Oil Hydrocarbon Degradation Capability of Bacterial Strains Isolated from the Sapanca Lake, Turkey

Abstract

In this study, the analyses were carried out to determine oil-degradation capacity and oil-resistance levels of bacteria isolated from water surface (0-30 cm) of nine stations of the Sapanca Lake from September of 2008 to May of 2010. Twenty-seven bacteria species belonging three classes and six families total of eighty-five wild bacteria were identified and screened against crude oil with respect to Minimum Inhibitory Concentration (MIC). Bacterial isolates showing resistance against crude oil were chosen for Emulsification Index (E₂₄) test. Isolates displaying higher E₂₄ values were selected for further degradation tests regarding pH and oil thickness values in experimental setups. Fifty bacterial strains of eighty-five isolates were recorded to be resistant against oil hydrocarbon. Positive reactions percentages of the isolates against crude oil were detected in variable ranges between 25% and 100%. The results of the emulsification index test for crude oil indicated that the isolates of S49-Stenotrophomonas maltophila, S50-Aeromonas hydrophila, S59-E. coli1, S38-Aeromonas hydrophila and S43-Enterobacter cloaceae have higher emulsification percentages. The results of the degradation test showed that isolate of S59-E. coli1 has higher degradation ability than all isolates tested. The bacteria screened against crude oil were detected to be sensitive against crude oil during the first year of the study. Presence of petroleum-resistant bacteria in subsequent tests was associated with the unexpected oil spill occurred in the Sapanca Lake at the time. Detected crude oil resistant bacteria isolates were stocked for a possible use in upcoming bioremediation related studies.