Biodegradation of crude petroleum by bacterial consortia from oil-contaminated soils in Ota, Ogun State, South-Western, Nigeria

Abstract

Abstract Pollution from petroleum products is of public health concern because of its attendant health and environmental impacts. Biodegradation of Bonny light crude petroleum and other selected hydrocarbons by bacteria isolated from soils of three different mechanic workshops in Ota, Ogun State were studied. Species of bacteria were isolated by the enrichment of the soil samples in minimal salt medium supplemented with 1% (v/v) crude petroleum as the sole carbon and energy source. The petroleum utilizing bacteria belonging to the genera Bacillus sp. SB4, Pseudomonas sp. SC8, Serratia sp. SC11, and Acinetobacter sp. SC12 were screened and subjected for oil degradation using turbidity and total viable count, reduction in pH and residual oil concentration as indices. Gas Chromatographic (GC) analysis was used to analyze the component and percentage of the petroleum utilized. Plasmid curing and profiling were done to determine whether the ability to utilize carbon is plasmid or chromosomally encoded. Results revealed that four bacteria strains were able to utilize petroleum as energy source. The GC fingerprints showed that both the aliphatic and aromatic components of crude petroleum were reduced to varying degree but the nonadecane C19 could not be reduced. Strain SC11 could not reduce anthracene, pyrene, benzo(a)pyrene and chrysene components. Strain SB4 depleted 24 to 57% aliphatics and 20 to 42% aromatics and strain SC8 depleted 38 to 67% aliphatics and 30 to 79% aromatics while strain SC11 depleted 12 to 46% aliphatics and 13 to 29% aromatics. All organisms harbored plasmid which could suggest that petroleum degradation capabilities could be plasmid encoded. This indicates that the petroleum utilizing bacteria are could be used bioremediation of the petroleum polluted environment.