The degradation pattern of cellulose by extracellular cellulases of aerobic and anaerobic microorganisms

Abstract

Cellulose (150 mg) was incubated with equal amounts of carboxymethylcellulase activity (5·0 IU) from cell-free culture filtrates of Clostridium themocellum, Neocallimastix frontalis, Trichoderma koningii and Penicillium pinophilum. No change in the crystallinity index was detected during enzymatic hydrolysis from 1 to 7 days. This finding suggests the simultaneous solubilization of both crystalline and amorphous regions. Major differences between different enzymes were detected with respect to the length of the cellulose chains. Although a considerable weight loss of the cellulosic substrate occurred no change in the chain length distribution of cellulose could be detected with the C. thermocellum cellulases, whereas a considerable shift to smaller units was seen when cellulose was incubated with cellulases of all other microorganisms. The main soluble degradation product of C. thermocellum cellulase was cellobiose, whereas all other enzyme systems liberated glucose as the main soluble sugar.