[01] Innocent Ojeba Musa, Department of Microbiology, Federal University of Technology, Minna, Nigeria. [02] Udeme Joshua Josiah Ijah, Department of Microbiology, Federal University of Technology, Minna, Nigeria. [03] Olabisi Peter Abioye, Department of Microbiology, Federal University of Technology, Minna, Nigeria. [04] Adebola Matthew Omoniyi, Department of Plant Biology, Federal University of Technology, Minna, Nigeria.

Spent engine oil management in Nigeria is not well supervised and the indiscriminate discharges into the soil drains and water of the pollutants. This has attendant implications on soil and water quality, contamination on soil ecosystem alters soil biochemistry, immobilizes nutrients. The study was designed to determine the microbial load and identify some of the microorganisms present in the hydrocarbon polluted soil were Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus megaterium, Pseudomona aeroginosa, Aspergilus flavus, Aspergilus fumigatus, Aspergilus niger, Fusarium oxysporium and Penicillium notatun. Minna, had more bacteria counts within the rhizosphere of the plants found within the vicinity of the automobile workshop with the Mean count of 1.42×10⁷±2.41×10⁷ cfu/g, while Bida had the lowest bacterial count in the Automobile workshop 1.56×10⁵±2.13×10⁵ cfu/g when compared to Minna and Suleja. For fungi, Bida had the highest count with a mean of 7.10×10⁶±1.20×10⁷ cfu/g while Minna had the lowest count with a mean count of 1.02×10⁶±1.72×10⁶ cfu/g in relative terms to Suleja, Bida and Tegina. Bacillus subtilis had the highest frequency of occurrence of (37.50%) while Staphylococcus epidermidis had the lowest occurrence (9.38%), in soil remediated with M. officinalis alone Bacillus subtilis had the highest frequency of occurrence (42.85%) and Staphylococcus epidermidis had the lowest frequency of occurrence (4.54%). That of fungi, A. niger had the highest frequency of occurrence (47.61%) while the fungi with the least occurrence was P. notatum (4.76%) with F. oxysporium with occurrence of 9.52% (Table 4), in soil remediated with M. officinalis alone (SP1), A. niger had the highest frequency of occurrence (52.17%) while P. notatum had the lowest frequency of occurrence (4.34%), in soil remediation. A. niger had the highest frequency of occurrence (45.83%) while P. notatum had the lowest frequency of occurrence (4.16%), soil polluted with 50cl of spent engine oil. A. niger had the highest frequency of occurrence (50.00%) while P. notatum and A. flavus and F. oxysporium had the lowest frequency of occurrence (11.11%). This Bacillus subtilis, Bacillus megaterium, Pseudomona aeroginosa, Aspergilus niger and Aspergilus flavus, showed great potential to withstand, tolerate and degrade spent engine oil (SEO), hence can used for biodegradation of hydrocarbon.

Microorganism, Soil, Contamination

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