Objective: Diesel oil can be considered as an environmental pollutant used in motor vehicles, causing environmental problems. The microbial consortium can play an important role in the degradation of petroleum hydrocarbons. The screening of new microbial decomposers on specific hydrocarbons provides new perspectives for the removal of hydrocarbons with various hazards to the environment. This study aimed to determine the effects of microbial consortium on the degradation of diesel oil.

Methods: Crude oil samples were collected from the petrochemical industry to establish the active microbial consortium. In order to perform wide screening, n-tridecane, n-tetradecane, n-hexadecane, sunflower oil, and olive oil were used in the culture media. Then, the degradation test was carried out by adding 0.5% and 0.25% of diesel oil and adding 50 ml of media enriched with various carbon sources. The bottles were incubated at 30°C on a rotary shaker at 200 rpm for 21 days. Gas Chromatography and gravimetric analysis did analytical analyzes. Gram reactions of selected isolates were screened in catalase, oxidase, KOH tests, lipase and protease activities. Genomic DNA isolations and molecular biological analyzes were performed to identify successful isolates.

Results: The CT1 consortium showed successful disintegrating activity. As a result of GC and gravimetric analysis, the CT1 consortium degraded 93% of diesel oil in 21 days. Members of this consortium are Citrobacter sp., Pseudomonas japonica, and Bacillus sp. have been determined.

Conclusion: CT1 consortium degraded 93% of the diesel oil. Diesel oil biodegradation could be an important step towards reducing dependence on fossil fuels and reducing environmental impacts.