Event Title

Salinity Tolerance and Survival of Laboratory and Environmental Strains of Escherichia coli

Poster Number

44

Presenter Information

Leigha Stahl, Winthrop University

Faculty Mentor

Matthew Heard, Ph.D. and Victoria Frost, Ph.D.

College

College of Arts and Sciences

Department

Biology

Location

Richardson Ballroom

Start Date

24-4-2015 3:20 PM

End Date

24-4-2015 4:50 PM

Description

Escherichia coli are commonly utilized as fecal indicators to assess contamination and water quality in a variety of ecosystems. One group of ecosystems of particular interest is sandy beaches, which are exposed to varying stressors from both terrestrial and marine sources. Historically, beach ecosystems were not thought to be ideal habitats for E. coli because salinity can inhibit growth and survival of these bacteria. However, recent studies have demonstrated that certain strains may be able to persist in these environments. Here, we expand upon this recent research and test the effects of salinity on the survival and growth of a laboratory strain of E. coli, as well as environmental strains collected from sand samples at Folly Beach, South Carolina. We exposed our strains of E. coli to salt concentrations ranging from 0.5-10 % and assessed the colony forming units (CFUs) following each of our treatments after a period of 24 hours at 37 °C. Our data indicated there was a significant decrease in CFUs and a noticeable reduction in diameter of colony size as salinity increased. In addition, we observed that there is a cut-off for salinity tolerance, as no colonies were able to grow in salinity concentrations greater than 5 %. Collectively, our findings suggest that E. coli can persist on sandy beaches despite the stress of salinity and may be a useful tool in the future for assessing these ecosystems for fecal contamination levels.

Comments

Supported by an NIH-INBRE grant from the National Center for Research Resources and the National Institute of General Medical Sciences

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Apr 24th, 3:20 PM Apr 24th, 4:50 PM

Salinity Tolerance and Survival of Laboratory and Environmental Strains of Escherichia coli

Richardson Ballroom

Escherichia coli are commonly utilized as fecal indicators to assess contamination and water quality in a variety of ecosystems. One group of ecosystems of particular interest is sandy beaches, which are exposed to varying stressors from both terrestrial and marine sources. Historically, beach ecosystems were not thought to be ideal habitats for E. coli because salinity can inhibit growth and survival of these bacteria. However, recent studies have demonstrated that certain strains may be able to persist in these environments. Here, we expand upon this recent research and test the effects of salinity on the survival and growth of a laboratory strain of E. coli, as well as environmental strains collected from sand samples at Folly Beach, South Carolina. We exposed our strains of E. coli to salt concentrations ranging from 0.5-10 % and assessed the colony forming units (CFUs) following each of our treatments after a period of 24 hours at 37 °C. Our data indicated there was a significant decrease in CFUs and a noticeable reduction in diameter of colony size as salinity increased. In addition, we observed that there is a cut-off for salinity tolerance, as no colonies were able to grow in salinity concentrations greater than 5 %. Collectively, our findings suggest that E. coli can persist on sandy beaches despite the stress of salinity and may be a useful tool in the future for assessing these ecosystems for fecal contamination levels.