Advanced oxidation of benzene, toluene, ethylbenzene and xylene isomers (BTEX) by Trametes versicolor

Advanced oxidation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) by the extracellular hydroxyl radicals ((OH)-O-center dot) generated by the white-rot fungus Trametes versicolor is for the first time demonstrated. The production of (OH)-O-center dot was induced by incubating the fungus with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-EDTA. Under these conditions, (OH)-O-center dot were generated through DBQ redox cycling catalyzed by quinone reductase and laccase. The capability of T. versicolor growing in malt extract medium to produce (OH)-O-center dot by this mechanism was shown during primary and secondary metabolism, and was quantitatively modulated by the replacement of EDTA by oxalate and Mn2+ addition to DBQ incubations. Oxidation of BTEX was observed only under (OH)-O-center dot induction conditions. (OH)-O-center dot involvement was inferred from the high correlation observed between the rates at which they were produced under different DBQ redox cycling conditions and those of benzene removal, and the production of phenol as a typical hydroxylation product of (OH)-O-center dot attack on benzene. All the BTEX compounds (500 mu M) were oxidized at a similar rate, reaching an average of 71% degradation in 6 h samples. After this time oxidation stopped due to 02 depletion in the closed vials used in the incubations. (C) 2010 Elsevier B.V. All rights reserved.