Optimization of Solid Fermentation Conditions to Produce Poly-γ-glutamic Acid

Objective To investigate the medium composition and cultivation conditions in solid-state fermentation of γ-PGA.Methods The single factor experiment was conducted to select the optimal carbon source,nitrogen source,pH and temperature.Subsequently,L9(34) orthogonal test was used to establish the optimum levels of all the factors,including optimal carbon source,optimal nitrogen source,water content of medium and inoculation volume.Results The optimum condition for the production of γ-PGA was as follows:starch 2.6%,soybean flour 24.6%,moisture content 55%,inoculation volume 12%,initial medium pH 7.0 and fermentation temperature 38℃.Conclusion The optimum combination of all the factors was determined by the orthogonal test.The production of γ-PGA was increased by the optimization of fermentation conditions.