Characterization of the Enzymatic and Biosorption Processes Involved in the Decolorization of Remazol Brilliant Blue R Dye by Pleurotus ostreatus Pellets

Synthetic dyes are highly recalcitrant and are discharged in large volumes in industrial wastewater, which represents a serious environmental pollution problem. Biological methods for dye degradation are a potentially effective option for these synthetic products. In this study, a strain of Pleurotus ostreatus was used to evaluate the decolorization of the Remazol Brilliant Blue R (RBBR) dye added to the culture medium in the exponential growth phase of the fungus. The dye removal capacity of live and inactivated pellets by biosorption, as well as the enzymatic degradation of the dye using a cell-free culture broth considered an extracellular extract (EE), were also evaluated. The activity of laccase and dye-decolorizing peroxidase was determined in both the EE and the intrapellet extract (IPE); their values increased in the presence of dye in the culture medium. A decolorization of 98.5% and 98.0% was obtained in the culture broth and by the EE, respectively; biosorption of the dye by the inactivated pellets was 17 mg/g. The results suggest that the decolorization of the dye is primarily enzymatic, although there are also bioadsorption and bioaccumulation of the dye, which is then enzymatically degraded, and could be used as a carbon source.