长期石油污染对盐碱化土壤中微生物群落分子生态网络的影响

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

长期石油污染改变了土壤微生物群落组成,降低了群落多样性,对生态系统造成严重的威胁.为了探讨长期石油污染对盐碱化土壤中微生物物种间相互作用关系的影响,采集胜利油田石油污染土壤和未污染土壤,利用随机矩阵方法构建分子生态网络.结果发现,污染土壤和未污染土壤中微生物功能基因组的分子生态网络存在显著差异(P<0.001).与未污染土壤相比,污染土壤的网络节点数、连接数、平均连通度、模块数和模块性都显著降低,说明在石油污染的影响下土壤微生物网络拓扑结构发生变化;污染土壤和未污染土壤的模块枢纽基因、连接器基因均没有重叠,模块枢纽基因和连接器基因的网络拓扑角色发生了变化.通过构建烷烃、多环芳烃降解基因网络,发现负相互作用的比例较大,这可能反映了微生物功能群落间的竞争关系.

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. Subnetworks 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.