Immobilization of Trametes Versicolor laccase on Cu-alginate beads for biocatalytic degradation of bisphenol A in water: Optimized immobilization, degradation and toxicity assessment

The present work investigated the immobilization of laccase ( Trametes versicolor ) on Cu-alginate beads by entrapment method and its utilization to degrade bisphenol A (BPA) in aqueous medium. The immobilized laccase demonstrated higher storage stability as compared to free enzyme. Box-Behnken experimental design was used to optimize the immobilization conditions (sodium alginate concentration, CuSO 4 molarity, and hardening time). The optimal conditions were found to be 3% sodium alginate concentration (W/V), 0.141 mM CuSO 4 and 90 min hardening time. Experimental data exhibited that immobilized laccase (0.5 g) could degrade 96.12% of BPA (10 mg/L) at pH 5.0, 30°C, 150 rpm and 1 h of reaction. The degradation products of BPA were identified by LC-MS analysis; hence the degradation pathways were suggested. The toxicity of BPA products was judged by phytotoxicity test. Immobilized laccase could also degrade BPA in real water, hence could be considered as an efficient candidate for removing BPA in water.