Polycyclic aromatic hydrocarbon (PAH)–degrading bacteria were isolated from aviation fuel contaminated soil at Inua Eyet Ikot in Ibeno, Nigeria. PAH-degrading bacteria in the contaminated soil were isolated by enrichment culture technique. Isolates with high PAH degrading potential characterized by their extensive growth on PAH-supplemented minimal salt medium were screened for their naphthalene, phenanthrene and chrysene degradability. The screening medium which contained selected PAHs as the sole source of carbon and energy showed that Micrococcus varians AFS-2, Pseudomonas putida AFS-3 and Alcaligenes faecalis AFS-5 exhibited a concentration–dependent growth in all the PAH–compounds tested. There were visible changes in the color of growth medium suggesting the production of different metabolites. Their acclimation to different PAH substrates was also evident as A. faecalis AFS-5 isolated from chrysene grew well on other less complex aromatic compounds. The isolate exhibited best growth (0.44 OD 600 ) when exposed to 10 ppm of chrysene for 5 days and could utilize up to 90 ppm of chrysene. This isolate and others with strong PAH-degrading potentials are recommended for bioremediation of PAHs in aviation fuel-contaminated sites in the tropics.

Polycyclic aromatic hydrocarbon (PAH) degrading potential of bacteria isolated from Iko River sediment, Akwa Ibom State, Nigeria was investigated. The mean total heterotrophic bacteria obtained from the sediment samples was 6.4 × 10 cfu/g while 9.8 x 103 cfu/g hydrocarbon utilizing bacteria was recorded. Preliminary screening of the hydrocarbonoclastic bacterial isolates revealed that among the 12 bacterial isolates, Pseudomonas aeruginosa, Bacillus subtilis, Alcaligenes sp exhibited the strongest ability to utilize crude oil. The result also revealed Bacillus subtilis and Pseudomonas aeruginosa as the best PAH degraders. A higher microbial cells count in the 2-ring PAH (naphthalene) supplemented –MSM was recorded. The levels of attenuance however varied with the test organism and were accompanied by fluctuations but decreasing pH levels and slight changes in temperature of the culture medium. In vitro degradation study carried out for the 21 days showed that the degradation of PAH when augmented with Pseudomonas aeruginosa and Bacillus subtilis respectively was faster than when un-augmented. The PAH content was reduced by Pseudomonas aeruginosa and Bacillus subtilis from 10.42 to 9.03 and 9.56 respectively. The hydrocarbon degradation by augmented cultures of Pseudomonas aeruginosa and Bacillus subtilis implies that bioaugmentation can be harnessed for bioremediation purposes.