Optimization of encapsulation of a microbial laccase enzymatic extract using selected matrices

The encapsulation of the laccase extract, obtained from Coriolus hirsutus, was investigated using selected matrices, including alginate, alginate-silica and silica sol-gel. Two methods, M1. and M2, were carried out for the hybridization of alginate with silica. The experimental findings indicated that the incorporation of silica into alginate, using M2, resulted by a higher (70%) encapsulation efficiency (EE) for the laccase extract as compared to that for the alginate (59%) alone. Furthermore, the encapsulation of the laccase extract in sol-gel resulted in an enhancement of its catalytic activity, with a concomitant increase (90%) in the EE. The alginate and sol-gel matrices also enhanced the laccase catalytic efficiency as compared to that for the free one, with a k(cat) of 89.9, 63.7 and 56.9 min(-1), respectively. The protein release profiles indicated that the laccase was more effectively confined in the sol-gel and alginate-silica M2 as compared to that for the alginate and alginate-silica M1. In addition, the laccase extract in sol-gel exhibited an enhanced re-usability, with a relative residual enzyme activity of 82.7%, after 5 continuous reaction cycles. The alginate, alginate-silica M2 and sol-gel matrices demonstrated complete storage stability at 4 degrees C, without any loss in laccase activity after 6 weeks of storage.