Monday, April 30, 2007

Construction and characterization of ptb-deleted mutant of Clostridium tyrobutyricum and its effect on hydrogen fermentation

Yali Zhang and Shang-Tian Yang. The Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W. 19th Ave., Columbus, OH 43210

There is a high interest to produce hydrogen form biomass because hydrogen is a clean fuel, has high energy content per unit weight, and can be easily converted to electricity by fuel cell. However, current production routes using catalytic fuel reforming and electrolysis of water are energy intensive and expensive. Some microorganisms have the capability to produce hydrogen directly from carbohydrates. Clostridium tyrobutyricum can produce acetate, butyrate and hydrogen from glucose and pentoses during anaerobic fermentation. The goal of this project is to develop a metabolically engineered C. tyrobutyricum mutant with enhanced hydrogen production by knocking out the genes involved in the butyrate pathway, which potentially can convert or shift some NADH to FADH2, the direct substrate for hydrogen production. In this study, homologous recombination is used to disrupt the ptb gene. The mutant is characterized by Southern blotting, enzyme assay, and SDS-PAGE. The gene knock-out effects on the fermentation and hydrogen production are also evaluated.