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(M/EH067) PAH cometabolic pathways in PAH-degrading soil bacteria. Parsons, John1, van Herwijnen, Rene1, Springael, Dirk2, 1 2 ABSTRACT- In the EU-funded project "Use of bioavailability-promoting micro-organisms to decontami-nate PAH-contaminated soils: preparation towards large-scale field application" ten participants are working to develop new approaches for bioremediation. In contaminated soils, PAH-degrading bacteria are confronted with complex mixtures of PAHs. It is therefore likely that cometabolism will play a significant role in the attenuation of PAHs levels in soil. In general, cometabolic pathways lead to incomplete degradation and the accumulation of me-tabolites. We have been studying PAH-cometabolic pathways in the fluorene-utilising Sphingomonas strain LB126. Cultures of this strain were grown on pyruvate in the presence of different PAHs and were analysed for PAH degradation and the formation of accumulating metabolites using HPLC, LC-MS and GC-MS techniques. The results obtained so far indicate that cometabolism proceeds via reactions similar to those performed by strains able to grow on these compounds. For example, anthracene was transformed into hydroxylated metabolites whereas phenanthrene and fluoranthene were converted into ring-cleaved products. In the case of the heterocyclic compound dibenzothiophene there was clear accumulation of the product of oxidation of the sulphur atom. The results will be used to monitor the degradation of PAHs and the possible accumulation of metabolites in pilot scale remediation systems. Key words: PAHs, biodegradation, pathways, metabolites |
