Distribution patterns and driving factors of bacterial communities in water and sediment of Lake Taihu

水体和沉积物是湖泊生态系统中迥异但又紧密相连的两类生境,栖息在这两类生境中的细菌在维持生态系统平衡和驱动元素循环中起着关键性作用。为了探究湖泊水体和沉积物细菌群落的分布格局,本文对太湖四个湖区水体和沉积物中细菌群落进行调查,基于高通量测序技术和统计分析手段,分析这两类生境中的细菌群落组成和多样性水平、分布特征及其驱动因素。结果表明:放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和蓝细菌门(Cyanobacteria)是水体细菌群落中最主要的细菌门,而沉积物中Proteobacteria占据优势地位。在两类生境中,太湖西部区域细菌群落丰富度和独特性(LCBD)相对较高,各区域群落结构表现出显著性差异。对水体而言,电导率、pH值、PC1(重金属组成)和沉积物孔隙度是驱动细菌丰富度的重要因子,PC1、水温及pH值是影响细菌群落LCBD的重要因子,而细菌网络复杂性随pH值的增加而增加,且在高pH环境中占主导地位;对沉积物而言,其丰富度和LCBD的重要影响因子均是沉积物中总磷和锂,细菌网络复杂性随金属元素施加的环境压力增大而降低,但随总磷、磷酸盐和铵态氮浓度的增加而增加。本文揭示了太湖水体和沉积物细菌群落是由不同的环境因素所驱动,为太湖水生态保护和水资源管理提供了新的视角。;Water and sediment are two different but closely related habitats in the lake ecosystem, and the bacteria inhabiting these two habitats play a key role in maintaining the ecosystem balance and driving elemental cycling. To investigate the distribution patterns of bacterial communities in lake water and sediment, this paper investigated the bacterial communities in water and sediment in four regions of Lake Taihu, and analysed the bacterial community composition and diversity levels, distribution characteristics and their drivers in these two types of habitats based on high-throughput sequencing technology and statistical analysis. The results showed that Actinobacteria, Proteobacteria and Cyanobacteria were the main bacteria in the surface water bacterial community, while Proteobacteria dominated in the surface sediment. In the two habitats, bacterial richness and local contribution to beta diversity (LCBD) were relatively higher in the western region of Lake Taihu, and the community structure showed significant regional differences. For surface water bacterial communities, the important factors influencing community richness were water conductivity, pH, sediment porosity and PC1 (principal component of heavy metal elements), while the important factors influencing community uniqueness were PC1, water temperature and pH. In addition, network complexity increased significantly with increasing pH. For surface sediment bacterial communities, total phosphorus and lithium were the most important factors influencing community richness and community uniqueness. Furthermore, network complexity decreased with increasing metallic element content, whereas it increased with increasing total phosphorus, ammonium and phosphate concentrations in the sediment. These results showed that the bacterial communities in the water and sediment were driven by different environmental factors, providing a new perspective for aquatic ecosystem conservation and water resource management in Lake Taihu.