the same CSI within these two unrelated groups of bacteria is not due to lateral gene transfer, rather the CSI likely developed independently in these two groups of thermophiles due to selective pressure. The insert is located on the surface of the protein in the ATPase domain, near the binding site of ADP/ATP. Molecular dynamic stimulations revealed a network of hydrogen bonds formed between water molecules, residues within the CSI and a ADP/ATP molecule. It is thought that this network helps to maintain ADP/ATP binding to the SecA protein at high temperatures, contributing to the overall thermostable phenotype some Thermotogales species. Phylogeny Taxonomy This phylum presently consists of a single class (Thermotogae), four orders (Thermotogales, Kosmotogales, Petrotogales, and Mesoaciditogales) and five families (Thermatogaceae, Fervidobacteriaceae, Kosmotogaceae, Petrotogaceae, and Mesoaciditogaceae). It contains a total of 15 genera and 52 species. In the 16S rRNA trees, the Thermotogota have been observed to branch with the Aquificota (another phylum comprising hyperthermophilic organisms) in close proximity to the archaeal-bacterial branch point. However, a close relationship of the Thermotogota to the Aquificota, and the deep branching of the latter group of species, is not supported by phylogenetic studies based upon other gene/protein sequences. and also by conserved signature indels in several highly conserved universal proteins. The Thermotogota have also been scrutinized for their supposedly profuse Lateral gene transfer with Archaeal organisms. However, recent studies based upon more robust methodologies suggest that incidence of LGT between Thermotogota and other groups including Archaea is not as high as suggested in earlier studies. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) Class Thermotogae Reysenbach 2002 Genus Caldotoga Xue et al. 1999 Order Thermotogales Reysenbach 2002 Family Fervidobacteriaceae Bhandari & Gupta 2014 Genus Fervidobacterium Patel et al. 1985 Genus Thermosipho Huber et al. 1989 non Kantor et al. 2013 Family Thermotogaceae Reysenbach 2002 Genus Pseudothermotoga Bhandari & Gupta 2014 Genus Thermopallium Duckworth et al. 1996 Genus Thermotoga Stetter and Huber 1986 Order Kosmotogales Bhandari & Gupta 2014 Family Kosmotogaceae Bhandari & Gupta 2014 Genus Kosmotoga DiPippo et al. 2009 [Thermococcoides Feng et al. 2010] Genus Mesotoga Nesbo et al. 2013 Order Mesoaciditogales Itoh et al. 2015 Family Mesoaciditogaceae Itoh et al. 2015 Genus Athalassotoga Itoh et al. 2015 Genus Mesoaciditoga Reysenbach et al. 2013 Order Petrotogales Bhandari & Gupta 2014 Family Petrotogaceae Bhandari &