异源表达木糖异构酶基因对克雷伯氏菌合成1,3-丙二醇的影响

【目的】提高克雷伯氏菌胞内还原力以强化1,3-丙二醇合成。【方法】将来源于大肠杆菌的木糖异构酶基因在克雷伯氏菌中异源表达，构建重组菌。研究重组菌添加不同浓度木糖为辅底物与甘油共发酵过程中代谢产物和NADH的变化规律。【结果】与对照菌相比，重组菌细胞内还原力NADH提高了0.1?0.3倍，1,3-丙二醇产量达到23.31 g/L，提高20%，1,3-丙二醇转化率从0.60 mol/mol提高到0.73 mol/mol。【结论】木糖异构酶基因的表达强化了木糖代谢途径，经磷酸戊糖途径积累大量还原力，促进了1,3-丙二醇的生成。

Impact of the heterologous expression of xylose isomerase gene on the biosynthesis of 1,3-propanediol by Klebsiella pneumoniae

Objective] In order to enhance the production of 1,3-propanediol by Klebsiella pneumoniae, the regeneration of reducing power was strengthened. Methods] The xylose isomerase gene (xylA) from Escherichia coli was cloned and expressed in Klebsiella pneumoniae. The relevant metabolites and NADH concentrations of the recombinant strain were analyzed when it was cultured with xylose and glycerol as co-substrates. Results] The intracellular reducing equivalent of the recombinant Klebsiella pneumoniae was increased by 0.1?0.3 fold. The titer of 1,3-propanediol of the recombinant strain reached 23.31 g/L, which was 20% higher than that of the parent strain. The conversion rate of 1,3-propanediol of the genetic engineered Klebsiella pneumoniae was improved from 0.60 mol/mol to 0.73 mol/mol. Conclusion] The xylose metabolic pathway and intracellular reducing power is enhanced with the expression of xylA gene, resulted in the improved 1,3-propanediol concentration.