赣江南昌段丰水期细菌群落特征

细菌群落是河流生态系统的重要组成部分，本次研究基于高通量测序技术分析了赣江南昌段丰水期（4～8月）细菌群落特征.结果表明，赣江南昌段细菌优势类群为放线菌门（Actinobacteria, 41.18%）和变形菌门（Proteobacteria, 31.79%），其次为厚壁菌门（Firmicutes, 10.04%），拟杆菌门（Bacteroidetes, 7.26%），蓝藻菌门（Cyanobacteria, 4.01%）.在属分类水平上，相对丰度最高的是hgcI_clade（16.39%）.赣江南昌段细菌丰度和多样性在城区上游、城区中心和城区下游采样点间没有显著差别，在不同月份有显著差别.除变形菌门（Proteobacteria）和疣微菌门（Verrucomicrobia）外，其它门水平分类细菌相对丰度在不同月份都有显著差异；不同采样点中，只有Proteobacteria差异显著（主要是Betaproteobacteria差异显著），其它门水平分类细菌相对丰度在不同采样点的差异均不显著.温度和流量是影响河流细菌群落的主要因子，其中温度与细菌可操作分类单元（OTU）相关性更高，流量则与门分类水平细菌相关性更高，暴雨径流中Firmicutes取代Actinobacteria和Proteobacteria成为丰度最高的菌群.温度、流量和电导率（EC）是影响OTU的最佳环境因子组合，流量和温度是影响门水平细菌群落的最佳环境因子组合.河水化学指标对细菌群落的影响小于温度、流量等水文气象条件.

Bacterial communities in Nanchang section of the Ganjiang River in wet seaon

Bacteria are key players in the ecosystem of rivers. In this study, bacterial communities in Nanchang section of the Ganjiang River in wet season (April to Auguest) were analyzed. The results showed that the dominant phyla were Actinobacteria (41.18%) and Proteobacteria (31.79%), followed by Firmicutes (10.04%), Bacteroidetes (7.26%) and Cyanobacteria (4.01%). The dominant genus was hgcI_clade (16.39%). There were no significant differences of the bacterial community abundance and diversity in river water between the upstream, the downtown and the downstream of urban area, while there were significant differences between months. Except for Proteobacteria and Verrucomicrobia, there was significant difference of the bacterial phyla abundance between months. Proteobacteria (mainly Betaproteobacteria) was the only phylum whose abundance showed significant difference between sampling sites. Temperature and streamflow were the main environmental factors influencing bacterial communities in river water, while temperature was more correlated with the bacterial Operational Taxonomic Unit (OTU), and streamflow was more correlated with bacterial phyla communities. Firmicutes became the dominant phylum instead of Actinobacteria and Proteobacteria in a stormflow. The optimal subset of environmental variables with the best correlation to OTU abundance included temperature, flow rate and EC, and with the best correlation to phylum abundance included temperature and flow rate. The influence of water chemical parameters on bacterial communities was less than that of hydrometeorological factors including temperature and streamflow.