Polycyclic aromatic hydrocarbon biodegradation in extracellular fluids and static batch cultures of selected sub-tropical white rot fungi

Four sub-tropical white rot fungi, Trametes versicolor, Trametes pocas, Trametes cingulata and isolate DSPM95 were studied alongside the well studied white rot fungus, Phanerochaete chrysosporium, for their ability to remove polycyclic aromatic hydrocarbons (PAHs) from culture media. Both static shallow cultures and extracellular fluids were studied using media contaminated with a defined mixture of the PAHs; fluorene, phenanthrene, anthracene, pyrene and benzo(a)anthracene. With all isolates, the total loss of the parent compound in 31 days was high for fluorene, at +60%, phenanthrene at +40% and anthracene at +42%. Biotransformation of pyrene and benzo(a)anthracene by all the isolates was low, with the highest reduction of pyrene of 15.2% and benzo(a)anthracene of 15.8% being achieved with P. chrysosporium. Disappearance of the more condensed PAHs, pyrene and benzo(a)anthracene, increased in shallow static cultures with the addition of glucose and glucose oxidase as a source of additional H2O2. The addition of Mn2+ and ABTS (2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)) to culture supernatants was associated with higher levels of biotransformation. Comparison of the isolates T. versicolor, T. pocas, T. cingulata and isolate DSPM95 with P. chrysosporium showed that these strains were competitive in the reduction of the PAHs, reducing the PAHs by more or less the same magnitude. Also these sub-tropical isolates did not accumulate a lot of HPLC detectable metabolites as much as P. chrysosporium.