Cross-comparison of human wastewater-associated molecular markers in relation to fecal indicator bacteria and enteric viruses in recreational beach waters

Abstract

Detection of human wastewater contamination in recreational waters is of critical importance to regulators due to the risks posed to public health. To identify such risks, human wastewater-associated microbial source tracking (MST) markers have been developed. At present, however, a greater understanding of the suitability of these markers for the detection of diluted human wastewater in environmental waters is necessary to predict risk. Here, we compared the process limit of detection (PLOD) and process limit of quantification (PLOQ) of six human wastewater-associated MST markers (Bacteroides HF183 [HF183], Escherichia coli H8 [EC H8], Methanobrevibacter smithii nifH, human adenovirus [HAdV], human polyomavirus [HPyV], and pepper mild mottle virus [PMMoV]) in relation to a fecal indicator bacterium (FIB), Enterococcus sp. 23S rRNA (ENT 23S), and three enteric viruses (human adenovirus serotypes 40/41 [HAdV 40/41], human norovirus [HNoV], and human enterovirus [EV]) in beach water samples seeded with raw and secondary-treated wastewater. Among the six MST markers tested, HF183 was the most sensitive measure of human fecal pollution and was quantifiable up to dilutions of 10-6 and 10-4 for beach water samples seeded with raw and secondary-treated wastewater, respectively. Other markers and enteric viruses were detected at various dilutions (10-1 to 10-5). These MST markers, FIB, and enteric viruses were then quantified in beach water (n=12) and sand samples (n=12) from South East Queensland (SEQ), Australia, to estimate the levels of human fecal pollution. Of the 12 sites examined, beach water and sand samples from several sites had quantifiable concentrations of HF183 and PMMoV markers. Overall, our results indicate that while HF183 is the most sensitive measure of human fecal pollution, it should be used in conjunction with a conferring viral marker to avoid overestimating the risk of gastrointestinal illness.