广州市流溪河沉积物反硝化细菌群落丰度与结构多样性研究

摘要

[目的]研究广州市流溪河沉积物中反硝化细菌的多样性,探讨环境因子对反硝化细菌群落结构和丰度的影响.[方法]通过构建基因文库和实时荧光定量PCR(RT-qPCR)对沉积物中反硝化细菌的群落结构和丰度进行分析,并结合主坐标分析(PCoA)和冗余分析(RDA)研究反硝化细菌群落与环境因子之间的相关性.[结果]流溪河流域不同采样位点沉积物中nirS型反硝化细菌的组成和丰度存在明显差异.沉积物中大多数nirS序列与已知的反硝化细菌亲缘关系较远,而与其他环境样品中的微生物亲缘关系较近,与流溪河沉积物中nirS反硝化细菌亲缘关系较近的物种有产黄杆菌属Rhodanobacter、副球菌属Paracoccus、Polymorphum gilvum、草螺菌属Herbaspirillum和陶厄氏菌属Thauera.氨氮(NH4+–N)和硝酸盐(NO3––N)含量对反硝化细菌群落结构起决定性作用.反硝化细菌nirS基因拷贝数范围为8.26×101~5.45×104g–1,nirS型反硝化细菌数量与化学需氧量(COD)、总氮(TN)、NH4+–N、和NO3––N含量之间存在显著相关性.[结论]流溪河中化学污染物以及活性氮的大量存在显著影响了反硝化细菌群落结构和多样性.%[Objective]To investigate the diversity of denitrifying bacteria in sediments of Guangzhou Liuxi River, and explore the effects of environmental factors on structure and abundance of bacterial community.[Method]The community structure and abundance of denitrifying bacteria in sediments were analyzed by constructing gene library and real-time quantitative PCR (RT-qPCR). The principal coordinate analysis (PCoA) and redundancy analysis (RDA) were used to investigate the correlations between denitrifying bacterial community and environmental factors.[Result]The composition and abundance of nirS-type denitrifier communities in different sampling sites of Liuxi River had distinctive discrepancy. Phylogenetic analysis showed that most of nirS gene sequences obtained in sediments had distant relationships with the known denitrifying bacteria, and the relationships with microorganisms from other environments were closer. The species that had close relationships with nirS-type denitrifier in sediments of Liuxi River were Rhodanobacter, Paracoccus,Polymorphum gilvum,Herbaspirillum and Thauera.Ammonium(NH4+–N)and nitrate(NO3––N) contents had decisive effects on the structure of denitrifying bacterial community.The nirS gene copy numbers were ranged from 8.26×101to 5.45×104g–1,and nirS-type denitrifier abundance was significantly correlated with chemical oxygen demand, total nitrogen, ammonium and nitrate concentrations.[Conclusion]The abundant occurrence of chemical contaminants and reactive nitrogen in Liuxi River significantly influences denitrifying bacterial community structure and diversity.