Due to widespread use of petroleum products, the number of petroleum-contaminated sites has abounded. Natural attenuation, which relies on in situ biodegradation of pollutants, has received a large amount of attention, especially for petroleum contamination. Therefore in this research two types of samples, natural and enriched, from two different sources, soil and water were chosen and oil degrading microorganisms were isolated using different gasoline containing mineral media supplemented with yeast extract and or glucose. Fifty-five isolated strains were selected according to their simultaneous good growth on mineral medium with oil and nutrient agar. Several micromorphological and biochemical characteristics of isolated oil-degrading strains were determined. 73% of them were gram negative, 42.5% oxidase negative, 40.7% catalase positive, 59% showed oxidative glucose metabolism. The dominant portion of the strains could possibly belong to the family Pseudomonadaceae, while an other dominant group was members of the Coryneform taxa. By checking the biodegradative ability of our selected oil-degrading strains on individual hydrocarbon derivatives we showed that 10% of our strains could decompose n-dodecane easily and very fast. The utilization of 1-dodecene, naphtalene, benzol, and cyclohexane, respectively seems to be characteristic for always less and less strains. The speed of growth of 1-dodecene was lower than other compounds.

Keywords