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 life"”.
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A Changing Climate Beneath Our Feet: How plant and microbial life in tropical soils are shifting and what that could mean for the future of our warming planet
… expansive, covert realm where plant roots, microbial communities and soil dynamics interact. These belowground systems are crucial for cycling carbon through the Earth and regulating the climate, but relatively little is known about them compared to aboveground systems. This is especially …
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Bacterial genes and genome dynamics in the environment
One of the most marvelous features of microbial life is its ability to thrive in such diverse and dynamic environments. My scientific interest lies in the variety of modes by which microbial life accomplishes this feat. In the first half of this thesis I present tools to leverage high throughput …
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Microbial Ecology of Dry Permafrost from Elephant Head, Antarctica
… this thesis is to determine if a viable, active microbial community could persist in cold, oligotrophic, dry permafrost soils from Elephant Head, Antarctica. Low amounts of microbial activity were measured in some microcosm samples at 5, 0, and -5C, as assessed using radiorespiration assays with …
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Improved Inference of Ecological Interaction Types
Inference of microbial interaction types allows us to understand the growth and development of microbial life forms found on earth. Numerous methods have been proposed to infer the interaction type(s) of microbes in a microbial communities using a population dynamics model. However, due to dynamic …
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Geochemistry and Microbiology of Extremely Alkaline (Ph > 12) Ground Water in the Calumet Slag -Fill Aquifer
… alkaline conditions are poorly supportive of microbial life, in part because an environment lacking in hydrogen ions (H+) is likely to interfere with the proton motive force, and with the need to maintain a circum-neutral intracellular pH (Horikoshi and Akiba, 1982). Here I describe a diverse …
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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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The Search For Volatile Biogenic Emissions In Geothermal Areas
… discipline of astrobiology is the search for life outside of the earth’s ecosystem. Detecting biosignatures in outer space is one way this search is conducted. To understand the biosignatures to look for and study in space, it is useful to gain a better understanding of life in diverse …
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The Search For Volatile Biogenic Emissions In Geothermal Areas
… discipline of astrobiology is the search for life outside of the earth’s ecosystem. Detecting biosignatures in outer space is one way this search is conducted. To understand the biosignatures to look for and study in space, it is useful to gain a better understanding of life in diverse …
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Towards a paradigm shift in the modeling of soil organic carbon decomposition for earth system models
… models that explicitly account for microbial biomass pools and enzyme kinetics that catalyze soil carbon decomposition produce notably different results and provide a closer match to recent observations. However, a systematic evaluation of the advantages and disadvantages of the …
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On the molecular diversity of dimethylsulphoniopropionate catabolism by marine bacteria
… cycling of sulphur, and as a nutrient source for microbial life. In recent years, the molecular basis of DMSP catabolism by marine bacteria has begun to be unravelled, through the discovery of six different DMSP lyases and a DMSP demethylase, as well as downstream pathways. From these studies, it …
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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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Computer modeling and experimental work on the astrobiological implications of the martian subsurface ionising radiation environment
Any microbial life extant in the top meters of the martian subsurface is likely to be held dormant for long periods of time by the current permafrost conditions. In this potential habitable zone, a major environmental hazard is the ionising radiation field generated by the flux of exogenous …
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Observing microbial processes at the microscale with in situ technology
… has been investigated in the laboratory with microbial isolates and theoretical models, microbial ecologists have lacked adequate tools to interrogate microscale processes directly in the natural environment. Within this thesis I introduce three new technologies that enable interrogation of …
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On the non-microbial sources and sinks of dissolved metabolites in seawater
… These chemicals are the flows of the “microbial loop”—the principle that most of the photosynthesized matter in the ocean is exchanged, respired, and restructured by single-celled organisms. Metabolites have critical biological utility, so they are considered extremely labile; estimates …
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Physiological and Phylogenetic Studies of the Biogeography of Alkaliphilic Heterotrophic Bacteria from Serpentinizing Habitats
… hydrogen. Hydrogen provides an energy source for microbial metabolism and in combination with mineral catalysts can lead to the abiogenic synthesis of small organic compounds, such as methane. Serpentinite habitats contain abundant potential electron donors, but microorganisms presumably have …
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On the non-microbial sources and sinks of dissolved metabolites in seawater
… These chemicals are the flows of the “microbial loop”—the principle that most of the photosynthesized matter in the ocean is exchanged, respired, and restructured by single-celled organisms. Metabolites have critical biological utility, so they are considered extremely labile; estimates …
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The integration of fine-scale DNA-DNA associations by inclusion of Hi-C DNA cross-linking information into metagenomic community analysis
Much of our understanding of the microbial world has been obtained using culture-based methodologies, a paradigm that has stood since the 19th century. And yet it has long been known that most of the Earth’s microbial species are resistant to laboratory culture. It is reasonable to expect; …
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Preservation Potential of Permian Gypsum Beds, Nippewalla Group, USA
ABSTRACT During the Permian, what is now southern Kansas and northern Oklahoma was a drying inhospitable environment, as evidenced by the extensive red-beds and evaporites of the Nippewalla Group. Due to the fact that animals could not live in much of this extreme environment, there is a lack of a …
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Exploring B vitamin biosynthesis and exchange in understudied marine stramenopiles and their communities
Microbes are the dominant form of life on Earth. Environmental sequencing has revealed the extent of the diversity of microbial life in all environments, not least the ocean. In this vast aquatic environment microbes, both prokaryotic and eukaryotic, play essential roles in the cycling of …
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Magmatic volatiles at rifts and arcs: Sources and fractionation effects
… light, potentially carrying the signature of microbial life into the deep mantle.