Impact of Petroleum Contamination on the Structure of Saline Soil Bacterial Communities

Petroleum contamination may lead to variations in soil microbial community structure and activities. The bioremediation of petroleum-contaminated soil typically depends on the characteristics and activities of oil-degrading microorganisms, which can be introduced or be part of the native soil microbiota. Thus, analyzing the structure of the microbial community and internal relationships in the bioremediation process is critical. Our study characterized the physical and chemical properties, microbial community structure, and microbial diversity of surface soil collected near an oilfield. The total carbon (TC), total organic carbon (TOC), and microbial diversity in oil-contaminated soil was found higher than in uncontaminated samples. Proteobacteria abundance was inhibited with oil pollution, while Actinomycetes abundance was enhanced. Some indigenous hydrocarbon-degrading bactera were enriched by oil pollution, such as Bacillus, Actinomarinalesnorank, Balneolaceaeuncultured, Marinobacter, and Pseudomonas. Furthermore, Rokubacteria, Nitrospirae, and Entotheonellaeota were significant differences in the contaminated group. There were 16 genera with significant differences in the polluted group, such as Woeseia, Pelagibius, Pontibacillus, IS_44, Aliifodinibius, while Halothiobacillus, Algoriphagus, Novosphingobium, etc. had significant differences in the uncontaminated group. Redundancy analysis demonstrated that the responses of the microorganisms to the evaluated environmental factors were different, and TC was the most important driver of microbial community variation. Moreover, TOC was the largest contributor to operational taxonomic unit (OTU) and Chao index variations. Our results provide a theoretical basis for the enhancement of microbial activity in oil-contaminated soil, which might improve bioremediation efficacy.