Microbiology Commons^™

Characterization Of Mroq-Dependent Regulation Of Staphylococcus Aureus Quorum Sensing, Madison Ruth Stock

Dissertations

Gram-positive bacteria produce small autoinducing peptides (AIPs), which act to regulate expression of genes that promote adaptive traits including virulence. The Gram-positive pathogen Staphylococcus aureus generates a cyclic AIP that controls expression of virulence factors via the accessory gene regulatory (Agr) system. S. aureus strains belong to one of four Agr groups (I, II, III, and IV), and each group harbors allelic variants of AgrD, the precursor of AIP. In a prior screen for S. aureus virulence factors, the Alonzo lab identified MroQ, a putative peptidase. A ΔmroQ mutant closely resembled a Δagr mutant and had significant defects in AIP …

Host-Microbe Interactions In Non-Native Estuarine Anemones: Biogeography And Temperature, Parker K. Lund

Cal Poly Humboldt theses and projects

Non-native species are increasing in prevalence around the world, resulting in negative economic and ecological impacts. However, the broad distributions of non-native species also offer a system for investigating the response of host-associated microbial communities to environmental factors across a range of ecological scales. At the broadest scale, I investigated the geography of microbial communities in the non-native estuarine anemone Diadumene lineata on the west coast of the United States of America. Across latitudes, microbial community composition was very similar and displayed a high percentage of Klebsiella spp. at all sites. However, the communities in California tended to exhibit higher …

Changes And Relationships Of Soil Aluminum, Organic Matter, And Hydrogen Ion Concentration With Rye Cover Crop, Arron Wilder

Cal Poly Humboldt theses and projects

Soil acidity is a common agricultural problem worldwide, as approximately 50% of all potentially arable soils are affected by pH limitations. At soil pH 3+) is considered to be the chemical form of aluminum in acid soil that hinders plant growth the most. Potentially, soil organic matter (SOM) can ameliorate the toxic effects of Al³⁺ on plants and microbes by binding with Al³⁺, thus preventing Al³⁺ (and other species of aluminum) from interacting in the rhizosphere. Increasing SOM also increases soil health indicators (i.e., microbial activity, soil water holding capacity, aggregate stability, porosity, etc.) while the …

Marineepi: A Gui-Based Matlab Toolbox To Simulate Marine Pathogen Transmission, Gorka Bidegain, Tal Ben-Horin, Eric N. Powell, John M. Klinck, Eileen E. Hofmann

CCPO Publications

The Graphical User Interface (GUI) MarineEpi is presented as a Matlab toolbox for easily (i) constructing disease transmission models for different marine host-pathogen systems, (ii) running simulations by specifying initial conditions and model parameters, and (iii) interpreting the resulting time series of the host and pathogen population dynamics. MarineEpi users can generate models for systems in which pathogen transmission occurs through contact with infected individuals (SI), contact with dead infected individuals (SID), contact with environmental pathogens released by infected individuals (SIP), and contact with environmental pathogens released by dead infected individuals (SIPD). MarineEpi is a freely available GUI that provides …

Connecting Antibiotic Resistance To The Environment (Care): Introducing A Novel Framework Integrating Chemical Cross-Resistance And Place-Based Engagement To The Blue Marsh Watershed In Reading, Pennsylvania, Jill Felker

Antioch University Dissertations & Theses

Antibiotic resistance is a serious health threat around the world. Millions of individuals are infected with antibiotic-resistant bacteria yearly, and thousands die from previously curable illnesses. Although antibiotic resistance occurs naturally, misuse of antibiotics accelerates the loss of their effectiveness. Public health campaigns focusing on antibiotic awareness have not effectively communicated and educated the public on this health crisis. New efforts to combat antibiotic resistance are urgently needed. This dissertation focuses on the ecological and public health components of antibiotic resistance research that must be addressed to decelerate antibiotic resistance. A new interdisciplinary theoretical framework was developed to Connect Antibiotic …

Nitrite Cycling In The Primary Nitrite Maxima Of The Eastern Tropical North Pacific, Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, Karen L. Casciotti

OES Faculty Publications

The primary nitrite maximum (PNM) is a ubiquitous feature of the upper ocean, where nitrite accumulates in a sharp peak at the base of the euphotic zone. This feature is situated where many chemical and hydrographic properties have strong gradients and the activities of several microbial processes overlap. Near the PNM, four major microbial processes are active in nitrite cycling: ammonia oxidation, nitrite oxidation, nitrate reduction and nitrite uptake. The first two processes are mediated by the nitrifying archaeal/bacterial community, while the second two processes are primarily conducted by phytoplankton. The overlapping spatial habitats and substrate requirements for these microbes …

