Portland State University. Department of Physics
Jay L. Nadeau
Term of Graduation
Date of Publication
Master of Science (M.S.) in Physics
1 online resource (x, 120 pages)
Motility of microorganisms is understudied but provides useful insights into their behavior. Organisms' ability to move autonomously changes how they interact with their environment--finding nutrients, interacting with other organisms, and avoiding unfavorable conditions. Understanding motility features can also be used to identify specific species, such as the identification of Vibrio cholerae in human samples. Motility might also be used as evidence of life existing in even the most extreme environments on Earth, and possibly beyond. Specialized microscopy systems can be required to examine the motility of microorganisms due to the nature of the environments to which the instruments are exposed. For example, some extremophilic organisms cannot swim below 85°C, such as the thermophilic archaea Pyrococcus furiosus. To address these types of samples, we built a heated system for increasing ambient sample temperature up to 100°C with the ability to adjust and maintain such temperatures while performing microscopic imaging. This system has been used for the examination of the heat stress response of Bacillus subtilis and further work is being done to understand P. furiosus.
Another example of the need for specialized microscopy comes from the need for in situ observations. This includes Earth analog sites for the ocean worlds like Europa and Enceladus. These sites occur in environments where sample return is difficult and preservation of live organisms may be impossible. It also includes the restrictions and requirements for exposing these organisms to microgravity aboard the International Space Station. Given increased virulence found in organisms in microgravity and the suppressed immune system of astronauts on board the International Space Station, special system considerations needed to be addressed for both astronaut safety and organism survival.
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Dubay, Megan Marie, "System Design for the Quantification of Microbial Motility in Extreme Environments" (2022). Dissertations and Theses. Paper 6184.
Available for download on Thursday, August 31, 2023