Eawag, Swiss Federal Institute for Aquatic Science and Technology, Überlandstr. 133, CH-8600 Dübendorf, Switzerland.
Water Res. 2013 Jun 1;47(9):3015-25. doi: 10.1016/j.watres.2013.03.002. Epub 2013 Mar 15.
Biological stability of drinking water implies that the concentration of bacterial cells and composition of the microbial community should not change during distribution. In this study, we used a multi-parametric approach that encompasses different aspects of microbial water quality including microbial growth potential, microbial abundance, and microbial community composition, to monitor biological stability in drinking water of the non-chlorinated distribution system of Zürich. Drinking water was collected directly after treatment from the reservoir and in the network at several locations with varied average hydraulic retention times (6-52 h) over a period of four months, with a single repetition two years later. Total cell concentrations (TCC) measured with flow cytometry remained remarkably stable at 9.5 (± 0.6) × 10(4) cells/ml from water in the reservoir throughout most of the distribution network, and during the whole time period. Conventional microbial methods like heterotrophic plate counts, the concentration of adenosine tri-phosphate, total organic carbon and assimilable organic carbon remained also constant. Samples taken two years apart showed more than 80% similarity for the microbial communities analysed with denaturing gradient gel electrophoresis and 454 pyrosequencing. Only the two sampling locations with the longest water retention times were the exceptions and, so far for unknown reasons, recorded a slight but significantly higher TCC (1.3 (± 0.1) × 10(5) cells/ml) compared to the other locations. This small change in microbial abundance detected by flow cytometry was also clearly observed in a shift in the microbial community profiles to a higher abundance of members from the Comamonadaceae (60% vs. 2% at other locations). Conventional microbial detection methods were not able to detect changes as observed with flow cytometric cell counts and microbial community analysis. Our findings demonstrate that the multi-parametric approach used provides a powerful and sensitive tool to assess and evaluate biological stability and microbial processes in drinking water distribution systems.
饮用水的生物稳定性意味着在分配过程中，细菌细胞的浓度和微生物群落的组成不应发生变化。在这项研究中，我们使用了一种多参数方法，该方法涵盖了微生物水质的不同方面，包括微生物生长潜力、微生物丰度和微生物群落组成，以监测苏黎世未氯化分配系统饮用水的生物稳定性。饮用水是在处理后直接从水库和网络中的几个位置采集的，这些位置的平均水力停留时间（6-52 小时）不同，在四个月的时间内重复一次，两年后再重复一次。使用流式细胞术测量的总细胞浓度（TCC）在整个分配网络中从水库中的水到大多数位置都保持着惊人的稳定，保持在 9.5（±0.6）×10（4）细胞/ml，在整个时间段内都是如此。传统的微生物方法，如异养平板计数、三磷酸腺苷浓度、总有机碳和可同化有机碳浓度也保持不变。用变性梯度凝胶电泳和 454 焦磷酸测序分析两年间采集的样本，微生物群落的相似度超过 80%。只有两个水保留时间最长的采样点是例外，目前尚不清楚原因，记录到 TCC 略有但显著升高（1.3（±0.1）×10（5）细胞/ml），与其他位置相比。流式细胞术检测到的微生物丰度的这种微小变化也明显反映在微生物群落谱向丰度更高的 Comamonadaceae 成员的转变（60%比其他位置的 2%）。传统的微生物检测方法无法检测到与流式细胞术细胞计数和微生物群落分析观察到的变化。我们的研究结果表明，所使用的多参数方法提供了一种强大而敏感的工具，可用于评估和评估饮用水分配系统中的生物稳定性和微生物过程。
