3-羟基丙酸分批发酵过程中的pH控制策略研究

本文利用重组大肠杆菌以甘油为底物发酵合成3．羟基丙酸，考察了不同pH对3．羟基丙酸产量及菌体生长的影响，发现在pH6．5条件下，细胞比生长速率达到最大值，延迟期也相对较短；而pH7．0有利于3-羟基丙酸的合成，控制pH7．0可以使3-羟基丙酸产量达到7．39g／L。基于不同pH条件下对细胞比生长速率和3-羟基丙酸比生成速率的分析，提出3．羟基丙酸分批发酵过程中的pH控制策略，即在发酵过程前5h将pH控制在6．5，5h～15h控制pH为7．0，此时有利于细胞生长；而后在15h-25h控制pH为7．5，25h后控制pH为7．0，从而使细胞具有较高的3．羟基丙酸比合成速率。在此控制策略下经过34h发酵3-羟基丙酸的终产量达到8．76g／L，比pH7．0条件下的3-羟基丙酸产量提高了18．54％。

Research on pH control strategies during batch fermentation of 3-hydroxypropionic acid

3-hydroxypropionic acid has wide development and applicative prospect due to its unique properties. In this study, recombinant Escherichia coli was used to produce 3-hydroxypropionie acid from glycerol and the effects of different pH on cell growth and 3-hydroxypropionic acid production were investigated. The results showed that the maximum cell specific growth rate was obtained at pH 6.5, while 3-hydroxypropionic acid got the maximum production of 7.39 g/L at pH the 7.0. Therefore, pH control strategy during the batch fermentation of 3-hydroxyprepionie acid was present according to analysis of the results at different pH values. The pH was controlled at 6.5 during the first 5 hours and at 7.0 during the 5th-15＇h hours for cell growth ; then pH was changed to 7.5 during the 15th-25th hours and 7.0 after the 25th hours, re- spectively, for higher specific production rate of 3-hydroxypropionic acid. The results indicated that the production of 3- hydroxypropionic acid could reach to 8.76 g/L by using this pH control strategy, which increased 18.54% compared to that at pH 7.0.