This Small Business Innovation Research (SBIR) Phase I project will demonstrate the feasibility of using a novel enzyme from a marine bacterium as part of a process to convert biomass to ethanol. The Trillium laboratory has preliminary data that indicates that this enzyme has unique characteristics that enables a low-cost process for converting xylose, a common biomass-derived sugar, into ethanol using robust conventional yeasts. Phase I work will characterize the biochemical performance of the enzyme and use it in a bench-scale xylose-to-ethanol process. Successful execution of the Phase I project will set the stage for a Phase II project that will develop high-volume production of this enzyme and use it in a pilot-scale Simultaneous Isomerization and Fermentation (SIF) system.
The broader/commercial impacts of this research are dramatic cost reductions for conversion of cellulosic biomass to ethanol, and thus more rapid deployment of commercial cellulosic ethanol processes. The current United States Renewable Fuels Standard (RFS) mandates that 18 billion gallons per year of cellulosic ethanol be blended into the nation?s transportation fuel supply by 2022. Progress toward this goal is not being met due to the lack of economic cellulosic ethanol processes. The innovation of this proposal will result in a process that increases ethanol yield per ton of biomass by 30-40% and thus dramatically improve overall process economics. A cost-effective cellulosic ethanol process will drive the investment of 100 billion dollars of capital capacity to meet the RFS and create jobs in the biofuels industry and agriculture sector.
This Small Business Innovation Research (SBIR) Phase I project successfully demonstrated the feasiblity of using a unique enzyme derived from a marine bacterium in a process to convert the biomass sugar xylose to ethanol. Xylose is the second most abundant sugar in most biomass after glucose. Glucose is easily fermented to ethanol, but xylose is not. Efficient conversion of the xylose portion to ethanol is essential for an economic process. The properties of the studied enzyme, called xylose isomerase, make it particularly suitable for this purpose. This xylose isomerase has optimal activity and stability at levels of acidity compatible with fermentation (i.e., pH~6). The new enzyme also is resistant to deactivation by inhibiting components that are frequently present in these fermentations. The positive feasibility results indicate that this enzyme could enable a simpler process to convert biomass-derived xylose to ethanol on a commercial scale. The proposed process converts xylose to xylulose (isomerization) while yeast simultaneously ferment the xylulose to ethanol. Ethanol from local cellulosic materials is a sustainable transportation fuel that reduces greenhouse gas emissions by an average of 87% according to the Argonne National Lab’s GREET model. The toxicity of tailpipe emissions are also reduced relative to petroleum-based fuels. As a domestic source of fuel, cellulosic ethanol adds to U.S. energy security and strengthens our economy. By creating jobs and recycling dollars into the U.S. economy, cellulosic ethanol improves the trade deficit and lessens the dependence on foreign petroleum. By developing a low-cost enzyme that is added directly to the fermentation, difficulties with genetically modified fermentation organisms are avoided. This not only simplifies the ethanol production process, but also reduces the GMO content of co-products that may enter the food chain.
