Zhao Li, Zheng Yu, Ma Xingyuan, Wei Dongzhi
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, 200237, Shanghai, People's Republic of China.
Bioprocess Biosyst Eng. 2009 Apr;32(3):313-20. doi: 10.1007/s00449-008-0250-4. Epub 2008 Aug 6.
Glycerol dehydrogenase (GDH) and 1,3-propanediol (1,3-PD) oxidoreductase had been proved two key enzymes for 1,3-PD production by Klebsiella pneumoniae. Fed-batch fermentations of the recombinant K. pneumoniae strains, over-expressing the two enzymes individually, were carried out under micro-aerobic conditions, and the behaviors of the recombinants were investigated. Results showed that over-expression of 1,3-PD oxidoreductase did not affect the concentration of 1,3-PD. However, it enhanced the molar yield from 50.6 to 64.0% and reduced the concentration of by-products. Among them, the concentrations of lactic acid, ethanol and succinic acid were decreased by 51.8, 50.6 and 47.4%, respectively. Moreover, in the recombinant the maximal concentration of 3-hydroxypropionaldehyde decreased by 73.6%. Over-expression of GDH decreased the yield of ethanol and 2,3-butanediol, meanwhile it increased the concentration of acetic acid. No significant changes were observed both in 1,3-PD yield and glycerol flux distributed to oxidative branch.
甘油脱氢酶（GDH）和1,3 - 丙二醇（1,3 - PD）氧化还原酶已被证明是肺炎克雷伯菌生产1,3 - 丙二醇的两种关键酶。对单独过量表达这两种酶的重组肺炎克雷伯菌菌株进行了补料分批发酵，并在微需氧条件下进行，同时研究了重组菌的发酵行为。结果表明，过量表达1,3 - PD氧化还原酶并不影响1,3 - 丙二醇的浓度。然而，它将摩尔产率从50.6%提高到了64.0%，并降低了副产物的浓度。其中，乳酸、乙醇和琥珀酸的浓度分别降低了51.8%、50.6%和47.4%。此外，重组菌中3 - 羟基丙醛的最大浓度降低了73.6%。过量表达GDH降低了乙醇和2,3 - 丁二醇的产率，同时增加了乙酸的浓度。在1,3 - 丙二醇产率和分配到氧化分支的甘油通量方面均未观察到显著变化。
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