Development of a scalable production system for expansin proteins for use in converting cellulosic biomass to biofuel.

In the 2007 State of the Union address, President Bush called for 35 billion gallons of alternative fuel use in the US by 2017 which would replace 20% of the nation's petroleum consumption. It is apparent that this goal cannot be achieved with existing technology and existing feedstocks alone. New technology is needed to improve the conversion of non-grain (cellulosic) feedstocks. In the US, total fuel ethanol production in 2006 reached 4.86 billion gallons - a 24% increase over 2005. Domestic demand for fuel ethanol rose 33% over 2005 to 5.4 billion gallons (Renewable Fuels Association, March 2007.) There are 114 ethanol biorefineries in operation in the US with an aggregate capacity of 5.6 billion gallons. Nearly all fuel ethanol is produced by fermentation of corn glucose (from corn grain) in the US. Presently, there are no commercial cellulosic ethanol biorefineries in operation (Renewable Fuels Association, February 2007.) Commercialization of ETI's proprietary technology will address present and future needs for the growing biofuels market. In the short-term, ETI's biocatalyst will be developed as an accessory protein used in conjunction with the most advanced cellulase technologies. Successful implementation of the proposed Phase I and subsequent research and development effort will result in the use of an ETI protein as a separate, plant-derived additive to cellulase during the hydrolysis of recalcitrant cellulose to glucose. Longer term protein development will shift from use in biomass conversion to functionality in a dedicated, genetically modified biofuel crop. Since expansin proteins are ubiquitous in plant cell walls, it is possible that, through genetic engineering, expression of a select expansin protein will enhance the accessibility of plant cellulose to enzymatic attack. Developments in this arena could lead to proprietary plant crops which encode the ETI protein. The present Phase I application will provide important fundamental insight into the technical feasibility of this approach.