Development of a robust enzyme cascade system: co-immobilization of laccase and versatile peroxidase on polyacrylamide hydrogel for enhanced BPA degradation.

Biodegradation using a synergically integrated system of laccase (E.C. 1.10.3.2) and versatile peroxidase (EC 1.11.1.16) co-immobilized on the polyacrylamide (PAM) hydrogel presents a promising solution for removing endocrine disrupting chemicals (EDCs) like bisphenol A (BPA) from wastewater. In this study, we developed a tailored biocatalyst consisting of a fungal laccase from Pleurotus ostreatus IBL-02 and versatile peroxidase, enzyme cascade co-immobilized covalently on a 7% (w/v) PAM hydrogel, offering high catalytic potential across various pH and temperature ranges. The PAM-VP/Lac structure was analyzed using scanning electron microscopy and Fourier-transform infrared spectrophotometry, revealing improved characteristics compared to free counterparts (FLac and FVP). The optimal pH for FLac, FVP, Lac/VP, and PAM-VP/Lac was 4, 5, 6, and 7, respectively. PAM-VP/Lac exhibited optimal activity at 50-60 °C, higher than FLac, FVP, and Lac-VP. PAM-VP/Lac showed superior operational stability, retaining 99.2% of its activity after eight cycles, with an immobilization efficiency of 78.62 ± 1.15% and activity recovery of 33.71 ± 0.2%. It also demonstrated enhanced thermal stability, with a two-fold increase in half-life at 50-70 °C. Thermodynamic analysis showed significant improvements in stability parameters for PAM-VP/Lac. This system achieved complete BPA degradation within two and a half hr, highlighting its potential for industrial-scale environmental remediation.