Doctoral Dissertations
Date of Award
12-2023
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Comparative and Experimental Medicine
Major Professor
Stephen A. Kania
Committee Members
Kristina Kintziger, Marcy J. Souza, Richard W. Gerhold Jr, Mark Waugh
Abstract
Bacillus licheniformis and Bacillus paralicheniformis are Gram positive, endospore forming bacteria, present in a wide variety of environments. Until 2015, when B. paralicheniformis was identified from fermented soybeans, it was impossible to distinguish it from B. licheniformis. B. licheniformis and its products have established many biotechnological applications. On the other hand, B. paralicheniformis, being less studied, is considered a promising bacterium with significant biotechnological applications. Bacteria in this study were isolated from Yellowstone National Park hot springs [YNP] which are naturally occurring hydrothermal features. In this remote environment with limited resources, competition among microorganisms is crucial for survival. Certain microorganisms may be able to hinder or kill surrounding competitors through antibiotic production, effectively lowering competition for resources and enhancing their own chances of survival and reproduction. Simultaneously, microorganisms with antibiotic resistance genes can tolerate the effects of antibiotics, allowing them to survive in the presence of antibiotics. This resistance could be genetically inherited or acquired by horizontal gene transfer. To gain insights into these thermophilic bacteria, this study characterized thermophilic strains of B. licheniformis and B. paralicheniformis isolated from hot springs in YNP and performed a comparative genomic analysis with genomes of non-thermophilic bacteria isolated from various vi environments. This study revealed that the genomes of B. licheniformis and B. paralicheniformis encode multiple biosynthetic gene clusters [BGC] and antibiotic resistance genes. These BGC are responsible for the production of various compounds, including antimicrobials, as well as others whose functions remain unknown. These BGC and antibiotic resistance genes in thermophilic bacteria share significant similarities with those found in non-thermophilic bacteria. This finding underscores the potential for horizontal gene transfer and the exchange of genetic information across bacterial populations, regardless of their thermal preferences. Understanding the presence and distribution of these BGC and antibiotic resistance genes, as well as their relationship with mobile genetic elements, provides vital insights into bacterial genetic diversity and adaptation mechanisms. It adds to our understanding of the genetic basis of antibiotic synthesis, resistance, and the possibility for horizontal gene transfer, which has consequences for antibiotic discovery, resistance mechanisms, and microbial ecology.
Recommended Citation
Elsakhawy, Ola, "Characterization of Antibiotic-Producing Thermophilic Bacteria from Remote Environments. " PhD diss., University of Tennessee, 2023.
https://trace.tennessee.edu/utk_graddiss/8990