Oxidation of polycyclic aromatic hydrocarbons by laccase of Coriolus hirsutus

The oxidation of five polycyclic aromatic hydrocarbons; anthracene, benzo(alpha)pyrene, fluoranthene, phenanthrene and pyrene was catalyzed by laccase from Coriolus hirsutus in the presence of the redox mediators, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). In the ABTS-mediated system, benzo(alpha)pyrene was the most rapidly oxidized substrate, with anthracene being the most rapidly oxidized in the HBT-mediated system. There was no clear relationship between the ionization potential and the oxidation of the substrates. ABTS increased the oxidation of benzo(alpha)pyrene more than HBT but the oxidation of the other PAHs tested were the opposite. The mediators used in conjunction increased the oxidation of benzo(alpha)pyrene compared to using the mediators alone.