Identification Of Novel Biosynthetic Gene Clusters Encoding For Polyketide/Nrps-Producing Chemotherapeutic Compounds From Marine-Derived Streptomyces Hygroscopicus From A Marine Sanctuary, Hannah Ruth Flaherty

Honors Theses and Capstones

Nearly one out of six deaths in 2020, around ten million people, were caused by cancer, making it a leading cause of death worldwide (WHO, 2022). This major public health issue, in addition to the rise of multidrug-resistant (MDR) pathogens, provides a high demand for the discovery of new pharmaceutical drugs to be used clinically to treat these conditions. The Streptomyces genus accounts to produce 39% of all microbial metabolites currently approved for human health, indicating its potential as an important species to study for antimicrobial and anticancer agents. The long linear genome of Streptomyces contains specialized sequences known as …

Odd Bedfellows & Marriage Of Necessity: Public Health And Politics In American Federalism, Gabriella Victoria Chianese

Honors Theses and Capstones

In the wake of the coronavirus disease 2019 (COVID-19) pandemic, while the public disagrees over mask mandates, required vaccinations, and social distancing, it seems like one common sentiment exists – a distaste for the odd bedfellows of politics and public health. There are those who cry for the compartmentalization of the science of public health and the art of politics to rectify this situation. In the wake of so much confusion and chaos, it is not unjustified to demand the depoliticization of public health; however, this response is unrealistic given the modern political climate, demonstrates a narrow understanding of the …

Effects Of Altering Physiologically Relevant Cholesterol Levels And Media Types On Porin Gene Expression In Klebsiella Pneumoniae And The Resulting Impact On Antibiotic Resistance, Megan R. Camden

UNF Graduate Theses and Dissertations

Klebsiella pneumoniae is a Gram-negative, non-motile bacterium belonging to the Enterobacteriaceae family. K. pneumoniae is a rising threat in the clinical setting, as there has been a large increase in the presence of antibiotic resistant isolates. While much research is conducted on laboratory and clinical strains of bacteria, not much is known regarding the impact that human physiology can have on bacterial gene expression, and in response, to antibiotic susceptibility. The goal of this study is to determine if physiologically relevant cholesterol levels and media types impact porin gene expression and antibiotic resistance in K. pneumoniae. To accomplish this, …

Monitoring Archaeal Persistence In Cultivation, Payton Hall

Honors Program Theses

It was previously thought that microbes in the domain Archaea were only found in extreme environments such as hot thermal vents at the bottom of the ocean and hypersaline environments, but as scientists began to use environmental DNA to survey soil, they detected archaea from the phylum Thaumarchaeota in relatively benign environments including farm fields, forests, and prairies. In spite of their widespread global distribution, relatively few of these species have been grown in laboratory culture. It is now known that Thaumarchaeota play an important role in the nitrogen cycle because they can generate energy through ammonia-oxidation. To increase the …

Evaluation Of Methods To Analyze Microbial Composition In Soils, Joseph Correa

Honors Program Theses

DNA testing has become a vital tool for studying microbes in their natural environments, but there is a lack of standardization in the protocols for extracting environmental DNA. Cave systems provide a special and unique area to research how life thrives in extreme environments. Many parts of caves receive no sunlight and very little nutrients yet harbor microbial communities. Previous work in our lab developed a DNA extraction protocol that works with a wide range of microbial species and with different soil types. I updated this protocol by adding a pre-lysis rinse step and tested whether it performed better with …

Staff Education To Promote Probiotic Breastfeeding Therapy, José Diaz

Walden Dissertations and Doctoral Studies

Preterm birth is the leading cause of death in children under 5. In addition, there are 22 million babies born underweight each year which also contributes to the infant mortality rate. Some reasons for the inability to thrive and survive are the infants' immature system, allostatic load inadaptability, and undiversified and underdeveloped microbiota. Human breast milk (HBM) provides lifesaving nutrients, which prevents necrotizing enterocolitis and mortality. In addition, probiotic supplementation helps reduce late-onset sepsis, morbidities, and mortality. A literature review provided substantial evidence that HBM and probiotics can improve an infant's microbiota, thus improving thrivability and survivability. Probiotics offset the …

