Improvement of Vitamin K2 Production by Bacillus subtilis mutant with leakage fermentation

Abstract Menaquinone-7 (MK-7), a highly valuable member of the vitamin K2 series, is an essential nutrient for humans. It plays an important role in the treatment of coagulation, osteoporosis, promotion of liver function recovery and prevention of cardiovascular diseases. In this study, in order to further improve the metabolic synthesis of MK-7 by the mutant strain, the effect of metabolic synthesis of MK-7 by mutant strain Bacillus subitilis 168 KO-SinR (BS168 KO-SinR) was analyzed by adding surfactants. The results showed that the addition of surfactants changed the permeability of the cell membrane of the mutant strain and the structural components of the biofilm, as indicated by scanning electron microscopy and flow cytometry. When 0.7% Tween-80 was added into the medium, the extracellular and intracellular synthesis of MK-7 reached 28.8 mg/L and 59.2 mg/L, respectively, increasing the total synthesis of MK-7 by 80.3%. qRT-PCR showed that the addition of surfactant significantly increased the expression level of MK-7 synthesis-related genes, and the results of electron microscope showed that the addition of surfactant changed the permeability of cell membrane. The research results of this paper provide a certain reference value for the industrial development of MK-7 prepared by fermentation.