Detection of human fecal pollution in environmental waters using human mitochondrial DNA and correlation with general and human-associated fecal genetic markers

Abstract

Human mitochondrial DNA (mtDNA) genetic markers are abundant in sewage and highly human-specific, suggesting a great potential for the environmental application as human fecal pollution indicators. Limited data are available on the occurrence and co-occurrence of human mtDNA with fecal bacterial markers in surface waters, and how the abundance of these markers is influenced by rain events. A 1-year sampling study was conducted in a suburban watershed impacted by human sewage contamination to evaluate the performance of a human mtDNA-based marker along with the bacterial genetic markers for human-associated Bacteroidales (BacHum and HF183) and Escherichia coli. Additionally, the human mtDNA-based assay was correlated with rain events and other markers. The mtDNA marker was detected in 92% of samples (n = 140) with a mean concentration of 2.96 log10 copies/100 ml throughout the study period. Human mtDNA was detected with greater abundance than human-associated Bacteroidales that could be attributed to differences in the decay of these markers in the environment. The abundance of all markers was positively correlated with rain events, and human mtDNA abundance was significantly correlated with various bacterial markers. In general, these results should support future risk assessment for impacted watersheds, particularly those affected by human fecal pollution, by evaluating the performance of these markers during rain events.

Elevated Fecal Mitochondrial DNA from Symptomatic Norovirus Infections Suggests Potential Health Relevance of Human Mitochondrial DNA in Fecal Source Tracking

“…Studies on the fate and persistence of fecal mtDNA , are needed to understand how the signal is attenuated in environments relative to that of infectious pathogens. , Before human mtDNA, a nucleic acid marker, can serve as a risk-relevant FST marker, we need to understand its relationship with infectious pathogens . Because human mtDNA FST markers are typically found at lower concentrations in sewage than those of other human-associated FST markers, improved concentration and recovery methods of mtDNA are needed. ,− Better understanding of potential nonfecal sources of mtDNA and at what concentrations nonfecal sources shed mtDNA are also needed . Potential carry over from consumption of meat or feces of other species should also be investigated. , Despite these knowledge and technical gaps, results from this study add to previous evidence supporting the utility of human mtDNA as FST markers.…”

Microbe–sediment interactions in Great Lakes recreational waters: Implications for human health risk

“…The human mitochondria target (MT‐ND2) was omitted as its own representative for these statistical analyses because it only had one observance detected at LE beach on 13 September (2.22 log copies/g). Mitochondrial DNA has been widely used as a source tracking target to assess recreational waters for host‐specific faecal contamination with high sensitivity and specificity (Malla & Haramoto, 2020; Tanvir Pasha et al, 2020). The detection of this target at LE strongly suggests possible human faecal contamination in this area on that date.…”

Elevated fecal mitochondrial DNA from symptomatic norovirus infections suggests potential health relevance of human mitochondrial DNA in fecal source tracking

“…Before human mtDNA, a nucleic acid marker, can serve as a riskrelevant FST marker, we need to understand its relationship with infectious pathogens 54 . Because human mtDNA FST markers are typically found at lower concentrations in sewage than those of other human-associated FST markers, improved concentration and recovery methods of mtDNA are needed 10,[58][59][60][61] . Better understanding of potential non-fecal sources of mtDNA and at what concentrations non-fecal sources shed mtDNA are also needed 62 .…”