Isopropanol-Butanol-Ethanol(IBE) Fermentation using Clostridium acetobutylicum and Its Derivative

Abstract

A primary/secondary alcohol dehydrogenase (SADH, encoded by adhI) from Clostridium beijerinckii NRRL B-593 was introduced into C. acetobutylicum ATCC 824 under the control of adc promoter. The resulting strain was able to produce isopropanol with trace amount of acetone.In order to furtherincrease isopropanol and butanol production, a synthetic acetone operon (act operon) consisting of three homologous genes (adc, ctfA, and ctfB) was constructed using the adc promoter. Simultaneous expression of act operon and adhI in C. acetobutylicum ATCC 824 resulted in increased isopropanol production, and the butanol titer was comparable with wild-type in the flask culture. Further increase of total alcohol titer was achieved using C. acetobutylicum PJC4BK, where the butyrate kinase gene is inactivated.