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 degrees 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.