Microbial Systems Ecology, Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098, XH Amsterdam, the Netherlands.
Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911, MA Leeuwarden, the Netherlands.
Water Res. 2023 Sep 1;243:120404. doi: 10.1016/j.watres.2023.120404. Epub 2023 Jul 25.
Slow sand filters (SSF) are widely used in the production of drinking water as a last barrier in the removal of pathogens. This removal mainly depends on the 'Schmutzdecke', a biofilm-like layer on the surface of the sand bed. Most previous studies focused on the total community as revealed by DNA analysis rather than on the active community, which may lead to an incorrect understanding of the SSF ecology. In the current study, we determined and compared the DNA- (total) and RNA-displayed (active) communities in the Schmutzdecke layer from 10 full-scale slow sand filters and further explored the SSF core microbiome in terms of both presence (DNA) and activity (RNA). Discrepancies were observed between the total and the active community, although there was a consistent grouping in the PCoA analysis. The DNA-displayed community may be somewhat inflated, while the RNA-displayed community could reveal low abundance (or rare) but active community members. The overall results imply that both DNA (presence) and RNA (activity) data should be considered to prevent the underestimation of organisms of functional importance but lower abundance. Microbial communities of studied mature Schmutzdecke were shaped by the influent water. Nevertheless, a core microbiome was shared by the mature Schmutzdeckes from independent filters, representing the dominant and consistent microbial community composition in slow sand filters. In the DNA samples, a total of 33 VSC families ('very strict core', with a relative abundance >0.1% and 100% prevalence) were observed across all filters. Among the RNA samples, there were 18 VSC families, including 16 families that overlapped with the DNA VSC families and 2 unique RNA VSC families. The core microbial community structure was influenced by the operational parameters, including the Schmutzdecke age and the sand size, and was less influenced by water flow. In addition, indicator organisms ('biomarkers') for the Schmutzdecke age, which show the longest duration that SSF can maintain a good operation, were observed in our study. The abundant presence of bacteria belonging to bacteriap25 and Caldilineaceae was associated with older Schmutzdeckes, revealing longer periods of stable operation performance of the filter, while the high abundance of bacteria belonging to Bdellovibrionaceae and Bryobacteraceae related to short periods of stable operation performance.
慢砂滤池（SSF）作为去除病原体的最后一道屏障，广泛应用于饮用水生产中。这种去除主要依赖于砂床表面的生物膜状层“Schmutzdecke”。以前的大多数研究都集中在 DNA 分析揭示的总群落上，而不是活跃的群落，这可能导致对 SSF 生态的不正确理解。在本研究中，我们测定并比较了 10 个全规模慢砂滤池中 Schmutzdecke 层的 DNA（总）和 RNA（活跃）显示群落，并进一步从存在（DNA）和活性（RNA）两方面探讨了 SSF 的核心微生物组。尽管在 PCoA 分析中存在一致的分组，但总群落和活跃群落之间存在差异。DNA 显示的群落可能有些膨胀，而 RNA 显示的群落可能揭示低丰度（或稀有）但活跃的群落成员。总体结果表明，应同时考虑 DNA（存在）和 RNA（活性）数据，以防止低估具有重要功能但丰度较低的生物体。研究成熟 Schmutzdecke 的微生物群落受进水影响。然而，成熟 Schmutzdeckes 之间存在核心微生物组，代表了慢砂滤池中占主导地位且一致的微生物群落组成。在 DNA 样本中，总共观察到 33 个 VSC 家族（“非常严格核心”，相对丰度>0.1%，100%流行），在所有滤器中均存在。在 RNA 样本中，有 18 个 VSC 家族，包括与 DNA VSC 家族重叠的 16 个家族和 2 个独特的 RNA VSC 家族。核心微生物群落结构受操作参数的影响，包括 Schmutzdecke 年龄和砂粒大小，受水流影响较小。此外，在本研究中观察到了指示 Schmutzdecke 年龄的指示生物（“生物标志物”），它们显示了 SSF 能够维持良好运行的最长时间。属于细菌 p25 和 Caldilineaceae 的细菌的大量存在与较老的 Schmutzdeckes 相关，揭示了滤池稳定运行性能的较长时间，而属于 Bdellovibrionaceae 和 Bryobacteraceae 的细菌的高丰度与稳定运行性能的较短时间有关。
