title: Geographic isolation of Escherichia coli genotypes in sediments and water of the Seven Mile Creek - A constructed riverine watershed.
abstract: Escherichia coli is used to indicate fecal contamination in freshwater systems and is an indicator of the potential presence of human pathogens. However, naturalized E. coli strains that persist and grow in the environment confound the use of this bacterium as a fecal indicator. Here we examined the spatial and temporal distribution of E. coli in water and sediments of the Seven Mile Creek (SMC), a constructed, ephemeral watershed. E. coli concentrations showed variation by site and date, likely due to changes in temperature and rainfall. Horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprint analyses indicated that E. coli populations were very diverse and consisted of transient and naturalized strains, which were especially prevalent in sediment. E. coli fingerprints from water and sediment collected in the same year clustered together with significant overlap, indicating exchange of strains between matrices. Isolates obtained during periods of flow, but not during non-flow conditions, clustered together regardless of sample site, indicating that transport between sites occurred. Naturalized E. coli strains were found in the SMC and strains become geographically isolated and distinct during non-flow conditions. Isolates collected during late spring to fall clustered together at each site, suggesting that temperature and growth of naturalized strains are likely factors affecting population dynamics. Results of this study show that newly introduced and naturalized E. coli strains are present in the SMC. Results of this study highlight an important concern for resource managers using this species for water quality monitoring.
authors: BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, USA.
authors: Ramyavardhanee
authors: R
authors: Chandrasekaran
authors: BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, USA; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, USA.
authors: Matthew J
authors: MJ
authors: Hamilton
authors: BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, USA.
authors: Ping
authors: P
authors: Wang
authors: BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, USA.
authors: Christopher
authors: C
authors: Staley
authors: Water Resource Center, Minnesota State University, Mankato, MN 55108, USA. Electronic address: scott.matteson@state.mn.us.
authors: Scott
authors: S
authors: Matteson
authors: Minnesota Department of Agriculture, St. Paul, MN 55108, USA. Electronic address: abirr@mncorn.org.
authors: Adam
authors: A
authors: Birr
authors: BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, USA; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, USA. Electronic address: Sadowsky@umn.edu.
authors: Michael J
authors: MJ
authors: Sadowsky
mesh_terms: D016172:DNA Fingerprinting; D004269:DNA, Bacterial; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D014644:Genetic Variation; D005838:Genotype; D019015:Geologic Sediments / Q000382:microbiology*; D009820:Ohio; D016133:Polymerase Chain Reaction; D014871:Water Microbiology; D014876:Water Pollution / Q000032:analysis*
chemical_list: D004269:DNA, Bacterial
keywords: DNA fingerprinting; Escherichia coli; Growth; Naturalized population; Sediment; Water quality