Other Microbiology Commons^™

Bioindicators Of Mercury In Riverine Systems, Kathryn Mudica

All-Inclusive List of Electronic Theses and Dissertations

This study focuses on the bioaccumulation and biomagnification of mercury in freshwater food webs, with emphasis on bioindicators, such as macroinvertebrates, crayfish, and river otters. Despite regulatory efforts and advancements in monitoring, significant gaps remain in understanding mercury dynamics in freshwater systems—especially regarding its transport, methylation, and bioavailability across different ecosystems. To address these knowledge gaps, this study adopts a biocentric approach, emphasizing the role of living organisms in their environment. By utilizing macroinvertebrates, crayfish, and river otters as bioindicators, we aim to assess mercury bioavailability and distribution. These organisms provide varying temporal and spatial scales of mercury accumulation, offering …

The Absence Of Cxcl10 Activity Does Not Affect The Capability Of Cd8+ T Cells To Migrate And Eliminate The Tissue Cysts Of Toxoplasma Gondii From The Brains Of Chronically Infected Mice, Rajesh Mani, Yasuhiro Suzuki

Markey Cancer Center Faculty Publications

Toxoplasma gondii forms tissue cysts in neurons and astrocytes in the brain to establish chronic infection, and astrocytes express the CXCL10 chemokine in chronically infected mice. Since chemokines mediate the migration of T cells to attack their targets, and since CXCL10 plays key roles in T cell-mediated control of the proliferation of tachyzoites (the acute stage form) of T. gondii during the acute stage of infection, we examined whether CXCL10 is involved in recruiting anti-cyst CD8+ cytotoxic T cells to eliminate the cysts in their brains. We employed adoptive transfer of CD8+ immune T cells to infected, T cell-deficient SCID …

The Role Of Efflux Pump Inhibitor In Enhancing Antimicrobial Efficiency Of Silver Nanoparticles And Methylene Blue As An Effective Photodynamic Therapy Agent, Yaran Allamyradov

Masters Theses & Specialist Projects

Efflux pumps are critical active transport systems utilized by cells to expel toxic substances, including antibiotics and photosensitizer complexes, thereby contributing to antimicrobial resistance. Efflux pump inhibitors (EPIs), which are compounds that obstruct the transport of molecules through these pumps, play a pivotal role in enhancing the effectiveness of antimicrobial therapies against pathogens. This study investigates the effects of the EPI reserpine on the photodeactivation rate of pathogens when used in conjunction with silver nanoparticles (Ag NPs) and methylene blue (MB), a common photosensitizer.

Our research reveals that the application of reserpine, in combination with Ag NPs and MB, leads …

Antimicrobials Produced By Ants: Chemical Properties And Microbe Specificity, Katy Chon

Master's Theses

Antibiotic resistance is a growing public health concern worldwide, and for over a decade, we have been witnessing the growth of difficult to treat infectious diseases caused by bacteria that are becoming resistant to antibiotics. This resistance can be mostly related to the misusing and improper use of antibiotics in both humans and animals. To restore this problem, humans have turned to new sources for the production of antibiotics. In this study, we focused on using ants. Social insects, including ants and bees, have faced strong disease pressures during their evolution and have developed a range of methods to fight …

Characterizing The Quorum Sensing (Qs) System In The Model Eukaryote Chlamydomonas Reinhardtii, Kirstin Donnette Cutshaw

Theses and Dissertations

Group behaviors in microorganisms are often regulated by low-molecular weight molecules that enable them to sense population density, a signaling system known as quorum sensing (QS). QS in prokaryotes has provided insight into the role ‘social’ behaviors play in the bacterial world and refined our models of virulence, bacterial motility, and more. While less common, similar behaviors are observed in certain fungi, primarily yeasts, in which QS controls cell morphology, biofilm production, and other phenotypes. We have recently pursued the potential for QS to be more broadly distributed among unicellular eukaryotes, which could significantly alter our understanding of social behaviors …

