Crude Oil Degradation Potentials of Bacterial Communities from Humic Freshwater Ecosystem of Eniong River Sediment Samples

Abstract

Crude oil degradation potentials of bacterial communities from humic freshwater sediment of Eniong River were determined using diverse bacteriological and analytical procedures. The humic sediment harbours remarkable bacteria load such as heterotrophic bacteria with a mean count of 5.94±0.41 log10cfu/g, sulphate reducing bacteria with a mean count of 5.51±0.62 log10cfu/g and hydrocarbon utilizing bacteria with an average count of 4.48±0.95 log10cfu/g. The characterization studies of the isolates from the humic sediment ecosystem revealed 19 genera and 25 species of bacteria and 1 genus and 1 species of Actinomycetes. The screening tests revealed 14 out of 19 species of bacteria encountered in the black water ecosystem possess the ability to utilize hydrocarbons. Among the isolates, Bacillus subtilis, Micrococcus sp., Bacillus cereus and Pseudomonas aeruginosa showed very strong crude-oil degrading potentials. The results of the effect of environmental factors showed that the best growth was obtained by Pseudomonas aeruginosa (2.60x102cfu/g) at 30oC while the best growth was exhibited by B. cereus (1.20x102cfu/g) at pH of 6. Pseudomonas aeruginosa (log106.93cfu/ml) exhibited the highest growth at day 10 and 180 revolution per minute (rpm). The profiles showing the relationship between cell numbers and pH indicate a steady increase in cell numbers and decrease in pH of the medium as incubation periods increase from day 1 to day 10. The result showed the rich assemblage of different bacteria with the ability to degrade crude oil and therefore should be harnessed for application in remediation of the crude oil polluted ecosystems.