Degradation of crystalline cellulose by the brown-rot basidiomycete Fomitopsis palustris.

This study demonstrated that the brown rot basidiomycete Fomitopsis palustris was able to degrade crystalline cellulose (Avicel). This fungus could also produce the three major cellulases (exoglucanases, endoglucanases, and beta-glucosidase) when the cells were grown on 2.0% Avicel. Avicel degraded by F. palustris showed a decrease in relative crystallinity from 83% to 78.5% after 14 days of incubation. The characterization study indicated that optimum pH was 4.5 and optimum temperature was 70 degrees C for exoglucanase (cellobiohydrolase) activity. Hydrolysis of Avicel by the crude enzyme from F. palustris yielded 1.6 mg/ml of glucose after 43 h, which corresponded to a cellulose conversion degree of 3.2%. Therefore, this study revealed for the first time that the brown rot basidiomycete F. palustris produces cellulases capable of yielding soluble sugars from crystalline cellulose.