Biodegradation of crude oil by newly enriched biosurfactant-producing bacterial consortium

Crude oil contamination in different environmental media is a global environmental problem, biodegradation is a potential, environmentally friendly method for remediating this pollutant. In the present study, a biosurfactant-producing and crude oil degrading bacterial consortium (S1) was enriched from a contaminated soil, and its degradation efficiency of crude oil in solution and soil under the optimum conditions was studied. The results showed that the predominant species of S1 were Pseudomonadaceae and Alcaligenaceae. S1 could produce surfactant, with the maximum content of 2.27 g/L, which was identified as rhamnolipids. The optimal pH, temperature, and (NH₄)₂SO₄ concentration for crude oil degradation were 7.0, 40 °C, and 3 g/L, respectively, with the maximum degradation efficiency of 51.51 % after 7 days incubation. Plackett-Burman experiment and response surface methodology demonstrated that Cu, Co, and Zn could significantly promote the degradation of crude oil, with their optimum concentration of 0.36, 0.88, and 0.60 mg/L, respectively. Under the optimum conditions, the highest crude oil degradation efficiency reached 53.23 % within 7 days. Kinetic analysis showed that the first-order reaction kinetic was suitable for describing the degradation of crude oil by S1, with a half-life of 4.57 days. Furthermore, S1 also could degrade the crude oil in soil efficiently, with the maximum degradation efficiency of 60.34 % within 56 days. These results indicate that S1 has great potential for practical application in remediation of crude oil contamination.