Uses Of Herbal Extracts In Endodontology: A Literature Review, Reem Chamseddine, Roula S. Abiad

BAU Journal - Science and Technology

The use of natural herbal extracts in the field of dentistry, and specifically in endodontology had gained a high popularity in the past few years. The main objective of endodontic treatment is to prevent and eliminate the infection from the root canal, seize the invasion of microorganisms to periradicular tissues and preserve the natural dentition. Studies had shown that some herbs are better alternatives to traditional chemical irrigants or medicaments used in root canal treatment, based on their potential antimicrobial effect, smear layer removal capabilities, tissue dissolution effect, antioxidant, anti-inflammatory and regenerative properties. Aim: The purpose of this literature review …

Establishment Of Bacteroides In The Gut And Its Role In The Cystic Fibrosis Gut-Lung Axis, Rebecca A. Valls

Dartmouth College Ph.D Dissertations

In the quest to understand the complex interplay between the gut microbiota and cystic fibrosis (CF), a disease characterized by chronic upper respiratory complications and an exacerbated proinflammatory response, our lab engaged in a collaborative study with Dartmouth-Hitchcock Medical Center (DHMC) to characterize the gut microbiota of pediatric CF patients. Initial analyses established a connection between gut microbial composition and respiratory health, particularly highlighting a scarcity of Bacteroides species compared to healthy controls. In following investigations, we utilized random forest models to understand how stool microbiota may influence clinical outcomes of these pediatric CF patients, including: age, upper respiratory infections, …

The Interplay Of Gut Microbiota And Their Metabolites As Potential Regulators Of Resilience Or Susceptibility To Traumatic Stress In Male And Female Rats, Arax Tanelian

NYMC Student Theses and Dissertations

Exposure to traumatic stress is a major risk factor for the development of mood disorders in a subpopulation of individuals, while others remain resilient. Notably, women are twice as likely as men to develop affective disorders in the aftermath of trauma. The mechanisms and contributing factors that influence sex-related disparities in mood disorders and variations in resilience remain unclear. We hypothesized that sex-specific inter-individual differences in microbial composition, functionality, and metabolites would contribute to host resilience or susceptibility to stress-induced psychopathologies. In this study, we used single prolonged stress (SPS), an animal model of Post- Traumatic Stress Disorder (PTSD), to …

Understanding The Non-Canonical Regulation Of Srebp In Aspergillus Fumigatus, Muhammad Abubakar Khan

Dartmouth College Ph.D Dissertations

Aspergillus fumigatus is an opportunistic fungal pathogen causing invasive pulmonary aspergillosis (IPA), with high mortality rates in immunocompromised individuals. Adaptation to the hypoxic microenvironment of IPA is crucial for fungal virulence. The transcription factor SrbA, a Sterol Regulatory Element-Binding Protein (SREBP) homolog, plays a key role in this hypoxic response and regulates genes involved in hypoxic growth, sterol biosynthesis, and azole resistance, making it an attractive therapeutic target.

However, SrbA activation in A. fumigatus lacks critical components of the canonical SREBP pathway, such as SCAP, Site-1 protease (S1P), and Site-2 protease (S2P). Instead, the rhomboid protease RbdB, signal peptide peptidase …

Survival Of Methanogens Desiccated On Mars Soil Simulants: Implications For Life On Mars, Lanee Knight

Biological Sciences Undergraduate Honors Theses

Because of Mars’s chemical features, it can be studied in the search for life and is a significant figure in the study of astrobiology (McKay, 2010). Dr. Kral’s laboratory studies methanogens, microorganisms in the domain Archaea, as possible life forms on Mars. Since some methanogens can withstand harsh environmental conditions and emit methane as a waste product, the growth of these microorganisms can be used as an indicator of potential life in the Mars subsurface (Kral et al., 1998). In this research, four methanogens, Methanothermobacter wolfeii, Methanobacterium formicicum, Methanosarcina barkeri, and Methanococcus maripaludi were desiccated in the …

Growth Of Methanogens On Kaolinite, A Clay That Has Been Identified On Mars, Hailey Littrell

