Transfer of Bacillus schlegelii to a novel genus and proposal of Hydrogenibacillus schlegelii gen. nov., comb. nov.

Analysis of the 16S rRNA gene sequences of species currently assigned to the genus Bacillus has shown an extensive intrageneric phylogenetic heterogeneity. The 16S rRNA gene sequence of Bacillus schlegelii ATCC 43741(T) shows only 82.2-85.9% sequence similarity to type strains of other members of the genus Bacillus and <88.5% sequence similarity to recognised species of the most closely related genera, Calditerricola (88.4-88.5 %), Planifilum (87.3-87.8%) and Caldalkalibacillus (87.2-87.9%). Furthermore, B. schlegelii ATCC 43741(T) could not be assigned to an existing family by phylogenetic analysis. The predominant menaquinone was MK-7. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and two unidentified glycolipids. The major fatty acids were iso-C-16:0, C-16:0, iso-C-17:0 and anteiso-C-17:0. Both the polar lipid profile and the fatty acid composition clearly distinguished B. schlegelii DSM 2000(T) from the type species of the genus Bacillus, Bacillus subtilis. Hence, there is no evidence for a clear phenotypic grouping of this organism into the genus Bacillus nor to the genera Calditerricola, Caldalkalibacillus or Planifilum. A proposal is made to transfer Bacillus schlegelii to a novel genus and species, Hydrogenibacillus schlegelii gen. nov., comb. nov., and to emend the species description. The type strain of the type species is DSM 2000(T) (=ATCC 43741(T)=CCUG 26017(T)=CIP 106933(T)).