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Differential Effects of Solar Ultraviolet Radiation on Culturable Enterococcus faecalis and Enterococcus DNA Determined Using Real-time Quantitative PCR
ZEPP, R. G., E. M. WHITE, AND M. MOLINA. Differential Effects of Solar Ultraviolet Radiation on Culturable Enterococcus faecalis and Enterococcus DNA Determined Using Real-time Quantitative PCR. Presented at 2008 ASLO Summer Meeting, St. John's, NL, CANADA, June 08 - 13, 2008.
The overall objective of the proposed study is to evaluate the loadings, fate and transport of bacterial contaminants from agricultural non-point sources in surface waters through the use of DNA-based technology that can quantify and track fecal contamination back to its source.
Biological contamination of aquatic environments by pathogenic microorganisms is often assessed using fecal indicator bacteria such as enterococci. The concentrations of enterococci are commonly determined by culturing techniques, but there has been recent interest in using molecular microbial analysis methods with shorter reporting times. The quantitative polymerase chain reaction (qPCR) applied to detect DNA concentrations of Enterococcus is one rapid technique that shows great promise for evaluating recreational water quality. Very little is known about factors that affect enterococci qPCR results in freshwater environments. Studies conducted near UV -disinfected effluents of sewage treatment plants typically indicate that the ratios of qPCR - to culture-determined concentrations of enterococci ranged up to several orders of magnitude. These results indicate that the sensitivity of these two indicators to solar ultraviolet (UV) radiation may be very different. In this paper we compare the effects of solar UV radiation on culturable Enterococcus faecalis with its effects on Enterococcus measured using real-time qPCR. As part of this study, we also report the effects of chromophoric dissolved organic matter (CDOM) and suspended sediments on the light-induced degradation of these indicators.