The Immobilization Of Candida Lipase

Lipases are the third largest industrial enzymes in the world. They come from the various sources. The special immobilization method and carrier shoud be applied for the certain lipase.The choice of the ideal carriers and the immobilization methods are always the research hotspot in the field of the enzyme immoblization.In the first chapter of this thesis, the fermentive conditions for the lipase production by Candida lipolytica were studied.The yield of lipase increased by 10% and the clarification degree of the fermentation broth was also improved. The clear broth was necessary for the following purification of the lipase.A new and excellent purification process had been developed.The lipase recovery rate was high and reached to 86.5% after the two-steps column chromatography packed with two types of the resins. The first one was the macroporous resin and the next one was DEAE-agarose ion exchange resin. The operation was fast and quite simple, the cost was low.Lipase from Candida lipolytica was respectively immobilized on two kinds of the carriers, one was chitosan (highly hydrophilic) and the other was 3-aminopropyl silica gel (lower hydrophilic), using glutaraldehyde as the crosslinking agent. The activity of the immobilized lipase on chitosan reached the maximum when the 2.5% of glutaraldehyde and 4125U/g of the enzyme supply were used. The optimal glutaraldehyde concentration and enzyme supply was 2% and 3456U/g respectiviely when 3-aminopropyl silica gel was used as the immobilization carrier. The stability of the immobilization lipases against the temperatures were remarkably enhanced than the free enzyme and can be stored for the longer time at room temperature and 4℃. The immoblilied lipase on 3-aminopropyl silica gel still kept 14% of the initial activity after 3 hours' storage at 50℃. The results showed that 3-aminopropyl silica gel was the better immobilized carrier than chitosan.