Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, China.
Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, Zhejiang, China.
ISME J. 2023 May;17(5):671-681. doi: 10.1038/s41396-023-01378-0. Epub 2023 Feb 11.
The operation of modern wastewater treatment plants (WWTPs) is driven by activated sludge microbiota, a complex assemblage of trophically interacting microorganisms. Microbial predation is crucial to fundamental understanding of how biological interactions drive microbiome structuring and functioning of WWTPs. However, predatory bacteria have received little attention regarding their diversity, activity, and ecological function in activated sludge, limiting the exploitation of food web interactions for wastewater microbiome engineering. Here, by using rRNA-stable isotope probing of activated sludge microbiota with C-labeled prey bacteria, we uncovered diverse as-yet-uncultivated putative predatory bacteria that actively incorporated C-biomass. Myxobacteria, especially Haliangium and the mle1-27 clade, were found as the dominant active predators, refreshing conventional views based on a few predatory isolates of Bdellovibrionota from WWTPs. The identified predatory bacteria showed more selective predation on prey compared with the protists dominated by ciliates, providing in situ evidence for inter-domain predation behavior divergence in activated sludge. Putative predatory bacteria were tracked over a two-year microbiome monitoring effort at a local WWTP, revealing the predominance of Myxococcota (6.5 ± 1.3%) over Bdellovibrionota (1.0 ± 0.2%) lineages. Phylogenetic analysis unveiled highly diverse myxobacteria inhabiting activated sludge and suggested a habitat filtering effect in global WWTPs. Further mining of a global activated sludge microbiome dataset revealed the prevalence of Myxococcota (5.4 ± 0.1%) species and potential impacts of myxobacterial predation on process performance. Collectively, our findings provided unique insights into the predating activity, diversity, and prevalence of Myxococcota species in activated sludge, highlighting their links with wastewater treatment processes via trophic regulation of enteric and functional bacteria.
现代污水处理厂（WWTP）的运行依赖于活性污泥微生物群落，这是一个营养相互作用的微生物复杂组合。微生物捕食对于理解生物相互作用如何驱动微生物组结构和 WWTP 的功能至关重要。然而，关于捕食细菌的多样性、活性和生态功能，在活性污泥中却很少受到关注，这限制了对食物网相互作用的利用来进行废水微生物组工程。在这里，我们通过使用 C 标记的猎物细菌对活性污泥微生物群落进行 rRNA 稳定同位素探测，发现了多样化的、尚未培养的、具有潜在捕食能力的细菌，它们能够主动掺入 C 生物质。粘细菌，特别是黄杆菌属和 mle1-27 分支，被发现是主要的活跃捕食者，刷新了基于 WWTP 中少数捕食性孤立的 Bdellovibrionota 的传统观点。与以纤毛虫为主的原生动物相比，鉴定出的捕食细菌对猎物具有更强的选择性捕食，为活性污泥中不同生物域捕食行为的差异提供了原位证据。在当地 WWTP 进行了为期两年的微生物组监测工作中追踪了潜在的捕食细菌，结果表明 Myxococcota（6.5±1.3%）比 Bdellovibrionota（1.0±0.2%）谱系更为普遍。系统发育分析揭示了栖息在活性污泥中的高度多样化的粘细菌，并表明在全球 WWTP 中存在栖息地过滤效应。进一步挖掘全球活性污泥微生物组数据集揭示了 Myxococcota（5.4±0.1%）物种的普遍性和粘细菌捕食对工艺性能的潜在影响。总的来说，我们的研究结果为活性污泥中粘细菌的捕食活性、多样性和普遍性提供了独特的见解，并通过对肠内和功能细菌的营养调节，突出了它们与废水处理过程的联系。
