Metabolic and process engineering of Clostridium tyrobutyricum for efficient hydrogen production from sugarcane molasses

Clostridia is the dominant microorganism in dark-fermentative biohydrogen production, but there have been relatively few studies on hydrogen production by Clostridium tyrobutyricum using cheap biomass. In this study, the important process parameters for hydrogen fermentation, such as substrate concentration, pH and temperature, were optimized systematically. Then, the effect of endogenous hydrogenases overexpression on hydrogen production was studied. To achieve economical hydrogen production from cheap substrate sugarcane molasses, the sucrose metabolic pathway was further introduced into C. tyrobutyricum. As a result, the engineered C. tyrobutyricum produced 1098.4 mL hydrogen with a yield of 248.2 mL/g sugar and productivity of 199.6 mL/ L/h under the optimum fermentation conditions, which is the highest hydrogen production (910.37 mmol/L) reported so far using molasses. This study demonstrates that C. tyrobutyricum is a promising cell factory for hydrogen production from cheap and renewable biomass resources.