克雷伯氏杆菌发酵生产1,3-丙二醇的代谢通量优化分析

Optimization of microbial production of 1,3-propanediol by Klebsiella pneumoniae under anaerobic and microaerobic conditions by metabolic flux analysis

以克雷伯氏杆菌为研究对象,系统研究了1,3-丙二醇厌氧和微氧代谢途径.采用代谢通量分析法建立了代谢通量平衡模型,通过线性规划对1,3-丙二醇厌氧和微氧发酵进行了优化分析,得到其最优代谢通量分布和最大理论得率,并分析了比生长速率、底物浓度以及乙醇生成速率、氧气消耗速率、呼吸商对1,3-丙二醇得率的影响.

In this paper, a simplified metabolic network was constructed according to glycerol metabolism in Klebsiella pneumoniae under anaerobic and microaerobic conditions. A model of metabolic flux balance was set up by using metabolic flux analysis. The maximum theoretical yield of 1,3-propanediol （1,3-PD） to glycerol and the optimal flux distributions were obtained by using linear programming. In addition, the influences of specific growth rates, ethanol formation rates, molar fraction of NADH2 oxidized completely by molecular oxygen in TCA （tricarboxylie acid） cycle and respiratory quotient （RQ） on the maximum theoretical yield of 1,3-PD to glycerol were analyzed as well. The metabolic flux analysis showed that the maximum theoretical yield of 1,3-PD to glycerol could reach 0. 875 mol · mol^-1 rather than 0.75 mol · mol^-1 if all aeetyl-CoA entered into TCA cycle under mieoraerobie conditions instead of acetic acid pathway under anaerobic conditions. The theoretical yield of 1,3-PD decreased as the specific growth rate and the ethanol formation rate increased. There existed an optimum oxygen uptake rate and a RQ value at different specific growth rates.