[Effects of PAHs Pollution on the Community Structure of Denitrifiers in a Typical Oilfield].

Agricultural soils in the oilfields have the potential risk of PAHs (polycyclic aromatic hydrocarbons) pollution, and the denitrification process with nitrate as the terminal electron acceptor might be important for soil PAHs elimination under anaerobic condition. In this study, 9 soil samples listed as JH-1 to JH-9 were collected from the JiangHan oilfield with a history of more than 50 years. Using the functional genes (-nitrite reductase gene; -nitrite reductase gene) involved in denitrification as biomarkers, the community structure of soil denitrifiers was investigated by quantitative-PCR and T-RFLP (terminal-restriction fragment length polymorphism) combined with clone library, and the relationship between soil properties and community structure of soil denitrifers was discussed. The result indicated that the copy numbers of were higher than those of in all soil samples, and the lowest copy numbers of and were both detected in the JH-4 with the highest PAHs content. Meanwhile, the correlation analysis also showed a negative correlation between the copy numbers of those functional genes and soil PAHs content (=0.54, <0.05; =0.58, <0.05). Furthermore, the result of T-RFLP indicated that the community structures in different soil samples varied significantly, which was obviously unique in the sample (JH-4) with the highest PAHs content. The subsequent RDA (redundancy analysis) also demonstrated that soil PAHs content as well as the available nitrogen and phosphorus belonged to the most important factors affecting the community structure in this oilfield soil. Compared with , little variation was shown about the community structure among the soil samples. However, the abundance of -harboring had a remarkably positive relation with the soil PAHs content, which indicated that , a well known bacterial genus with strong ability to degrade organic pollutants, might be an essential driver for PAHs degradation via denitrification process in this oilfield soil.