Thermotoga

Thermotoga is a genus of the phylum Thermotogae. Members of Thermotoga are hyperthermophilic bacteria whose cell is wrapped in a unique sheath-like outer membrane, called a "toga".

Thermotoga
Outline of a Thermotoga maritima section showing the "toga"
Scientific classification
Domain:	Bacteria
Phylum:	Thermotogae
Order:	Thermotogales
Family:	Thermotogaceae
Genus:	Thermotoga
Species
Thermotoga caldifontis[1] Thermotoga elfii Thermotoga hypogea Thermotoga lettingae Thermotoga maritima Thermotoga naphthophila Thermotoga neapolitana Thermotoga petrophila Thermotoga profunda[1] Thermotoga subterranea Thermotoga thermarum

The members of the phylum stain Gram-negative as they possess a thin peptidoglycan in between two lipid bilayers, albeit both peculiar.[2] The peptidoglycan is unusual as the crosslink is not only meso-diaminopimelate as occurs in Proteobacteria, but D-lysine.[NB 1][3]

The species are anaerobes with varying degrees of oxygen tolerance. They are capable of reducing elemental sulphur (S₀) to hydrogen sulphide, which in turn can be used.[2]

Whether thermophily is an innovation of the lineage or an ancestral trait is unclear and cannot be determined.
The genome of Thermotoga maritima was sequenced in 1999, revealing several genes of archaeal origin, possibly allowing its thermophilic adaptation.[4] The CG (cytosine-guanine) content of T. maritima is 46.2%;[2] most thermophiles in fact have high CG content; this has led to the speculation that CG content may be a non-essential consequence to thermophily and not the driver towards thermophily.[5][6]

Members and relatives

The type species of the genus is T. maritima, first described in 1986.[2] At the time, it was the first species of the phylum to be described. The genus Thermotoga now contains nine official species,[7] while the phylum contains a single family (Thermotogaceae) with ten official genera (Fervidobacterium, Geotoga, Kosmotoga, Marinitoga,Mesotoga, Petrotoga, Thermococcoides, Thermosipho, Thermotoga and Oceanotoga).

T. subterranea strain SL1 was found in a 70 °C deep continental oil reservoir in the East Paris Basin, France.[8]

The precise relation of the Thermotogae to other phyla is debated (v. bacterial phyla): several studies have found it to be deep-branching (in Bergey's manual it appeared in fact in "Volume I: The Archaea and the deeply branching and phototrophic Bacteria"),[9] while other have found Firmicutes to be deep-branching with Thermotogae clustering away from the base.

Name

The paper and the chapter in Bergey's manual were authored by several authors including the microbiologists Karl Stetter and Carl Woese.[2]

The new Latin feminine name "thermotoga" means "the hot outer garment", being a combination of the Greek noun θέρμη (therme, heat)[10] or more correctly the adjective θερμός, ή, όν (thermos, e, on, hot)[11] and the Latin feminine noun toga (the Roman outer garment).[2]

Footnotes

1. All proteinogenic amino acids have the L- configuration; in peptidoglycan some amino acids with the D- configuration are present.
   Lysine is synthesised from meso-diaminopimelate by Diaminopimelate decarboxylase.

References

1. LPSN lpsn.dsmz.de
2. Huber, R.; T. A. Langworthy; H. Konig; M. Thomm; C. R. Woese; U. B. Sleytr; K. O. Stetter (1986). "Thermotoga maritima sp. nov. represents a new genus of unique extremely thermophilic eubacteria growing up to 90°C" (PDF). Arch. Microbiol. 144 (4): 324–333. doi:10.1007/BF00409880.
3. Boniface, A.; Parquet, C.; Arthur, M.; Mengin-Lecreulx, D.; Blanot, D. (2009). "The Elucidation of the Structure of Thermotoga maritima Peptidoglycan Reveals Two Novel Types of Cross-link". Journal of Biological Chemistry. 284 (33): 21856–21862. doi:10.1074/jbc.M109.034363. PMC 2755910. PMID 19542229.
4. Fraser, C. M.; Clayton, K. E.; Gill, R. A.; Gwinn, S. R.; Dodson, M. L.; Haft, R. J.; Hickey, D. H.; Peterson, E. K.; Nelson, J. D.; Ketchum, W. C.; McDonald, K. A.; Utterback, L.; Malek, T. R.; Linher, J. A.; Garrett, K. D.; Stewart, M. M.; Cotton, A. M.; Pratt, M. D.; Phillips, M. S.; Richardson, C. A.; Heidelberg, D.; Sutton, J.; Fleischmann, G. G.; Eisen, R. D.; White, J. A.; Salzberg, O.; Smith, S. L.; Venter, H. O.; Fraser, J. C. (1999). "Evidence for lateral gene transfer between Archaea and bacteria from genome sequence of Thermotoga maritima". Nature. 399 (6734): 323–329. Bibcode:1999Natur.399..323N. doi:10.1038/20601. PMID 10360571.
5. Pasamontes, A.; Garcia-Vallve, S. (2006). "Use of a multi-way method to analyze the amino acid composition of a conserved group of orthologous proteins in prokaryotes". BMC Bioinformatics. 7: 257. doi:10.1186/1471-2105-7-257. PMC 1489954. PMID 16709240.
6. Puigbò, P.; Pasamontes, A.; Garcia-Vallve, S. (2008). "Gaining and losing the thermophilic adaptation in prokaryotes". Trends in Genetics. 24 (1): 10–14. doi:10.1016/j.tig.2007.10.005. PMID 18054113.
7. thermotoga entry in LPSN [Euzéby, J.P. (1997). "List of Bacterial Names with Standing in Nomenclature: a folder available on the Internet". International Journal of Systematic and Evolutionary Microbiology. 47 (2): 590–2. doi:10.1099/00207713-47-2-590. PMID 9103655.]
8. Li H, Yang SZ, Mu BZ, Rong ZF, Zhang J (2007). "Molecular phylogenetic diversity of the microbial community associated with a high-temperature petroleum reservoir at an offshore oilfield". FEMS Microbiol Ecol. 60 (1): 74–84. doi:10.1111/j.1574-6941.2006.00266.x. PMID 17286581.
9. Boone, David R.; Castenholz, Richard W. (May 18, 2001) [1984(Williams & Wilkins)]. George M. Garrity (ed.). The Archaea and the Deeply Branching and Phototrophic Bacteria. Bergey's Manual of Systematic Bacteriology. 1 (2nd ed.). New York: Springer. pp. 721. ISBN 978-0-387-98771-2. British Library no. GBA561951.
10. θέρμη. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
11. θερμός. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project