survival [1]. T. rubrum may also contaminate items such as clothing or bedding. Though much about T. rubrum is still unknown, through the identification processes of its genome sequence that have been undertaken it appears that some of its gene expression had been linked to the presence of cytotoxic drugs [5]. For the time being, T. rubrum may not be making any direct contributions to the environment, but the studies of it may lead to many technological advances and methodologies to diagnose other forms of dermatophytosis [1].

Pathology

Severe case of athlete's foot. Credit: James Heilman, MD

T. rubrum is the most common infectious, anthrophilic species of dermatophytes [1]. Very little is known about the mechanism of its invasion and pathogenicity [5]. Though it is usually not life-threatening, infections are long-lasting, recurring, and incredibly difficult to cure. The fungal pathogen’s ability to produce and secrete proteolytic enzymes is a major virulence factor [6]. T. rubrum attacks the human skin and nails via keratin degradation [1]. Keratin, a fibrous protein, is a major structural component of the human skin and nails; thus T. rubrum invades through the stratum corneum, the outermost layer of the epidermis, to obtain keratin. This invasion causes dermatophytosis infections such as athlete’s foot, fungal infections between fingernails, jock itch, and may be painful. The infections may be transmitted from person to person. Anti-fungal medications are available to prevent infections, however infections typically reoccur.

References

1. White, T., Henn, M., et al., Genomic Determinants of Infection in Dermatophyte Fungi. The Fungal Genome Initiative, Mar. 2012 http://www.genome.gov/Pages/Research/Sequencing/SeqProposals/Dermatophyte_WP_seq.pdf

2. De Biervre, C. and Dujon, B. Organisation of the mitochondrial genome of Trichophyton rubrum. Current Genetics, Volume 26, Issue 6: 553-559.

3. Yang, J., Chen, L., Wang, L., et al., TrED: the Trichophyton rubrum Expression Database. BMC Genomics, Volume 8: 250.

4. Silveira, H.C.S., Gras D.E., Cazzaniga, R.A., et al. “Transcriptional profiling reveals genes in the human pathogen...”. Microbial Pathogenesis, Volume 48, Issue 2, 2010: 91-96.

5. Maranhao, F.C.A., Paniao, F.G., Martinez-Rossi, N.M.. “Isolation of transcripts over-expressed in human pathogen...”. Microbial Pathogenesis, Volume 43, Issue 4, 2007: 166- 172.

6. Chen, J., Yi, Jinling, Liu, Li, et al. “Substrate adaptation of Trichophyton rubrum...”. Microbial Pathogenesis, Volume 48, Issue 2, 2010: 57-61.

7. Ellis, D., Trichophyton rubrum granular strain. Mycology Online, Apr. 2012 http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/rubrum.html


Edited by Melinda Dao of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio

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