Contamination by petroleum products is a common occurrence in various depots in Nigeria. Suleja depot in recent times has recorded several petroleum spillages and fire incidence attributed to petroleum products storage and distribution. This study was aimed at determining the microbiological quality of soil and water sources in communities around petroleum products depot in Suleja, Nigeria. Soil and water samples were collected from petroleum depot and the five communities around the petroleum products depot and a control site. Microorganisms in the soil and water samples were enumerated by spread inoculation on general purpose media and selective media. Bacterial and fungal isolates were tested for their potential to utilize petroleum products in a Bushnell Haas Broth containing 0.05 mL of petroleum products (diesel, kerosene, engine oil, crude oil) as a source of carbon and energy. The utilization rate was determined by spectrophotometry. The capacities of selected bacterial and fungal isolates to mineralize crude oil were further tested in minimal salt medium. The bacteria isolated were Staphylococcus aureus, Streptococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa, Bacillus subtilis and Escherichia coli. The microbial isolates were not evenly distributed in the six experimental and control plots. Soil samples had higher aerobic heterotrophic bacterial counts than the water samples. Crude oil was most utilized by the microbial isolates. Bacterial isolates from genera Pseudomonas and Bacillus had the highest capacity in utilizing the petroleum products. Among the fungal species, Aspergillus niger and Penicillium notatum exhibited greater capacity to utilize the petroleum products. Present study revealed isolates capable of utilizing the various petroleum products which can be useful in oil spill bioremediation in the tropical environments.

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A yeast biofilter consisting of Candida krusei, Candida morbosa, Torulopsis dattila, Torulopsis glabrata, and Saccharomyces chevalieri was constructed to bioremediate abattoir wastewater. Potato peels were used as filter bed for the growth of the yeasts. Wastewater samples were collected from three different points in Sokoto (Nigeria) abattoir and the physiochemical as well as the microbiological qualities of the wastewater were determined before and after biofiltration. The results revealed that after the biofiltration process, the pH, biochemical oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), and the nitrate content of the wastewater were drastically reduced. Similarly, there was a decrease in the variety of microorganisms isolated as well as in microbial counts after the biofiltration process. Salmonella typhi, Neisseria lactamica, Serratia marcescens, Branhamella catarrhalis, Shigella sp, Penicillium sp, Curvularia sp, and Trichophyton rubrum were completely eliminated after the biofiltration process. The reduction in the pH, BOD, DO, COD, nitrate as well as in the variety and total counts of bacteria and fungi for the wastewater after the biofiltration process indicated that the biofilter was effective in bioremediation of the wastewater. The percentage efficiency of the biofilter was found to be 42.5%.