E.coli M15 (pQTPL)高效发酵生产酪氨酸酚裂解酶的控制策略

在摇瓶和4 L发酵罐上研究了营养和环境条件对重组菌E. coli M15 (pQTPL)分批发酵生产酪氨酸酚裂解酶(TPL)的影响. 在培养基中添加20 g/L葡萄糖和1.0 g/L玉米浆使TPL酶活提高到63.1 U/g(干重). 在此基础上，维持发酵液中溶氧水平为30%，可使菌体浓度在8 h达到4.78 g/L，酶活为54.6 U/g，比对照组(不控制溶氧)分别提高了21%和31.6%. 采用溶氧反馈调节-限制性补料策略，可使菌体浓度提高到31.5 g/L. 采用两阶段温度和pH控制策略，在发酵前8 h控制pH 7.0、温度37℃，8 h 至发酵结束之间控制pH为8.0、温度为30℃，可使重组菌的TPL酶活达到154.4 U/g，并使TPL在细胞中过量表达，实现了高菌体浓度和高TPL酶活的统一.

Enhanced Production of Tyrosine Phenol Lyase by Recombinant E.coli M15 (pQTPL) through Controlling Nutritional and Environmental Conditions

The effects of nutritional and environmental conditions on production of tyrosine phenol lyase (TPL) were investigated in flask and 4 L fermentor. The optimal concentrations of glucose and corn steep liquor for recombinant strain growth and TPL production were 20 g/L and 1.0 g/L, respectively. When the level of dissolved oxygen was kept at 30%, a high cell concentration and TPL activity reached 4.78 g/L and 52.8 U/g (DCW), which were 21% and 36.1% higher than those without dissolved oxygen control, respectively. The cell concentration reached 31.5 g/L when the strategies of dissolved oxygen feedback regulation and restrictive supplement of nutrients were used. By using a bi-stage pH and temperature control strategy, in which pH value and temperature were controlled at 7.0 and 37℃ in the first 8 h and then switched to pH 8.0 and 30℃, a high cell concentration and high TPL activity 154.4 U/g (DCW)] were achieved.