Autumn Saunders, “Determining the Correlation between Siderophore-Encoding Genes in E. coli Strains and Their Survivability in a Freshwater Sand Environment”
Mentors: Sandra McLellan and Brigid Meyers, Freshwater Sciences
Poster #115

Escherichia coli is a bacterium that can live in varying environments using adaption mechanisms to scavenge for limited nutrients and compete with neighboring lifeforms. One such mechanism of adaption is the production of siderophores. Siderophores are molecules secreted when bacteria are under iron-limiting conditions: their structure has a high affinity to bind ferric iron. E. coli, used as a fecal indicator bacterium in water quality assessment, has been shown to survive within beach sand over a long period of time. The objective of this research is to learn more about the distribution of siderophore-encoding genes between different strains of E. coli and identify correlations between the siderophore production and survival of those strains. Genomic screening for siderophore genes will be performed on isolates demonstrating long-term survival from past microcosm experiments. This information will then be compared to the genetic profiles of the isolates initially inoculated into the microcosm. We will be using end-point polymerase chain reaction (PCR) to identify the isolates containing the genes for any of the four siderophores produced by E. coli: aerobactin, yersiniabactin, salmochelin, and enterobactin, and their corresponding receptors. It is expected that there will be more siderophore production and genetic prevalence of siderophore-encoding genes in the genomic profiles of output microcosm E. coli strains than that of the input isolates overall, due to selection of these strains as survivors in the microcosm experiments. This research will allow for more accurate beach safety readings and water quality assessments by providing a better understanding of how E. coli survives in beach sands.