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Classification

cellular organisms; Bacteria; Thermodesulfobacteria; Thermodesulfobacteria; Thermodesulfobacteriales; Thermodesulfobacteriaceae; Thermodesulfatator; Thermodesulfatator atlanticus [2]

Description and Significance

Thermodesulfatator atlanticus, a novel species, is a thermophile that was found in the walls of an active deep-sea hydrothermal vent on the Mid-Atlantic Ridge at Rainbow vent. Thermophiles are species that can grow at high temperatures. T. atlanticus was categorized as a Thermodesulfatator because it shares 97.8 % similarity with the species that is representative of that genus, Thermodesulfatator indicus. Both species are anaerobic, chemolithoautotrophs, thermophiles, and sulfate reducers found in deep-sea hydrothermal vents. The two species do differ in a few key ways, however. T. indicus is strictly a chemolithoautotroph, where as T. atlanticus has the ability to use both inorganic and organic Carbon sources for energy. T. atlanticus is also able to survive in a wider range of pH conditions. [1]

T. atlanticus was placed in the Thermodesulfobacteriacae family because of its 16S rRNA gene sequences. [1]

Structure, Metabolism, and Life Cycle

T. atlanticus is a gram-negative rod-shaped bacteria. The cells tend to be about 1.04–6.08 μm in length and 0.30–0.75 μm wide, and are found mostly in singular form. It possesses a single polar flagellum, which gives the cell high motility. The cell divides by constriction. The genome of T. atlanticus has a high GC content of 45.6 mol%, which adds stability to the cell since GC pairs are more stable than AT pairs. This is because GC bonds are held together by three hydrogen bonds rather than the two hydrogen bonds that make up the AT pairs. [1]

T. atlanticus is an obligate anaerobe, meaning it cannot survive in the presence of oxygen. It generally uses CO₂ as a Carbon source, but monomethylamine, peptone, and yeast extract can also be used for this purpose. This is different from T. indicus, which cannot use any organic Carbon sources. In metabolism, T. atlanticus uses Hydrogen (H₂) as the electron donor and sulfate (SO₄^2-) as the terminal electron acceptor. Although it is able to reduce sulfate to H₂S, it cannot use sulfite (SO₃^2-) as a terminal electron acceptor. It is also unable to utilize any electron donors other than Hydrogen. [1]

Some antibiotics that T. atlanticus is sensitive to include penicillin, ampicillin, vancomycin, tetracycline, rifampicin, and chloramphenicol. It is resistant to both streptomycin and kanamycin. [1]

Ecology and Pathogenesis

T. atlanticus is able to survive a range of temperatures from 55°C-75°C, although no spore formation has been detected. It can live in pH's between 5.5 and 8.0, and in an environment containing 1.5%-4.5% NaCl. Optimal growth is observed in temperatures between 65°C and 70°C, at a pH somewhere between 6.5-7.5, and in the presence of 2.5% NaCl. Its natural habitat includes warm places with a fairly neutral pH, such as the walls of thermal vents in the Atlantic Ocean. [1]

References

[1] Alain, K., A. Postec, E. Grinsard, F. Lesongeur, D. Prieur, and A. Godfroy. "Thermodesulfatator Atlanticus Sp. Nov., a Thermophilic, Chemolithoautotrophic, Sulfate-reducing Bacterium Isolated from a Mid-Atlantic Ridge Hydrothermal Vent." International Journal Of Systematic And Evolutionary Microbiology 60.1 (2010): 33-38. Web. http://ijs.sgmjournals.org/content/60/1/33.long

[2] "Taxonomy Browser." NCBI. U.S. National Library of Medicine, n.d. Web. 19 July 2013. http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info.

Author

Page authored by Taylor Blomme, student of Mandy Brosnahan, Instructor at the University of Minnesota-Twin Cities, MICB 3301/3303: Biology of Microorganisms.