Concentration and quantification of somatic and F+ coliphages from recreational waters

Abstract

Somatic and F+ coliphages are promising alternative fecal indicators, but current detection methods are hindered by lower levels of coliphages in surface waters compared to traditional bacterial fecal indicators. We evaluated the ability of dead-end hollow fiber ultrafiltration (D- HFUF) and single agar layer (SAL) procedure to concentrate and enumerate coliphages from 1L and 10L volumes of ambient surface waters (lake, river, marine), river water with varying turbidities (3.74-118.7 NTU), and a simulated combined sewer overflow (CSO) event. Percentage recoveries for surface waters were 40-79% (somatic) and 35-94% (F+). The method performed equally well in all three matrices at 1L volumes, but percent recoveries were significantly higher in marine waters at 10L volumes when compared to freshwater. Percent recoveries at 1L and 10L were similar, except in river water where recoveries were significantly lower at higher volume. In highly turbid waters, D-HFUF-SAL had a recovery range of 25-77% (somatic) and 21-80% (F+). The method produced detectable levels of coliphages in diluted wastewater and in unspiked surface waters, emphasizing its applicability to CSO events and highlighting its utility in recovery of low coliphage densities from surface waters. Thus D-HFUF-SAL is a good candidate method for routine water quality monitoring of coliphages.

Microbial Indicators of Fecal Pollution: Recent Progress and Challenges in Assessing Water Quality

“…While simulation studies indicate that the concentrations at which bacterial indicators represent elevated risk of illness are well above the limits of detection [153], enteric viruses, protozoan parasites, and some alternative indicators (e.g., coliphages) commonly require larger sample volumes for reliable capture, necessitating concentration methods to obtain test sample volumes that can be accommodated by the chosen detection method [44,128]. Filtration approaches that allow simultaneous concentration of a wide range of organisms are increasingly used to process samples, including as part of automated large-volume samplers, prior to culture or molecular detection [128,[154][155][156]. Ultrafiltration techniques in particular have demonstrated reasonably efficient and consistent recovery for a variety of organisms, water types, and sample volumes, providing a natural complement to multitarget arrays, and increasingly appear to be the default concentration approach for many applications [154,[157][158][159][160][161].…”

“…Filtration approaches that allow simultaneous concentration of a wide range of organisms are increasingly used to process samples, including as part of automated large-volume samplers, prior to culture or molecular detection [128,[154][155][156]. Ultrafiltration techniques in particular have demonstrated reasonably efficient and consistent recovery for a variety of organisms, water types, and sample volumes, providing a natural complement to multitarget arrays, and increasingly appear to be the default concentration approach for many applications [154,[157][158][159][160][161]. Co-concentration of qPCR inhibitors during ultrafiltration is a concern, but effective inhibition mitigation has been demonstrated by further processing of the concentrate prior to analysis [160,[162][163][164].…”

Evaluating the fate of bacterial indicators, viral indicators, and viruses in water resource recovery facilities

“…Potential NPDES coliphage effluent limits are not expected to be a concern for these WRRFs, as the final effluent concentration for coliphages at Facilities B and C were at or below the detection limit. If tertiary treatment log removal of indigenous indicators is to be determined, future work is needed with additional methods to concentrate larger volumes of water for quantification (e.g., McMinn, Huff, Rhodes, & Korajkic, 2017;Rhodes, Huff, Hamilton, & Jones, 2016;USEPA, 2018), such as 1-10 L. Alternatively, spiking with high stock solutions of indicators is possible for validating process performance. For example, MS2 coliphage is used to estimate log reduction values for microfiltration and ultrafiltration (Amarasiri et al, 2017) and is used to validate UV reactors.…”

Viral and Bacterial Fecal Indicators in Untreated Wastewater across the Contiguous United States Exhibit Geospatial Trends

“…In response to these limitations, rapid molecular biology-based technologies that can measure enterococci and E. coli in a matter of hours, offering the option for same-day water quality notification, have been developed (10)(11)(12). Other researchers are investigating the use of viral cultures for surface water quality monitoring that target somatic and F ϩ coliphages (13)(14)(15)(16). Coliphage monitoring may offer a more public health-protective approach due to the increased similarities of coliphages to enteric viral pathogens in morphology, inactivation in the environment, and persistence during treatment (17)(18)(19).…”