Abstract:Lipase (EC 3.1.1.3) is one of hydrolases that specifically catalyzes the hydrolysis of triglyceride. It plays an important role in the food improvement, the health care, and the environment protection. The lipase of our interest here is produced by a marine microorganism YS2071 and has high enzymetic capability. Chitosan is a type of biological sources which possesses good biocompatibility and biodegradation. It is a natural, biological, and macromolecular polysaccharide, the solution of which is a non-toxic and functional gel. Therefore, chitosan is an excellent immobilization carrier. The separation and recycling of materials have been a challenge in the industrial production process. In this study we aimed to solve this problem by immoblizing YS2071 lipase on a chitosan microsphere. The properties of the immoblized lipase was compared to the free lipase to verify the immobilization method. The activity of the immobilized enzyme reached the maximum when the conditions were as below: 2% chitosan (m/v), 1% acetic acid concentration (v/v), 0.25% glutaraldehyde concentration (v/v), 12% sodium hydroxide concentration (m/v), crosslinking time 12 h, and 2 ml (1120 U) enzyme. The recovered activity of the immobilized lipase was 69.4%. The optimal temperature for the functions of the free lipase and the immobilized lipase was 40℃ and 45℃ respectively. The optimal pH for both the free lipase and the immobilized lipase was 8.0. It was also showed that immobilization obviously increased the stability of the temperature and pH. After 10-time reuse the recovered enzyme activity was still higher than 65%. The storage half-life of the immobilized lipase was 96 days while it was only 33 days for the free lipase. The free lipase and the immobilized lipase exhibited distinct stabilities in different organic reagents. These results suggested that the immobilized lipase might have great values in the industrial process.
