Comparison of different fermentation processes for the Vitamin K2 (Menaquinone-7) production by a novel Bacillus velezensis ND strain

Abstract In this study, a novel MK-7 producing bacterial strain, Bacillus velezensis ND, was isolated and characterized. Multiple low-cost substrates were used in Bacillus velezensis ND culture medium to reduce the MK-7 production cost, MK-7 concentration of 43.8 ± 2.8 mg/L was obtained using raw soybean flour by liquid-state fermentation (LSF). To improve the MK-7 production, LSF, biofilm-based fermentation (BF), and the solid-state fermentation (SSF) were compared. The highest MK-7 yield was achieved by SSF is 150.0 ± 4.9 mg/kg. The associated synthetic gene expressions under these three fermentation processes were investigated as well. The result indicated that the key genes menF, menH, and menG in the MK synthesis pathway are positively correlated with the increase of MK-7 biosynthesis.