Isolation and Characterization of a Thermophilic Oil-Degrading Bacterial Consortium

In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45-65℃(with 55℃being the optimum temperature) was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis (DGGE) showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33%of saturates, 27.06%of aromatics, 13.24%of resins and the oil removal efifciency reached up to 58.73%at 55℃when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C19, and the n-alkanes ranging from C20-C33 were signiif-cantly degraded. The ratios of nC17/Pr and nC18/Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efifciency in KO8-2 composting reactor reached 50.12%after a degradation duration of 60 days.