1B-06

Can Cellulase Adsorption on Lignin be Reduced?

Bin Yang* and Charles E. Wyman

Thayer School of Engineering

Dartmouth College

Hanover, NH 03755

Phone: (603) 646-3193

Fax: (603) 646-2277

E-mail: bin.yang@dartmouth.edu

Cellulase adsorption on cellulose is vital to achieving high yields of glucose from cellulosic biomass by enzymatic hydrolysis processes, and the surface area of cellulose available to cellulase is a potential determinant of hydrolysis rates and yields. However, not all cellulase acts effectively due to its non-specific adsorption on non-cellulose components such as lignin, hurting performance. In this study, we developed a new treatment by ingredients that preferentially attach to lignin to reduce nonproductive adsorption of cellulase components while leaving cellulose accessible to enzymes. Depending on prior biomass pretreatment conditions, this treatment enhanced yields from lignin containing biomass by 5-20% and 5-15% for enzymatic saccharification alone and simultaneous saccharification and fermentation (SSF), respectively. Alternatively, this approach can reduce enzyme loadings to achieve the same yields in saccharification alone or SSF. Experimental evidence suggests that non-productive adsorption of beta-glucosidase is particularly reduced, lowering supplementation requirements. In addition, initial enzymatic hydrolysis rates could be correlated with maximum cellulase adsorption for treated substrates. Based on this finding, a new method was devised to measure the specific surface area of cellulose in pretreated substrates at operational hydrolysis temperatures, leading to a kinetic model to predict the performance of enzymatic hydrolysis of pretreated substrates.