You are here:
Characterization of fecal concentrations in human and other animal sources by physical, culture-based, and quantitative real-time PCR methods
Citation:
Ervin, J. S., T. L. Russell, B. A. Layton, K. M. Yamahara, D. Wang, L. M. Sassoubre, Y. Cao, C. A. Kelty, Mano Sivaganesan, A. B. Boehm, P. A. Holden, S. B. Weisberg, AND O. C. Shanks. Characterization of fecal concentrations in human and other animal sources by physical, culture-based, and quantitative real-time PCR methods. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 47(18):6873-6882, (2013).
Impact/Purpose:
Informs public on matters relating to fecal concentrations in various human and animal sources as measured by different methods
Description:
The characteristics of fecal sources, and the ways in which they are measured, can profoundly influence the interpretation of which sources are contaminating water. Although feces from various hosts are known to differ, it is not well understood how those differences compare across fecal types and how differences depend on characterization methods. This study investigated how nine different fecal characterization methods provide different impressions of fecal concentration in water, and how those impressions varied across twelve fecal pollution sources. Fecal sources investigated included chicken, cow, deer, dog, goose, gull, horse, human, pig, pigeon, septage and sewage. A fecal stock was prepared for each source by mixing feces from 6-22 individual samples with artificial freshwater. Fecal concentrations were estimated by physical (wet fecal mass added and total DNA mass extracted), culture-based (E. coli and enterococci by membrane filtration and defined substrate), and quantitative real-time PCR (Bacteroidales, E. coli, and enterococci) characterization methods. The characteristics of each fecal stock and the relationships between physical, culture-based and qPCR-based characteristics varied within and among different fecal sources. An in silico exercise was performed to assess how different characterization methods can impact identification of the dominant fecal pollution source in a mixed source sample. A comparison of 10:90 mixtures, using enterococci by defined substrate as a benchmark characteristic, predicted a dominant source reversal in 27% of all possible combinations. This potential for disagreement in dominant source identification based on fecal source characterization method implies that, depending on how a fecal source is defined,highly variable impressions of that host’s fecal content as a water contaminant may result.
