1-59: Deletion analysis of genes involved in Clostridium thermocellum electron flux 

Clostridium thermocellum is a thermophilic anaerobic bacterium that specializes in the rapid solubilization and fermentation of crystalline cellulose to products that include ethanol. As such, it is considered a prime candidate for consolidated bioprocessing, the process by which a single organism is responsible both for the hydrolysis and fermentation of plant biomass for biofuel production. Recent deletion of the C. thermocellum phosphotransacetylase resulted in the elimination of acetate as a fermentation product but did not result in the dramatic increase in ethanol production seen in organisms such as Thermoanaerobacterium saccharolyticum, possibly due to a redox imbalance. To address this possibility, C. thermocellum deletion mutants have been constructed to eliminate pyruvate-formate lyase (pfl) and hydrogenases. C. thermocellum Dpfl no longer synthesizes formate, and both the pfl and hydrogenase mutants make less acetate than the parent strain. Phenotypic characterization of these strains gives insight into central metabolism for this organism and suggests future paths for the engineering of more efficient biofuel production.