Pre-treatment of cellulose by cellobiose dehydrogenase increases the degradation rate by hydrolytic cellulases

Cellobiose dehydrogenase (CDH) is an extra-cellular flavocytochrome with unknown biological function, produced by various wood degrading fungi. In the presence of Fe(III) and cellobiose, CDH produces hydroxyl radicals through a Fenton-type reaction. Treatment of cellulose with CDH, cellobiose, hydrogen peroxide and ferriacetate decreased cellulose's polymerization degree and increased its degradability for different functional types of hydrolytic cellulases, except for an exo-enzyme working from the reducing end. This suggests a biological role for CDH in fungal cellulose degradation, possibly by activating the cellulose for hydrolytic cellulases by depolymerization and disturbance of the hydrogen bonding pattern in cellulose.