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

Abstract

BACKGROUND Our study aimed to characterize and prospect immobilization strategies for a novel fungal peroxidase - POD (EC 1.11.1.7) and to insert it in the context of pollutant remediation, since these compounds pose risks to human and environmental health. The enzymatic extract was obtained by submerged fermentation of the fungus 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 catalytic properties of free POD were explored, and the most promising storage strategy to maintain the enzymatic activity was studied. RESULTS The novel guaiacol peroxidase expressed 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 4.0-8.0. Furthermore, the bioproduct immobilized on magnetic nanoparticles expressed up to 689% RA and 100% DP. An increase in the RA of the enzyme, both in free and immobilized form, was also observed after storage for up to 8 months. The synthesized magnetic nanozymes showed good reusability, maintaining 13546 U mg−1 after ten cycles and removing 94% of color in a second batch. Toxicological evaluation with Allium cepa indicated that the enzymatic process of color removal with immobilized POD was essential to eliminate genotoxic effects. CONCLUSION T. koningiopsis peroxidase production and immobilization presented in our work are promising for the enzyme market and for the wastewater treatment technologies, considering its high bioxidative potential.