Q-184. The Effect of Phenanthrene and Fluoranthene Addition on the Bacterial Communities Present in Unexposed and Pre-Exposed Soils

R. J. Grant1, L. M. Muckian2, N. J. W. Clipson2, E. M. Doyle2;
1Napier Univ., Edinburgh, UNITED KINGDOM, 2Univ. Coll., Dublin, IRELAND.

Polycyclic aromatic hydrocarbons (PAHs) are xenobiotics found in petroleum products, and have a number of uses, the greatest being in preservative treatments for wood. Pollution and contamination with PAHs is widespread and the higher molecular weight compounds are recalcitrant and very toxic. Treatment of contaminated soils in sites of usage, particularly large scale timber treatment plants, is required for land use and the prevention of further pollution. Stimulation of the microbial community present to promote biodegradation of the PAHs is one environmentally friendlier treatment than conventional processes to clean up such sites. Here we took two PAHs (phenanthrene and fluoranthene) and spiked two different soils (pristine (non-exposed) and pre-exposed) at three concentrations (50, 100 and 200 mg l-1). The loss of PAH and the changes in the microbial community composition were monitored over a 28 day period. Results showed greater rates of degradation in the phenanthrene cultures over the fluoranthene cultures (as expected due to molecular weight), and greater rates of degradation in the pre-exposed soil over the pristine soil (as expected). The changes in microbial community were monitored using terminal restriction fragment length polymorphism (TRFLP) analysis. This showed distinct measurable changes over time that were statistically supported. Such analysis of the microbial community and utilising the results to further enhance our understanding of the bioremediation process will allow us to improve rationales and continue our studies down to the genetic molecular level.