Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"microbial evolution"”.
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A Platform for Microbial Evolution and Characterization
… we describe a novel platform for the engineered evolution of microbes. Our platform consists of three major components, which we discuss in subsequent chapters. Technology: We have developed a novel continuous culture device called the Flexostat. The Flexostat is a flexible, programmable, eight …
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Microbial Evolution In Sea Ice: Communities To Genes
Microbial communities encased in growing sea ice must contend with the combined stresses of low temperature and high salinity, environmental pressures that only intensify over the course of the winter. This harsh physical environment was expected to negatively impact both the abundance and …
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Whole Genome Analysis of Escherichia coli and Pseudomonas aeruginosa Mixed Culture Biofilms Grown for 117 Days in Spaceflight
… effects of spaceflight on extended growth and microbial evolution of the biofilms. Of 24 spaceflight samples, 17 still had viability. Of those, E. coli was found only in non-treated (0ppb AgF) samples while P. aeruginosa survived the silver treatment (400ppb AgF). A total of 19 spaceflight …
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Bridging the gap between microbial and metazoan evolutionary history
While microbial life originated early in Earth history and continues to underpin most modern ecosystems, its evolutionary trajectory remains murky. This is predominantly due to the dearth of diagnostic microbial fossils and biomarkers. Conversely, metazoans (animals) emerged relatively recently and …
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A phylogenetic framework for large-scale analysis of microbial communities
… phylogenetics allows researchers to study microbial evolution, resolve strain-level relationships between microbes, and also taxonomically place and characterize novel and unknown microbial genomes. This thesis presents a novel computational phylogenetic approach implemented during my …
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Marine carbohydrate-active enzymes illuminate microbial ecology, evolution, and carbonate precipitation
Marine carbohydrate-active enzymes (CAZymes) in microbial mats build, modify, and degrade the matrix of exopolymeric substances (EPS) that structure these ancient ecosystems and control mineral formation via the alkalinity engine and organic surfaces involved in mineral nucleation and growth. …
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The evolution of hydrogen sulfide by Gluconobacter species
… thiosulfate. This finding is puzzling, since the microbial evolution of H₂S is characteristic of anaerobic or facultative bacteria. The goal of this research was to determine the physiological role of H₂S evolution for the gluconobacters. A methylene blue method was used to quantify the amount of …
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The evolutionary ecology of methylation-dependent bacterial defense systems
Mobile genetic elements (MGEs) are central to microbial evolution, acting both as vectors of host genomic innovation by transferring adaptive genes between lineages, and as parasites, infection by which has driven the evolution of diverse host defense systems. Although recent years have seen a …
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Evolution's footsteps : reconstructing in vitro and in vivo evolutionary trajectories via massively parallel sequencing and profiling
… selection is a fundamental question of biology. Microbial evolution studies provide the rare opportunity to experimentally elucidate the changes that allow an organism to adapt to novel conditions. In an in vitro experimental evolution system, cells evolve in response to a lab-controlled …
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Ediacaran Fronds from South Australia and Newfoundland
… (575-539 Ma) represents a seminal event in the evolution of life, the first abundant appearance of large, architecturally complex, soft-bodied organisms after three billion years of mostly microbial evolution. Fronds occupied all tiers of the Ediacaran ecosystem and were the first animals with a …
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Genomic signatures of sex, selection and speciation in the microbial world
Understanding the microbial world is key to understanding global biogeochemistry, human health and disease, yet this world is largely inaccessible. Microbial genomes, an increasingly accessible data source, provide an ideal entry point. The genome sequences of different microbes may be compared …
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Evolution of Pseudomonas aeruginosa in the Cystic Fibrosis Lung
… activity of mutator strains. To investigate the evolutionary role played by mutators, and to identify gene deletions and amplifications that arise and persist in chronic infections we undertook DNA microarray-based comparative genome hybridization and CLONDIAG miniarray analyses on 21 clinical P. …
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Evolution of Pseudomonas aeruginosa in the Cystic Fibrosis Lung
… activity of mutator strains. To investigate the evolutionary role played by mutators, and to identify gene deletions and amplifications that arise and persist in chronic infections we undertook DNA microarray-based comparative genome hybridization and CLONDIAG miniarray analyses on 21 clinical P. …
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The evolution and diversity of noncanonical microbial nitrogen metabolisms
Microbial nitrogen cycling underpins Earth’s most basic ecology. The environmental and commercial significance of nitrogen biogeochemistry has prompted substantial study of the modern nitrogen cycle, but much remains unknown about the evolution of nitrogen biochemistry through deep time. This …
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Computational approaches to stochastic systems in physics and biology
… arising during quenches and forcing, and complex microbial communities living and evolving withing the gastrointestinal tracts of vertebrates. As such, this dissertation is organized into two parts. In Part I, I create a model for quantum fluids, which incorporates a conservative and dissipative …
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Reconstructing local redox conditions, mineral precipitation processes and nutrient availability in seawater during deposition of the Transvaal Supergroup, South Africa
… rare earth element (REE) data from contorted microbial laminae and adjacent carbonate cement from microbial carbonates, alongside a new compilation of existing data to explore the implications for pre-GOE molecular oxygen availability. A novel methodology that involves cutting along bedding …
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Genome evolutionary studies of the Salmonella enterica serovars: implications for the dynamics of horizontal gene transfer, the pangenome concept, and bacterial and archaeal taxonomy
With the vast expansion of complete microbial genome sequences, it is increasingly apparent that the genomes of free-living and facultative microbes living in competitive environments are astonishingly dynamic. That is, such microbes appear to be constantly subjected to gene gain and gene loss …
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Proteome, transcriptome and metabolome plasticity in closely related strains of Escherichia coli - K12 and its diversity during molecular evolution processes
… E. coli is frequently used in molecular evolutionary studies. A few potential reasons for this are: its capacity to propagate and reproduce quickly, facilitating the evolution experiments for many generations in a short time span, and capability to store the evolved and ancestor strains, …
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Molecular evolution of biological sequences
Evolution is an ubiquitous feature of living systems. The genetic composition of a population changes in response to the primary evolutionary forces: mutation, selection and genetic drift. Organisms undergoing rapid adaptation acquire multiple mutations that are physically linked in the genome, so …
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Investigating a novel Asgard archaeon and its tubulin-like proteins
… may have originated prior to eukaryogenesis (the evolutionary process that gave rise to the Last Eukaryotic Common Ancestor (LECA)). Phylogenetic analyses of the many Asgard archaeal MAGs that have become available suggest a strong affiliation between Asgard Archaea and Eukarya, either as sister …