On the mode of action of fungal cellulases

Summary The mode of action of the cellulolytic enzymes of two strong cellulose decomposing fungi, Penicillium oxalicum Curie et Thom and Helminthosporium cyclops Drechsler, was studied. The culture filtrates and enzyme preparations obtained from them showed high cellulase activity and very weak cellobiase activity. The cellulolytic system of both experimental organisms seems to be multicomponent. The cellulase component showed its activity mainly extracellulary and the cellobiase component, mainly intracellulary. It seems, therefore, that during growth of both fungi on a cellulose medium, the extracellular cellulase acts hydrolytically on the cellulose substrate forming cellobiose which is further acted upon by intracellular cellobiase to form glucose. Paper chromatographic assay of the products of the enzymatic reaction sub-stantiated this conclusion.