Activated sludge is comprised of diverse microorganisms which remediate wastewater. Previous research has characterized activated sludge using 16S rRNA gene amplicon sequencing, which can help to address questions on the relative abundance of microorganisms. In this study, we used 16S rRNA transcript sequencing in order to characterize “active” populations (via protein synthesis potential) and gain a deeper understanding of microbial activity patterns within activated sludge. Seasonal abundances of individual populations in activated sludge change over time, yet a persistent group of core microorganisms remains throughout the year which are traditionally classified on presence or absence without monitoring of their activity or growth. The goal of this study was to further our understanding of how the activated sludge microbiome changes between seasons with respect to population abundance, activity, and growth. Triplicate sequencing batch reactors were sampled at 10-min intervals throughout reaction cycles during all four seasons. We quantified the gene and transcript copy numbers of 16S rRNA amplicons using real-time PCR and sequenced the products to reveal community abundance and activity changes. We identified 108 operational taxonomic units (OTUs) with stable abundance, activity, and growth throughout the year. Nonproliferating OTUs were commonly human health related, while OTUs that showed seasonal abundance changes have previously been identified as being associated with floc formation and bulking. We observed significant differences in 16S rRNA transcript copy numbers, particularly at lower temperatures in winter and spring. The study provides an analysis of the seasonal dynamics of microbial activity variations in activated sludge based on quantifying and sequencing 16S rRNA transcripts.

中文翻译：

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使用16S rRNA转录本扩增子测序评估分批反应器中活性污泥微生物组的季节性动态。

活性污泥由多种微生物组成，可修复废水。先前的研究已使用16S rRNA基因扩增子测序对活性污泥进行了表征，可帮助解决有关微生物相对丰度的问题。在这项研究中，我们使用16S rRNA转录本测序来表征“活跃的”种群（通过蛋白质合成潜能）并加深对活性污泥中微生物活性模式的了解。活性污泥中各个种群的季节性丰度会随着时间而变化，但全年仍会保留一组持久的核心微生物，传统上，这些微生物按存在与否进行分类，而不监控其活动或生长。这项研究的目的是使我们进一步了解活性污泥微生物组在种群数量，活动和生长方面随季节变化的方式。在所有四个季节的整个反应周期中，以10分钟的间隔对一式三份测序批处理反应器进行采样。我们使用实时PCR定量了16S rRNA扩增子的基因和转录本拷贝数，并对产物进行了测序，以揭示社区的丰富度和活性变化。我们确定了108个运营生物分类单位（OTU），它们在全年中具有稳定的丰度，活动和增长。不扩散的OTU通常与人类健康有关，而显示季节性丰度变化的OTU先前已被确定与絮凝物的形成和膨大有关。我们观察到16S rRNA转录本拷贝数存在显着差异，特别是在冬季和春季较低的温度下。该研究基于对16S rRNA转录本进行定量和测序，从而分析了活性污泥中微生物活性变化的季节性动态。