Bacterial assessment of drinking water and downstream distribution systems in highlands localities of Ecuador

Bacterial communities on drinking water provide a comprehensive understanding of its quality and insights applicable to public health. Water treatment systems in rural areas, compared to urban systems, are not adequately monitored involving a health risk. Culture-dependent methods are traditionally employed to evaluate the microbiological content of drinking water. This approach has an inherent limitation in the detection of unculturable microorganisms. Amplicon metagenomics provides a tool for analysis of the drinking water microbiome and improves the detection of etiological agents that are of interest to public health. We used 16S rRNA amplicon sequencing to analyze the natural microbiome present in the Water Treatment Plants (WTP) at two rural communities and one city in the highlands of Ecuador and the available downstream water available for human consumption in water schools and reservoirs. A set of physicochemical variables were also evaluated as part of the factors related to the observed bacterial community. Predominant bacteria in the analyzed samples belonged to Proteobacteria and Actinobacteria. The Sphingobium genus, which is a chlorine resistance group, was among the most abundant. Of concern was the presence of Fusobacteriaceae, Lachnospiraceae, and Ruminococcaceae in drinking water reservoirs, since species of these families are associated with human and poultry fecal contamination, and which we propose as relevant biomarkers for future system monitoring water systems in agricultural land uses. High nitrogen content in the drinking water reservoir was strongly correlated to the presence of Hyphomicrobiaceae, which was three times more abundant than the other groups. Our assessment of bacterial composition and abundance in three water systems in the Ecuadorian highlands provides a complete evaluation of the present bacterial microbiome as evidence to improve water management-related decisions.