Optimization of Fermentation Conditions for γ-PGA Production by Bacillus subtilis QM3

γ-Polyglutamic acid (PGA) is a high molecular polymer polymerized by glutamic acid (Glu).In the γ-PGA production pathway, the production of γ-PGA by microbial fermentation in the laboratory has become the main way of γ-PGA synthesis because of its convenient operation, low cost, and considerable effect.In order to find the high yield of γ-PGA strain and increase the yield of γ-PGA produced by microorganisms, B. subtilis QM3 was used as the experimental material to optimize the nutrition conditions and culture conditions of γ-PGA production by QM3 fermentation.The results showed that the optimum medium composition and fermentation conditions for the production of γ-PGA by B. subtilis QM3 fermentation were as follows: glucose 4%, yeast extract 1%, sodium glutamate 1%, MgSO 4 •7H 2 O 0.025%, K 2 HPO 4 0.2% department NH 4 Cl 0.3%, initial pH 6, 250 ml flask, liquid volume 30 ml, 121˚C sterilization 20 min, inoculum 2%, shaker speed 220 rpm 42˚C shaker culture for 72 hours, at this time, the yield of γ-PGA was the highest, reaching 124.58 g•L.