银川市第二排水沟沉积物细菌群落结构特征与构建机制研究

Investigation of Characteristics and Assembly Mechanisms of Bacterial Community Structure in Sediments of the Second Drainage Ditch in Yinchuan City

摘要:

为探讨银川市第二排水沟沉积物细菌群落结构特征及其群落构建过程的影响，结合高通量测序技术、非度量多维尺度分析（NMDS）、中性群落模型（NCM）以及结构方程模型（SEM），分析沉积物理化特征及细菌的结构特征、群落构建及驱动机制。结果表明，电导率（EC）与Chao1指数、Observed指数、Shannon指数、Simpson指数均存在显著性正相关，而总氮（TN）和铵态氮（NH4N）含量与α多样性指数均不存在显著性。细菌优势菌门为变形菌门和脱硫杆菌门，优势菌属为Thiobacillus、Bacteroidetes_vadinHA17和Dechloromonas菌属。从2021年8月到2022年8月，基于NCM模型、PER-SIMPER和DNCI的结果均表明细菌群落构建主要受随机过程的影响。SEM分析表明中性模型随机性过程（R2）和共现网络结构稳定性主要受EC、NH4N和总磷（TP）含量驱动，其中EC能够直接影响共现网络结构的稳定性，且存在显著性负相关（r=-0.369）；TP含量直接影响R2，同时存在显著性正相关（r=0.504）。本研究不仅拓展了对水域沉积物细菌群落结构特征认识，也探明了细菌构建机制及共现网络拓扑特性，以及理化因子对R2和共现网络结构稳定性的驱动过程。

Abstract:

High-throughput sequencing technology, non-metric multidimensional scaling (NMDS), neutral community model (NCM) and structural equation modelling (SEM) were used to analyze sediment physicochemical properties, bacterial structural features, community assembly, and driving mechanisms in order to examine the bacterial community structure characteristics and community assembly processes of sediments in the Second Drainage Channel of Yinchuan City. The findings indicated that whereas total nitrogen (TN) and ammonium nitrogen (NH4N) concentrations did not substantially correlate with α-diversity indices, electrical conductivity (EC) did considerably positively correlate with Chao1, Observed, Shannon, and Simpson diversity indices. Thiobacillus, Bacteroidetes_vadinHA17, and Dechloromonas were the major genera in the bacterial phyla Proteobacteria and Desulfobacterota. Results from PER-SIMPER, DNCI, and the NCM model consistently showed that stochastic processes dominated the bacterial community assembly between August 2021 and August 2022. EC, NH4N, and total phosphorus (TP) were the main drivers of the neutrality model’s stochasticity (R2) and the stability of the co-occurrence network structure, according to SEM analysis. Co-occurrence network stability was specifically directly and significantly impacted negatively by EC （r=-0.369) and positively by TP （r=0.504). The research revealed the bacterial assembly methods, co-occurrence network topology, and the driving impacts of physicochemical parameters on R2 and network stability, in addition to advancing the understanding of structure characteristics of bacterial communities in aquatic sediments.