Isolation of bacteria from mechanic workshops’ soil environment contaminated with used engine oil T. K. C. Udeani*, A .A. Obroh, C .N. Okwuosa, P. U. Achukwu and N. Azubike Department of Medical Laboratory Sciences, College of Medicine, University of Nigeria, Enugu Campus, Enugu, Nigeria. Accepted 28 May, 2008
The study was designed to evaluate the bacterial diversity of soil environment contaminated with used engine oil. Ten mechanic workshops within Enugu metropolis were selected and six soil samples were collected from each site. These were analyzed using Bushnell Haas enrichment medium. Samples were enumerated using ten fold dilutions from 1:10 to 1:100000 from the soil samples. The result showed the isolation of Bacillus Stearothermophilus (8.3%) and Cyanobacteria (1.7%) from the sites sampled. The number of viable bacterial growth of B. Stearothermophilus and Cyanobacteria were enumerated and 4 4 5 expressed in colony forming units. Agbani had bacteria densities of 5 x 10 , 1.25 x 10 and 6.25 x 10 4 4 from the three different sites respectively, Asata with 5.10 x 10 and 2.5 x 10 , independence layout with 2 4 5 bacterial density of 2.5 x 10 and Uwani/Coal camp with 2.5 x 10 and 6.25 x 10 . Amongst the 10 5 different sites studied, Agbani and Uwani/Coal camp had the highest bacteria density of 6.25 x 10 . Key words: Used engine oil, contaminated soil, pollution. INTRODUCTION Environmental pollution with petroleum and petroleum products (complex mixture of hydrocarbons) has been recognized as one of the most serious current problems especially when associated with accidental spills on large-scale. If this occurs, hydrocarbons may reach the water table before becoming immobilized in the soil. They spread horizontally on the ground water surface and continue to partition into ground water, soil pore space, air and to the surface of soil particles. The vast range of substrates and metabolites present in hydrocarbonimpacted soils surely provides an environment for the development of a quite complex microbial community (Butier and Mason, 1997). It is used to lubricate the parts of automobile engine in order to keep everything running smoothly (Hagwell et al., 1992). Used oil was defined by the US Environmental Protection Agency (40CFR Pan 270) as oil that has been refined from crude oil or any synthetic oil; this has been used and as a result of such use is contaminated by chemical impurities which contribute to chronic hazards including mutagenicity and carcinogenicity as well as environmental hazard with global ramifications (Blodgette, 2001). Bioremediation has become an alternative way to remedy oil polluted sites, where the addition of specific microorganism (bacteria, cyanobac-teria, algae, fungi, protozoa) or enhancement of microorganism already present, can improve biodegradation efficiency (Hagwell et al., 1992). These microorganisms can degrade a wide range of target constituents present in oil sludge (Barathi and Vanudevan, 2001; Mishra et al., 2001). A large number of pseudomonas strains capable of degrading polycyclic aromatic hydrocarbons have been isolated from soil (Johnson et al., 1996; Kiyohara et al., 1992). Other petroleum hydrocarbon degraders include Yokenella spp., Alcaligenes spp., Roseomanas spp., Sreanotrophomanas spp., Acinetobacter spp., Flavobacter spp., cyanobacterium spp., capnocytophage spp., Moraxella spp. and Bacillus spp. (Antai 1990; Bhattacharya et al., 2002). Other microorganism such as fungi is also capable of degrading the hydrocarbons in engine oil to a certain extent. However, they take longer
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Udeani et al.
Table 1. Number of isolates from the various mechanic workshops’ soil environment contaminated with used...