Sphingomonas sp.P2, an isolate from lubricant-contaminated soil with capability of utilizing phenanthrene and several other PAHs for growth, was studied for ability to degrade and utilize fluorene when grown in CFMM liquid medium containing 100 mg of fluorene/L for 7 days. It showed slightly growth and low ability to degrade fluorene (5.7%) although the color of the medium was changed to yellow with maximum absorption at 450-460 nm. The HPLC analysis also showed only small amount of intermediates from the degradation. Addition of organic nutrients i.e. yeast extract in the CFMM resulted in increasing fluorene utilizing ability of this bacterium in which the residual fluorene of 0.44 mg/l was found after 7 days of incubation. Addition of 0.5 % yeast extract to the medium at the beginning of cultivation, Sphingomonas sp. P2 could rapidly grow and degrade fluorene to undetectable amount after 36 h of incubation with highest accumulated intermediates detected by HPLC at 15 h of incubation. The major intermediate was isolated and purified by preparative HPLC and its mass spectrum was compared with that of the standard compound. It was identified as 9- fluorenol, a first intermediate of fluorene degradation, resulted from addition of oxygen atom into cyclo-pentene ring of fluorene. Moreover, soil extracts were also tested as nutrient supplements instead of yeast extract on enhancement of fluorene degradation by Sphingomonas sp. P2. The result showed 40% increase in fluorene degradation comparing with that of without soil extract and only 48.1 mg of fluorene per litre was remained in the medium after 7 days of incubation.
