Abstract:γ-Polyglutamic acid（γ-PGA）is a type of biopolymer used in food，agriculture，and medicine.In the batch fermentation without feeding process of γ-PGA，the growth and development of the bacteria and the synthesis of γ-PGA were restricted by insufficient carbon and nitrogen sources in the medium.To obtain a high yield of γ-PGA，the fed-batch fermentation method was used to supplement the carbon and nitrogen sources required for bacterial growth and metabolism.γ-PGA fed-batch fermentation was optimized in a 5 L fermenter，with amplification in a 200 L fermenter.The experimental results showed that when the glucose and ammonia nitrogen concentrations in the medium were lower than 5 g/L and 0.5 g/L，respectively，the feed was started；the glucose and ammonia nitrogen concentrations were maintained at 5 g/L-15 g/L and 0.5 g/L-1.0 g/L，respectively，for 12 h.Compared with conventional batch fermentation，this optimized method extended the exponential growth period by 6 h，and the biomass（OD660）reached 0.62（39.01%increase vs.control）.The glutamate level was reduced to 16 g/L，and the glutamate utilization rate was increased by 48.38%.The productivity and yield of γ-PGA were 15.69 g/（L·d）and（47.09±0.82）g/L，respectively，demonstrating an increase of 38.45%.This study provides useful information for enhancing the industrial production of γ-PGA.