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).