Immobilization of cellulase on modified mesoporous silica shows improved thermal stability and reusability

Cellulase was covalently immobilized using modified mesoporous silica as carrier, and the characters of immobilized cellulase were investigated including the optimum pH, the optimum temperature, thermal stability, reusability, storage stability and enzyme kinetics. As compared to the free enzyme, the optimum pH of the immobilized cellulase showed no changes, the optimum temperature showed a slight increase to 60°C. The immobilized enzymes demonstrated enhanced thermal stability, while the free enzymes lost almost 40% initial activity, the immobilized forms lost only 9% initial activity within a period of 120 min at 60°C. The immobilized cellulase showed excellent reusability. After 11 cycles, the cellulase immobilized on modified mesoporous silica still retained 89% of its initial activity. At optimized conditions, Km and Vmax values for the immobilized enzyme were slightly increased when compared with those of free enzyme. The characters of cellulase immobilized on modified mesoporous silica suggest that the immobilized enzyme has high potential for application in the industrial degradation of cellulose.   Key words: Renewable energy, cellulose, immobilization, mesoporous silica, cellulose.