Biological Sciences Undergraduate Honors Theses

Methanogens have been studied as a model for life on Mars for 28 years now in the Kral lab. The discovery of methane in the Martian atmosphere by ground-based and orbital observations as well as Curiosity Rover (Formisano, V. et al., Krasnopolsky, V.A. et al., Mumma, M.J. et al.) has added relevance to these types of studies. Methanogens were chosen due to their ability to live in harsh environments, very similar to the Martian terrain. In addition to methane in the atmosphere, phyllosilicate clays have also been identified. One of those clays is kaolinite. Kaolinite has been found to not …

A Meta-Analysis For Laboratory Diagnostics For Coccidioidomycosis, Mary C. Cowen

Biological Sciences Undergraduate Honors Theses

Coccidioidomycosis, commonly referred to as Valley Fever, is a fungal infection found in arid regions of the southwestern United States and Mexico. Infection occurs through inhalation of airborne spores from Coccidioides species, Coccidioides immitis and/or Coccidioides posadasii, and proceeds in both pulmonary and disseminated fashions. Approximately 60% of patients with coccidioidomycosis remain asymptomatic, while 40% will experience symptoms. Within the literature, there are no papers that summarize sensitivity and specificity values between different tests; therefore, this paper presents sensitivity and specificity results across different tests and companies (Meridian, IMMY, and MiraVista).

An Exploration Of The Effectiveness Of Xanthorrhiza Simplicissima And Its Secondary Alkaloids As Antibiotics Against Staphylococcus Aureus With The Use Of Reserpine, Donald Bothe, Savita Chaurasia

Undergraduate Theses

Xanthorhiza simplicissima is a plant that is steeped in medical history. It has been used for hundreds of years by the Native Americans, and later by the Europeans, of Appalachia for its medicinal properties. One of the most useful medical applications of this plant are its antibiotic properties, as typified by its use as a tea that was consumed to treat mouth sores. These antibiotic properties can be attributed to some of its secondary alkaloids such as berberine, liriodenine, oxyacanthine, and magnoflorine. These compounds have been studied in other systems; however, oxyacanthine and magnoflorine have not been researched in tandem …

Staphylococcus Aureus Oleate Hydratase Produces Ligands That Activate Host Ppara, Christopher D. Radka, Matthew W. Frank, Tyler S. Simmons, Cydney N. Johnson, Jason W. Rosch, Charles O. Rock

Markey Cancer Center Faculty Publications

Commensal gut bacteria use oleate hydratase to release a spectrum of hydroxylated fatty acids using host-derived unsaturated fatty acids. These compounds are thought to attenuate the immune response, but the underlying signaling mechanism(s) remain to be established. The pathogen Staphylococcus aureus also expresses an oleate hydratase and 10- hydroxyoctadecanoic acid (h18:0) is the most abundant oleate hydratase metabolite found at Staphylococcal skin infection sites. Here, we show h18:0 stimulates the transcription of a set of lipid metabolism genes associated with the activation of peroxisome proliferator activated receptor (PPAR) in the RAW 264.7 macrophage cell line and mouse primary bone marrow-derived …

Do Duckweeds Adapt To Water And Microbes?, Ava M. Rose

Honors Theses and Capstones

Organisms in their home environment sometimes outperform transplanted individuals native to other areas, in a phenomenon termed local adaptation. While local adaptation is traditionally considered to be driven by the abiotic factors of an environment, scientists have recently increased consideration of biotic factors. Specifically, of interest to many is host-associated microbiomes, which can alter host trait expression. As the desire to commercialize microbiome treatments for agriculture and medicine grows, it is important to analyze the potential value of local microbiomes, which may be adapted to their hosts, or to which local hosts may have adapted. Using Lemna minor (duckweed) as …

Social Interactions And Spatial Structure Drive Community Assembly Of Bacterial Biofilm, Matthew C. Bond

