一株γ-聚谷氨酸高产菌株的筛选鉴定及发酵培养基优化

The Screening of a High Yieldingγ-Polyglutamic Acid Strain and Optimization of Fermentation Conditions

从传统食品腐乳中分离得到一株谷氨酸依赖型γ-聚谷氨酸(γ-PGA)高产菌株,经过比对16S rRNA和gyrA基因序列将该菌株命名为Bacillus amyloliquefaciens YB-9.为了增强菌株生产能力,使用Plackett-Burman试验结合单因素试验结果筛选出谷氨酸、柠檬酸和六水三氯化铁3个最显著因素.针对上述因素,应用最陡爬坡试验和Box-Behnken试验完成响应面模型的构建.并使用该模型预测最佳的发酵培养基.在220 r/min,30℃震荡培养48 h条件下γ-PGA实际产量最大值为19.39 g/L,比优化前增加了132.25%.

A strain of glutamate-dependentγ-PGA high yielding Bacillus amyloliquefaciens YB-9 was screened and characterized from the fermented bean curd.In order to increase the productivity of the strain,the Plackett-Burman test combined with the single factor test results were performed to screen out the three most significant factors of glutamic acid,citric acid and ferric chloride hexahydrate affecting the yielding ofγ-PGA.Using the steepest climb test and the Box-Behnken test to optimize the three factors,a response surface model was constructed and the model was used to predict the optimized fermentation medium.Under the conditions of 220 r/min,and the oscillating culture at 30℃for 48 h,the maximum yielding ofγ-PGA was 19.39 g/L and increased by 132.25%via the fermentation medium optimization.