微生物发酵合成γ-PGA发酵条件优化

Optimization of Fermentation Conditions forγ-PGA Synthesis by Microbial Fermentation

γ-聚谷氨酸(γ-PGA)是由谷氨酸缩合聚合而成的高分子聚合物,它具有可降解性、可交联性、水溶性、抗冻性、抗氧化性等优良性质,基于其分子量的差异可呈现不同的功能,可被广泛应用于食品、医疗、农业、环保等诸多领域中。通过单因素及响应面试验设计,以发酵液中γ-PGA产量为指标,对一株枯草芽孢杆菌B.subtilis YSH18发酵合成γ-PGA培养基及条件进行了优化,结果显示:玉米糖化液30 g·L^(-1)、谷氨酸钠36 g·L^(-1)、酵母浸粉7 g·L^(-1)、氯化钠12 g·L^(-1)、磷酸氢二钾5 g·L^(-1)、装液量50 mL/250 mL、转速150 r/min、温度37℃,经过48 h发酵γ-PGA终产量为10.252 g·L^(-1),优化后的产量达到优化前的2倍。

γ-polyglutamic acid(γ-PGA)is a high molecular polymer formed by the condensation polymerization of glutamic acid,which has excellent properties such as degradability,crosslinking ability,water solubility,freezing resistance,oxidation resistance,etc.According to the difference of molecular weight,it can present different functions,which can be widely used in many fields such as food,medical treatment,agriculture,environmental protection and so on.Taking the yield ofγ-PGA as the evaluation index,the fermentation medium and conditions for the synthesis ofγ‑PGA by B.subtilis YSH18 are optimized by single factor and response surface methodology.The results shows that the final yield ofγ-PGA is 10.252 g/L after fermented 48 h under the conditions of 30 g/L corn saccharification liquid,36 g/L sodium glutamate,7 g/L yeast extract powder,12 g/L sodium chloride,5 g/L potassium dihydrogen phosphate,50 mL/250 mL liquid volume,150 r/min rotation speed at 37℃.The yield after optimization is twice as that before optimization.