Genomic insight into Anoxybacillus dikiliensis sp. nov., a hot spring isolate from Dikili exhibiting...

Gram-positive, thermophilic, endospore-forming, yellow, rod-shaped bacteria, D401a^T and D404, were isolated from soil samples of a hot spring in Dikili, Izmir. They can synthesize silver nanoparticles and biotechnologically important thermostable alpha-amylase, alpha-glucosidase and nitrate reductase, which were also confirmed by in silico analyses. 16S rRNA gene phylogenetic analysis revealed that D401a^T was most closely related to D404 (99.9%) and had less than 98.9% similarity to Anoxybacillus flavithermus DSM 2641^T, Anoxybacillus thermarum DSM 7141^T, Anoxybacillus mongoliensis DSM 19169^T and Anoxybacillus ayderensis from the genus Anoxybacillus. Their 2.7 Mb whole-genome analyses indicated that strains D401a^T and D404 represented a novel species within the genus Anoxybacillus, by displaying low average nucleotide identity and in silico DNA-DNA hybridization values between A. ayderensis DSM 14988 (92.9%-50.5%), A. ayderensis DSM 10112^T (92.4%-48.6%), A. thermarum DSM 17141^T (92.6%-48.8%) and Anoxybacillus gonensis NCIMB 13933^T (91.3%-43.8%) below 95% and 70%, respectively. The G+C content of genomic DNA was calculated to be 42.0 mol%. The percentage of conserved protein values of two strains within the genus Anoxybacillus ranged from 89.3% to 85.0% and average amino acid identity values from 95.1% to 91.6%, indicating the overall genus-specific boundaries. In silico chemotaxonomic analysis revealed the presence of complete gene sets encoding iso-C15:0, iso-C17:0 and C16:0 fatty acids, menaquinone-7, polar lipids of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and meso-diaminopimelate-type peptidoglycan were identified. Their genomes encoded type III polyketide synthases that produce biotin. They harboured additional terpene/carotenoid and terpene precursor biosynthetic clusters with secondary metabolites of carotenoids (C30), vitamin E and sesquiterpenes (C15). By morphological, physiological, phylogenetic and phylogenomic features, D401a^T and D404 are assigned to be a new species of the genus Anoxybacillus, which the name Anoxybacillus dikiliensis sp. nov. is proposed (type strain D401a^T=DSM 120222^T=NCIMB 15614^T).