Bioethanol enhancement

About

The Problem As a consequence of the surge in demand for biofuels, ethanol-producing microorganisms, such as the Gramnegative bacterium Zymomonas mobilis, are of considerable interest due to their potential for bioethanol production. Z. mobilis has the advantage of rapid sugar uptake, lower biomass production and does not require addition of oxygen during fermentation. However its utilizable substrate range is restricted to six carbon sugars such as glucose, fructose and sucrose. In addition, although Z. mobilis has a higher tolerance for ethanol than yeast, ethanol productivity is still limited by the accumulation of ethanol in the fermentation. The Technology Solution We have discovered a molecule from a common bacterium that stimulates the production of ethanol in Zymomonas mobilis by more than 50%. This enhanced bioethanol production is likely achieved through a coordinated expression of all of the genes in the ethanol metabolic pathway. An added benefit of this invention is the discovery that the ethanol enhancing molecule also activates protein extrusion in Zymomonas mobilis. This extrusion property could be used as a platform system for the expression of heterologous proteins involved in the degradation of cellulose and five carbon sugar fermentation. Technology Application This technology has application in both the enhancement of ethanol production, and as a potential platform for the expression of enzymes responsible for the degradation of lignocellulose and five carbon sugars such as xylose and arabinose. Zymomonas is an ethanologenic microorganism of great interest for the Production of fuel ethanol. In comparison with Saccharomyces cerevisae, the popular ethanol producing yeast, Z. mobilis grows and ferments rapidly, and has a product rate and yield significantly higher than the yeast. Our discovery enhances the ethanol yield in Z. mobilis by more than 50%, making this bacterium even more attractive as the producer organism of choice in fuel ethanol manufacture. Other desirable traits in a fuel ethanol producer are an ability to express and export hydrolytic enzymes to degrade biomass and release pentoses for fermentation. The current invention has the potential to develop an engineered Zymomonas that will convert biomass materials directly to ethanol at high yield.