活性污泥微生物泛化种和特化种的构建机制与进化速率

Assembly mechanisms and evolutionary rates of microbial generalists and specialists in activated sludge

摘要:

【背景】 活性污泥中细菌和微型真核生物在污水处理中扮演了重要角色，然而目前对其泛化种和特化种的研究尚不充分。【目的】 分析活性污泥中微生物泛化种和特化种的结构与环境因子相关性，研究其群落构建机制、进化速率和多样化潜力。【方法】 以中国东南沿海某地污水厂中活性污泥微生物群落为研究对象，利用扩增子测序技术和多元统计技术分析了泛化种和特化种的结构特征，并通过基于系统发育分箱的零模型(infer community assembly mechanisms by phylogenetic-bin-based null model analysis, iCAMP)和二分成种与灭绝(binary-state speciation and extinction, BiSSE)模型分别研究了其构建机制及进化速率。【结果】 细菌泛化种和特化种与电导率、NH₄⁺-N和NO₂^--N显著相关，而总氮(total nitrogen, TN)是影响微型真核生物泛化种和特化种的关键因子。此外，电导率和NO₂^--N对微型真核生物特化种也有着重要影响。以漂变和扩散限制为主的随机作用是影响上述群落的主要生态学机制(泛化种大于特化种)，并且对微型真核生物的影响更强。相较于微型真核生物，细菌具有较高的成种速率、多样化潜力及较低的灭绝速率；相较于泛化种，特化种具有较高的成种速率、灭绝速率和多样化潜力。【结论】 NH₄⁺-N、NO₂^--N和电导率是影响细菌泛化种、细菌特化种和微型真核生物特化种的重要环境因子。泛化种和特化种主要受漂变和扩散限制的影响，其成种速率存在差异。

Abstract:

[Background] The bacterial and microeukaryotic communities in activated sludge (AS) play crucial roles in wastewater treatment. However, limited information is available regarding the microbial generalists and specialists in AS. [Objective] Aims to study the relationships between environmental factors and AS microbial generalists and specialists, and explore the community assembly mechanisms, evolutionary rates, and diversification potential of AS microbial generalists and specialists. [Methods] Amplicon sequencing and multivariate statistical analysis were employed to explore the community structures of AS microbial generalists and specialists from wastewater treatment plants located in the southeastern coastal region of China. Additionally, the infer community assembly mechanisms by phylogenetic-bin-based null model analysis (iCAMP) was conducted to explore the assembly mechanisms of those groups, while the evolutionary rates were assessed by the binary-state speciation and extinction (BiSSE) model. [Results] The community structures of bacterial generalists and specialists were significantly correlated with electrical conductivity, ammonia nitrogen, and nitrite nitrogen, while the total nitrogen was the primary factor influencing the community structures of the microeukaryotic generalists and specialists. However, electrical conductivity and nitrite nitrogen played major roles in shaping the microeukaryotic specialists. Stochastic processes played a dominant role in the community assembly of both bacteria and microeukaryotes in AS, especially for the generalists than the specialists as well as for the microeukaryotes than the bacteria. Bacteria exhibited higher speciation rates and lower extinction rates than microeukaryotes, which suggested higher diversification potential. The specialists exhibited higher speciation rates, extinction rates, and diversification potential than the generalists. [Conclusion] Ammonia nitrogen, nitrite nitrogen, and electrical conductivity were significant environmental factors influencing the community structures of bacterial generalists and specialists, and microeukaryotic specialists. Stochastic processes mainly drove the community assembly of the generalists and specialists. Moreover, the AS generalists and specialists exhibited different speciation rates.