Bacterial species associated with soils contaminated with used petroleum products in Keffi town, Nigeria

This investigation was carried out to determine the bacterial flora of soils contaminated with used oil (petroleum products) in Keffi town. Pour plate method involving the use of serial dilutions was employed for the isolation of the bacteria. Soil samples from 10 different mechanic workshops in Keffi town were obtained and plated out on plate count agar, eosin methylene blue agar, brilliant green agar, desoxycholate citrate agar and mannitol salt agar to isolate the bacterial species from the soils contaminated with petroleum products. The bacterial species isolated were Pseudomonas sp., Streptococcus sp., Escherichia coli, Staphylococcus sp., Klebsiella sp., Bacillus sp., Mycobacterium sp., Enterobacter aerogenes, Salmonella sp., and Micrococcus sp. The hydrocarbon substrates (petroleum products) used were petrol, kerosene, diesel and engine oil. Pseudomonas sp., Streptococcus sp., and Bacillus sp., were found to utilize all the four petroleum products as their sole source of carbon and energy. Staphylococcus sp., and Micrococcus sp., utilized petrol, kerosene and diesel, while Klebsiella sp., and Mycobacterium sp., utilized only petrol and diesel. Salmonella sp., E. aerogenes and E. coli did not utilize any of the test substrates (Petrol, kerosene, diesel and engine oil). The results of this study revealed that Pseudomonas sp., Streptococcus sp., and Bacillus sp., are the most versatile species of bacteria that could utilized petroleum products in the soil environment of Keffi. The investigation demonstrates that Pseudomonas sp., Streptococcus sp. and Bacillus sp. could be harnessed for use in bioremediation of land polluted with petroleum and petroleum products.