OXIDATION OF ANTHRACENE AND BENZO[A]PYRENE BY LACCASES FROM TRAMETES-VERSICOLOR

The in vitro oxidation of the two polycyclic aromatic hydrocarbons ant hracene and benzo[a]pyrene, which have ionization potentials of less t han or equal to 7.45 eV, is catalyzed by laccases from Trametes versic olor. Crude laccase preparations were able to oxidize both anthracene and the potent carcinogen benzo[a]pyrene. Oxidation of benzo [a] pyren e was enhanced by the addition of the cooxidant 2,2'-azinobis(3-ethylb enzthiazoline-6-sulfonate) (ABTS), while an increased anthracene oxidi zing ability was observed in the presence of the low-molecular-weight culture fluid ultrafiltrate. Two purified laccase isozymes from T. ver sicolor were found to have similar oxidative activities towards anthra cene and benzo[a]pyrene. Oxidation of anthracene by the purified isozy mes was enhanced in the presence of ABTS, while ABTS was essential for the oxidation of benzo[a]pyrene. In all cases anthraquinone was ident ified as the major end product of anthracene oxidation, These findings indicate that laccases may have a role in the oxidation of polycyclic aromatic hydrocarbons by white rot fungi.