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Theses/Dissertations

Life Sciences

Bacteria

James Madison University

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Structure/Function Analysis Of Fega And Fhua In Bradyrhizobium Sp., Alexander James Herd Jan 2019

Structure/Function Analysis Of Fega And Fhua In Bradyrhizobium Sp., Alexander James Herd

Senior Honors Projects, 2010-2019

Bradyrhizobium japonicum is a Gram-negative soil bacterium commonly known for its agriculturally significant mutualistic relationship with soybean. In this symbiosis, the bacteria and plant undergo complex molecular signaling characterized by sent and received signals resulting in the formation of infection threads and root nodules. This research aimed to compare two related bacterial outer membrane proteins, FegA and FhuA, associated with the molecular signaling between the bacteria and plant. Previous work has led to the hypothesis that the N-terminal domain (NTD) of FegA in B. japonicum is needed for a functional symbiosis to occur. Recombinant bacterial strains expressing altered FegA proteins …


Survey Of Microbial Urea Degrader Diversity In Two Freshwater Ecosystems: Lake Shenandoah And The Shenandoah River, Naomi E. Gilbert May 2017

Survey Of Microbial Urea Degrader Diversity In Two Freshwater Ecosystems: Lake Shenandoah And The Shenandoah River, Naomi E. Gilbert

Senior Honors Projects, 2010-2019

One of the primary drivers of cyanobacterial harmful algal blooms (cHABs) in freshwater systems is nutrient loading, particularly of nitrogen and phosphorus. There has been an increased focus on assessing the role of nitrogen (N) in freshwater lakes and rivers that suffer cHABs. Urea, a widely-used, N-rich fertilizer, is a source of interest due to its abundance in freshwater ecosystems, primarily caused by anthropogenic nutrient loading. While recent work has shown that cHAB population succession may favor the toxic cyanobacterium Microcystis in urea-rich waters, the diversity of the associated bacterial community capable of degrading urea has yet to be determined. …


The Antimicrobial And Biofilm Disruption Activity Of Novel Amphiphiles, Elizabeth A. Rogers May 2017

The Antimicrobial And Biofilm Disruption Activity Of Novel Amphiphiles, Elizabeth A. Rogers

Masters Theses, 2010-2019

Antibiotic resistant infections are responsible for approximately 23,000 deaths every year in the United States alone. The formation of bacterial biofilms makes resistant bacteria difficult to eliminate completely using chemical treatment. Therefore, novel antimicrobial compounds such as amphiphiles are essential to slow or stop the spread of resistant bacteria. Several novel series of amphiphiles were synthesized, and discrete aspects of their chemical structure were altered to investigate the relationship between structure and antibacterial activity. Minimum inhibitory concentration (MIC) assays were used to measure antibacterial activity against two Gram-negative and five Gram-positive bacteria, and the most effective compounds were tested for …


Comparative Analysis Of Anti-Bd Bacteria From Six Malagasy Frog Species Of Ranomafana National Park, Kelsey Savage May 2015

Comparative Analysis Of Anti-Bd Bacteria From Six Malagasy Frog Species Of Ranomafana National Park, Kelsey Savage

Senior Honors Projects, 2010-2019

As Malagasy amphibians are facing an impending extinction crisis from the lethal skin fungus Batrachochytrium dendrobatidis (Bd), it has become imperative to proactively mitigate the threat. Bd sporangia develop in the skin of infected amphibians and cause the skin to thicken, leading to ionic imbalance and eventual heart failure. It has been shown that certain bacterial species are able to inhibit Bd growth on amphibians by producing antifungal metabolites. Community-based probiotics are one approach used to combat chytridomycosis by inoculating an environment with Bd-inhibitory bacteria so that many amphibian species are treated at once. With this method, it is important …