Genome-Based Classification of Calidifontibacillus Erzurumensis Gen. Nov., Sp. Nov., Isolated From a Hot Spring in Turkey, With Reclassification of Bacillus Azotoformans as Calidifontibacillus Azotoformans Comb. Nov. and Bacillus Oryziterrae as Calidifontibacillus Oryziterrae Comb. Nov

Abstract

A novel Gram-stain-positive, rod-shaped, endospore-forming, motile, aerobic bacterium, designated as P2(T), was isolated from a hot spring water sample collected from Ilica-Erzurum, Turkey. Phylogenetic analyses based on 16S rRNA gene sequence comparisons affiliated strain P2(T) with the genus Bacillus, and the strain showed the highest sequence identity to Bacillus azotoformans NBRC 15712(T) (96.7 %). However, the pairwise sequence comparisons of the 16S rRNA genes revealed that strain P2(T) shared only 94.7% sequence identity with Bacillus subtilis subsp. subtilis NCIB 3610(T), indicating that strain P2(T) might not be a member of the genus Bacillus. The digital DNA-DNA hybridization and average nucleotide identity values between strain P2(T) and B. azotoformans NBRC 15712(T) were 19.8 and 74.2%, respectively. The cell-wall peptidoglycan of strain P2(T) contained meso-diaminopimelic acid. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an aminophospholipid, five unidentified phospholipids and two unidentified lipids while the predominant isoprenoid quinone was MK-7. The major fatty acids were iso-C-15:0 and iso-C-16:0. The draft genome of strain P2(T) was composed of 82 contigs and found to be 3.5 Mb with 36.1 mol% G+C content. The results of phylogenomic and phenotypic analyses revealed that strain P2(T) represents a novel genus in the family Bacillaceae, for which the name Calidifontibacillus erzurumensis gen. nov., sp. nov. is proposed. The type strain of Calidifontibacillus erzurumensis is P2(T) (=CECT 9886(T)=DSM 107530(T)=NCCB 100675(T)). Based on the results of the present study, it is also suggested that Bacillus azotoformans and Bacillus oryziterrae should be transferred to this novel genus as Calidifontibacillus azotoformans comb. nov. and Calidifontibacillus oryziterrae comb. nov., respectively.