诱导蜂房哈夫尼菌产L-赖氨酸脱羧酶条件的研究

用响应面法对蜂房哈夫尼菌（Hafnia alvei）L-赖氨酸脱羧酶产酶诱导条件进行优化。首先通过单因素实验对产酶体系的pH、震荡培养时间、静置培养时间、诱导物添加量和Ⅷ添加量进行优化。在此基础上，用部分因子重复试验筛选出对酶活影响显著的3个因素（静置培养时间，诱导物添加量，VB6添加量），再通过Box-behnken实验对这三个因素进行优化，得出最优值。最终得到产酶最佳诱导条件为：震荡培养阶段培养基pH6．5，静置培养阶段pH5．5；摇床震荡培养11h后静置培养7．5h，诱导物L一赖氨酸加入量为5．18dL，维生素B6加入量为1．38g／L时酶活最高，达到71．2U／mL，为优化前（1．74u／mL）的41．8倍，在单因素的基础上提高了19％。

Studies on inducible conditions of L-lysine decarboxylase produced by Hafnia alvei

Response Surface Methodology（RSM） was used to optimize inducible conditions of L-lysine decarboxylase by Hafnia alvei. Firstly, the pH of the fermentation medium, the times of aerobic culture and stationary culture, the concentration of the inducement and the concentration of VB6 were optimized using single factor experiment. Based on these, design assay fractional factorial was used to evaluate five factors related to L-lysine decarboxylase enzymatic activity and three significant factors（stationary culture time, the concentration of the inducement and the concentration of VB6 ） were selected. And then Box-behnken experiment was used to obtain the best value. Finally, the opitimal factor concentrations were determined, i.e. the pH of fermentation medium at aerobic culture step 6.5 h and in stationary culture step 5.5 h, the aerobic culture time llh and the standing cultrue time 7.5 h, the concentration of inducement 5.18g/L and the concentration of VB6 1.38g/L, respectively. Under the optimized conditions, the enzymatic activity was 71.2 U, increased by 41.8 times, and 1.19 times high than that of the single factor experiment result.