Bacillus aerolatus sp. nov., a novel member of the genus Bacillus, isolated from bioaerosols in a school playground.

A Gram-positive, endospore-forming, rod-shaped bacterium with a single flagellum, and a motile strain, designated CX253, was isolated from bioaerosols. The isolate is facultatively anaerobic, is able to grow at 25-45 ℃ (optimum 37 ℃) and pH 6.5-10.0 (optimum 7.5), and can tolerate up to 5.0% NaCl (w/v) under aerobic conditions. The diagnostic diamino acid in the cell wall of strain CX253 is meso-diaminopimelic acid, while major isoprenoid quinone is menaquinone 6 (MK-6) along with a smaller amount of MK-7 (20%). The polar lipid profile is composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids and glycolipids. The major cellular fatty acid is iso-C and anteiso-C. Phylogenetic analysis based on 16S rRNA gene and genome sequence grouped strain CX253 into the genus Bacillus. The strain was most closely related to Bacillus thermotolerans CCTCC AB 2012108 by comparison of 16S rRNA gene sequence (97.2% similarity) and to Bacillus wudalianchiensis CCTCC AB 2015266 by comparison of gyrB gene sequence (80.1% similarity). The draft genome of strain CX253 comprised 3,929,195 bp with a G + C content of 43.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain CX253 and phylogenetically related Bacillus species were lower than 95% and 70%, respectively. Thus, the polyphasic evidence generated through phenotypic, chemotaxonomic and genomic methods confirmed that strain CX253 (= GDMCC 1.1608 = KACC 21318) was a novel species of the genus Bacillus, for which the name Bacillus aerolatus sp. nov. is proposed.