EFFICIENT CELLULOSE SOLUBILIZATION BY A COMBINED CELLULOSOME-BETA-GLUCOSIDASE SYSTEM

The cellulosome, the multienzyme complex of the cellulase system of Clostridium thermocellum, that mediates the solubilization of insoluble cellulose, is strongly inhibited by the major end product, cellobiose. By combining a purified beta-glucosidase from Aspergillus niger with the cellulosome, accumulated cellobiose was hydrolyzed thereby resulting in a dramatic enhancement (up to 10-fold) of cellulose degradation. The observed enhancement was expressed both in the rate and degree of solubilization of microcrystalline cellulose, compared with that observed for the unsupplemented cellulosome. Near-complete conversion of cellulose to glucose could be obtained from dense substrate suspensions (up to at least 200 g/L).