丙酸杆菌的两种固定化细胞反应器发酵生产丙酸及其代谢通量分析

Metabolic flux analysis of propionic acid biosynthesis with two immobilized cell reactors fermentation by Propionibacterium

根据构建的费氏丙酸杆菌合成丙酸的生化反应网络,利用代谢通量分析法分析了课题组构建的两种固定化细胞反应器对丙酸发酵的影响。结果表明,固定化细胞发酵可以调节葡萄糖-6-磷酸、磷酸烯醇式丙酮酸和丙酮酸节点处的代谢通量分布,从而最终影响生物量和各种有机酸的合成。与游离发酵相比,两种固定化发酵方式戊糖磷酸途径通量都有显著提高,乙酸和乳酸通量均有减少。与植物纤维床反应器主要靠直接加强丙酸合成途径使丙酸产率提高了242.72%不同,多点式棉纤维床反应器发酵主要是通过琥珀酸合成途径的增强而使丙酸产率提高了56.80%。比较了相关关键酶的比活,酶活变化与代谢通量结果基本一致。

The metabolic network of Propionibacterium freudenreichii CCTCC M207015 for propionic acid biosynthesis,with glucose as the sole carbon source,was built based on the stoichiometric balance equations to illustrate the carbon flux distribution of intermediates and metabolites.The propionic acid production with two immobilized cell reactors fermentation was studied by using the metabolic flux analysis method.The results showed that the flux distribution of nodes of glucose 6-phosphate,phosphoenolpyruvate and pyruvate changed after immobilized cells fermentation regulation.Compared with free cells fermentation,the flux of HMP of the two immobilized cells fermentation significantly increased,also with decrease fluxes of acetic acid and lactic acid.The productivity of propionic acid in plant fibrous-bed reactor fermentation increased 242.72% mainly by directly enhancing propionic acid synthesis pathway,while in the multi-point fibrous-bed reactor fermentation it increased 56.80% through the enhancement of succinic acid biosynthetic pathway,and the relevant key enzyme activity and metabolic flux variation had good consistency.