Probabilistic analysis showing that a combination of bacteroides and methanobrevibacter source tracking markers is effective for identifying waters contaminated by human fecal pollution
Environmental Science & Technology
By: Christopher Johnston, Muruleedhara N. Byappanahalli, Jacqueline MacDonald Gibson, Jennifer A. Ufnar, Richard L. Whitman, and Jill R. Stewart
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Abstract
Microbial source tracking assays to identify sources of waterborne contamination typically target genetic markers of host-specific microorganisms. However, no bacterial marker has been shown to be 100% host-specific, and cross-reactivity has been noted in studies evaluating known source samples. Using 485 challenge samples from 20 different human and animal fecal sources, this study evaluated microbial source tracking markers including the Bacteroides HF183 16S rRNA, M. smithii nifH, and Enterococcus esp gene targets that have been proposed as potential indicators of human fecal contamination. Bayes' Theorem was used to calculate the conditional probability that these markers or a combination of markers can correctly identify human sources of fecal pollution. All three human-associated markers were detected in 100% of the sewage samples analyzed. Bacteroides HF183 was the most effective marker for determining whether contamination was specifically from a human source, and greater than 98% certainty that contamination was from a human source was shown when both Bacteroides HF183 and M. smithii nifH markers were present. A high degree of certainty was attained even in cases where the prior probability of human fecal contamination was as low as 8.5%. The combination of Bacteroides HF183 and M. smithii nifH source tracking markers can help identify surface waters impacted by human fecal contamination, information useful for prioritizing restoration activities or assessing health risks from exposure to contaminated waters.
Suggested Citation
Johnston, C., Byappanahalli, M., Gibson, J.M., Ufnar, J.A., Whitman, R.L., and Stewart, J.R., 2013, Probabilistic analysis showing that a combination of bacteroides and methanobrevibacter source tracking markers is effective for identifying waters contaminated by human fecal pollution: Environmental Science & Technology, v. 47, no. 23, p. 13621-13628, https://doi.org/10.1021/es403753k.
ISSN: 1520-5851 (online)
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Probabilistic analysis showing that a combination of bacteroides and methanobrevibacter source tracking markers is effective for identifying waters contaminated by human fecal pollution |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es403753k |
| Volume | 47 |
| Issue | 23 |
| Publication Date | November 20, 2013 |
| Year Published | 2013 |
| Language | English |
| Publisher | American Chemical Society |
| Contributing office(s) | Great Lakes Science Center |
| Description | 8 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Environmental Science and Technology |
| First page | 13621 |
| Last page | 13628 |