Investigation of Biodegradation Potential of Polycyclic Aromatic Hydrocarbon with Bacteria Isolated from Tabriz City and Petroleum Refinery Soils

Petroleum aromatic hydrocarbons are important sources of soil and environmental pollution in our country especially around oil refineries. In order to remove these pollutants, biological methods using native microorganisms of oil contaminated soils are preferred because of their cheapness and availability. Existing soil microorganisms use these hydrocarbons as carbon and energy sources and finally produce water, CO2, biomass and harmless materials. In the present study, the sampling was conducted from different unpolluted soils of Tabriz city and oil-polluted soils of Tabriz Petroleum Refinery. The soil suspensions were cultured in YGM and SCA media and finally, 100 microbial isolates were obtained. Phenanthrene at a rate of 1000 mg/L was added to the MHB medium and then the fixed amounts of these bacterial isolates were added separately. They were incubated in shaker with 130 rpm, at 28˚C for one week. The rate of phenanthrene destruction was evaluated by spectro photometery. Thereafter the reliability of primary aromatic compounds was assayed by TLC method. Eighty-seven bacterial isolates with phenanthrene destruction rates of 3.2-93.8% were selected. Some secondary metabolites originated from destruction of hydrocarbons were subjected to the GC-Mass analysis. Some non- toxic mediatory substances were identified as result of phenanthrene biological degradation. Bacterial isolates possessing of phenanthrene degradation up to 50% were identified. By improving the growth and proliferation of effective bacteria it will be possible to remediate polluted soils from PAHs in industrial pilots.