Members of the order Thermotogales: from microbiology to hydrogen production.

Members of the deep-branching order Thermotogales are widespread in various terrestrial, submarine and subterrestrial extreme environments. This bacterial order included both thermophilic and hyperthermophilic anaerobic microorganisms so far pertaining to 10 genera. It is only recently (2011) that cultivation of a mesophilic member of this order belonging to a novel genus Mesotoga, has been successful. All members, with the exception of Mesotoga spp., are recognized as high hydrogen producers having possible applications in biotechnology with a peculiar emphasis for members of the genus Thermotoga (e.g. T. maritima and T. neapolitana). The ecology, phylogeny and metabolism linked to hydrogen production of these bacteria, are reviewed