补料分批培养提高转氨酶发酵产酶密度的研究

转氨酶是苯丙酮酸酶法制备L-苯丙氨酸的关键酶源,为提高转氨酶的发酵产酶密度,文章采用补料分批培养方式对大肠杆菌A5发酵产酶进行了研究。优化的补料培养工艺为:初始葡萄糖质量浓度5 g/L,初始氮源体积分数为玉米浆5 mL/L、蛋白胨质量浓度1.5 g/L,控制发酵过程pH值7.5,当葡萄糖质量浓度下降为2 g/L,开始每隔2 h补加质量浓度为120 g/L的葡萄糖溶液,从8 h起每隔2 h补加20 mL/L玉米浆+6 g/L蛋白胨及0.6 g/L的4种氨基酸溶液(L-甲硫氨酸、L-缬氨酸、L-异亮氨酸和L-谷氨酸)。在此条件下发酵培养24 h,菌体干质量浓度达10.5 g/L,比优化前产酶量提高了126%。

Improvement of fermentation density of aminotransferase by batch-feeding culture

Aminotransferase is a key enzyme for the enzymatic preparation of L-phenylalanine from phenylpyruvate.In order to improve the fermentation density of aminotransferase,the optimum batch-feeding culture technique of Escherichia coli A5 was studied.The initial glucose mass concentration was 5 g/L,the initial nitrogen resource was the mixture solution of 5 mL/L corn slurry and 1.5 g/L peptone,and the pH value of fermentation was controlled at 7.5.When the initial glucose mass concentration decreased to 2 g/L,the glucose content in the culture was controlled at this level by feeding 120 g/L glucose every 2 h.After 8 h of culture,the mixture solution with corn slurry 20 mL/L,peptone 6 g/L and the solution 0.6 g/L of four kinds of amino acid(L-methionine,L-valine,L-isoleucine,L-glutamic) were fed every 2 h.After 24 h culture under such conditions the mass concentration of dry cell of Escherichia coli A5 was up to 10.5 g/L,increased by 126% compared with the batch fermentation.