Full Length Research Paper

Bacterial diversity in a tropical crude oil-polluted soil undergoing bioremediation

C. B. Chikere¹*, G. C. Okpokwasili¹ and B. O. Chikere²

¹Department of Microbiology, University of Port Harcourt, P. M. B. 5323 Port Harcourt, Nigeria.

²Health, Safety and Environment, Shell Petroleum Development Company Limited, P. O. Box 263 Port Harcourt, Nigeria.

*Corresponding author. E-mail: ujuazed@yahoo.com. Tel.: +2348057770448.

Accepted 7 April, 2009

The bacterial diversity in a tropical soil experimentally polluted with crude oil during a 57 days bioremediation was investigated in five 1 m² plots using total culturable hydrocarbon utilizing bacteria, heterotrophic bacteria and gas chromatographic analyses. Four out of the five experimental plots received each 4 L of Bonny light crude oil while three treatment plots received 3 kg of NPK, urea fertilizers or poultry droppings with periodic tilling. Two plots, oil-contaminated and pristine served as controls. Bacterial counts increased 200 fold and 2 fold in the NPK treated and poultry-dropping-treated plots respectively, by day 31 post-inoculation. Detectable hydrocarbons in the treatment plots decreased by 84 - 95% and 96 - 99%, 31 and 57 days post-inoculation, respectively, compared with the petroleum contaminated control. Bacterial strains isolated included Rhodococcus sp., Nocardia sp., Arthrobacter sp., Gordonia sp., Mycobacterium sp., Corynebacterium sp., Bacillus sp., Micrococcus sp., Flavobacterium sp., Pseudomonas sp. and Alcaligenes sp. The overall data suggest an important contribution of Actinobacteria during bioremediation of crude oil-polluted soil.

Key words: Niger Delta, Nigeria, crude oil pollution, bonny light, bioremediation, Actinobacteria, fertilizers.