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

Abstract

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.

Keywords

• electrochemistry; fermentation; corynebacterium crenatum; electrical current stimulation; metabolic flux