| Summary: | In this study, a laccase LAC-Yang1 was successfully purified from a white-rot fungus strain <i>Pleurotus ostreatus</i> strain yang1 with high laccase activity. The enzymatic properties of LAC-Yang1 and its ability to degrade and detoxify chlorophenols such as 2,6-dichlorophenol and 2,3,6-trichlorophenol were systematically studied. LAC-Yang1 showed a strong tolerance to extremely acidic conditions and strong stability under strong alkaline conditions (pH 9–12). LAC-Yang1 also exhibited a strong tolerance to different inhibitors (EDTA, SDS), metal ions (Mn<sup>2+</sup>, Cu<sup>2+</sup>, Mg<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>, Zn<sup>2+</sup>, Al<sup>3+</sup>, Co<sup>2+</sup>, and metal ion mixtures), and organic solvents (glycerol, propylene glycol). LAC-Yang1 showed good stability in the presence of Mg<sup>2+</sup>, Mn<sup>2+</sup>, glycerol, and ethylene glycol. Our results reveal the strong degradation ability of this laccase for high concentrations of chlorophenols (especially 2,6-dichlorophenol) and chlorophenol mixtures (2,6-dichlorophenol + 2,3,6-trichlorophenol). LAC-Yang1 displayed a strong tolerance toward a variety of metal ions (Na<sup>2+</sup>, Zn<sup>2+</sup>, Mn<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and metal ion mixtures) and organic solvents (glycerol, ethylene glycol) in its degradation of 2,6-dichlorophenol and 2,3,6-trichlorophenol. The phytotoxicity of 2,6-dichlorophenol treated by LAC-Yang1 was significantly reduced or eliminated. LAC-Yang1 demonstrated a good detoxification effect on 2,6-dichlorophenol while degrading this compound. In conclusion, LAC-Yang1 purified from <i>Pleurotus ostreatus</i> has great application value and potential in environmental biotechnology, especially the efficient degradation and detoxification of chlorophenols.
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