Research on Liquid-state Fermentation Condition of γ-polyglutamic Acid

[Objective]To optimize the liquid-state fermentation conditions to improve the production of γ-Poly glutamic acid(γ-PGA) of an bacillus subtilis N-2. [Method]Single factor experiments and response surface methodology(RSM) were used to optimize the cultivation conditions and medium. [Result]Under the liquid-state fermentation,the optimum medium was sucrose 31. 5 g /L,soy peptone 4. 0 g /L,L-glutamic acid 44. 4 g /L,potassium dihydrogen phosphate 0. 3 g /L,calcium chloride anhydrous 0. 2 g /L and NaCl 3. 0 g /L. The optimized cultivation conditions were decided as follows: initial pH value 7. 5,medium volume 30%,inoculums size 7 % and temperature 37 ℃. The maximum yield ofγ-PGA was 18.7 g/L after 48 h under the optimum conditions. [Conclusion]This paper finds the best combination of factors to promote the production of γ-PGA and contributes to the further research of γ-PGA.