S22: Metabolic engineering the Saccharomyces yeast to co-ferment glucose and xylose for cost effective production of renewable fuels and chemicals

 

After the first worldwide energy crisis in the 1970s, the US government agencies strongly focused their support on the development of technologies to produce ethanol from renewable cellulosic feedstocks.  The efficient production of cellulosic ethanol (ethanol produced from cellulosic biomass) requires having effective microorganisms that can convert all sugars, particularly the major sugars (glucose and xylose), present in all types cellulosic materials to ethanol; effective pretreatment processes to release the polymers; as well as commercially available affordable cellulases to breakdown the polymers of cellulose present in cellulosic biomass to glucose.  Now these required technologies have been developed.  Since 1980, my laboratory at Purdue University has been devoted to metabolic engineering the Saccharomyces yeast for efficient fermenting not only glucose but also xylose as well as the other minor sugars present in cellulosic biomass to ethanol.  Our current yeast has been used by industry to produce cellulosic ethanol in small scale since 2004.  A company, Green Tech America, Inc. (GTA), has been established to closely collaborate with Purdue University to market and continue improving the yeast, particularly to enable the yeast to produce high-value coproducts during ethanol production in order to make the process more cost effective.  In this presentation, I will report the capabilities of our current yeast as well as further improved yeast in producing ethanol from real cellulosic biomass hydrolysates containing high concentrations of the major sugars, glucose and xylose.  We believe the technologies are ready and continually being improved for large-scale industrial cellulosic ethanol production.