Comparative Studies on the Biodegradation of Crude Oil-polluted Soil by Pseudomonas aeruginosa and Alternaria Species Isolated from Unpolluted Soil

Aims: To examine the efficiency and compare the ability of Pseudomonas aeruginosa and Alternaria sp to degrade hydrocarbons found in crude oil-polluted soil.

Study Design: The study made use of a purposive sampling method.

Place and Duration: Department of Microbiology, University of Abuja and Environmental Biotechnology Laboratory, Sheda Science and Technology Complex (SHESTCO), Abuja between May and November, 2015.

Methodology: Soil samples were collected from non-contaminated garden in Gwagwalada, Abuja and were screened for the presence of these organisms using spread plate technique. These microorganisms were confirmed via morphological characteristics, biochemical tests and molecular techniques involving primer specific polymerase chain reaction. Degradation of crude oil by the bacterium and fungus was done by inoculating fresh cultures of these organisms in conical flasks containing Bushnell and Haas (1941) media supplemented with 5% v/v crude oil and incubated appropriately. The level of hydrocarbon degradation was determined using gas chromatography-mass spectroscopy (GCMS) analysis.

Results: Alternaria sp was almost twice as effective in degrading octane and decane (57.48%, 78.28%) in the sample as Pseudomonas aeruginosa (32.20%, 35.62%) respectively. However, the P. aeruginosa was more effective than Alternaria sp. in degrading dodecane and tetradecane by 63.33% and 100%, in comparison to the 45.70% and 54.27% by the fungus. The highest percentage of residual oil in the reaction vessel containing Pseudomonas aeruginosa was octane and decane at 67.8% and 64.38%. In the case of Alternariasp., dodecane and pentadecane had the highest residual oil fractions at 54.10% and 48.71% after 21 days.

Conclusion: The result of this study indicates that organisms have the potential for bioremediation of crude oil and could be employed in large scale to remediate crude oil contaminated sites in consortium with known microorganisms possessing the same ability.