Thermal

The Thermogood family is the only representative of the Thermotogales order, also the only one in the Thermotogae type and class. As of July 2015, the family includes 10 genera ^[10] :

• Defluviitoga Ben Hania et al. 2012
• Fervidobacterium Patel et al. 1985
• Geotoga Davey et al. 1993
• Kosmotoga DiPippo et al. 2009 emend. Nunoura et al. 2010 [ syn. Thermococcoides Feng et al. 2010 ]
• Marinitoga Wery et al. 2001
• Mesotoga Nesbø et al. 2013
• Oceanotoga Jayasinghearachchi and Lal 2011
• Petrotoga Davey et al. 1993
• Thermosipho Huber et al. 1989 emend. Ravot et al. 1996
• Thermotoga Stetter and Huber 1986 typus

Another genus is part of the family according to the NCBI : Thermopallium Duckworth et al. 1996 ^[11] .

It was found that in a phylogenetic tree constructed on the basis of 16S rRNA sequences , Thermotogae branch with Aquificae (another type consisting of hyperthermophilic organisms) near the branching point of bacteria and archaea ^{[5] [6]} . However, the deep kinship between Thermotogae and Aquificae , as well as the early branch of the latter, are not confirmed by phylogenetic studies based on a comparison of the sequences of other genes and proteins ^{[12] [13] [14] [15]} , as well as conservative taxa-specific indels (inserts and deletions) in several highly conserved ubiquitous proteins ^[16] . Thermotoga e has also attracted the attention of scientists due to reports of the likely very significant horizontal gene transfer between these bacteria and archaea ^{[17] [18]} . However, recent studies based on more reliable methods show that cases of horizontal gene transfer between Thermotogae and other groups, including Archaea , are not as widespread as was suggested in earlier studies ^{[19] [20] [21] [22]} .

Until recently, no biochemical or molecular genetic markers were known that distinguished species of the Thermotogae type from all other bacteria ^[5] . However, recent comparative genomic analysis revealed a large number of conserved taxon-specific indels (inserts and deletions) (“preserved signature indel”, CSIs) in important proteins that are specific for either the entire Thermotogae type or some of its subgroups ^[21] .

Eighteen of these conserved indices in proteins important for life, such as Pol1, RecA, TrpRS and ribosomal proteins L4, L7 / L12, S8, S9, etc., are unique and are present in all Thermotogaceae species whose genome was sequenced . In addition, these studies also revealed 14 conservative indones specific to the clade , including the genera Fervidobacterium and Thermosipho , 12 conservative indones specific to the genus Thermotoga (except Thermotoga lettingae ), and 8 conservative indels that can serve as molecular markers for species of the genus Thermosipho ^[21] .

Also, the existence of a separate clade, consisting of the species Petrotoga mobilis , Kosmotoga olearia, and Thermotogales bacterium mesG1, early branching from the main trunk of the phylogenetic tree, is justified by the presence of 7 conserved indones common to these species ^[21] . In addition, the authors report that some CSIs confirm data on horizontal gene transfer between Thermotogae and other groups of prokaryotes ^[21] .

The taxonomy adopted today is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) ^{[10] [23]} and phylogeny corresponds to the release of The All-Species Living Tree Project 111 based on 16S rRNA sequences ^[24] .

Notes:
♠ The strain is found in the National Center for Biotechnology Information NCBI, but is not listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN)
♥ The strain is absent in the National Center for Biotechnology Information NCBI, but is indicated in the List of Prokaryotic names with Standing in Nomenclature (LPSN)

Because of their ability to feel good at high temperatures, some Thermotogaceae species are considered attractive candidates for use in industrial processes ^[25] . The ability of Thermotogaceae in the process of metabolism to use various complex hydrocarbons , while emitting hydrogen gas, leads to the fact that these species are mentioned as a possible biotechnological energy source, alternative to fossil fuels ^[26] .

• Eubacteria taxonomy