A systematic review of the genera and : their evolution, current taxonomic status and major applications.

The genus , belonging to the phylum is one of the most important genera and comprises thermophilic bacteria. The genus was erected with the taxonomic reclassification of various species. Taxonomic studies of remain in progress. However, there is no comprehensive review of the characteristic features, taxonomic status and study of various applications of this interesting genus. The main aim of this review is to give a comprehensive account of the genus . At present the genus acomprises 25 taxa, 14 validly published (with correct name), nine validly published (with synonyms) and two not validly published species. We describe only validly published species of the genera and . Vegetative cells of species are Gram-strain-positive or -variable, rod-shaped, motile, endospore-forming, aerobic or facultatively anaerobic, obligately thermophilic and chemo-organotrophic. Growth occurs in the pH range 6.08.5 and a temperature of 37-75 °C. The major cellular fatty acids are iso-C15:o, iso-C16:0 and iso-C17:o. The main menaquinone type is MK-7. The G-+C content of the DNA ranges between 48.2 and 58 mol%. The genus is widely distributed in nature, being mostly found in many extreme locations such as hot springs, hydrothermal vents, marine trenches, hay composts, etc. species have been widely exploited in various industrial and biotechnological applications, and thus are promising candidates for further studies in the future.