1B-31

Enzyme-pretreatment of Grass Lignocellulose for Potential High-value

Co-products and an Improved Fermentable Substrate

William F. Anderson,^1* Joy Peterson,² Danny E. Akin³ and W. Herbert Morrison III³

¹Coastal Plain Experiment Station

ARS-USDA

PO Box 748

Tifton, Georgia 31793

Phone: (229)386-3170

Fax: (229)391-3701

E-mail: banderson@tifton.usda.gov

²Department of Microbiology

University of Georgia

Athens, Georgia

³Russell Research Center

ARS-USDA

Athens, Georgia

Lignocelluloses of grasses are potential sources of biofuel to expand the bioethanol industry currently based on corn grain. While crop biomass yield is high for grasses, aromatics in the lignocelluloses impede hydrolysis of cell wall polysaccharides and reduce substrates suitable for fermentation. These aromatics are diverse, existing as recalcitrant lignins (phenylpropanoids) of various types and also as the phenolic acids, i.e., ferulic and p-coumaric, that are ester-linked to carbohydrates. Research has been conducted to locate and identify the various types of aromatics within grass lignocellulose and to rank their role in recalcitrance to biodegradation. Enzyme pretreatment strategies may provide environmentally friendly methods for release of phenolic acids from lignocellulose for a potentially high-value co-product while improving ferment ability of the residue. Preliminary research using a commercial ferulic acid esterase, before saccharification with cellulase, showed a substantial increase in supernatant ferulic and p-coumaric acids, arabinose, xylose, and cellulose over cellulase treatment alone. The most appropriate cultivars of grasses were identified for pretreatment with esterases and initial results on the fermentation of enzyme-pretreated grass lignocellulose-indicated potential improvements in fermentation over non-esterase treated grasses.