Enhancement of butanol production in Clostridium acetobutylicum SE25 through oxidation-reduction potential regulation and analysis of its metabolic mechanisms

Abstract

In this study, an exogenous regulatory strategy named as oxidation-reduction potential (ORP) regulation was performed in the butanol biosynthesis process by Clostridium acetobutylicum SE25 to accelerate the carbon metabolism flow to butanol and enhance butanol production. The findings show that the dithiothreitol and potassium ferricyanide were the optimal redox agents for regulating the ORP of the fermentation system. Specifically, when the ORP value of fermentation broth was controlled at −400 mV, the highest production of butanol (14.30 ± 0.65 g/L) was obtained, which was 10.80 % higher than that of the control group. And the yield and productivity of butanol were 0.24 g/g and 0.24 g/L/h, respectively. Furthermore, the physiological mechanisms of the effects of different ORP levels on butanol synthesis was investigated, and the results demonstrate that ORP could both regulate the level and ratio of energy charge and NADH/NAD+, and redistribute metabolic flux. Thus, the ORP control strategy, according to the results in this study, is an effective and attainable approach to obtain the high production of butanol.