Abstract: The petroleum-degrading bacteria in Shengli Oil Field wetland soil were isolated and identified by traditional experiment methods, and their diversity was analyzed by PCR-DGGE (denaturing gradient gel electrophoresis). A total of thirteen petroleum-degrading bacterial strains were isolated, among which, six strains were found to have the ability of degrading the majority of C12〖KG-*2〗-〖KG-*7〗C26 petroleum hydrocarbon, with a degradation rate of >90%. These petroleum degraders were phylogeneticly identified as the members of Halomonas, Alcanivorax, and Marinobacter, which were all belonged to γ-proteobacteria. The uncultured predominant bacteria in Shengli Oil Field wetland soil were of Sulfurovum, Gillisia and Arcobacter. Among the predominant bacteria, γ-proteobacteria accounted for a larger proportion, followed by α-proteobactiria, ε-proteobactiria, Actinobacteria, and Flavobacteria.

Key words: climate warming, passive nighttime warming (PNW), soil pH, soil available nutrient, root system, winter wheat.