Major
Biology
Advisor
Ramsey, Kathryn
Advisor Department
Cell and Molecular Biology
Date
5-2022
Keywords
bacterial pathogen; environmental bacteria; long-term survival
Abstract
Francisella tularensis is a Gram-negative pathogenic bacterium and is the causative agent for tularemia. While our understanding of F. tularensis survival in the environment is limited, it is clear they can persist in freshwater aquatic environments for long periods of time. Currently, there is a gap in knowledge with the understanding of the genes involved with the long-term survival of F. tularensis in an aquatic environment. In the laboratory setting, it has been found that lower temperatures seem to allow longer survival. The aim of this project is to identify laboratory conditions that allow F. tularensis to survive longterm in freshwater, so in the future I can identify the genes required for this survival. To find this information, I prepared samples of LVS F. tularensis in freshwater that were incubated in triplicate at three different temperatures, 4°C, 16°C, and 25°C. The timepoints that I assessed were days 0, 1, 4, 7, 14, and 21. To determine the number of viable bacteria, I performed serial dilutions of each sample and plated them on solid growth media. Every plate was placed in the incubator for a minimum of two days or until the colonies were large enough to count. I counted the plates to measure CFU, colony forming unit, to determine the number of viable cells. We found that the optimal temperature is 4°C as the largest number of cells remained viable the longest duration at this condition. We are also piloting viable cell counting by flow cytometry.