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Correlative Assessment of Fecal Indicators Using Human Mitochondrial DNA as a Direct Marker
Citation:
Kapoor, V., C. Smith, J. W. Santodomingo, T. Lu, AND D. Wendell. Correlative Assessment of Fecal Indicators Using Human Mitochondrial DNA as a Direct Marker. ENVIRONMENTAL SCIENCE & TECHNOLOGY. ACS Publications, Washington, DC, 47(18):10485-10493, (2013).
Impact/Purpose:
The detection of human sources of fecal pollution is performed using molecular assays that target fecal anaerobic bacteria. While some of these assays are useful, they have been shown to cross-react with other fecal sources. In this study we compared the use of mitochondrial specific markers with bacterial-based markers to determine the occurrence of human fecal pollution in an urban creek system.
Description:
Identifying the source of surface water fecal contamination is paramount to mitigating pollution and risk to human health. Fecal bacteria such as E. coli have been staple indicator organisms for over a century, however there remains uncertainty with E. coli-based metrics since these bacteria are abundant in the environment. The relationships between the presence of direct indicator of human waste (human mitochondrial DNA), human-specific Bacteroidales and E. coli were studied for water samples taken from an urban creek system (Duck Creek Watershed, Cincinnati OH) impacted by combined sewer overflows. Logistic regression analysis show that human-specific Bacteroidales correlates much more closely to human mitochondrial DNA (R =0.62), relative to E. coli (R =0.33).We also examine the speciation of Bacteroidales within the Duck Creek Watershed using next-generation sequencing technology (Ion Torrent) and show the most numerous populations to be associated with sewage. Here we demonstrate that human-specific Bacteroidales closely follow the dynamics of human mitochondrial DNA concentration changes, indicating that these obligate anaerobes are more accurate than E. coli for fecal source tracking, lending further support to risk overestimation using coliforms, especially fecal coliforms and E. coli.
