pH对克雷伯氏菌1,3-丙二醇合成关键酶酶活及发酵特性的影响

Effects of pH on activities of key enzymes and 1,3-propanediol fermentation properties with Klebsiella pneumoniae

在5 L发酵罐进行甘油脉冲流加发酵,分析了不同pH值对克雷伯氏肺炎杆菌发酵特性的影响,pH 6.5为菌体最佳生长条件,克雷伯氏肺炎杆菌合成1,3-丙二醇的产量最高。在1,3-丙二醇合成速率较大的对数中前期,进行甘油脉冲流加发酵,提高甘油浓度促进甘油脱水酶、1,3-丙二醇氧化还原酶和甘油脱氢酶活性。不同pH值的脉冲试验表明,甘油脱水酶,2,3-丁二醇脱氢酶比酶活随着pH值的升高而升高,1,3-丙二醇氧化还原酶,乳酸脱氢酶比酶活在pH6.5最高,因此偏酸性的发酵条件和对数期维持一定的甘油浓度能够促进1,3-丙二醇的合成。

The glycerol fed-batch fermentation was performed in 5 L fermentor and the effects of pH value of culture on properties were investigated. Results indicated that pH 6.5 was desirable for cell growth and 1,3-propanediol synthesis by Klebsiella pneumonicte. The exponential growth phase contributed the main production of 1,3-propanediol and another important byproduct 2,3-butanediol. The glycerol pulse-fed fermentations were conducted to analyze the variation of the specific activities of related enzymes. The enzyme activities of glycerol dehydrotase, glycerol dehydrogenase and 1,3- propanediol oxidoreductase were strictly associated with the change of glycerol concentration. The specific activities of l, 3-propanediol oxidoreductase and 2, 3-butanediol oxidoreductase increased with the increasing pH value. The highest lactate dehydrogenase was detected at pH 6.5. Therefore, the certain amount glycerol in exponential growth phase and lower pH value might facilitate the synthesis of 1,3-propanediol.