Thermo-active and alkaliphilic amalgamated laccase immobilized on sodium alginate for synthetic dye decolourization

Purified crude laccase of Enterobacter sp. Kamsi and Bacillus sp. NU2 in the hybrid and combined form was immobilized on sodium alginate beads and applied to decolourize various textile dyes through several decolourization reaction cycles. The enzyme/alginate (E/A) loading efficiency and immobilization yield were evaluated. The SEM-EDX analysis, pH, and temperature effects of both forms of immobilized laccases were examined. The maximum condition for Kamsi and NU2 laccases into Na-alginate beads is 2.5% (w/v), which resulted to >83 and 61.71% immobilization and loading efficiency, respectively. The SEM-EDX analysis showed a rough-spherical surface attributable to significant entrapment of the laccase at the centre of the beads. The hybrid laccase in the free and immobilized form showed >52% and 80% decolourization effects, while the amalgamated laccase showed >63 and 83% decolourizing effect on Malachite Green (MG), Remazol Brilliant Blue R (RBBR), Reactive Blue 4 (RB4), Congo Red (CR), and Methyl Orange (MO), respectively. The immobilized laccase retained >50 and 81% activity of the hybrid and amalgamated laccases, respectively, after six successive treatment cycles. The results showed that the immobilization technique of the Kamsi and NU2 laccase holds the potential for textile dye effluents degradation, but the amalgamation of an enzyme from different species could improve decolourization potentials for various dyestuff treatments.