7-36: Improved cellulases for high temperature saccharification of lignocellulose

Production of fuels and chemicals from lignocellulosic biomass holds the potential to displace petroleum-based processes, promoting energy self-sufficiency and reducing environmental costs. However, the recalcitrance of cellulose to enzymatic hydrolysis has so far remained a barrier to industrial utilization of lignocellulose. This presentation will give an overview of Novozymes’ progress in developing robust enzyme systems capable of cost-effectively converting cellulose and hemicellulose to sugars on a variety of biomass feedstocks over a broad range of pH and temperature conditions, with specific emphasis on developing improved cellulases for high-temperature saccharification of lignocellulosic biomass. The hydrolysis at elevated temperatures has a number of advantages over conventional saccharification at 50ºC, including reduced hydrolysis time, decreased risk of microbial contamination, and reduced viscosity of biomass slurries. Several approaches for improving the hydrolysis efficiency of our current Trichoderma reesei enzyme systems will be described, including (1) replacing existing components with improved components, (2) supplementing the T. reesei cellulase system with novel synergistic proteins, and (3) optimizing synergies between essential components. The iterative improvements are driven by broad screening of naturally occurring cellulolytic systems and subsequent protein engineering to solve some of the problems that have been identified with certain enzyme components. The development of improved enzyme mixtures for hydrolysis of dilute-acid pretreated corn stover (PCS) from NREL within the US DOE co-funded Project DECREASE will be described, and ample experimental evidence showing that the enzyme performance improvements obtained on NREL PCS translate to a wide variety of commercially relevant substrates will be presented.