Linking non-culturable (qPCR) and culturable enterococci densities with hydrometeorological conditions

Science of the Total Environment
By: , and 



Quantitative polymerase chain reaction (qPCR) measurement of enterococci has been proposed as a rapid technique for assessment of beach water quality, but the response of qPCR results to environmental conditions has not been fully explored. Culture-based E. coli and enterococci have been used in empirical predictive models to characterize their responses to environmental conditions and to increase monitoring frequency and efficiency. This approach has been attempted with qPCR results only in few studies. During the summer of 2006, water samples were collected from two southern Lake Michigan beaches and the nearby river outfall (Burns Ditch) and were analyzed for enterococci by culture-based and non-culture-based (i.e., qPCR) methods, as well as culture-based E. coli. Culturable enterococci densities (log CFU/100 ml) for the beaches were significantly correlated with enterococci qPCR cell equivalents (CE) (R = 0.650, P < 0.0001, N = 32). Enterococci CE and CFU densities were highest in Burns Ditch relative to the beach sites; however, only CFUs were significantly higher (P < 0.0001). Culturable enterococci densities at Burns Ditch and the beaches were significantly correlated (R = 0.565, P < 0.0001, N = 32). Culturable E. coli and enterococci densities were significantly correlated (R = 0.682, P < 0.0001, N = 32). Regression analyses suggested that enterococci CFU could be predicted by lake turbidity, Burns Ditch discharge, and wind direction (adjusted R2 = 0.608); enterococci CE was best predicted by Burns Ditch discharge and log-transformed lake turbidity × wave height (adjusted R2 = 0.40). In summary, our results show that analytically, the qPCR method compares well to the non-culture-based method for measuring enterococci densities in beach water and that both these approaches can be predicted by hydrometeorological conditions. Selected predictors and model results highlight the differences between the environmental responses of the two method endpoints and the potentially high variance in qPCR results

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Publication type Article
Publication Subtype Journal Article
Title Linking non-culturable (qPCR) and culturable enterococci densities with hydrometeorological conditions
Series title Science of the Total Environment
DOI 10.1016/j.scitotenv.2010.04.051
Volume 408
Issue 16
Year Published 2010
Language English
Publisher Elsevier
Publisher location Amsterdam, Netherlands
Contributing office(s) Great Lakes Science Center
Description 6 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Science of the Total Environment
First page 3096
Last page 3101
Time Range Start 2006-06-01
Time Range End 2006-09-21
Country United States
Other Geospatial Lake Michigan
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