南淝河表层沉积物细菌群落结构特征及驱动因素

为了探讨南淝河不同河段沉积物细菌群落结构特征差异及其主要驱动因素，在对南淝河不同土地利用区域河段表层沉积物的主要理化指标（pH、CEC、TOC、DOC、氮分级形态）进行分析基础上，重点通过MiSeq高通量测序技术对沉积物中细菌群落结构特征进行了分析，并利用冗余分析（RDA）方法探讨了导致群落结构差异的主要驱动因素.结果表明：沉积物中门水平下优势细菌种群为变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）和拟杆菌门（Bacteroidetes）；纲水平下除未分类外主要是厌氧绳菌纲（Anaerolineae）、γ-变形菌纲（Gammaproteobacteria）、梭状芽胞杆菌纲（Clostridia）、δ-变形菌纲（Deltaproteobacteria），此外ε-变形菌纲（Epsilonproteobacteria）主要在南淝河下游采样点被检测到，说明其在南淝河沉积物生态系统中并不是普遍存在的；属水平下大多为未分类序列，长绳菌属（Longilinea）和芽孢杆菌属（Bellilinea）有优势地位.南淝河不同河段所在流域土地利用方式不同会导致污染物类型、污染源强和沉积物理化指标的不同，进而影响沉积物细菌群落结构，中游城区和工业区段的细菌多样性整体上高于上、下游；RDA分析结果表明，表层沉积物的CEC、TOC、DOC、TP、WAEF-N和IEF-N是导致细菌群落结构特征差异的主要影响因子，其中变形菌门、拟杆菌门和厚壁菌门受TP影响较大，绿弯菌门则受弱酸浸取态氮（WAEF-N）影响较大.

Microbial community structure characteristics and its key driving factors in surface sediments along Nanfei River

In order to explore the differences in bacterial community structure and its driving factors in the sediment of Nanfei River, the key physiochemical parameters including pH, CEC, TOC, DOC, and various forms of nitrogen were determined in the surface sediment samples along Nanfei River with different land uses such as urban, suburb, industrial park and rural areas. Specially, sediment bacterial community structure characteristics were analyzed by using MiSeq high-throughput sequencing technology. The relationships between sediment bacterial community structure and aforementioned physiochemical parameters were examined by redundancy analysis (RDA). The results showed that the major bacterial phylum is Proteobacteria in the surface sediments, followed by Chloroflexi, Bacteroidetes, Firmicutes. At the level of class, the major bacterial class are Anaerolineae, Gammaproteobacteria, Clostridia, Deltaproteobacteria besides the unclassified. Epsilonproteobacteria were detected mainly in sediment samples from downstream of the Nanfei River, suggesting that they were not ubiquitous in the sediment ecosystem of the Nanfei River. Most of the genus is unclassified, with Longilinea and Bellilinea being predominant species. Different types of land uses along the Nanfei River led to different pollution sources and discharging load will result in different physicochemical properties of surface sediment, which in turn reshape the bacterial community structure of the sediment. The bacterial diversity in the sediments from urban and industrial areas of the middle reaches is generally higher than that in the upper and lower reaches. RDA analysis indicated that the sediment CEC, TOC, DOC, TP, nitrogen in weak acid extractable form (WAEF-N) and nitrogen in ion exchangeable form (IEF-N) were the key factors driving the differences in the structural characteristics of bacterial communities in the sediment of Nanfei River. The influence of TP was significant on Proteobacteria, Bacteroidetes and Firmicutes, and WAEF-N had a greater influence on Chloroflexi.