(449a) Improving Cellulose Hydrolysis with New Cellulase Compositions

Cellulose is the most abundant organic molecule on the earth, and a seemingly inexhaustible feedstock for the production of fuels and chemicals. While abundant, cellulose is remarkably recalcitrant to breakdown into its monomeric form, glucose. Bacteria and fungi have evolved complex enzymatic systems enabling their growth on plant material rich in cellulose, but these organisms typically require weeks, months, or even years to decompose a fallen log or a tilled corn stalk. For chemical or fuel production from these same materials, industry requires affordable chemical or enzymatic systems that can do the job in hours or in days.

Novozymes has been working to improve cellulases for the conversion of lignocellulose to fermentable sugars. Supported in part for four years by a research subcontract from National Renewable Energy Lab, with funds from the U.S. Department of Energy, our efforts have been focused on improving the performance of existing cellulases. Starting with a widely used soft rot fungus (Trichoderma reesei) as a cellulase producing organism, and dilute-acid pretreated corn stover (PCS) as the target substrate, one approach was to elucidate substrate and enzyme characteristics that limit the timely and complete saccharification of lignocellulose. Several methods aimed at overcoming these limitations have been tested, resulting in a substantial decrease in the enzyme loading requirement. Using the tools of biotechnology, we have successfully transferred a number of genes from other organisms, creating a super-cellulase producing fungus capable of meeting industrial needs.