(341f) High Titer Butanol-Producing Clostridium Beijerinckii Mutant Strain and Its Proteome Analysis

Butanol received increasing interest due to its potential as an alternative fuel and expanding demand as an industrial chemical. Biological production of butanol is promising because it can use renewable biomass as feedstock and is environmentally friendly. However, butanol production by solventogenic Clostridia in conventional acetone-butanol-ethanol (ABE) fermentation is limited by its low yield, productivity and titer. To make the bioprocess more economically attractive, a mutant strain of Clostridium beijerinckii with high butanol tolerance and productivity was developed through in-process adaptation in a fibrous bed bioreactor (FBB) followed with extensive strain screening. Compared with the parental strain, the mutant showed several good traits, including improved butanol tolerance, autolysis resistance, robust adjustment of membrane fatty acid composition, more complete substrate utilization, and dramatically increased butanol titer. A high butanol titer of 28.2 g/L was achieved in batch fermentation with the mutant immobilized in a FBB. To investigate the molecular basis for the acquired traits of the mutant, the proteomic profiles of the mutant and its parental strain during early exponential phase and late stationary phase were analyzed using 2-D gel electrophoresis. Proteins with dramatic difference in their expression levels were identified and classified based on their potential roles. The comparative proteome analysis between the mutant and its parental strain suggested several novel gene targets for metabolic engineering of the solventogenic Clostridia to further improve butanol tolerance and production in ABE fermentation.