Bacillus miscanthi sp. nov., a alkaliphilic bacterium from the rhizosphere of Miscanthus sacchariflorus.

Abstract

A novel bacterial strain, designated AK13T (=KACC 21401T=DSM 109981T), was isolated from the rhizosphere of Miscanthus sacchariflorus. Strain AK13T was found to be an aerobic, Gram-stain-positive, endospore-forming and rod-shaped bacterium. It formed yellow circular colonies with smooth convex surfaces. The genomic DNA G+C content of strain AK13T was estimated to be 40 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that this strain was most closely related to Bacillus lehensis MLB2T (99.4 %), Bacillus oshimensis K11T (98.8 %) and Bacillus patagoniensis PAT 05T (96.6 %). The average nucleotide identity values between strain AK13T and B. lehensis MLB2T, B. oshimensis K11T and B. patagoniensis PAT 05T were 90.93, 91.05 and 71.87 %, respectively, with the digital DNA-DNA hybridization values of 42.7, 42.6 and 18.8 %, respectively. Cells grew at 5-40 °C (optimum, 28-35 °C), pH 6.5-13 (optimum, pH 8-9) and in the presence of 0-13.0 % (w/v) NaCl (optimum, 1 %). The cell wall of strain AK13T contained meso-diaminopimelic acid, and the major isoprenoid quinone was MK-7. Results of fatty acid methyl ester analysis revealed that iso-C15 : 0 was the predominant cellular fatty acid. Two-dimensional thin-layer chromatography analysis indicated that the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and glycolipid. The genotypic and phenotypic characteristics suggested that strain AK13T represented a novel species of the genus Bacillus, and thus the name Bacillus miscanthi sp. nov. is proposed.