Microbial Populations of Agricultural Soil Polluted With Crude Oil

Crude oil pollution of the soil has become a public health and environmental concern. It impacts soil microbial diversity and population. In this study, the microbial population of crude oil polluted soil and unpolluted were determined. The potential for the indigenous organisms to utilize hydrocarbon as a source of carbon was also determined. A soil sample was obtained from an agricultural field and polluted with a defined amount of crude oil for 12 weeks. The microbial population in the polluted soil and unpolluted soil were estimated and characterized following standard microbiological methods. The heterotrophic bacterial and fungal counts in the unpolluted and polluted soil were 6.5 x 104CFU/g and 4.7 x 104 CFU/g, and 6.3 x104 CFU/g and 3.5 x104 CFU/g respectively. Total hydrocarbon utilizing bacterial and fungal counts in the polluted soil was 4.6 x 104 CFU/g and 2.8 x 104 CFU/g. The genera of bacteria and fungi identified in the soil samples were Bacillus, Enterococcus, Micrococcus, Escherichia, Pseudomonas, Staphylococcus, Serratia, Proteus, Klebsiella, Arthrobacter, Aspergillus, Candida, Penicillium, Fusarium, Trichoderma, Cladosporium and Hyphopichia. The preliminary screening for hydrocarbon utilization shows that Bacillus cereus, Bacillus subtilis, Aspergillus niger and Hypopichia burtonii were excellent hydrocarbon utilizers and can be used in bioaugmentation.