Characterization of culturable bacterial communities in petroleum hydrocarbon contaminated sludge of oil refineries and oil exploration sites

Oil industries generate large amounts of oily sludge consisting of hazardous alkanes, aromatic hydrocarbons, NSO (Nitrogen, Sulphur and Oxygen) compounds and asphaltenes. Compared to conventional treatment technologies, microorganisms based bioremediation has been considered as an effective and economic strategy for the treatment of hydrocarbon contaminated wastes/sites. In the present study, eight different hydrocarbon contaminated sludge/soil samples, collected from oil -refineries/-exploration sites were characterized through chemical and microbial analyses. According to UPGMA analysis, the closest three samples (GR1, DB2 and DJ3) were chosen for further investigation. To determine culturable bacterial community composition in these samples 104 aerobic, heterotrophic bacterial strains were isolated and identified by 16S rRNA gene sequence analysis. Bacterial community in GR1 sample was composed of genera Bacillus (75%), Burkholderia (22%) and Paenibacillus (3%), while DJ3 sludge exhibited presence of Pseudomonas (47%), Bacillus (41%), Stenotrophomonas (9%) and Enterobacteria (3%) and DB2 sample showed the genera Pseudomonas (67%), Bacillus (20%), Pandoraea (7%) and Kocuria (6%). Metabolic potentials of bacterial isolates were characterized in terms of their growth with different nutrients, biosurfactant production, heavy metal tolerance and ability to utilize different petroleum hydrocarbons (Benzene, Toluene, Ethylbenzene, Xylene and crude oil) as sole source of carbon and energy. Overall observation indicated the bioremediation potential of isolated microorganisms indigenous to oily sludge.

Bioremediation ,

Oily sludge ,

Microbial diversity ,

16S rRNA gene ,

Biosurfactant ,