Polycyclic Aromatic Hydrocarbon (PAH) Degrading Potential of Bacteria Isolated from Iko River Sediment

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.