Anoxybacillus rupiensis sp. Nov., a novel thermophilic bacterium isolated from Rupi basin (Bulgaria)

Three strains of a novel thermophilic, strictly aerobic, Gram-positive, spore-forming hemo-organotrophic bacterium were isolated from three hot springs in the region of Rupi basin, Bulgaria as producers of amylolytic enzymes. Their 16S rRNA gene sequences (first 500 nucleotides) were very similar (99.8%). Strains were able to ferment a wide spectrum of carbohydrates such as sugars, polyols, and polysaccharides like xylan, glycogen and starch. Optimal growth was observed at 55–58°C, and pH at 6.0–6.5. Phylogenetic analysis of the whole 16S rRNA gene sequence clustered the strain R270^T with the representatives of the genus Anoxybacillus and with Geobacillus tepidamans. The G + C content of the genomic DNA was 41.7%. DNA–DNA hybridization analysis revealed low homology with the closest relatives (32.0 mol% homology to Geobacillus tepidamans). Fatty acid profile (major fatty acids iso-C15:0 and iso-C17:0) confirmed the affiliation of the strain to the genus Anoxybacillus. On the basis of the data presented here, we propose that strain R270^T, represents a new species of the genus Anoxybacillus for which, we recommend the name Anoxybacillus rupiensis sp. nov. (=DSM 17127^T = NBIMCC 8387^T). The 16S rRNA gene sequence data of a strain R270^T have been deposited in the EMBL databases under the accession number AJ879076.