解淀粉芽孢杆菌GSBa-1产凝乳酶培养基组成的优化

从甜酒曲中分离筛选得到1株解淀粉芽孢杆菌菌株GSBa-1,为了提高该菌株液态发酵产凝乳酶的能力,采用单因素实验和响应面法优化其产酶培养基组成。通过单因素实验分析了碳源、氮源、金属盐、磷源对菌株GSBa-1产凝乳酶的影响,并采用响应面法对产酶培养基中麦芽糖、蛋白胨和酵母浸粉含量3个主要因素的优化组合进行了定量研究,确定解淀粉芽孢杆菌GSBa-1产凝乳酶的优化培养基组成为:麦芽糖1.93g/L、蛋白胨10.89g/L、酵母浸粉2.15g/L。在此优化培养基培养条件下,该菌株产凝乳酶活力可达(562.57±7.67)Su/mL,接近理论预测值537.10Su/mL,且平均误差为4.53%。优化后解淀粉芽孢杆菌GSBa-1产凝乳酶活力比基础培养基提高了1.88倍。

Optimization by Response Surface Methodology of Medium Composition for Producing Milk-clotting Enzyme by Bacillus Amyloliquefaciens GSBa-

A Bacillus amyloliquefaciens strain GSBa-1 was isolated from sweet Jiuqu. In order to improve the ability of producing a milk-clotting enzyme (MCE) by liquid fermentation of strain GSBa-1, the single factor test and response surface methodology were employed to optimize the composition of the medium used. The single factor experiment was carried out to analyze the influence of different carbon source, nitrogen source, metal salt and phosphorus source on production of MCE by strain GSBa-1. Then the Box-Behnken design based RSM experiment was used to study the optimum combination of three main factors such as the content of maltose, peptone and yeast extract powder in the medium. The optimal medium composition for producing MCE by GSBa-1 was as follows:maltose 1.93g/L, peptone 10.89g/L, and yeast extract powder 2.15g/L. When the optimal culture medium was used, MCE activity was up to (562.57±7.67)Su/mL, which is similar as the theoretical prediction value of 537.10 Su/mL with an average error of 4.53%. After optimization of the medium composition, the MCE activity produced by strain GSBa-1 increased by 1.88 times compared with that of the basal medium.