Constructed wetlands (CWs) are complicated ecosystems that include vegetation, sediments, and the associated microbiome mediating numerous processes in wastewater treatment. CWs have various functional zones where contrasting biochemical processes occur. Since these zones are characterized by different particle-size composition, physicochemical conditions, and vegetation, one can expect the presence of distinct microbiomes across different CW zones. Here, we investigated spatial changes in microbiomes along different functional zones of a free-water surface wetland located in Moscow, Russia. The microbiome structure was analyzed using Illumina MiSeq amplicon sequencing. We also determined particle diameter and surface area of sediments, as well as chemical composition of organic pollutants in different CW zones. Specific organic particle aggregates similar to activated sludge flocs were identified in the sediments. The highest accumulation of hydrocarbons was found in the zones with predominant sedimentation of fine fractions. Phytofilters had the highest rate of organic pollutants decomposition and predominance of Smithella, Ignavibacterium, and Methanothrix. The sedimentation tank had lower microbial diversity, and higher relative abundances of Parcubacteria, Proteiniclasticum, and Macellibacteroides, as well as higher predicted abundances of genes related to methanogenesis and methanotrophy. Thus, spatial changes in microbiomes of constructed wetlands can be associated with different types of wastewater treatment processes.

中文翻译：

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沿自由水表面湿地不同功能区的微生物群落的空间变化

人工湿地（CW）是复杂的生态系统，包括植被，沉积物以及相关的微生物组，介导了废水处理中的许多过程。化学武器具有不同的功能区，在这些功能区发生相反的生化过程。由于这些区域的特征在于不同的粒径组成，理化条件和植被，因此人们可以期望在不同的CW区域存在不同的微生物群。在这里，我们调查了位于俄罗斯莫斯科的自由水面湿地不同功能区微生物群落的空间变化。使用Illumina MiSeq扩增子测序分析了微生物组结构。我们还确定了沉积物的粒径和表面积，以及不同连续波区域中有机污染物的化学组成。在沉积物中发现了类似于活性污泥絮凝物的特定有机颗粒聚集体。在细小颗粒的主要沉积区中发现了碳氢化合物的最高积累。植物滤池的有机污染物分解率最高，占优势。Smithella，Ignavibacterium和Methanothrix。沉淀池具有较低的微生物多样性，并具有较高的Parcubacteria，Plasticiclasticum和Macellibacteroides相对丰度，以及与产甲烷和甲烷氧化有关的基因的丰度较高。因此，人工湿地微生物群落的空间变化可能与不同类型的废水处理过程有关。