The effect of pH on the production of cellulases in Aspergillus terreus

Summary

The optimal pH for the production of extracellular cellulolytic enzymes in the wild strain of Aspergillus terreus was shown to be pH 5.0. After 160 h of cultivation, carboxymethyl cellulase reached 9.0 IU/ml, filterpaper, cellulase 0.5 IU/ml and β-glucosidase 0.9 IU/ml. The rate of synthesis of CM- and FP-cellulases decreased after 90 h of cultivation but β-glucosidase was produced linearly for 160 h. Some of the enzymes produced were released into the medium during the fungal growth while others remained bound. The binding of enzymes to cells and residual crystalline cellulose was strongly affected by the pH of the medium. FP-cellulase and particularly β-glucosidase were bound more effectively, at lower pHs. Cold shock treatment of the cell suspension increased the activities of FP- and CM-cellulases but β-glucosidase activity was not affected.