Plant Expression of Cellulase for Biomass Ethanol Production

The Energy Independence and Security Act of 2007 provides a federal mandate to increase the domestic supply of clean, renewable energy sources. The EIS Act amends the 2005 Renewable Fuels Standard by increasing the goal for renewable fuels use to 9 billion gallons in 2008, 15.2 billion gallons in 2012, and culminating in 36 billion gallons by 2022. Achieving these ambitious goals will be difficult. In the next few years U.S. ethanol production, currently at about 6 billion gallons annually, will be limited by the supply of low-cost corn grain. Producing cellulosic ethanol from "cellulosic" biomass such as corn stover and other biomass crops such as switchgrass can substantially increase ethanol production capacity, but with costs above $2.50 per gallon existing cellulosic technologies are too expensive. Accordingly, there is an urgent need for new approaches to lower the cost of cellulosic ethanol. In this USDA SBIR Phase II project, Edenspace is continuing to bioengineer a promising biofuel crop, switchgrass (Panicum virgatum L.), to reduce costs of cellulosic ethanol production by more than 70%. Switchgrass is an attractive biofuel crop because it is native to the Great Plains of the U.S. and has wide adaptability to marginal soils and vigorous growth (optimum annual biomass yields of 10-20 tons/hectare). Importantly, the enhanced switchgrass itself will produce enzymes such as cellulases, helping to reduce the capital costs and operating costs of manufacturing these enzymes in microbial bioreactors, and reducing the costs of acid and heat now used to pretreat the biomass.