ABSTRACT
Petroleum contain fractions that are potentially toxic, carcinogenic and or mutagenic. Thus the intrinsic biodegradability of petroleum hydrocarbon and distribution in the environment of competent catabolic microorganisms are critical to the implementation of bioremediation strategies for the clean-up of petroleum polluted environments
towards ecosystem and public health preservation. In the present study, the petroleum degrading potentials of bacteria species isolated from petroleum refinery sludge was evaluated. The bacterial species were isolated and identified using standard microbiological techniques. The petroleum degrading potentials of isolates was
determined by a 14-day enrichment assay using basal salt medium (BSM) supplemented with 2% Escravos light crude oil (ELCO) and assessed by gas chromatography (GC). The petroleum degrading isolates were identified as Micrococcus sp., Bacillus sp., Arthrobacter sp., Bacillus sp., Staphylococcus sp. and Streptomyces sp. The mean bacterial counts during enrichment assay ranged between 0.95 × 101 cfu/ml and 9.7 × 101 cfu/ml. Staphylococcus sp. exhibited the highest (96.20%) total petroleum hydrocarbon (TPH) degrading potential; while Micrococcus sp. showed the least
(35.42%) TPH degrading capacity. The isolates were also remarkable in the degradation of polycyclic aromatic hydrocarbon (PAH), removing between 4 and 10 PAH compounds after treatment in the following order (highest to lowest): Staphylococcus sp. >Streptomyces sp. >Arthrobacter sp. >Bacillus sp. >Micrococcus sp. >Bacillus sp.
The study demonstrated that the bacterial isolates were remarkable petroleum degraders with great potentials for deployment as candidates in bioremediation of petroleum polluted sites in the Niger Delta region of Nigeria.
KEYWORDS: Petroleum sludge; Biodegradation; TPH; PAH; Bacteria