Fermentation Medium Optimization for γ-PGA Production of Bacillus subtilis HD-F9 by Response Surface Methodology

Using response surface methodology,the authors optimized the fermentation medium for γ-polyglutamic acid production of Bacillus subtilis HD-F9.Firstly,evaluating influence of seven related factors by Plackett-Burman design,glucose,yeast extract and monosodium glutamate were found as important factors in the medium.Secondly,the optimal region of γ-polyglutamic acid production by the steepest ascent path was approached.Finally,the optimal concentrations of the key factors by Box-Behnken design and response surface analysis were determined as glucose 60.03 g/L,yeast extract 8.1 g/L and monosodium glutamate 41.7 g/L.The optimized yield of γ polyglutamic acid was obtained as 14.56 g/L,increased by 53.26 %.