Covalent immobilization of Candida rugosa lipase on aldehyde functionalized hydrophobic support and the application for synthesis of oleic acid ester

This study focuses on Candida rugosa lipase (CRL) immobilization by covalent attachment on poly(ethylene terephthalate)-grafted glycidyl methacrylate (PET-g-GMA) fiber. The immobilization yielded a protein loading of 2.38?mg?g^-1 of PET-g-GMA fiber. The performances of the immobilized and free CRLs were evaluated with regard to hydrolysis of olive oil and esterification of oleic acid. The optimum activity pH of the CRL was changed by immobilization to neutral range. The maximum activity of the free and immobilized CRLs occurred at 40 and 45?°C respectively. The immobilized lipase retained 65% of its original activity at 50?°C for 2?h. It was found that the immobilized lipase stored at 4?°C retained 90% of its original activity after 35?days, whereas the free lipase stored at 4?°C retained 69% of its original activity after the same period. In the esterification experiments, the immobilized CRL could maintain a high activity at a water content range from 1.5 to 6% (v/v), while the activity of free CRL showed a clear dependence on water content and decreased rapidly at above 3% (v/v) water content. In addition, after five reuses, the esterification percent yield of the immobilized CRL slightly decreased from 29 to 27%.