Taxonomic revision of the genus Geobacillus : emendation of Geobacillus , G. stearothermophilus , G. jurassicus , G. toebii , G. thermodenitrificans

Abstract

Sixty-two strains of thermophilic aerobic endospore-forming bacteria were subjected to polyphasic taxonomic study including 16S rRNA gene sequence analysis, polar lipid and fatty acid analysis, phenotypic characterization, and DNA-DNA hybridization experiments. Distinct clusters of the species Geobacillus stearothermophilus, Geobacillus thermodenitrificans, Geobacillus toebii and Geobacillus thermoglucosidasius were formed, allowing their descriptions to be emended, and the distinctnesses of the poorly represented species Geobacillus jurassicus, Geobacillus subterraneus and Geobacillus caldoxylosilyticus were confirmed. It is proposed that the name Geobacillus thermoglucosidasius be corrected to G. thermoglucosidans. Bacillus thermantarcticus clustered between Geobacillus species on the basis of 16S rRNA gene sequence analysis, and its transfer to Geobacillus is proposed. The above-mentioned species, together with Geobacillus thermoleovorans and Geobacillus thermocatenulatus, form a monophyletic cluster representing the genus Geobacillus. The distinctness of 'Geobacillus caldoxylosilyticus' was confirmed and it is proposed that it be accommodated, along with Geobacillus tepidamans, in Anoxybacillus. The type strain of Geobacillus debilis was not closely related to any members of Anoxybacillus and Geobacillus, and it is proposed that this species be placed in the new genus Caldibacillus

Anoxybacillus geothermalis sp. nov., a facultatively anaerobic, endospore-forming bacterium isolated from mineral deposits in a geothermal station

“…In contrast, for Anoxybacillus rupiensis DSM 17127 T these fatty acids represented 5.4 and 2.0 %, only. The significant contribution of these two fatty acids (C 16 : 0 and iso-C 16 : 0 ) is particularly noteworthy, as these fatty acids are rarely found representing 25 % of the total fatty acid content in other species of the genus Anoxybacillus (Cihan et al, 2011;Coorevits et al, 2012;Poli et al, 2009). The respiratory menaquinones found were MK-8 (92 %) and MK-7 (5 %).…”

“…The respiratory menaquinones found were MK-8 (92 %) and MK-7 (5 %). These appear also to be characteristic of strain GSsed3 T compared with other species of the genus Anoxybacillus for which the information is available and that had as major respiratory menaquinone MK-7 (Cihan et al, 2011(Cihan et al, , 2014Coorevits et al, 2012;Gul-Guven et al, 2008;Inan et al, 2013). The total hydrolysate (4 M HCl, 16 h at 100 C) of the peptidoglycan contained the amino acids meso-diaminopimelic acid (meso-Dpm), alanine (Ala) and glutamic acid (Glu).…”

“…The analysis of polar lipids, with abundant diphosphatidylglycerol (Fig. S2), showed a polar lipid profile of the strain GSsed3 T similar to that of Anoxybacillus caldiproteolyticus, as shown in the supplementary material of Coorevits et al (2012).…”

“…The genus Anoxybacillus belongs to the family Bacillaceae and is related to the genus Geobacillus, which explains why, for instance, a former representative of the genus Geobacillus, Geobacillus tepidamans (Schaffer et al, 2004), is now classified as Anoxybacillus tepidamans (Coorevits et al, 2012). The name given to the genus suggests that species assigned to it thrive under anoxic conditions, and, indeed, the first species classified as members of the genus Anoxybacillus were aerotolerant anaerobes (Pikuta et al, 2000).…”

“…The name given to the genus suggests that species assigned to it thrive under anoxic conditions, and, indeed, the first species classified as members of the genus Anoxybacillus were aerotolerant anaerobes (Pikuta et al, 2000). Nevertheless, at the time of writing, from the 22 species of the genus Anoxybacillus, 16 are facultative anaerobes (Atanassova et al, 2008;Belduz et al, 2003;Cihan et al, 2011Cihan et al, , 2014Dai et al, 2011;De Clerck et al, 2004;Dulger et al, 2004;Kevbrin et al, 2005;Namsaraev et al, 2010;Poli et al, 2006;Schaffer et al, 2004;Yumoto et al, 2004;Zhang et al, 2011), five are strict aerobes (Coorevits et al, 2012;Derekova et al, 2007;Inan et al, 2013;Poli et al, 2009;Zhang et al, 2013) and one is an aerotolerant anaerobe (Pikuta et al, 2000). Species that belong to the genus Anoxybacillus share common characteristics, mainly concerning their major fatty acids (iso-C 17 : 0 and iso-C 15 : 0 ), the rod shape of the vegetative cells and the terminal/subterminal position of their endospores.…”