Effects of H2and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037

Abstract

A conventional fermenter (CF), a single-cathode fermenter (SCF), and a double-cathode fermenter (DCF) were employed to evaluate and compare the effects of H2 and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037. The source of the external reducing power for CF was H2, for the SCF was electrochemically reduced neutral red-modified graphite felt electrode (NR-GF), and for the DCF was electrochemically reduced combination of NR-GF and platinum plate electrodes (NR-GF/PtP). The metabolites produced from glucose or CO2 by strain KCTC1037 cultivated in the DCF were butyrate, ethanol, and butanol, but ethanol and butanol were not produced from glucose or CO2 by strain KCTC1037 cultivated in the CF and SCF. It is possible that electrochemically reduced NR-GF/PtP is a more effective source of internal and external reducing power than H2 or NR-GF for strain KCTC1037 to produce metabolites from glucose and CO2. This research might prove useful in developing fermentation technology to actualize direct bioalcohol production of fermentation bacteria from CO2.