Targeted 16S rRNA metagenomic analysis of E. coli contaminated private drinking well waters in southern Ontario
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Given that water is essential to sustaining life, contamination of drinking water sources poses a potential threat to human and environmental health. In Ontario, a proportion of private well water supplies, which are the primary source of drinking water for the majority of rural Ontarians, are at risk of becoming microbially contaminated, which is of utmost concern given water remains a significant pathway of infectious disease transmission. Microbial indicators of water health and quality, particularly when measured using traditional culture or molecular methods, are only successfully detected for a small portion of contaminating microbes and limit the study of the diversity of groundwater health indicators. Next Generation Sequencing (NGS) technology, such as 16S rRNA sequencing, bypasses the need for isolation or cultivation of microorganisms, providing insight into the environmental metagenome; this technology promises to give rise to a grander understanding of microbial communities and pathogens inhabiting drinking water environments. This study investigates the metagenomics of private well waters of previously determined regions at increased risk of Escherichia coli (E. coli) contamination in southern Ontario, and is among the first to investigate the bacterial metagenome of private drinking well water. Traditional and alternative fecal indicator bacteria, E. coli and species-specific Bacteroides species, were investigated in the context of the drinking well water metagenome. The microbial community analysis revealed that a distinct drinking water community exists within E. coli positive drinking well waters. The lack of correlation and disagreement between the fecal indicators (E. coli and Bacteroides) with fecal associated families within the bacterial community highlights the research need to investigate techniques and indicators that are capable of designating a true positive or negative result for fecal contamination in private well water supplies. Although not expected to be feasible for routine application in laboratories, further investigation of the well water microbiome and fecal signatures within these communities may enable discovery of better assessment tools for private drinking well water quality and source water protection.