Abstract

This study shows the potential of various types of bacterial isolates that utilizes hydrocarbon substrates which enhances the degradation of this pollutant in the environment. Soil samples used for this purpose were obtained from oil-producing Ayetoro community in Ilaje Local Government of Ondo State, Nigeria. Bacterial isolates were recovered by culturing them on nutrient agar and Mineral Salt Medium (MSM). Of the twenty two (22) bacterial isolates, thirteen (13) were Gram positive and nine (9) were Gram negative. The Gram positive bacteria were identified by Gram staining and biochemical tests while the Gram negative bacterial isolates were identified with the use of API® identification kit. Five (5) of thebacterial species including Micrococcus luteus, Bacillus cereus, Bacillus subtilis, Pseudomonas aeruginosa and Acinetobacterlwoffi exhibited potential to degrade Bonny light crude oil by showing visible growth around the oil in MSM using the hole-plate diffusion method. The study also showed microbial growth indicated by varying turbidity on MSM broth incorporated with Bonny light oil with optical density range of 0.18-0.85 at 540nm. From this study, Pseudomonas aeruginosa showed the highest optical density of 0.76-0.85 and has the greatest potential to degrade hydrocarbon. Thus, these oil-degrading properties of the microorganisms informed the choice of this group of organisms for bioremediation of oil-polluted sites.

Keywords: Bioremediation; Hydrocarbon; Microbial isolates; Nigeria; Oil pollution