Cytochrome P450 content in gut of earthworm (Eisenia fetida) for monitoring PAHs contaminated soil

Polycyclic aromatic hydrocarbons (PAH) are known to be pollutants in soil, however there are no effective methods available for determining their ecotoxic effects. We investigated Cytochrome P450 (P450) in earthworms (Eisenia fetida) as a potential biomarker of PAR pollutants in soil. Three types of PAHs were tested which included phenanthrene (Phe), fluoranthene (Fla) and pyrene (Py). Earthworm gut was selected to measure the total P450 content in cellular microsomes. Dose-response relationships between total P450 content in earthworm gut and PAR concentration (60, 120, 240, 480 and 960 mu g kg(-1) soil (dry weight)) were determined for different exposure durations (1, 3, 7 and 14 days). Results showed that the content of P450 in earthworm changed with exposure to each of PAHs. Biphasic effects were identified in response to each of PAHs tested, in which total P450 content increased due to short, low concentration doses, and decreased due to longer, high concentration doses. Alterations to total P450 content in the presence of PAHs, show that it is a promising biomarker for identifying ecotoxic pollutants at sublethal dose ranges in soil. Further research to identify the specific activity of P450 isoenzymes could further develop and also complement this tool.