Metabolic Engineering of E. Coli for Hydrogen Production

Escherichia coli excretes a mixture of organic acids such as formate, acetate, succinate, lactate and ethanol when growing on glucose under anaerobic conditions in the absence of electron donor. The hydrogenase 3 and formate dehydrogenase forms the membrane-associated formate hydrogenlyase, which converts formate further into carbon dioxide and hydrogen in E. coli under anaerobic conditions. Therefore, E. coli can be a bio-catalyzer to convert glucose into hydrogen. In this study we over-expressed the fdhF gene which encodes formate hydrogenlyase in E. coli to produce hydrogen with glucose as a carbon source. Since the formate hydrogenlyase system requires NADH as the source of proton, pathway manipulations were employed in this study to eliminate reduced metabolites' excretion so that reducing power can be reserved for hydrogen production. The metabolic engineered systems were characterized under anaerobic conditions to evaluate their hydrogen production ability.