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Full-Text Articles in Environmental Microbiology and Microbial Ecology

Determining The Ecological And Physiological Factors Contributing To The Competitive Success Of Prochlorococcus In The Oligotrophic Ocean, Benjamin C. Calfee Dec 2021

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 …


Extracellular Polymeric Substances In Oxygenic Photogranules: Investigation Of Their Role In Photogranulation In A Hydrostatic Environment, Wenye Camilla Kuo-Dahab Sep 2021

Extracellular Polymeric Substances In Oxygenic Photogranules: Investigation Of Their Role In Photogranulation In A Hydrostatic Environment, Wenye Camilla Kuo-Dahab

Doctoral Dissertations

The purpose of this dissertation was to assess the critical role of extracellular polymeric substances (EPS) in the photogranulation of activated sludge, in a hydrostatic environment. The first section evaluates the fate and dynamics of different fractions of EPS in sludge-based photogranulation under hydrostatic conditions. The study shows that during the transformation of activated sludge into a photogranular biomass, sludge’s base-extractable proteins selectively degrade. Strong correlations between base-extracted proteins and the growth of chlorophyll a and chlorophyll a/b ratio suggest that the bioavailability of this organic nitrogen is linked with selection and enrichment of filamentous cyanobacteria under hydrostatic conditions. The …


Ecophysiology Of Toxic Bloom-Forming Cyanobacteria And Their Symbionts, Dominique J. Lockwood Aug 2021

Ecophysiology Of Toxic Bloom-Forming Cyanobacteria And Their Symbionts, Dominique J. Lockwood

Masters Theses, 2020-current

Currently, there is a pernicious microbe in the genus Microcystis that is putting the world’s freshwater resources at risk. A member of the phylum Cyanobacteria, otherwise referred to as blue-green algae, Microcystis forms massive algal blooms in lakes and has the potential to produce a toxin, which does not only harm humans, but also pets, livestock, and aquatic life. As recently as 2016, in the city of Toledo, Ohio, nearly 1 million residents went without clean drinking water for an entire weekend due to one of these Microcystis blooms. However, Microcystis does not only bloom in Ohio. In fact, …


Physiological Constraints, Mechanisms, And Mineral Transformations Of Iron Reduction In Hyperthermophilic Crenarchaea, Srishti Kashyap Apr 2021

Physiological Constraints, Mechanisms, And Mineral Transformations Of Iron Reduction In Hyperthermophilic Crenarchaea, Srishti Kashyap

Doctoral Dissertations

Dissimilatory iron reduction by hyperthermophilic archaea occurs in many geothermal environments and typically relies on microbe-mineral interactions that transform various iron oxide minerals. However, the kinds of iron oxides that can be used, growth rates, extent of iron reduction, and the mineral transformations that occur due to this metabolism are poorly understood. This dissertation improves our fundamental understanding of the physiological mechanisms and mineral transformations of hyperthermophilic iron reduction using two model crenarchaea, Pyrodictium delaneyi and Pyrobaculum islandicum. Using growth yields and metabolite production rates, we demonstrated that a broad range of Fe(III) (oxyhydr)oxides of variable thermodynamic stability was …


Taxonomic Microbiome Profiling And Abundance Patterns In The Cacao (Theobroma Cacao L.) Rhizosphere Treated With Arbuscular Mycorrhizal Fungi And Bamboo Biochar, Angelbert D. Cortes, Nelly S. Aggangan, Rina B. Opulencia Mar 2021

Taxonomic Microbiome Profiling And Abundance Patterns In The Cacao (Theobroma Cacao L.) Rhizosphere Treated With Arbuscular Mycorrhizal Fungi And Bamboo Biochar, Angelbert D. Cortes, Nelly S. Aggangan, Rina B. Opulencia

The Philippine Agricultural Scientist

Biochar and arbuscular mycorrhizal fungi (AMF) are agricultural interventions adopted by farmers to improve the growth of crops in nutrient-deficient acidic soil, which relatively influence the biological properties in the rhizosphere. This greenhouse study investigated the changes in prokaryotic diversity in the rhizosphere of cacao plants grown in acidic soil with AMF and bamboo biochar (BB) for 15 months under nursery conditions. Metagenomic analysis of the V3-V4 region of the 16S rRNA gene of the rhizosphere with AMF, 15% BB, and AMF + 15% BB revealed that the addition of AMF and BB reduced the sample's diversity, but the treatments …


The Response Of Marine Synechococcus To A Landscape Of Environmental Stressors: A Proteomic Exploration, Dana E. Michels Mar 2021

The Response Of Marine Synechococcus To A Landscape Of Environmental Stressors: A Proteomic Exploration, Dana E. Michels

Master's Theses

In the field of marine microbial ecology, many questions remain unanswered with regards to the physiological trade-offs made by phytoplankton to maximize growth (e.g., nutrient acquisition) and minimize loss (e.g., predation defenses). These tradeoffs, which occur at the cellular level, have wide reaching impacts on food web dynamics and global biogeochemical cycles. In the first chapter, we explored the use of a non-canonical amino acid (NCAA) technique, bioorthogonal non-canonical amino-acid tagging (BONCAT), in phytoplankton model systems. This technique has potential to work well in natural systems by enabling isolation of only newly synthesized proteins during an incubation period with the …


Inhibition Of Biofilm Formation By The Synergistic Action Of Egcg-S And Antibiotics, Shrameeta Shinde, Lee Lee, Tinchun Chu Jan 2021

Inhibition Of Biofilm Formation By The Synergistic Action Of Egcg-S And Antibiotics, Shrameeta Shinde, Lee Lee, Tinchun Chu

Department of Biology Faculty Scholarship and Creative Works

Biofilm, a stress-induced physiological state, is an established means of antimicrobial tolerance. A perpetual increase in multidrug resistant (MDR) infections associated with high mortality and morbidity have been observed in healthcare settings. Multiple studies have indicated that the use of natural products can prevent bacterial growth. Recent studies in the field have identified that epigallocatechin gallate (EGCG), a green tea polyphenol, could disrupt bacterial biofilms. A modified lipid-soluble EGCG, epigallocatechin-3-gallate-stearate (EGCG-S), has enhanced the beneficial properties of green tea. This study focuses on utilizing EGCG-S as a novel synergistic agent with antibiotics to prevent or control biofilm. Different formulations of …


Roles Of Non-Frankia Bacteria In Root Nodule Formation And Function In Alnus Sp., Kelsey Christine Mercurio Jan 2021

Roles Of Non-Frankia Bacteria In Root Nodule Formation And Function In Alnus Sp., Kelsey Christine Mercurio

Honors Theses and Capstones

Plant roots are home to a wide variety of beneficial microbes; understanding and optimizing plant-microbe interactions may be critical to enhance global food security in a sustainable, equitable way. With the help of their nitrogen-fixing bacterial partner, Frankia, actinorhizal plants form symbiotic root nodules and play important roles in agroforestry and land reclamation. However, Frankia does not live alone in nodules, and the other microbial residents may contribute to nodule formation and function. We collected root nodules from alder trees (Alnus sp.) in 2018 and 2019, then isolated DNA and individual bacterial strains to characterize the nodule microbial …