Developing novel enzyme repertoires for the efficient deconstruction of plant biomass tailored for the bioenergy industry

Abstract

Plant biomass, commonly referred to as lignocellulose, represents a renewable and thus sustainable substrate for the liquid biofuel and chemical industries, which is carbon dioxide neutral. There is much debate concerning the economic viability of lignocellulose-based liquid biofuels based, primarily, on the cost of the enzymes required to saccharify plant biomass into its component sugars. As a result there has been a substantial investment in enzyme technology targeted towards improving the efficiency of plant cell wall degradation. This Chapter provides an overview of our current knowledge of plant cell wall degrading enzymes at a structural and biochemical level. The article also describes strategies that can be deployed to discover novel, industrially significant, enzyme functions, and how protein engineering can be used to increase the catalytic efficiency of some enzymes, and broaden the substrate specificity of others. Finally the Chapter highlights the emerging importance of polysaccharide oxidases in lignocellulosic deconstruction focussing on the role these enzymes play in opening up the structure of crystalline cellulose, explaining how they are capable of potentiating the activity of glycoside hydrolases (cellulases) against these recalcitrant structures.