Scientific Research and Essays

  • Abbreviation: Sci. Res. Essays
  • Language: English
  • ISSN: 1992-2248
  • DOI: 10.5897/SRE
  • Start Year: 2006
  • Published Articles: 2755

Full Length Research Paper

Determination of the relative abundance and distribution of bacteria and fungi in Bonny light crude oil-contaminated sandy loam soil

  Eze C. N.*, Ogbonna J. C., Anyanwu C. U. and Eze E. A.   
1Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria.
Email: [email protected]

  •  Accepted: 21 February 2013
  •  Published: 04 March 2013



This study was undertaken to investigate the effects of Bonny light crude oil (specific gravity = 0.81; API gravity 43.20) on the numerical composition of soil bacteria and fungi and relative distribution of Gram positive and Gram negative soil bacteria. Eight different levels of the crude oil (0.5, 1.0, 2.0, 2.5, 5.0, 10.0, 15.0 or 20.0% v/w of soil) were used for the controlled pollution of soil samples obtained from the Botanical Garden, University of Nigeria Nsukka. Studies on the effects of crude oil on bacterial and fungal populations were carried out by plate count procedures using nutrient agar and Sabouraud dextrose agar respectively. Crude oil significantly (p<0.05) inhibited bacterial and fungal growth in a dose-dependent manner. Bacterial counts in the control soil sample ranged between 2.32 × 109 and 2.80 × 109 cfu/g while those of the contaminated samples ranged between 2.00 × 108 and 2.77 × 109 cfu/g. Fungal counts ranged from 1.02 × 107 to 1.39 × 107 cfu/g in the control and 1.60 × 105 to 1.18 × 107 cfu/g in the contaminated samples. At 15.0 and 20.0% levels of crude oil, the growth inhibitory effects of crude oil were maximum for bacteria and fungi respectively. Microbial respiration decreased concomitantly with increase in crude oil pollution during the first four weeks of the study. There was a prevalence of Gram positive bacteria over Gram negatives in the unpolluted soil but a preponderance of Gram negative rods over Gram positives and other morphological forms of Gram negatives in the polluted samples.


Key words: Bonny light crude oil, bacteria, fungi, contamination, hydrocarbon, biodegradation.