Laccase-Mediated Oxidative Degradation of the Herbicide Dymron

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Abstract
The present study reports the successful and effective degradation of the persistent herbicide dymron catalyzed by the oxidative enzyme laccase in the presence of a reaction mediator (a laccase/mediator system). Using 2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the mediator, over 90% of dymron was degraded within 24 h, while the half-life of dymron is 50 days in soil. The results suggested that oxidation of dymron resulted in the production of decomposed compounds with a single aromatic ring. We also found that edible surfactants and a dishwashing detergent were useful to solubilize dymron in an aqueous solution and did not inhibit the oxidative degradation. Degradation proceeded at acidic pH and in a broad range of temperatures (303-353 K). The use of natural mediators also allowed the oxidative degradation of dymron to some extent. In conclusion, we propose the possible use of a laccase/mediator system for the treatment of soils and drainwater contaminated with herbicides.