酒糟降解内切葡聚糖酶工程菌发酵条件的优化

Optimization of Fermentation Conditions for Endoglucanase Engineering Strain of Distiller’s Grains Degrading

采用响应面法对工程菌BL21-P7的发酵条件进行优化,旨在提高工程菌全细胞酶活。采用单因素实验研究发酵阶段接种量、培养基pH值、发酵温度、发酵时间、摇床转数对BL21-P7的全细胞酶活影响,利用Box-Behnken Design中心组合实验设计,对发酵阶段接种量、培养基pH值、发酵温度、摇床转数进行响应面优化。通过回归分析,BL21-P7的最佳发酵条件为接种量5%,发酵温度37℃,培养基pH5.0,摇床转速180 r/min,培养时间16 h。在该条件下,工程菌全细胞酶活为2.854 U/mL,与预测值符合较好,工程菌破碎后的上清液酶活为18.57 U/mL,是出发菌株的7倍。优化后BL21-P7对酒糟的纤维素降解率为34.22%,高于出发菌株及商业芽孢杆菌,且适用于酒糟的酸性环境。

Response surface methodology was used to optimize the fermentation conditions of engineering strain BL21-P7 in order to improve the whole cell enzyme activity.The single factor experiment was used to study the effects of inoculum amount,medium pH,fermentation temperature,fermentation time and shaking table rotating speed on the whole cell enzyme activity of BL21-P7.The response surface optimization of inoculum amount,medium pH,fermentation temperature and shaking table rotating speed were carried out by using the experimental design of Box-Behnken center combination design.Through regression analysis,the optimal fermentation conditions of BL21-P7 were 5% inoculum amount,37 ℃ fermentation temperature,5.0 pH of medium,180 r/min rotating speed of shaking table and 16 h culture time.Under this condition,the whole cell enzyme activity of engineering bacteria was 2.854 U/mL,which was in good agreement with the predicted value.The enzyme activity of the supernatant was 18.57 U/mL,which was 7 times higher than that of the original strain.The results showed that the cellulose degradation rate of BL21-P7 to distiller’s grains was 34.22%,which was better than wild bacteria and commercial bacillus,and was suitable for the acidic environment of distiller’s grains.