School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, People's Republic of China.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-Sen University), Guangzhou, People's Republic of China.
Appl Environ Microbiol. 2020 Sep 1;86(18). doi: 10.1128/AEM.00991-20.
Fungi are known to play important roles in pollutant transformation in activated sludge-based wastewater treatment plants (WWTPs). However, the seasonality and distributions of fungal populations in different-sized flocs have still remained largely unknown. In this study, seasonal population dynamics and community separation of fungi in a municipal WWTP across a 1-year period were investigated. We classified all taxa into six categories based on abundances to assess their roles and contributions to the whole community. The results showed that the rare taxa (<0.01%) contributed greatly to species richness (95.27%). Conversely, although low in species diversity, abundant taxa (≥1%) accounted for the majority (89.45%) of the total relative abundance, which suggested that a few core abundant fungi existed in the activated sludge ecosystem. The abundant, conditionally rare, and rare taxa contributed 30.14%, 31.11%, and 38.75%, respectively, to temporal shifts in community structure, and their abundances responded differently to environmental variables, suggesting that these three subcommunities exhibited a large difference in environmental sensitivity. Importantly, the results revealed seasonal dynamics of the whole fungal community and the subcommunities of all the microbial taxon categories, resulting in significant differences in community structures between warm and cold seasons. Furthermore, fungal diversity and the compositions of the whole community and subcommunities differed significantly among flocs of different sizes, which underlined the size-based fungal community separation in activated sludge of WWTPs. The findings of this work improved our understanding of fungal population dynamics and community separation in WWTPs. Fungi are important contributors to the various functions of activated sludge in wastewater treatment plants (WWTPs). Unlike previous studies, this work demonstrated the seasonality of the fungal community over a longer time span while it also systematically assessed the contributions of abundant, conditionally rare, and rare taxa to the whole community. Importantly, in the present study, we considered sludge flocs of a certain size range rather than the whole sludge flocs as a community. Our results revealed significant differences in fungal community structure among different-sized flocs, which supported the idea that size-based fungal community segregation is occurring in activated sludge ecosystems. The findings provide new insights into the dynamic changes or distribution of fungi in the bioaggregates of sludge flocs in WWTPs.
真菌在基于活性污泥的污水处理厂（WWTP）中污染物转化中起着重要作用。然而，不同大小絮体中真菌种群的季节性和分布仍然很大程度上未知。在这项研究中，我们调查了一个城市 WWTP 在一年中的真菌季节性种群动态和群落分离。我们根据丰度将所有分类单元分为六类，以评估它们在整个群落中的作用和贡献。结果表明，稀有分类单元（<0.01%）对物种丰富度贡献很大（95.27%）。相反，尽管物种多样性低，但丰富的分类单元（≥1%）占总相对丰度的大多数（89.45%），这表明活性污泥生态系统中存在少数核心丰富真菌。丰富、条件稀有和稀有分类单元分别对群落结构的时间变化贡献了 30.14%、31.11%和 38.75%，它们的丰度对环境变量的响应不同，这表明这三个亚群落在环境敏感性方面存在很大差异。重要的是，结果揭示了整个真菌群落和所有微生物分类群亚群落的季节性动态，导致了温暖和寒冷季节之间群落结构的显著差异。此外，真菌多样性以及整个群落和亚群落的组成在不同大小的絮体之间存在显著差异，这强调了 WWTP 中活性污泥的基于大小的真菌群落分离。这项工作的结果提高了我们对 WWTP 中真菌种群动态和群落分离的理解。真菌是污水处理厂（WWTP）中活性污泥各种功能的重要贡献者。与以前的研究不同，这项工作展示了在较长时间跨度内真菌群落的季节性，同时还系统地评估了丰富、条件稀有和稀有分类单元对整个群落的贡献。重要的是，在本研究中，我们考虑了一定大小范围内的污泥絮体，而不是整个污泥絮体作为一个群落。我们的结果表明，不同大小絮体中的真菌群落结构存在显著差异，这支持了基于大小的真菌群落分离在活性污泥生态系统中发生的观点。这些发现为 WWTP 中污泥絮体生物聚集体中真菌的动态变化或分布提供了新的见解。
