Bacillus safensis subsp. osmophilus subsp. nov., isolated from condensed milk, and description of Bacillus safensis subsp. safensis subsp. nov.

Abstract

A bacterial strain, designated BC09T, was isolated from a contaminated sample of condensed milk. Phylogenetic analyses based on 16S rRNA gene sequences placed strain BC09T into the genus Bacillus with its closest relatives being Bacillus safensis and Bacillus australimaris with 100 and 99.9 % similarity, respectively. Analysis of the gyrB gene confirmed the closeness of strain BC09T with respect to the species B. safensis since it presented 97.8 and 95.2 % similarity values, respectively, to the type strains of B. safensis and B. australimaris. DNA-DNA hybridization confirmed these results showing averages of 67 and 56 %, respectively, between strain BC09T and the type strains of B. safensis and B. australimaris. Average nucleotide identity blast values obtained for BC09T compared to the closest relative type strains were 95.7 and 67.6 %, respectively, and predicted DNA-DNA hybridization values were 93.1 and 51.9 %, respectively. However, strain BC09T differs from the type strains of its closest relatives in several phenotypic characteristics. MK-7 was the only menaquinone detected and iso-C15:0 and anteiso-C15:0 were the major fatty acids. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, two unidentified phospholipids, two unidentifed glycolipids, three unidentified lipids and one unidentifed phosphoglycolipid. Meso-diaminopimelic acid was detected in the peptidoglycan. The G+C content was 40.9 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain BC09T represents a new subspecies of B. safensis, for which the name Bacillus safensis subsp. osmophilus subsp. nov. is proposed. The type strain is BC09T (=LMG 30124T, =CECT 9344T).