Influence of Varying Hydrocarbon and Heavy Metal Concentrations on the Microbial Density of Agricultural Soil Samples Polluted With Crude Oil

The research  study was aimed at investigating the influence of varying hydrocarbon and heavy metal concentrations on the microbial density of agricultural soil samples polluted with crude oil. Soil samples were randomly collected at depths of 0-15cm and 15-30cm from Botanical Garden  of  University of Calabar, Calabar . The study was completed within a duration of six months. Standard microbiological techniques were used to isolate, identify and characterize isolates from the collected soil samples. The result obtained from the study showed that the mean total heterotrophic bacterial and fungal counts were higher in the soil samples collected during the wet season compared to its counterpart collected during the dry season. The mean total heterotrophic bacterial and fungal counts were higher in the crude oil polluted soil sample compared to its un-polluted soil counterpart. The microbial density of the analyzed soil samples increased with a corresponding increase in crude oil exposure (0% - 10%) but decreased at 15% of crude oil exposure.  Also, the microbial density of the collected soil samples were observed to decrease with  increasing concentrations (0%, 5%, 10%, 15%) of lead, manganese, and zinc (mg/l). Microbial diversity in the polluted soil sample were identified as Bacillus, Escherichia coli, Pseudomonas, Klebsiella, Aeromonas, Serratia, Enterobacter, Corynebacterium, Yersinia, Shigella, Penicillium, Aspergillus and Candida. Comparison of the mean physicochemical parameters of the crude oil polluted and the un-polluted soil samples showed significantly (P< 0.05) lower values of pH and available phosphorus in the polluted soil sample, whereas the organic carbon, and total nitrogen, exchangeable cat ion capacity, lead, manganese, and  zinc were significantly (P<0.05)  higher in the polluted soil compared to that of the un-polluted soil sample. However, from this study, it is evident that the presence of crude oil in soil environment influences the microbial density, diversity and physicochemical characteristics of soil, and this in-turn could stimulate a wide variety of environmental issues, therefore these calls for environmental consciousness to be instilled into the public to avoid indiscriminate spillage or disposal of oil.

[1]  Arezoo Tahmourespour,et al.  The Study of Heterotrophic and Crude Oil-utilizing Soil Fungi in Crude OilContaminated Regions , 2015 .

[2]  G. Paton,et al.  Effects of hydrocarbon contamination on soil microbial community and enzyme activity , 2015 .

[3]  A. G. Jaboro,et al.  Susceptibility to heavy metals and hydrocarbonclastic attributes of soil microbiota. , 2013 .

[4]  R. Siezen,et al.  Hydrocarbon‐degrading bacteria: the oil‐spill clean‐up crew , 2009, Microbial biotechnology.

[5]  Ravi Naidu,et al.  Tolerance of Heavy Metals by Gram Positive Soil Bacteria , 2009 .

[6]  J. Bragg,et al.  Bioremediation of marine oil spills: when and when not – the Exxon Valdez experience , 2009, Microbial biotechnology.

[7]  H. Roslan,et al.  Biodegradation of aliphatic hydrocarbon by indigenous fungi isolated from used motor oil contaminated sites , 2008 .

[8]  I. Saadoun,et al.  Microbial populations of crude oil spill polluted soils at the Jordan-Iraq desert (the Badia region) , 2008, Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology].

[9]  Monica Cheesbrough,et al.  District Laboratory Practice in Tropical Countries: Acknowledgements , 2005 .

[10]  J. Ramos,et al.  Evidence for in situ crude oil biodegradation after the Prestige oil spill. , 2005, Environmental microbiology.

[11]  G. Paton,et al.  Microbial communities in different soil types do not converge after diesel contamination , 2002, Journal of applied microbiology.

[12]  Cortis K. Cooper,et al.  Natural seepage of crude oil into the marine environment , 2001 .

[13]  M. Cheesbrough,et al.  District Laboratory Practice in Tropical Countries, Part 2 , 2006 .

[14]  F. Schinner,et al.  Monitoring of bioremediation by soil biological activities. , 2000, Chemosphere.

[15]  Ronald M. Atlas,et al.  BIOREMEDIATION OF PETROLEUM POLLUTANTS , 1995 .

[16]  T. K. Misra.  Bacterial resistances to inorganic mercury salts and organomercurials. , 1992, Plasmid.

[17]  D. Nies.  Resistance to cadmium, cobalt, zinc, and nickel in microbes. , 1992, Plasmid.

[18]  G. Okpokwasili,et al.  BIODETERIORATION POTENTIALS OF MICROORGANISMS ISOLATED FROM CAR ENGINE LUBRICATING OIL , 1988 .

[19]  S. T. Cowan.  Bergey's Manual of Determinative Bacteriology , 1948, Nature.