Bacillus glycinifermentans sp. nov., isolated from fermented soybean paste.

Abstract

Two independent isolates of a Gram-stain-positive, facultatively anaerobic, motile, rod-shaped bacterium were recovered from cheonggukjang, a Korean fermented soybean paste food product. Preliminary sequencing analysis of the 16S rRNA gene indicated that these strains were related most closely to Bacillus sonorensis KCTC-13918T and Bacillus licheniformis DSM 13T. In phenotypic characterization, the novel strains were found to grow between 15 and 55 °C and to tolerate up to 8 % (w/v) NaCl. Furthermore, the strains grew in media of pH 5-10 (optimal growth at pH 7.0). The predominant cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0.The isoprenoid quinone was menaquinone 7 (MK-7). The cell-wall peptidoglycan contained meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unknown glycolipid. Draft genomes of the two strains were determined and in silico DNA-DNA hybridizations with their nearest neighbour (B. sonorensis KCTC-13918T) revealed 29.9 % relatedness for both strains. Phylogenomic analysis of the genomes was conducted with the core genome (799 genes) of all strains in the Bacillus subtilis group and the two strains formed a distinct monophyletic cluster. In addition, the strains differed from the two most closely related species in that they did not metabolize maltose, d-galactose, d-sorbitol or d-gluconic acid. The DNA G+C content was 45.9 mol%. Based upon the consensus of phylogenetic and phenotypic analyses, these strains represent a novel species of the genus Bacillus, for which the name Bacillus glycinifermentans sp. nov. is proposed. The type strain is GO-13T ( = KACC 18425T = NRRL B-65291T).