Date of Graduation

12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Physics (PhD)

Degree Level

Graduate

Department

Physics

Advisor/Mentor

Pradeep Kumar

Committee Member

Jeffrey Lewis

Second Committee Member

Woodrow Shew

Third Committee Member

Surendra Singh

Keywords

Cell Division, Escherichia coli, Extreme Conditions, Filamentous cells, Growth and Division, Stochastic simulation

Abstract

Life is remarkable in how resilient it can be. Many organism, classified as ex- tremophiles, can not only survive in extreme environments, but they can thrive in them. In the search for extraterrestrial life, the best candidates to harbor life exist with some kind of extreme condition. Europa, for example, is a favorite for the possibility of accommodating life as we know it within our solar system. Thought there is believed to be a liquid ocean under its icy surface, this habitat would be under immense pressures and high salinity. To best know where to look for extraterrestrial life, it is important to first fully understand life as we know it on a simpler scale. Escherichia coli, a mesophilic bacterium, is a common and well studied organism. They play a vital role in our lives and have been well-studied for this fact as well as its ease to work with. Some of these studies involve putting the limits of E. coli to the test. They are subjugated to many stresses that aren’t unlike those found on Europa or other contenders for harborers of life. The organism’s cycles of growth and division can be altered when in the presence of these extreme situations. Understanding how these dynamics change with a given stress could have great implications on how life may arise in these extreme environments. This collection of work will investigate the effects of extreme conditions on the cell division dynamics of E. coli. Firstly, the effect of high hydro- static pressure on the cell division dynamics of E. coli. From this study, a new, physically motivated model of cell division will be proposed. Next, the effect of growth media richness on the growth and division of E. coli will be examined. Then, cell division dynamics of E. coli cells in an environment of high concentrations of sodium sulfate will be discussed. This work could have implications to how living organisms would adapt to a salty ocean such as that of Europa. Finally, the real-time gene expression of various genes of E. coli at elevated levels of two salts, magnesium sulfate and sodium sulfate, will be shared. Knowing which genes are being expressed in these stressful environments could explain why the cell division dynamics differ in the way they do. The results discussed here will have implications for the search for extraterrestrial life, as well as deepening the knowledge of how simple life functions here on Earth.

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