Characterization and evaluation of the immobilized laccase enzyme potential in dye degradation via one factor and response surface methodology approaches

Abstract

In the current study, calcium alginate was used as a carrier for Agaricus bisporus CU13 laccase immobilization, with an immobilization yield of the entrapped laccase of 91.95%. Free and immobilized enzymes showed their best enzyme activity at 60 °C as an optimum temperature. Free laccase was nearly completely inactivated at high temperatures (70 and 80 °C C) after 30 min, whereas the immobilized form retained around 60 and 40% of its activity after 30 min at the same temperatures. The metal ion of MgSO₄ showed the best impact on the Agaricus bisporus laccase activity with a relative activity of 113.1 and 106.8% at concentrations of 10 mM and 2.5 mM, respectively. The best Cibacron D-Blue SGL dye degradation by laccase enzyme was obtained at pH 6.0, 0.354 U of laccase, and 100 mg/L of dye using hydroxybenzotriazole (HBT; 1 mM) as a mediator. Optimization ramps obtained from the central composite design (CCD) approach indicate that the rate at which the laccase enzyme decolorizes dye has increased significantly when the concentrations of the enzyme, and HBT increased, whereas dye concentration decreased. Finally, the immobilized enzyme was found to be efficient in decolorizing Cibacron D-Blue SGL dye in the presence of HBT as a mediator for different cycles.