Decontamination of PAH polluted soils by fungi. Subproject: PAH degradation balance and testing of the extended laboratory process. Final report

The aim of the research project was first to select a fungus with a high potential for mineralization of polycyclic aromatic hydrocarbons (PAH) and a good ability to colonize different soils. The application of this fungus for a degradation of PAH in soil had to be tested. In a screening of 57 white rot fungi the fungus Pleurotus sp. Florida fulfilled these requirements best. In pure culture it was able to metabolize and mineralize highly condensed 4-6 ring PAH to a great extent. For instance, up to 50% of 14C-pyrene or 39% of 14C-benzo(a)pyrene was mineralized to 14CO2 within 15 weeks. If different carriers for 14C-pyrene were used the mineralization correlated with the bioavailability, which was characterized by the desorption of the compound from the carriers with water. The mineralization of 14C-pyrene, 14C-benz(a)anthracene; 14C-benzo(a)-pyrene and 14C-dibenz(a, h)anthracene in native soils showed that a colonization with Pl. sp Florida inhibited the degradation of the less recalcitrant 14C-pyrene by the indigenous soil microflora. However, the mineralization of the carcinogenic, very recalcitrant and high condensed 14C-PAH was considerably supported by the fungus. Therefore this capabilities of the fungus could not be proven in a joint medium-scale soil experiment (0.8 m3 soil) which had been conducted within a parmership with scientists in Jena and an industriell firm. Because of safety aspects only the low condensed less recalcitrant PAH could be applied in this experiment. (orig./MG)