Lignocellulose degradation: An overview of fungi and fungal enzymes involved in lignocellulose degradation

Abstract

This review aims to present current knowledge of the fungi involved in lignocellulose degradation with an overview of the various classes of lignocellulose-acting enzymes engaged in the pretreatment and saccharification step. Fungi have numerous applications and biotechnological potential for various industries including chemicals, fuel, pulp, and paper. The capability of fungi to degrade lignocellulose containing raw materials is due to their highly effective enzymatic system. Along with the hydrolytic enzymes consisting of cellulases and hemicellulases, responsible for polysaccharide degradation, they have a unique nonenzymatic oxidative system which together with ligninolytic enzymes is responsible for lignin modification and degradation. An overview of the enzymes classification is given by the Carbohydrate-Active enZymes (CAZy) database as the major database for the identification of the lignocellulolytic enzymes by their amino acid sequence similarity. Finally, the recently discovered novel class of recalcitrant polysaccharide degraders-lytic polysaccharide monooxygenases (LPMOs) are presented, because of these enzymes importance in the cellulose degradation process.

Keywords: Biological pretreatment; Carbohydrate active enzymes; Fungi and fungal enzymes; Lignocellulose degradation; Plant cell wall.

Figure 1

Scheme of the enzymatic degradation of cellulose chain via synergistic interaction of cellulases (endoglucanase, exoglucanase, and β‐glucosidase) and LPMO (AA9 or 10) enzymes.