MICROBIAL-DEGRADATION OF PYRENE AND CHARACTERIZATION OF A METABOLITE

We report the degradation of pyrene by microorganisms present in sea w ater and sediment samples that were obtained from Kitimat Arm, BC, Can ada, an environment that is highly contaminated by polycyclic aromatic hydrocarbons because of nearby aluminum smelting activity. The utiliz ation of pyrene as sole carbon source by the microorganisms is demonst rated by monitoring the disappearance of pyrene and the production of its metabolite in the cultures. Pyrene (10 mu g) is degraded to an und etectable level after 120 h of incubation with 0.5 mi of the enriched culture and 10 ml of mineral salt medium. The extent of mineralization is also assessed by determining the radioactivity of the (CO2)-C-14 p roduced from the cultures containing C-14-labeled pyrene: up to 65% of the pyrene is mineralized after 12 days of incubation. A metabolite t hat accumulates in the pyrene degradation cultures can be isolated. Th is metabolite is identified as cis-dihydrodiol pyrene, an initial ring oxidation product, on the basis of its chromatographic behavior, abso rption spectrum, fluorescence excitation and emission spectra, and mas s spectra.