Preparation and properties of an immobilized cellulase on the reversibly soluble matrix Eudragit L-100

To prepare a smart biocatalyst, cellulase was immobilized on the reversibly soluble matrix Eudragit L-100 by non-covalent and covalent methods. Covalent immobilization using carbodiimide coupling exhibited superior enzyme loading and reusability compared with non-covalent immobilization, and the covalent loading was increased by almost 20% through the addition of N-hydroxysuccinimide. The temperature optimum of the cellulase was not improved apparently by immobilization but the pH optimum increased from 4.75 to 5.25. Immobilized cellulase was more active than free cellulase above pH 5.0. Immobilized cellulase was more stable than free cellulase during storage at 4°C, room temperature and 50°C. Km values of immobilized and free cellulase were 85.55 and 73.84 g L−1, respectively. About 50% productivity was retained after five cycles for hydrolysis of steam-exploded straw.