Location, kinetics and stability of cellulases induced in Trichoderma reesei cultures

Amorphous cellulose induced the synthesis of endoglucanase in Trichoderma reesei to a greater extent than did cellobiose, lactose, sucrose or other commercial celluloses. In contrast, none of these carbohydrates was able to induce significant levels of endoglucanase activity in Aspergillus niger or Pseudomonas pickettii. Both endoglucanase and β-glucosidase activities were found in cell wall, cell-free extracts and extramycelial fractions of Trichoderma reesei cultures grown on amorphous cellulose. When carboxymethyl cellulose was used as substrate, Km and Vmax values of 1.32% (w/v) and 405.5 μmol glucose ml−1 h−1 for carboxymethyl cellulase were obtained Additionally, the activity was maximum over a pH range of 4.5–5.5, declining sharply beyond 5.5. The optimum temperature was between 50 and 70°C, with maximum activity at 60°C. The half-life of the enzyme appeared to be 9.4 h at 55°C and 4.3 h at 60°C.