Dartmouth College Ph.D Dissertations

Despite the critical nature which microbial communities play in the natural world and human civilization, the breadth of understanding remains shallow. Challenged by scale, high variability between environments, and extensive diversity, microbial ecologists strive to understand connections between a community’s structure and function, as well as the ecological and evolutionary mechanisms underlying observed natural patterning of communities. Biofilms are the predominate mode of growth for microbial communities—characterized by cellular attachment to a surface via a self-produced matrix and heterogeneous structure, often resulting in a primary growth front along the biofilm surface due to differential access to bulk nutrients (cite). This …

Determination Of Spore Viability In Concrete Across Several Factors Using Most Probable Number, Samuel Boyer

Williams Honors College, Honors Research Projects

To determine the lowest concentration of spore added to polyurethane-cement composite (PUCCO) particles that can still germinate after curing in concrete. This research project is a small addition to the larger research project being undertaken by Mirza Mohammed Rashiduzzaman for his Masters. The larger project involves the use of fungal spores added in concrete to act as a self-healing component when cracks form in the concrete structure over time. These spores are suspended in a protective oil and loaded into small, hardened sponge-like PUCCO cubes to act as growth points when water and air can reach the PUCCO in the …

The Development And Evaluation Of A Method For Complete Collagenase I Digestion Of Bos Taurus Bone Samples, Reilly Price

Master of Science in Forensic Science Directed Research Projects

Current methods for processing aged forensic bone samples for DNA analysis involve pulverization and organic extraction, which further destroys already degraded DNA and uses large amounts of limited samples. Additionally, the success rates for this type of analysis vary widely as homogenization incorporates PCR inhibitors into the sample. Little research has explored how pulverization results in DNA damage in profiles obtained from skeletal remains. This study proposes an enzymatic digestion method to separate osteocytes from PCR inhibitors in the extracellular bone matrix to improve the quality and quantity of DNA isolated from aged bone samples. The technique described here used …

Effects Of Subchronic Oral Pfos Exposure Via Drinking Water On Gut Microbiota Composition, Emma Ann Loder

Graduate Theses/Dissertations

Perfluorooctanesulfonic acid (PFOS) has been phased out of production in the United States, but because of its resistance to degradation and its persistence in the environment, PFOS can be found in drinking water across America. Oral exposure to PFOS has been linked to adverse developmental, immunological, hepatic, and endocrine health. Oral PFOS exposure may alter the gut microbiota and cause dysbiosis, which is implicated in the pathology of inflammatory diseases like Crohn’s disease, diabetes, and ulcerative colitis. The goal of the study was to investigate the effects of subchronic oral PFOS exposure on the composition of the gut microbiota. Adult …

The Sewage Microbiome Dynamics Of Different Serving Neighborhoods In Charleston, Illinois, Sandra Chiamaka Okoye

Masters Theses

The complex microbial ecosystem within sewage systems holds significant implications for environmental and public health. Unlike studies on wastewater treatment plant microbiomes, upstream sewage systems have not been studied widely. This research investigated the dynamic sewage microbiome across diverse serving neighborhoods in Charleston, Illinois, encompassing residential, hospital, industrial, and university areas. Drawing upon recent advancements in microbiome research, the study aimed to unravel the spatial and temporal variations in microbial structures. Three times between June to December 2023 sewage samples were collected from manholes in the areas mentioned above. Community DNA was extracted and sequenced for the V4-V5 region of …

Erwinia Amylovora Phage Therapy: Biocontrol Formulation, Receptor Identification, Resistance Mechanisms, Nassereldin Ibrahim

Theses and Dissertations (Comprehensive)

Fire blight is known as a disease of Rosaceae and it displays infection symptoms in about 200 species in 40 rosaceous genera. The most economically important crops that are affected by fire blight are apples and pears. Fire blight can cause severe outbreaks and a single fire blight outbreak can disrupt orchard production for years. The bacterium that causes this disease is indigenous in North America, and according to Statistics Canada, economic losses in apples and pears were valued at an estimated $4 million in 2005, which is approximately 5% of the total production. In addition, production costs can increase …