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%, MgSO₄？7H₂O 0.025%, K₂HPO₄ 0.2% department NH₄Cl 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.