Fluoranthene-2,3-and-1,5-diones are novel products from the bacterial transformation of fluoranthene

Fluoranthene is one of the predominant compounds found in soils and sedimen ts contaminated with polycyclic aromatic hydrocarbons (PAH). Four bacterial strains isolated from PAH-contaminated soils transformed fluoranthene to a number of products during growth on phenanthrene, including the novel meta bolites fluoranthene-2,3-dione (F230) and fluoranthene-1,5-dione (F15Q). Gi ven the known toxicity and mutagenicity of F23Q, we focused on characterizi ng this metabolite with respect to its effects on the metabolism of other P AH. The yield of F23Q from fluoranthene ranged from 2% for Sphingomonas yan oikuyae R1 to greater than 20% for Pseudomonas stutzeri P16 and Bacillus ce reus P21. None of the strains appeared capable of metabolizing F23Q any fur ther. F23Q strongly inhibited phenanthrene removal by strain R1 but had a n egligible to minor effect on phenanthrene degradation by the other organism s. At a concentration of 6.8 muM, F23Q also substantially inhibited the min eralization of benz[a]anthracene, benzo[a]pyrene (BaP), and chrysene by str ain R1 as well as BaP mineralization by Pseudomonas saccharophila P15. Inhi bition of BaP mineralization by strain P15 was still evident at an F23Q con centration of 0.68 muM. The inhibition of strain R1 by F23Q was explained i n pa rt by a cytotoxic effect, but results with strain P15 indicate that ot her mechanisms of inhibition occur. These findings suggest that quinones su ch as F23Q and F15Q have the potential to accumulate in PAH-contaminated sy stems and can inhibit the degradation of other PAH.