Blocking the butyrate-formation pathway impairs hydrogen production in Clostridium perfringens

Inactivating competitive pathways will improve fermentative hydrogen production by obligate anaerobes, such as those of genus Clostridium. In our previous study, the hydrogen yield of Clostridium perfringens W13 in which L-lactate dehydrogenase was inactivated increased by 44% when compared with its original strain W12. In this study, we explored whether blocking butyrate formation pathway would increase hydrogen yield. The acetyl-CoA acetyltransferase gene (atoB) encodes the first enzyme in this pathway, which ultimately forms butyrate. Clostridium perfringens W14 and W15 were constructed by inactivating atoB in W13 and W12, respectively. The hydrogen yield of W14 and W15 was 44% and 33% of those of W13 and W12, respectively. Inactivation of atoB decreased the pyruvate synthesis and its conversion to acetyl-CoA in both mutants, and increased ethanol formation in W14 and W15. Proteomic analysis revealed that the expressions of five proteins involved in butyrate formation pathway were up-regulated in W14. Our results suggest that butyrate formation deficiency improved ethanol production but not hydrogen production, indicating the importance of butyrate formation pathway for hydrogen production in C. perfringens.