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

Analyses of the 16S rRNA gene sequences of species still currently assigned to the genus Bacillus have shown an extensive intrageneric phylogenetic heterogeneity. The 16S rRNA gene sequence of Bacillus schlegelii DSM 2000T shows only 82.2 to 85.9% similarity to type strains of other Bacillus species and less than 88.5% sequence similarity to any other described species of closest related genera, Calditerricola (88.4-88.5%), Planifilum (87.3-87.8%), and Caldalkalibacillus (87.2 -87.9%). The strain could furthermore not be assigned to an existing family by phylogenetic analysis. The predominant menaquinone is MK-7. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylglycerol; one unidentified phospholipid and two unidentified glycolipids. Major fatty acids are iso-C16:0, C16:0, iso-C17:0 (17.6%), and anteiso-C17:0. Both polar lipids and fatty acid profiles clearly distinguish Bacillus schlegelii from the type species of the genus Bacillus, Bacillus subtilis. Hence, there is neither an 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 Hydrogenibacillus schlegelii gen. nov. comb. and to emend the species description. The type strain is DSM 2000T = ATCC 43741T = CCUG 26017T = CIP 106933T = LMG 7133 T).