Department of Civil and Environmental Engineering, Stanford University, Stanford, California, USA.
Department of Civil Engineering, The University of Texas at El Paso, El Paso, Texas, USA.
mSphere. 2024 Oct 29;9(10):e0065624. doi: 10.1128/msphere.00656-24. Epub 2024 Oct 3.
Organisms that are associated with feces ("fecal indicator organisms") are monitored to assess the potential for fecal contamination of surface water bodies in the United States. However, the effect of the complex mixtures of chemicals and the natural microbial community within surface water ("particles") on fecal indicator organism persistence is not well characterized. We aimed to better understand how particles, including biological (e.g., potential grazers) and inert (e.g., minerals) types, affect the fecal indicator organisms K-12 ("") and bacteriophage MS2 in surface waters. A gradient of particles captured by a 0.2-µm-pore-size filter ("large particles") was generated, and the additional particles and dissolved constituents that passed through the filter were deemed "small particles." We measured the ratio of MS2 and that survived over a 24-h incubation period for each condition (0%-1,000% large-particle concentration in raw water) and completed a linear regression that included large- and small-particle coefficients. Particles were characterized by quantifying plankton, total bacterial cells, and total solids. and MS2 persistence was not significantly affected by large particles, but small particles had an effect in most waters. Small particles in higher-salinity waters had the largest, negative effect on and MS2 survival ratios: Significant small-particle coefficients ranged from -1.7 to -5.5 day in the marine waters and -0.89 to -3.2 day in the fresh and estuarine waters. This work will inform remediation efforts for impaired surface water bodies.IMPORTANCEMany surface water bodies in the United States have organisms associated with fecal contamination that exceed regulatory standards and prevent safe recreation. The process to remediate impaired water bodies is complicated because these fecal indicator organisms are affected by the local environmental conditions. For example, the effect of particles in surface water on fecal indicator concentrations are difficult to quantify in a way that is comparable between studies and water bodies. We applied a method that overcomes this limitation to assess the effects of large particles, including natural plankton that could consume the seeded fecal indicator organisms. Even in environmental water samples with diverse communities of plankton present, no effect of large particles on fecal indicator concentrations was observed. These findings have implications for the interpretation and design of future studies, including that particle characterization of surface water may be necessary to assess the fate of fecal indicators.
与粪便相关的生物（“粪便指示生物”）被监测，以评估美国地表水体内粪便污染的潜在可能性。然而，复杂的化学混合物和地表水内的自然微生物群落（“颗粒”）对粪便指示生物持久性的影响还没有得到很好的描述。我们的目的是更好地了解颗粒，包括生物（如潜在的捕食者）和惰性（如矿物质）类型，如何影响地表水中的粪便指示生物 K-12（“”）和噬菌体 MS2。通过 0.2-µm 孔径的过滤器（“大颗粒”）捕获了一个颗粒浓度梯度，而通过过滤器的额外颗粒和溶解成分被认为是“小颗粒”。我们测量了每种条件（原水中大颗粒浓度为 0%-1000%）下 MS2 和 存活的比例，并完成了一个包含大颗粒和小颗粒系数的线性回归。通过量化浮游生物、总细菌细胞和总固体来表征颗粒。在大多数情况下，大颗粒对 和 MS2 的持久性没有显著影响，但小颗粒有影响。高盐度水中的小颗粒对 和 MS2 存活比例的影响最大：海洋水中的显著小颗粒系数范围为-1.7 至-5.5 天，淡水和河口水中的系数范围为-0.89 至-3.2 天。这项工作将为受污染地表水的修复工作提供信息。
重要性
美国许多地表水体内的与粪便污染相关的生物超过了监管标准，妨碍了安全娱乐。修复受损水体的过程很复杂，因为这些粪便指示生物受到当地环境条件的影响。例如，很难量化地表水颗粒对粪便指示生物浓度的影响，并且在不同的研究和水体之间无法进行比较。我们应用了一种方法来克服这一限制，以评估大颗粒的影响，包括可能消耗接种粪便指示生物的天然浮游生物。即使在有多种浮游生物群落存在的环境水样中，也没有观察到大颗粒对粪便指示生物浓度的影响。这些发现对未来研究的解释和设计具有重要意义，包括对地表水颗粒特征的描述可能有必要评估粪便指示物的命运。
