Graduate Studies

 

First Advisor

Nicole R. Buan

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biochemistry

Date of this Version

12-2024

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College at the University of nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Biochemistry

Under the supervision of Professor Nicole R. Buan

Lincoln, Nebraska, December 2024

Comments

Copyright 2024, Connor John Hines. Used by permission

Abstract

Methanogenesis is known to be one of the oldest forms of energy generation on our planet. Methanogens rely on this method of energy conservation and have evolved to metabolize a variety of substrates, including the waste products of other organisms. This feature has made methanogens beneficial to both wastewater treatment and landfill-to-energy projects. Methane itself is a greenhouse gas twenty times more potent than carbon dioxide, viewed as a particularly influential contributor to global greenhouse emissions. Climate change was known to be on the horizon throughout the 20th century but has made itself known vocally during this 21st century. The shift toward clean, renewable energy has always been inevitable as a means to mitigate the countless crises climate change will bring. The Permian Extinction, known to be the most severe extinction event in our planet’s history, occurred approximately 250 million years ago. Methanogens are suspected to be a key contributor to the climate change which drove the extinction of over half of all known biological families, ending the Permian Era. Perhaps we could give these unique microorganisms a second chance, harnessing their unique ability to transform waste to energy in order to mitigate anthropogenic climate change.

Coenzyme M (CoM) represents a critical component to methanogenesis which advanced our comprehension of the Wolfe Cycle. Chapter 1 is written as a perspective on CoM biosynthesis in methanogens, beginning with the history behind and the obstacles to demystify the process by which methanogens produce CoM. Chapter 1 closes with an investigation into the enzyme which catalyzes the final step of CoM biosynthesis methanogens, ComF. Chapter 2 reports our success in establishing a two-step metabolic pathway for the production of CoM from taurine and pyruvate. This pathway allowed us to confirm the elusive gene responsible for the final catalytic step in the biosynthesis of CoM and showed that Escherichia coli benefitted from the endogenous production of CoM to mitigate oxidative stress. Chapter 3 details the experiments and findings which laid the foundation for the research in the previous section; examining how methanogens also benefit from the antioxidative property of CoM. Finally, Chapter 4 is an exhaustive review on the application of exogenous antioxidants to plants, written in collaboration with the Roston, Glowacka, Stone, Wuellner, and Bickford labs. The collected data presents a comprehensive look at the beneficial and detrimental effects conferred by a variety of antioxidants to plants. This review allows one to imagine a scenario in which CoM can provide utility towards protecting plants from a variety of stresses in an unpredictable future shaped by climate change.

Advisor: Nicole R. Buan

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