Clostridium acetobutylicum

Clostridium acetobutylicum is a gram-positive, sporulating, obligate anaerobe capable of naturally producing acetone, butanol, and ethanol. Up until the 1960s, commercial fermentation of C. acetobutylicum for these solvents was economically competitive with petrochemical production. Now, with rising interest in environmentally friendly energy sources and concerns about long term oil prices, the feasibility of bacterial solvent production is increasingly intriguing.

Clostridium acetobutylicum metabolism in early growth is geared toward accumulation of the acids acetate and butyrate. Once the cells reach stationary phase, these acids are converted to acetone and butanol, respectively. A smaller amount of ethanol also accumulates. The Bennett group investigates the shift in metabolism with overexpression and knockout approaches, and also looks at the regulatory effect of genes involved in sporulation.

Optimizing solvent production and improving the economics of fermentation by genetic approaches is a goal. One approach involves using less expensive carbon sources such as plant cell wall material and the characterization of xylanases that can hydrolyze the hemicellulose component. Another project is studying the effects of solvent stress and lipid content to improve the concentration of solvent tolerated.

Beyond solvent production, our lab explores the potential use of C. acetobutylicum as a generator of hydrogen gas as alternative fuel, and as a producer of other chemicals such as esters, and acetoin.

C. acetobutylicum is able to biodegrade TNT, so one project seeks to characterize the compounds formed, analyze their toxicity and identify and characterize the relevant enzymes involved in the reductive degradation of nitroaromatics, and develop probes for monitering environmental communities and sites as well as defining other biodegradation activities of C. acetobutylicum.