Effect of Long-term Oil Contamination on the Microbial Molecular Ecological Networks in Saline-alkali soils

Abstract

Long-term oil contamination alters the structures of soil microbial communities, as well as decreases the community diversity, posing a great threat to the ecosystem. To determine the possible influence of long-term oil contamination on microbial interactions in saline-alkali soils, microbial functional molecular ecological networks were studied in both contaminated and uncontaminated soils from Shengli oil field by constructing random networks based on null model. The results demonstrated that the overall networks were significantly different between contaminated and uncontaminated soils (P<0.001). Network size, links, average connectivity, modules and modularity were all decreased in soil with oil contamination, indicating that oil contamination altered the topological structure of microbial functional molecular ecological network. Module hub and connectors were different in contaminated and uncontaminated soils. The topological roles of the genes (module hub and connectors) were altered by oil contamination. Sub-networks of genes involved in alkane and polycyclic aromatic hydrocarbon degradation were also constructed. Negative co-occurrence patterns prevailed among functional genes, thereby indicating probable competition relationships among functional groups.