DEGRADATION OF POLYCYCLIC AROMATIC-HYDROCARBONS (PAHS) BY A MIXED CULTURE AND ITS COMPONENT PURE CULTURES, OBTAINED FROM PAH-CONTAMINATED SOIL

A mixed culture, isolated from soil contaminated with polycyclic aroma tic hydrocarbons (PAHs), grew on and degraded fluoranthene in aqueous media supplemented with glucose, yeast extract, and peptone. Increased complex nitrogen levels in the medium promoted bacterial growth and a greater extent of fluoranthene degradation. Amendment of the media wi th high glucose levels also diminished specific fluoranthene degradati on. The mixed culture was capable of degrading a range of other PAHs, including benzo[a]pyrene,anthracene,phenanthrene, acenaphthene, and fl uorene. The mixed culture contained four predominant isolates, all of which were Gram-negative rods, three of which were identified as Pseud omonas putida. Flavobacterium sp., and Pseudomonas aeruginosa. Better degradation of a defined PAH mixture was observed with the mixed cultu re than with individual isolates. A reconstituted culture, prepared by combining the four individual isolates, manifested a similar PAH biod egradation performance to the original mixed culture. When compared wi th the mixed culture, individual isolates exhibited a relatively good capacity to remove more water-soluble PAHs (acenaphthene, fluorene, ph enanthrene, fluoranthene). In contrast, removal of less water-soluble PAHs (anthracene and pyrene) was low or negligible with isolated cultu res compared with the mixed culture.