中文摘要：

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 gL,初始氮源体积分数为玉米浆5 mLL、蛋白胨质量浓度1.5 gL,控制发酵过程pH值7.5,当葡萄糖质量浓度下降为2 gL,开始每隔2 h补加质量浓度为120 gL的葡萄糖溶液,从8 h起每隔2 h补加20 mLL玉米浆＋6 gL蛋白胨及0.6 gL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 gL,比优化前产酶量提高了126%。

英文摘要：

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.