Complete wastewater discoloration by a novel peroxidase source with promising bioxidative properties

Abstract

Abstract BACKGROUND Our study aimed to characterize and prospect immobilization strategies for a novel fungal peroxidase (POD) and insert it in pollutant remediation context. The enzymatic extract was obtained by submerged fermentation of Trichoderma koningiopsis in an alternative substrate consisting of fresh microalgal biomass. The immobilization efficiency was evaluated by monitoring the residual activity (RA) and the discoloration potential (DP) of a synthetic dye solution. Concomitantly, the POD catalytic properties were explored, and the most promising storage strategy to maintain the enzymatic activity was studied. RESULTS The novel and non‐purified guaiacol peroxidase from T. koningiopsis expressed a specific activity of up to 7801 U mg −1 in the free form, showing stability when subjected to up to 80 °C in a pH range between 4.0 and 8.0. Furthermore, the bioproduct immobilized on Fe 3 O 4 magnetic nanoparticles, named magnetic nanozymes (MN‐POD), expressed up to 689% RA and 100% removal for the Direct Brown 27 dye. An increase in the enzymatic activity, in both free and immobilized forms, was also observed after storage for up to 8 months. The synthesized magnetic nanozymes showed good reusability, maintaining 13 546 U mg −1 after 10 cycles, and removing 94% of color in a second batch. Toxicological evaluation with Allium cepa indicated that the enzymatic discoloration process with immobilized POD was essential for eliminating genotoxic effects. CONCLUSION The T. koningiopsis peroxidase production and immobilization presented in this work are promising for the enzyme market and for wastewater treatment technologies due to their high bioxidative potential. © 2022 Society of Chemical Industry (SCI).