电流刺激对钝齿棒杆菌厌氧条件下代谢通量分布的影响

Effect of Electrical Current Stimulation on the Metabolic Flux Distribution of Corynebacterium crenatum under Anaerobic Conditions

研究电流刺激对钝齿棒杆菌厌氧发酵特性的影响,结果显示电流刺激对葡萄糖的代谢及琥珀酸合成具有显著促进作用。当施加-5 mA电流时,与0 mA(对照组)相比,葡萄糖消耗速率提升了27.4%,发酵液中琥珀酸质量浓度增加了109.4%,琥珀酸产量增加了62.5%,磷酸戊糖途径(pentose phosphate pathway,HMP)的代谢流量增加了150.6%,胞内NADH/NAD+值增加了30.8%。代谢通量计算及关键酶基因表达水平分析结果表明,6-磷酸葡萄糖节点是影响琥珀酸产量的关键节点。电流刺激导致6-磷酸葡萄糖脱氢酶基因与磷酸烯醇式丙酮酸羧化酶基因表达水平上调、HMP与琥珀酸合成途径代谢流量增加,是琥珀酸产量升高的主要原因。本研究结果可为发酵工程与电化学学科的进一步交叉融合提供技术参考。

The effect of electrical current stimulation on the fermentation characteristics of Corynebacterium crenatum under anaerobic conditions was investigated,and the impacting mechanism was discussed by calculating metabolic fluxes and measuring gene expression levels.It turned out that electrical current stimulation greatly contributed to glucose metabolism and succinic acid synthesis.Applying an electric current of−5 mA increased the glucose consumption rate,the concentration of succinic acid in the fermentation broth,the yield of succinic acid,the metabolic flux in the pentose phosphate pathway(HMP),and intracellular NADH/NAD+ratio by 27.4%,109.4%,62.5%,150.6% and 30.8% respectively,compared with the control group(0 mA).The results of metabolic flux and key enzyme gene expression levels indicated that glucose-6-phosphate was the key node that could influence the production of succinic acid.Electrical current stimulation up-regulated the expression levels of the glucose-6-phosphate dehydrogenase gene(zwf)and the phosphoenolpyruvate carboxylase gene(pepc),and increased the metabolic fluxes in the HMP and succinic acid biosynthesis pathway,thereby increasing the production of succinic acid.These results support the combined application of electrochemistry and fermentation.