Enhancing cellulase commercial performance for the lignocellulosic biomass industry

Cellulase enzyme loading is one of the key challenges identified in the Biomass Program of DOE/EERE for the economic conversion of lignocellulosic biomass to ethanol. The goal of DuPont’s project, which ran from 2008 to 2012, was to address the technical challenge by creating more efficient enzymes that could be used at lower doses, thus reducing the enzymes’ cost contribution to the conversion process. We took the approach of protein engineering of cellulase enzymes to overcome the enzymatic limitations in the system of cellulosic-hydrolyzing enzymes to improve performance in conversion of biomass, thereby creating a more effective enzyme mix.

By protein engineering, we were able to improve the performance of our enzymes in a whole cellulase enzyme mixture and achieved a 4-fold reduction of enzyme dose for hydrolysis of an acid pretreated corn stover as compared to the starting-point Benchmark Enzyme mixture. We engineered four important enzymes, and designed screens that led to the identification of enzyme variants with improved properties including improved overall efficiency, improved thermal performance and/or reduced product inhibition. We successfully engineered our enzymes such that they, acting together and synergistically, confer substantial and real improvements under saccharification process-relevant conditions.