Microbial Metabolism of Polycyclic Aromatic Hydrocarbons (PAH) and Aza-PAH

We have investigated the ability of Pseudomonas paucimobilis, strain EPA 505, a soil bacterium capable of utilizing fluoranthene as the sole source of carbon and energy for growth, to metabolize a number of high-molecular-weight PAH and aza-PAH. After 17 hours of incubation with 10 ppm of the hydrocarbon, resting cells of P. paucimobilis grown on fluoranthene degraded 83.5, 82.8, 97.7, 70.0, and 50.2% of benzo[a]pyrene (B[a]P), chrysene, benz[a]anthracene (B[a]A), benzo[b]fluoranthene (B[b]F), and dibenz[a,h]acridine (DB[a,h]ACR), respectively. Studies with [7-¹⁴C]B[a]P showed that after 17 hours, the cells degraded 25.2% of the chemical to ¹⁴C0², suggesting that the organism is able to metabolize B[a]P via cleavage of the 7,8,9,10 benzo-ring. Analysis of the ethyl acetate extracts of the culture medium by reverse phase HPLC showed that B[a]P, chrysene, B[b]F and B[a]A were each degraded to a major, highly polar metabolite(s). Studies are in progress to characterize the metabolites.