Immobilization of laccase by alginate-chitosan microcapsules and its use in dye decolorization

Laccase is a ligninolytic enzyme that is widespread in white-rot fungi. Alginate-chitosan microcapsules prepared by an emulsification-internal gelation technique were used to immobilize laccase. Parameters of the immobilization process were optimized. Under the optimal immobilization conditions (2% sodium alginate, 2% CaCl2, 0.3% chitosan and 1:8 ratio by volume of enzyme to alginate), the loading efficiency and immobilized yield of immobilized laccase were 88.12% and 46.93%, respectively. Laccase stability was increased after immobilization. Both the free and immobilized laccase alone showed a very low decolorization efficiency when Alizarin Red was selected for dye decolorization test. When 0.1 mM 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was added into the decolorization system, the decolorization efficiency increased significantly. Immobilized laccase retained 35.73% activity after three reaction cycles. The result demonstrated that immobilized laccase has potential application in dyestuff treatment.