2 research outputs found
Performance Characteristics of qPCR Assays Targeting Human- and Ruminant-Associated <i>Bacteroidetes</i> for Microbial Source Tracking across Sixteen Countries on Six Continents
Numerous quantitative PCR assays
for microbial fecal source tracking
(MST) have been developed and evaluated in recent years. Widespread
application has been hindered by a lack of knowledge regarding the
geographical stability and hence applicability of such methods beyond
the regional level. This study assessed the performance of five previously
reported quantitative PCR assays targeting human-, cattle-, or ruminant-associated <i>Bacteroidetes</i> populations on 280 human and animal fecal
samples from 16 countries across six continents. The tested cattle-associated
markers were shown to be ruminant-associated. The quantitative distributions
of marker concentrations in target and nontarget samples proved to
be essential for the assessment of assay performance and were used
to establish a new metric for quantitative source-specificity. In
general, this study demonstrates that stable target populations required
for marker-based MST occur around the globe. Ruminant-associated marker
concentrations were strongly correlated with total intestinal <i>Bacteroidetes</i> populations and with each other, indicating
that the detected ruminant-associated populations seem to be part
of the intestinal core microbiome of ruminants worldwide. Consequently
tested ruminant-targeted assays appear to be suitable quantitative
MST tools beyond the regional level while the targeted human-associated
populations seem to be less prevalent and stable, suggesting potential
for improvements in human-targeted methods
Global Distribution of Human-Associated Fecal Genetic Markers in Reference Samples from Six Continents
Numerous bacterial genetic markers are available for the molecular detection of human sources of fecal pollution in environmental waters. However, widespread application is hindered by a lack of knowledge regarding geographical stability, limiting implementation to a small number of well-characterized regions. This study investigates the geographic distribution of five human-associated genetic markers (HF183/BFDrev, HF183/BacR287, BacHum-UCD, BacH, and Lachno2) in municipal wastewaters (raw and treated) from 29 urban and rural wastewater treatment plants (750ā4āÆ400āÆ000 population equivalents) from 13 countries spanning six continents. In addition, genetic markers were tested against 280 human and nonhuman fecal samples from domesticated, agricultural and wild animal sources. Findings revealed that all genetic markers are present in consistently high concentrations in raw (median log<sub>10</sub> 7.2ā8.0 marker equivalents (ME) 100 mL<sup>ā1</sup>) and biologically treated wastewater samples (median log<sub>10</sub> 4.6ā6.0 ME 100 mL<sup>ā1</sup>) regardless of location and population. The false positive rates of the various markers in nonhuman fecal samples ranged from 5% to 47%. Results suggest that several genetic markers have considerable potential for measuring human-associated contamination in polluted environmental waters. This will be helpful in water quality monitoring, pollution modeling and health risk assessment (as demonstrated by QMRAcatch) to guide target-oriented water safety management across the globe