Principal Investigator: Michael Sadowsky
Organization(s): University of Minnesota, Department of Soil, Water, and Climate
Sponsor: Clean Water Legacy Act
Award Amount: $192,804
Start Date: 7/1/2008 | End Date: 6/30/2010
Project Manager(s): Adam Birr
FINAL REPORT: Growth, Survival, and Structure of E.coli found in Ditch Sediments (PDF: 1.4 MB/45 pages)
Escherichia coli (E. coli) is currently used as an indicator of fecal contamination in freshwater systems. The presence of E. coli in water is thought to indicate recent fecal contamination and in turn signal the possible presence of pathogens. However, several studies have reported the presence of naturalized or indigenous E. coli strains that persist and potentially grow in the environment, regardless of new inputs.
In this study, researchers used molecular techniques to determine the sources of E. coli contamination and to examine the growth and survival of E. coli in a drainage ditch located within the Seven Mile Creek (SMC) watershed situated in eastern Nicollet County, Minnesota. The purpose of this study was to:
Samples were collected in 2008 (July - October), 2009 (April - October), and 2010 (April -June). Detailed methods describing sample collection and processing, enumeration of E. coli, E.coli isolation, and DNA extraction and analysis is in the methods section of the Final Report.
This project uses the polymerase chain reaction (PCR) method. PCR is a molecular biology analysis use to amplify a segment of DNA which can then be used to examine a specific genetic sequence.
Overall, researchers found that not all E. coli strains originated from fecal matter and many of these bacteria naturally occur in sediments. This means that in the absence of any inputs, a population of E. coli could still be present. Often the presence of any E. coli is associated with a recent contamination; while this study showed that specific strains are likely indigenous to a site and may not be the best indicator of contamination.
Tables of results can be found at the end of the Final Report.
Supervisor, Clean Water Technical Unit