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Articles 1 - 7 of 7
Full-Text Articles in Life Sciences
Response Of Soil Viral And Microbial Functional Diversity To Long-Term Agricultural Management In Jackson, West Tennessee, Ning Duan
Doctoral Dissertations
Soil microbial communities are a critical component for ecosystem stability and function. Viruses, as an important biotic controller, have the potential to regulate the abundance and diversity of bacterial communities through infection. Soil is known to harbor abundant and diverse viral assemblages but their ecological role and influence on microbial processes has not been fully elucidated. Microbes can be influenced by viruses not only from infection but though biogeochemical feedbacks of the “microbial (bacterium–phage–DOC) loop” or “viral shunt”. However, we know relatively little about the microbial community and function under the regulation of viruses in soil and how they respond …
Microbial Community Dynamics Of A Microcystis Bloom, Helena Pound
Microbial Community Dynamics Of A Microcystis Bloom, Helena Pound
Doctoral Dissertations
Harmful algal bloom events are notoriously associated with massive economic and environmental consequences, causing wildlife and human health risks. As these blooms increase in occurrence, duration, and severity around the world, it is essential to understand conditions leading to bloom formation and why they persist. Abiotic factors such as nutrients are commonly considered in bloom dynamics, but biotic interactions with co-occurring microbial species and viruses must also be taken into account. Harmful algal blooms dominated by the cyanobacterial genus Microcystis occur in bodies of water around the world and provide an ideal system in which to study top-down controls on …
Determining The Ecological And Physiological Factors Contributing To The Competitive Success Of Prochlorococcus In The Oligotrophic Ocean, Benjamin C. Calfee
Determining The Ecological And Physiological Factors Contributing To The Competitive Success Of Prochlorococcus In The Oligotrophic Ocean, Benjamin C. Calfee
Doctoral Dissertations
Prochlorococcus is a genus of extremely successful marine cyanobacteria. This success is realized through its pervasive biogeographical range and presence in almost all open ocean environments where it usually it the dominant phytoplankton. Limited capabilities of culturing and genetic manipulation of this organism have resulted in assumptions about this success overwhelmingly based on field observations. These studies have assumed adaptations for resource uptake and utilization in nutrient limited environments to cause dominance of Prochlorococcus over other photosynthetic microbes. In an attempt to definitively explain this through laboratory culture, we developed a culturing system to assay questions of nutrient limitation effects …
High Arctic Permafrost Microbial Characterizations: Siberian And Svalbard Microbiology Of Ancient And Active Layer Permafrost, Katie Sipes
Doctoral Dissertations
Permafrost is soil that has remained frozen for at least two years. The active layer is a surface portion above the permafrost that experiences seasonal thaw and refreezing. The environmental characteristics of permafrost and active layer are different but are directly related to each other. As the climate continues to warm, the active layer will expand into the permafrost and the continuously frozen soil will be subjected to seasonal thawing. The organisms that inhabit both the active layer and the permafrost soil will respond differently to the climate based on where in the soil they are present and the soil …
Impacts Of Soil Management On Microbial Assemblages Involved In Nitrogen Transformations In Agroecosystems In Tennessee, Usa, Jialin Hu
Doctoral Dissertations
Nutrient reduction, particularly with respect to nitrogen (N) losses, is an important goal for sustainably managed agroecosystems. Soil N-cycling microbial populations that modulate these processes are affected by agricultural management regimes. This research focused on the controls and dynamics of the major N-cycling microbial populations in high-input cotton field under agricultural management regimes and low-input native C4 forage grass systems under pasture management practices to determine the effects of management regimes on in situ seasonal dynamics of the functional microbes responsible for N fixation, nitrification, and denitrification processes. Molecular microbial ecology methods were combined with soil physicochemical properties and …
Biotic And Abiotic Dehalogenation Of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, And Tetrachloromethane, Briana M. Mcdowell
Biotic And Abiotic Dehalogenation Of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, And Tetrachloromethane, Briana M. Mcdowell
Doctoral Dissertations
Trichlorofluoromethane (CFC-11), dichlorofluoromethane (CFC-12), and tetrachloromethane (CT) are fully halogenated methanes that were produced as refrigerants in the early part of the 1900s and later used in many industrial processes. They are ozone-depleting agents and common groundwater contaminants. They are volatile chemicals that are moderately soluble in water. Due to their volatility when released to the environment, they are predominantly found in the atmosphere, though they also dissolve into the groundwater. In anaerobic environments, they can undergo dehalogenation reactions with several redox-active compounds. This dissertation presents results from two treatability studies from sites contaminated with CFC-11, CFC-12, and CT. Additionally, …
Investigating Microbial Genes Involved In Plant Colonization And The Effects On Plant Microbiome Assembly, David Grant
Investigating Microbial Genes Involved In Plant Colonization And The Effects On Plant Microbiome Assembly, David Grant
Masters Theses
The use of chemical fertilizers and pesticides has had negative impacts on ecological systems and alternatives will be needed to both enhance agricultural production and remediate waste that has accumulated via fertilizer use. A promising alternative to tackle both problems utilizes beneficial organisms in microbial communities associated with plants, which are known as bioinoculants. However, the benefits of bioinoculants are inconsistent in field application and require more research in order to harness them in ways to make them a suitable replacement for chemical fertilizers. Here, I investigate characteristics required to enhance bioinoculant efficiency, including mechanisms required to increase microbial colonization …