Enhance Vitamin K2 Production Via menA Gene Overexpression and a Two-Stage pH Control Strategy

Abstract:

To improve vitamin K2 production，1，4-dihydroxy-2-naphthoicacid polyprenyltransferase （MenA）which was a key enzyme for vitamin K₂ synthesis in Bacillus subtilis natto was overexpressed. The effects of pH on cell growth and vitamin K2 production was also investigated in a 5 L fermentator. It was shown that the vitamin K₂ production was enhanced by 51% when menA gene was overexpressed. The mono-control of pH could not balance the cell growth and vitamin K₂ production. A two-stage pH control strategy was employed，i.e. pH was controlled at 7.0 between 0~40 h and switched to 4.0 between 40~80 h. The biomass and vitamin K₂ production reached（11.46±0.67）g/L and（63.60±1.81） mg/L，which were 1.5 and 2.6 times of that of pH uncontrolled condition by original strain，respectively.