Green and sustainable approach for decoloration and detoxification of azo dye by bacterial-mediated thermo-halotolerant dye-decolorizing peroxidase (DyP)

Abstract

Textile dyes are common environmental pollutants, and their efficient removal from wastewater using green biocatalysts has attracted increasing attention. In this study, Serratia sp. AXJ-M exhibited the wilder substrate spectrum and high mineralization ability toward dye. The intensified bioactivity of DyP under oxidative stress (OS) promoted the decolorization of dyes. The DyP gene was cloned and heterologously expressed. The purified DyP was thermostable with an optimum temperature of 80 ℃and pH 9.0, and it was highly active under 50–80 ℃and pH 5.0–9.0. Furthermore, DyP was resistant to alkali, organic solvents and salt. The enzyme retained more than 65% residual activity at 900 mM metal ions and greater than 70% activity at 6 M NaCl. In addition, the organic solvents had no inhibitory effect on DyP activity. DyP was able to efficiently decolorize three different families of synthetic dyes without a mediator. DyP significantly decreased the target the parameters (TOC 90%, COD 85%, BOD 79% and color 80%) of dye wastewater and showed obvious detoxification based on systematic toxicity assessment using cell, bacteria, plant and animal models. Molecular docking deepens the understanding of the interaction between DyP and the dye. Thus, thermo-halotolerant-stable DyP has promising biotechnological application potential in textile wastewater bioremediation.