Complete saccharification of β-glucan using hyperthermophilic endocellulase and β-glucosidase from Pyrococcus furiosus

Hyperthermophilic cellulase is an industrially important enzyme for biomass saccharification at high temperature. Two hyperthermophilic cellulases from the hyperthermophile Pyrococcus furiosus, endocellulase (EGPf) and beta-glucosidase (BGLPf), exhibit optimal activity at 90-105 degrees C and a combination of two enzymes can hydrolyze a wide range of beta-linked substrates. EGPf cleaves the beta(1 -> 4) bond of various substrates containing either only the beta(1 -> 4) linkage or beta(1 -> 3),(1 -> 4) mixed-linkages. In contrast, BGLPf preferentially hydrolyzes the beta(1 -> 3) linkage over the beta(1 -> 4) linkage of disaccharides. beta-Glucans are polysaccharides of D-glucose monomers formed by beta(1 -> 3),(1 -> 4) mixed-linkage bonds. They occur most commonly as cellulose in plants, in the bran of cereal grains, the cell wall of baker's yeast, and in certain fungi, mushrooms, and bacteria. We reveal that beta-glucan can be completely degraded to glucose at high temperature with a combination of EGPf and BGLPf.