Petroleum pollution and microbial community structure in the soil of Liaohe Oilfield.

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We analyzed the soil physico-chemcial properties, microbial community structure, petroleum hydrocarbon contents and components in soil samples from the well sites of Shuguang, Huanxi-ling and Jinzhou oil exploitation sites in Liaohe Oilfield, with uncontaminated paddy soil as a control. The results showed that: 1) The soil around all the three oil exploitation sites were seriously polluted by petroleum with certain differences in the petroleum hydrocarbon contents and components. The average content of petroleum hydrocarbon in the soil of Shuguang and Huanxiling oil exploitation sites was two times higher than that of Jinzhou oil exploitation site. The content of resins and asphaltenes in the soil of Shuguang oil exploitation site was the highest, while the soils of Huan-xiling and Jinzhou oil exploitation sites had the highest alkane content, which accounting for more than 40% in all the sites. 2)Compared with the paddy soil, the microbial OTU numbers, Chao1 and Shannon indices in the soil of Jinzhou oil exploitation site increased. The dominant phyla and genera were similar in the soil of all oil exploitation sites but with large differences in abundance. The soil in Jinzhou oil exploitation site had higher abundance of Mycobacterium and Pseudomonas, while Sphingomonas and Nocardioides, Massilia in the soil of Shuguang oil exploitation site, and Lysobacter, Thiobacillus and Pseudomonas in the soil of Huanxiling oil exploitation site. 3) The abundances of Sphingomonas, Nocardioides, Thiobacillus, Massilia, Pseudomonas and the contents of total petroleum hydrocarbons, total organic carbon and resins and asphaltenes were significantly positively correlated, while Mycobacterium, Lysobacter and Pseudomonas were significantly positively correlated with the contents of total nitrogen and total phosphorus. This study systematically analyzed the petroleum hydrocarbon, physico-chemcial properties and microbial communities in the soil of different oil exploitation sites, and revealed the specific dominant bacterial genera and microbial communities in the soil of Liaohe Oilfield. Our results provided a theoretical basis for functional bacterium screening and microbial community construction in the remediation process of petroleum contaminated soil in Liaohe Oilfield, and a reference for efficient degradation bacteria screening in other oilfields.