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

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.