Bioresource Technology, Vol.243, 1000-1008, 2017
Enhanced robustness in acetone-butanol-ethanol fermentation with engineered Clostridium beijerinckii overexpressing adhE2 and ctfAB
Clostridium beijerinckii CC101 was engineered to overexpress aldehyde/alcohol dehydrogenase (adhE2) and CoA-transferase (ctfAB). Solvent production and acid assimilation were compared between the parental and engineered strains expressing only adhE2 (CC101-SV4) and expressing adhE2, ald and ctfAB (CC101-SV6). CC101-SV4 showed an early butanol production from glucose but stopped pre-maturely at a low butanol concentration of similar to 6 g/L. Compared to CC101, CC101-SV6 produced more butanol (similar to 12 g/L) from glucose and was able to re-assimilate more acids, which prevented "acid crash" and increased butanol production, under all conditions studied. CC101-SV6 also showed better ability in using glucose and xylose present in sugarcane bagasse hydrolysate, and produced 9.4 g/L solvents (acetone, butanol and ethanol) compared to only 2.6 g/L by CC101, confirming its robustness and better tolerance to hydrolysate inhibitors. The engineered strain of C. beijerinckii overexpressing adhE2 and ctfAB should have good potential for producing butanol from lignocellulosic biomass hydrolysates. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords:Acetone-butanol-ethanol fermentation;Aldehyde/alcohol dehydrogenase;Butanol;CoA-transferase;Clostridium beijerinckii;Sugarcane bagasse hydrolysate