Monday, April 30, 2007 - 9:30 AM

Enzymatic hydrolysis of lignocellulosics at high ethanol concentration

Alex Berlin, Kate Leinweber, Pablo Chung, Vera Maximenko, and Jack Saddler. Forest Products Biotechnology, Wood Science, The University of British Columbia, 4609-2424 Main Mall, Vancouver, BC V6T1Z4, Canada

In the past five years we have witnessed unprecedented research efforts focused on the improvement of the catalytic properties of biomass-degrading enzymes. The majority of applied strategies have been based on the search for isolated enzyme components with higher catalytic performance on the cellulose component of lignocellulosic biomass. Very little or no attention has been paid to approaches pursuing enhancement of enzyme stability or reduction of enzyme inhibition in severe environments such as those characterized by the presence of high concentration end-products (glucose, xylose, or ethanol). It is now clear that in order to achieve techno-economic feasibility lignocellulose-to-ethanol technologies will require for the enzymatic hydrolysis to be run at high concentrations of pretreated lignocellulosic solids (≥25% w/w) and most likely in a simultaneous saccharification and fermentation (SSF) technological scheme. Therefore, it is then expected that enzymatic hydrolysis of biomass will have to occur in an environment with relatively high concentration of end-products (≥5-15% w/w ethanol in the case of SSF). This presentation will describe the results of our studies on the effect of high ethanol concentrations on enzyme activity of cellulases and hemicellulases during hydrolysis of lignocellulosics (softwoods, hardwoods, and agricultural residues). It will include a detailed study of the mechanism of these inhibitory effects and it will propose feasible strategies to overcome this problem.