Kinetics of cellulose saccharification by Trichoderma reesei cellulases

In order to optimize the enzymatic hydrolysis of three celluloses (carboxymethyl cellulose, powdered cellulose and microgranular cellulose), the effect of varying enzyme and substrate concentration, temperature and pH was studied. The best experimental conditions found to degrade the celluloses were 48 h of incubation, an enzyme concentration of 7 U ml(-1) for the cellulases and 0.1 U ml(-1) for the beta -glucosidase (from A. niger) and a substrate concentration of 0.5%. Under these conditions, carboxymethyl, powdered and microgranular celluloses were degraded 11.2, 40.2 and 15.8%, respectively. Results suggested that cellulases induced in the presence of each substrate were able to hydrolyze more effectively, if substrate concentration was similar to that used in the induction of enzymes. The rate of saccharification of Sigmacell 100 at high substrate concentrations was 93% lower than the maximum rate observed with 0.5% cellulose. Differences in the degree of substrate inhibition when using different substrates were particularly relevant to the experimental design of comparative studies. (C) 2001 Elsevier Science Ltd. All rights reserved.