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''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". The members of the phylum stain Gram-negative as they possess a thin peptidoglycan in between two lipid bilayers, albeit both peculiar.〔 The peptidoglycan is unusual as the crosslink is not only meso-diaminopimelate as occurs in Proteobacteria, but D-lysine.〔All proteinogenic amino acids are in the levo conformation, in peptidoglycan some dextro forms are present. Lysine is synthesised from meso-diaminopimelate by Diaminopimelate decarboxylase.〕 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.〔 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. The CG (cytosine-guanine) content of ''T. maritima'' is 46.2%;〔 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. ==Members and relatives== The type species of the genus is ''T. maritima'', first described in 1986.〔 At the time, it was the first species of the phylum to be described. The genus ''Thermotoga'' now contains nine official species, 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. 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"), while other have found ''Firmicutes'' to be deep-branching with ''Thermotogae'' clustering away from the base. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thermotoga」の詳細全文を読む スポンサード リンク
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