The Identification Of A Novel Species In Bacillus Isolatedfrom Root Nodule Of Oxytropis Ochrocephala

This research aims to identify and determine the taxonomic position of a potentialnovel species isolated from root nodules of Oxytropis ochrocephala grown in the QilianMountain of Hexi Corridor, northwest of China on the basis of polyphasic taxonomyincluded morphological characterization, physiological and biochemistry characterization,phenotypic differences, chemotaxonomic and genotypic characterization.The cell of strain53-2^Tis a strictly aerobic rods,0.6-1.0×2.8-4.0μm, non-motile,Gram-positive, surface folding. Ellipsoidal endospores were located centrally in swollensporangia. Colony of isolate53-2^Toccurred after12h incubation on TY and LB agar platesand looks transparent. After24h incubation, colonies are circular, smooth, shiny, convex,translucence and ivory, then become opacitas and light red and a white dot will occur incentre of a colony after prolonged incubation.The optimum temperature for growth of isolate53-2^Tis37℃, pH and temperatureranges are5.0-9.5and20℃-60℃, respectively. NaCl is not essential for growth, but thecolonies can tolerate1%-6%（w/v） NaCl. Isolate53-2^Tis sensitive to antibiotic,Catalase-positive. Gelatin hydrolysis and nitrate reduction test are positive. According toBiolog Microbial Identification System, nine of carbohydrates are utilized to produce acidand its six of enzyme activities are positive. Forty-five of carbohydrates are utilized as thesole carbon source. Ninety-eight features are different from Ornithinibacillus contaminansCCUG53201Tand Bacillus acidicola105-2^Tin physiological and biochemistry test.The result of identification by molecular method revealed that isolate53-2^Tdiscriminate greatly from reported strains, the close related strains areOrnithinibacillus contaminans CCUG53201Tand Bacillus acidicola105-2^T. Similarity of16S rDNA gene sequence between53-2^Tand the two defined strains are only94.87%.Phylogenetic tree was constructed and we found that isolate53-2^Tformed an novel branchunrelating to any other known genus. Together with other phenotypic characterdifferentiation, a novel species was proposed. The DNA G+C content of53-2^Tis37.78%.The result of identification by chemical composition revealed that main fatty acid of isolate53-2^Tis saturated fatty acid, contained branched-chain （65.74%） and straight-chainfatty acid （20.85%）. Dominant fatty acids are anteiso-C_15:0（18.83%），iso-C_16:0（8.73%），C_16:0（8.90%）. The major menaquinone of the isolate53-2^Tis MK-7.Based on the above results,53-2^Tcan be classified as a novel species in the genusBacillus, Bacillus sp. Nov, Genbank accession number is KC847111.