Award Date
8-1-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Life Sciences
First Committee Member
Brian Hedlund
Second Committee Member
Duane Moser
Third Committee Member
Mira Han
Fourth Committee Member
Jeffery Shen
Fifth Committee Member
Ganqing Jiang
Number of Pages
175
Abstract
High-temperature geothermal springs are ecosystems that resemble early Earth, offering insights into the origins and early evolution of life. In these unique ecosystems, thermophilic microorganisms thrive. However, our knowledge of thermophiles remains limited. A major challenge is that many thermophiles remain uncultivated. The primary goal of this dissertation was to explore the diversity, metabolism, and ecological functions of thermophiles using cultivation-dependent and cultivation-independent approaches. Chapter 1 provides a broad overview of geothermal spring ecosystems and thermophiles, along with a roadmap of the dissertation. Chapter 2 documents a study on the response of specific thermophiles from Gongxiaoshe (GXS) Hot Spring in China to pulses of labile dissolved organic carbon, specifically acetate and aspartate, using quantitative stable isotope probing (qSIP) and metagenomics. The results indicate strong resource partitioning and a wider preference for aspartate incorporation into DNA over acetate. Chapter 3 explores the ecophysiology and evolution of a dominant archaeal species, designated Calditenuis ramacidaminiphagus, from Great Boiling Spring, Nevada, USA. By using fluorescence in situ hybridization coupled with nanoscale secondary ion mass spectrometry (FISH-NanoSIMS), metagenomics, metaproteomics, and laboratory cultures, we demonstrated branched-chain amino acids (BCAAs) specialization in C. ramacidaminiphagus. We also showed that BCAA specialization as a key trait for the genus Calditenuis. Chapter 4 summarizes our research findings and discusses future research perspectives. Chapter 5 describes my contributions to other research projects.
Keywords
extremophiles; geothermal spring; resource partitioning; thermophiles
Disciplines
Biology | Environmental Sciences | Microbiology
File Format
File Size
11500KB
Degree Grantor
University of Nevada, Las Vegas
Language
English
Repository Citation
Lai, Dengxun, "Probing the Ecological Functions of Thermophiles Using Cultivation-Dependent and Cultivation-Independent Techniques" (2024). UNLV Theses, Dissertations, Professional Papers, and Capstones. 5133.
https://digitalscholarship.unlv.edu/thesesdissertations/5133
Rights
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