Differential Protein Expression and Butanol Production using Clostridium beijerinckii

Abstract

Current events demand new forms of renewable energy. Ethanol from fermentation has been the standard in biofuel for years, but not for long. It has become apparent that ethanol has serious drawbacks. Ethanol is more corrosive to engines and only has approximately 60% the energy content of gasoline per gallon. This problem may be remedied by the use of butanol. Butanol is far less corrosive than ethanol and holds 95% the energy of gasoline per gallon. Our research uses the bacterium Clostridium beijerinckii as the model for the fermentative production of butanol using discarded lignocellulose from biomass, specifically wood. The wood biomass (wood chip), is processed by treatment with high temperature and pressure, resulting in a hydrolysate consisting of free sugars and other breakdown products of cellulose and hemi-cellulose. We have been able to grow C. beijerinckii in media containing xylose or glucose as the principle sugars, both which are present in the wood extract. We had limited success growing bacteria in media whose only carbon source (sugar). is wood hydrolysate. Analysis has shown that the sugar concentrations in these wood extracts were too low to support significant growth. More highly concentrated versions of the hydrolysate appeared to kill the organism completely presumably due to the increased inhibitory compounds. We continued to study the bacterial proteome in efforts to identifying key proteins that play role in the overall process of butanol fermentation. In the future we hope to genetically engineer microorganisms to efficiently carry out butanol fermentation at commercially significant levels. We were also able to find that the scaled up version of the reaction provided significantly higher production of butanol, presumably due to a more consistent growth environment.