Applicability of evaluating the ability of microbes isolated from an oil spill site to degrade oil

Hydrocarbon-utilizing microorganisms were isolated by enrichment techniques from soil and water samples collected from an oil spill site in the Niger delta area of Nigeria. The isolates included species of Micrococcus, Pseudomonas, Bacillus, Aeromonas, Serratia, Proteus, Penicillium, Aspergillus, Candida, Geotrichum and Rhizopus. Oil biodegradation potentials of the isolates were evaluated using Nigerian Forcados blend crude oil as sole carbon source in mineral salts medium. There were quantitative changes in the oil content due to microbial degradative activities. Degradation was more pronounced with mixed cultures than with single cultures of the microorganisms. The growth responses of selected isolates to varying concentrations of crude oil showed that while the growth of Pseudomonas, Micrococcus, Aspergillus and Candida species was not inhibited by increasing concentrations of the crude oil, that of Serratia and Rhizopus was significantly (p < 0.05) suppressed.