IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 8, Issue 5 Ver. II (May. 2014), PP 66-70 www.iosrjournals.org www.iosrjournals.org 66 | Page Biodegradation of Used Engine Oil By Bacteria Isolated From Soil Contaminated With Used Engine Oil in Ogbomoso, Nigeria Eniola K.I.T, Adegbola G.M. And Opasola O.A. 1 Department of Biological Sciences, Joseph Ayo Babalola University, Ikeji-Arakeji 2 Department of Food Science and Engineering (Food Microbiology Laboratory), LadokeAkintola University of Technology, P.M.B 4000 Ogbomoso. 3 Department of Pure and Applied Biology, LadokeAkintola University of Technology, P.M.B 4000 Ogbomoso. Abstract: The biodegradation potential of five bacteria isolated from used engine oil contaminated soil was investigated in this study. The bacteria were inoculated into used oil supplemented with Mineral Salt Medium and incubated at 37 o C for 25 days. The results obtained showed that all the bacteria were able to utilize the engine oil as source of carbon. IR analysis of the residual engine oil showed that the bacteria have exerted microbial action on the oil. The results obtained from IR analysis revealed 9 bands in P. vulgaris, B. cereus, S. typhi, S. faecium, 10 bands for P. aeruginosa while that of the control was recorded to 8 bands. This study showed that the bacteria strains used in this study could be relevant in the bioremediation of ecosystem that may be contaminated with hydrocarbons. Keyword: Biodegradation, MSM, Residual oil, Bioremediation. I. Introduction Used motor oil is the brown-to-black oily liquid removed from a motor vehicle, when the oil is changed. Used motor oil is similar to unused oil, except that it contains additional chemicals that are produced or build up in the oil, when it is used as an engine lubricant at high temperatures and pressures, inside an engine as it runs (Dorsey et al., 1997). Used motor oil also contains metals such as aluminium, chromium, copper, iron, lead, manganese, nickel, silicon and tin that comes from engine parts, as they wear down (Keith and Telliard, 2003). Some of these metals in used motor oil can dissolve in water and move through the soil easily, and may be found in surface water and ground water. Thus, metals from used oils can build up in plants, animals, soil, sediments and non-flowing surface water. Heavy metals and chemicals in used motor oil are absorbed and distributed into various tissues of human, plants and animals by their movement in the environment, which can result in serious health problem, such as anemia, tremor and consequently, resulting in death (Keith and Telliard, 2003). Other health hazards which can result from used motor oil include mutagenicity and carcinogenicity (Boonchan et al., 2000). In most countries of the world, oil spills at auto-mechanic workshops have been left uncared for over the years, and its continuous accumulation is of serious environmental concern because of the hazard associated with it. The physicochemical treatment technologies currently in use are expensive and not environmentally friendly. In addition, some of these technologies only transfer the contamination from one place to another. In recent times, a lot of efforts have been made towards reducing environmental pollution, by using natural processes to treat environmental pollution. These techniques include: bioremediation (use of microorganisms to degrade pollutants) and phytoremediation (use of plants to clean pollutants by bioaccumulation into the plant’s tissues). Bioremediation is the naturally occurring process by which micro-organisms transform environmental contaminants into harmless end-products, in order to obtain the sources of carbon and energy. During the process of bioremediation, which involves the activity of micro-organisms to remove pollutants, environmental parameters such as temperature, pH, oxygen and moisture content, are optimized to achieve accelerated biodegradation. Basically, there are two different approaches to bioremediation technologies, depending on the pollution situation and type of micro-organisms being used. The first is the one which involves the activation of the indigenous microflora in the polluted area by addition of nutrients and forming the best conditions of other chemical, physical and biological factor, or known as biostimulation. The second (bioaugumentation) is the one which involves the addition of oil-oxidizing micro-organisms isolated from other sites, or addition of genetically engineered micro-organisms (Amundet al., 1987). This study was primarily carried to investigate the bioremediation potentials of five bacteria Isolated from used engine oil contaminated soil in Ogbomoso, Oyo State, Nigeria.