Petroleum Contaminated Oil Sludge Degradation by Defined Consortium: Influence of Biosurfactant Production

Oil sludge degradation studies were conducted using individual bacterial strains and their formulated consortium “Oil busters” isolated from tank bottom oil sludge. Four potential strains were selected on the basis of biosurfactant production, presence of catabolic gene and aromatic fraction utilization which further characterized using hydrocarbon compounds as the carbon source. Surface tension, emulsification index and bacterial adhesion towards hydrocarbons (BATH) test were also performed. All four strains were selected for consortium preparation and degradation studies were conducted for 20 days in Minimal media inoculated with individual strains and consortium. The strains used after identification on the basis of 16 s rDNA sequencing were named as AAJ1; AAJ2, AAJ3 and AAJ4. At the end of the study, consortium showed effective degradation of oil and its components as compared to individual strains. The consortium degraded a maximum of 78 % of oil, followed by strains AAJ1 70 %, AAJ3 58 %, AAJ2 57 % and AAJ4 56 %. In the total petroleum hydrocarbons (TPH), highest degradation was found by consortium (75 %) followed by AAJ2 (57 %), AAJ3 (56 %), AAJ1 (55 %) and AAJ4 (54 %) respectively. The strains AAJ1 and AAJ2 were identified as Bacillus sp. and AAJ3 and AAJ4 as Pseudomonas sp., respectively. A total of nine polycyclic aromatic hydrocarbons (PAHs) were detected in aromatic fraction of oil sludge and gas chromatography-mass spectroscopy (GC–MS) profile confirmed the complete removal of these compounds in the presence of consortium. The findings come up with a potential bacterial formulation, i.e. “Oil buster” for planning bioremediation strategy for oil sludge/PAH contaminated sites. © 2016, The National Academy of Sciences, India.