In addition to specific bacteria, white rot fungi (WRF) have been shown to perform efficient degradation of a wide spectrum of PAHs, due to their relative non specific oxidative enzyme systems. However, toxic degradation intermediates may be produced and accumulate. Therefore, the project covers simultaneous and successive biodegradation of recalcitrant 3- to 5-ringed PAHs by WRF and activated sludge bacteria in both artificially and industrially contaminated soils and sediments. Biodegradation of PAHs is detected and resulting changes in toxicity of the bioremediated soils and sediments are monitored using a battery of ecotoxicity tests. Major products of PAH biodegradation are being characterised.