Amoebas are protists that are widespread in water and soil environments. Some species are pathogenic, inducing potentially lethal effects on humans, making them a major threat to public health. Nonpathogenic amoebas are also of concern because they have the potential to carry a mini-microbiome of bacteria, either transiently or via more long-term stable transport. Due to their resistance to disinfection processes, the physical removal of amoeba by filtration is necessary to prevent their propagation throughout drinking water distribution networks and occurrence in tap water. In this study, a model amoeba species Dictyostelium discoideum was used to study the transport and retention behavior of amoeba spores in porous media. The key factors affecting the transport behavior of amoeba spores in fully saturated media were comprehensively evaluated, with experiments performed using a quartz crystal microbalance with dissipation monitoring (QCM-D) and parallel plate chamber system. The effects of ionic strength (IS) on the deposition of spores were found to be in contrast to the predicted Derjaguin–Landau–Verwey–Overbeek (DLVO) theory that more deposition is observed under lower-IS conditions. The presence of extracellular polymeric substances (EPS) was found to be the main contributor to deposition behavior. Overall, these results provide plausible evidence for the presence of amoeba in tap water. Furthermore, this is one of the first studies to examine the mechanisms affecting the fate of amoeba spores in porous media, providing a significant baseline for future research to minimize the safety risk presented by amoeba in drinking water systems.

中文翻译：

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多孔介质中自由生活变形虫孢子的运输和保留：操作参数和细胞外聚合物物质的影响

变形虫是在水和土壤环境中广泛存在的原生生物。有些物种具有致病性，会对人类产生潜在的致命影响，使它们成为对公共健康的主要威胁。非致病性阿米巴原虫也值得关注，因为它们有可能携带微型细菌微生物组，无论是短暂的还是通过更长期的稳定运输。由于它们对消毒过程具有抵抗力，因此必须通过过滤物理去除变形虫，以防止它们在整个饮用水分配网络中传播并在自来水中发生。在这项研究中，模型变形虫物种盘基网柄菌用于研究变形虫孢子在多孔介质中的运输和滞留行为。通过使用具有耗散监测 (QCM-D) 和平行板室系统的石英晶体微天平进行实验，综合评估了影响完全饱和介质中变形虫孢子运输行为的关键因素。发现离子强度 (IS) 对孢子沉积的影响与预测的 Derjaguin-Landau-Verwey-Overbeek (DLVO) 理论相反，即在较低 IS 条件下观察到更多沉积。发现细胞外聚合物 (EPS) 的存在是沉积行为的主要贡献者。总体而言，这些结果为自来水中存在变形虫提供了可信的证据。此外，