Microbial Population of Soil and Water around Petroleum Depot Suleja, Nigeria, and their Hydrocarbon Utilisation

Abstract

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 samples and water samples were collected from defive 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 utilise 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 utilisation rate was determined by spectrophotometry. The capacities of selected bacterial and fungal isolates to mineralise 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 utilise the petroleum products. Results revealed isolates capable of utilising the various petroleum products which can be useful in oil spill bioremediation in the tropical environments.