Isolation and Identification of Bacillus amyloliquefaciens BY01 with High Productivity of Menaquinone for Cheonggukjang Production

To develop a cheonggukjang with high content of menaquinone (MK), bacterial strains were isolated from good quality cheonggukjang, and MK productivities of isolated strains were determined by high-performance liquid chromatography. After sensory evaluation and MK determination, a potential probiotics, BY01, with acceptable sensory quality and high productivity of MK was isolated. Fermentation under aerobic condition produced more MK than that obtained under anaerobic condition, and the synthesized MK mainly remained in the form of endocellular deposit. To identify species of strain BY01, biochemical tests and gyrase B gene (gyrB) sequence analysis were carried out, and strain BY01 was identified as Bacillus amyloliquefaciens. The content of MK in cheonggukjang fermented with B. amyloliquefaciens BY01 reached 7.54 μg/g, 2-fold higher than that of commercial cheonggukjang products. This is the first report on the isolation of B. amyloliquefaciens as a superior MK producer in cheonggukjang fermentation.