Bioremediation of pollutants by xenobiotic ligninolytic fungi

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Methods of degradation of dioxins and PCBs by white rot fungi were developed. Degradation of a mixture of total 10 kinds of tetra to octa of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), which were chlorinated 2-, 3-, 7- and 8-positions of the molecules, by white rot fungi Phanerochaete sordida YK-624 was studied in a stationary low nitrogen medium. The degradation rates of PCDDs and PCDFs were ca.40 (tetrachloro-) -76 (hexachloro-) % and 45 (tetrachloro-) -70 (hexachloro) %, respectively. Of PCDDs, metabolites of 2,3,7,8-tetrachloro-, and 1,2,3,4,6,7,8,9-octa-, dibenzo-p-dioxin by P.sordida YK-624 were studied and 4,5-dichloro-1,2-benzoquinone and 3,4,5,6-tetrachloro-1,2-benzoquinone were confirmed as oxidatitive cleavage products of dibenzodioxin nuclus. PCBs were first hydroxylated and then C-C bonds were cleaved to form benzoic acid derivatives. These results suggested that the white rot fungi are substantially able to degrade both PCDDs/PCDFs and PCBs. In conclusion, this is the first report on the degradation of highly chlorinated PCDDs and PCDFs by microorganisms.