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Characterizing Virus Decay in Environmental Freshwater Habitats
Citation:
McMinn, B., E. Rhodes, E. Huff, AND A. Korajkic. Characterizing Virus Decay in Environmental Freshwater Habitats. ASM Microbe 2017, New Orleans, LA, June 01 - 05, 2017.
Impact/Purpose:
This study describes the influence of ambient sunlight and indigenous microbiota on viral decay.
Description:
Recreational water quality is typically assessed using fecal indicator bacteria (FIB), however, FIB are inadequate surrogates for the viral pathogens. Bacteriophage share similar morphologies to viral pathogens allowing closer representation of viral behavior, making their inclusion in water quality monitoring of value. This study compared the relative effect of ambient sunlight and predation on the decay of select culturable bacteriophage and adenovirus. A submersible aquatic mesocosm was deployed for an 8-day in situ study at Lake Harsha investigating the decay of sewage borne, somatic and F-RNA coliphage, Bacteroides GB-124 phage as well as laboratory derived adenovirus serotype 2. Experimental design examined impacts of (presence or absence) ambient sunlight and predatory microbiota indigenous to lake water as environmental variables of interest. Bacteriophage and adenovirus were enumerated using either double-agar overlay or mammalian cell culture, respectively. In general, the three bacteriophages decayed significantly faster than adenovirus (paired t-test, P range 0.02 – <0.0001). Sunlight exposure was a significant driver of decay (two-way ANOVA, P range 0.0001 − < 0.0001) for all virus types contributing to 95% and 45% to total variation in somatic and F-RNA coliphage counts respectively, 87% variation of GB-124 Bacteroides phage densities and a 43% variation of culturable adenovirus. Exclusion of predator type had no effect on variation of either somatic coliphage or GB-124 Bacteroides phage, but it was an important contributor (18% and 20%) to decay of and both F-RNA coliphage and adenovirus, respectively (two-way ANOVA, P range 0.0087 − < 0.0001). Exclusion of either environmental variable affected decay, although the magnitude of that effect varied, suggesting differential response to environmental pressures among the viruses tested. Our findings imply that both ambient sunlight and predation may affect decay in freshwater habitats and warrant further investigation into virus specific decay dynamics.
