Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Abstract:
The dominant microorganisms present in soils, contaminated with hydrocarbon fractions in engine oils (used and unused) at various automobile workshops in five locations in the city of Lagos were isolated. The purpose of the work was to evaluate the effectiveness of the several microorganisms indigenous to the soil in remediating the soil. Bacillus species and Pseudomonas species were found in all the sites, while flavobacterium and micrococcus species were found in three of the sites and only one the site had the rhodococcus species. The effectiveness and efficiencies of degradation of the hydrocarbon components by the isolated organisms were studied in shake flaks containing minimal salt medium with varying concentrations of engine oil (0.5%, 1.0%, and 1.5%). Each isolated organism and mixtures of them were grown in the various media in an incubator shaker at room temperature. The extent of growth of organisms observed was linked to the ability of the organisms to biodegrade the hydrocarbon fractions present in the medium. The results obtained showed that the pseudomonas and rhodococcus species gave the best growth at all concentrations of engine oil used, degrading 60% and 80% of oil respectively. A co-culture of these two organisms gave a higher growth than each of them when cultured alone, suggesting a positive interaction between the two organisms. This could be attributed to their ability to degrade different types of hydrocarbons thus creating the synergy. It can be concluded that an efficient bioremediation programme can be put in place by the use of an appropriate mixture of organisms as well as other physico-chemical properties that might also influence the growth of these microorganisms.

Keywords: bioremediation; mixed culture; pseudomonas species; rhodococcus species

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