In order to evaluate the impact of xenobiotics on fungal communities of sediments, lentic ecosystems have been reconstituted in the laboratory and examined before as well as after contamination.
Microcosms (2 litres) have been treated with three different concentrations of pentachlorophenol (PCP) (3, 100, and 1000 mg 1-1) at 22 degC. The fungal strains present in the sediments were first isolated and identified before contamination with PCR Most of the strains belonged to Deuteromycetes (mainly Mucedinace~e and Dematiace~e) with a predominance of the genus Penicillium, and Ascomycetes were found in exceptional abundance. New isolations and identifications were made on days 1, 2, 4, 8, and 15 after contamination with PCP. The sensitivity of the various species were determined as a function of the level of PCP and the duration of contamination. Ascomycetes was particularly resistant to high concentrations of PCP. The toxicity of the xenobiotic towards strains belonging to various taxonomic groups is discussed, as well as the possibility that some of them may be useful for biodegradation and/or bioremediation processes, or as bioindicators of polluted sites.