Staff Education To Promote Probiotic Breastfeeding Therapy, José Diaz

Walden Dissertations and Doctoral Studies

Preterm birth is the leading cause of death in children under 5. In addition, there are 22 million babies born underweight each year which also contributes to the infant mortality rate. Some reasons for the inability to thrive and survive are the infants' immature system, allostatic load inadaptability, and undiversified and underdeveloped microbiota. Human breast milk (HBM) provides lifesaving nutrients, which prevents necrotizing enterocolitis and mortality. In addition, probiotic supplementation helps reduce late-onset sepsis, morbidities, and mortality. A literature review provided substantial evidence that HBM and probiotics can improve an infant's microbiota, thus improving thrivability and survivability. Probiotics offset the …

Structural Impact Of Epstein-Barr Virus- Encoded Small Rna -1 On Its Transport And Function, Zubaida Hassan

Dissertations

Epstein-Barr Virus (EBV)-Encoded RNAs (EBERs) are two small, noncoding, structurally conserved transcripts that are expressed in millions of copies in all stages of EBV infection. Despite their abundant expression, the role of EBERs in EBV biology or pathogenesis is not well defined. However, they are associated with driving cell proliferation and improving intercellular communication via their secretion in exosomes. In spite of the pathogenic potentials of EBERs, the mechanisms involved in their transport and function remain to be elucidated. The aim of this PhD dissertation was to investigate the structural impact of EBER1 in its transport and function. The conserved …

Extension Of The Ergot Alkaloid Gene Cluster, Samantha Joy Fabian

Graduate Theses, Dissertations, and Problem Reports (ETD)

Specialized metabolites produced by fungi impact human health. A large portion of the pharmaceuticals currently on the market are derived from metabolites biosynthesized by microbes. Ergot alkaloids are a class of fungal metabolites that are important in the interactions of environmental fungi with insects and mammals and also are used in the production of pharmaceuticals. In animals, ergot alkaloids can act as partial agonists or antagonists at receptors for 5-hydroxytryptamine (serotonin), dopamine, and noradrenaline as ergot alkaloids have chemical structures similar to those neurotransmitters. Therefore, they affect insects and mammals that consume them and can be used to produce drugs …

Early-Phase Drive To The Precursor Pool: Chloroviruses Dive Into The Deep End Of Nucleotide Metabolism, David Dunigan, Irina Agarkova, Ahmed Esmael, Sophie Alvarez, James L. Van Etten

Nebraska Center for Virology: Faculty Publications

Viruses face many challenges on their road to successful replication, and they meet those challenges by reprogramming the intracellular environment. Two major issues challenging Paramecium bursaria chlorella virus 1 (PBCV-1, genus Chlorovirus, family Phycodnaviridae) at the level of DNA replication are (i) the host cell has a DNA G+C content of 66%, while the virus is 40%; and (ii) the initial quantity of DNA in the haploid host cell is approximately 50 fg, yet the virus will make approximately 350 fg of DNA within hours of infection to produce approximately 1000 virions per cell. Thus, the quality and quantity of …

The Persistence And Stabilization Of Auxiliary Genes In The Human Skin Virome, Ema H. Graham, Wesley A. Tom, Alison C. Neujahr, Michael Adamowicz, Jennifer Clarke, Joshua R. Herr, Samodha C. Fernando

Nebraska Center for Virology: Faculty Publications

Background The human skin contains a diverse microbiome that provides protective functions against environmental pathogens. Studies have demonstrated that bacteriophages modulate bacterial community composition and facilitate the transfer of host-specific genes, potentially influencing host cellular functions. However, little is known about the human skin virome and its role in human health. Especially, how viral-host relationships influence skin microbiome structure and function is poorly understood.

Results Population dynamics and genetic diversity of bacteriophage communities in viral metagenomic data collected from three anatomical skin locations from 60 subjects at five different time points revealed that cutaneous bacteriophage populations are mainly composed of …

Soil And Compost Tea: A New Restoration Technique?, Carol E. Day

Master's Theses and Doctoral Dissertations

Historically, prairie restorations have lacked the plant diversity seen in remnant prairies. Most restoration practices focus on reestablishing the plant community but overlook the soil microbial community even though microbes are critical to habitat functioning. Developing techniques that increase soil microbes in prairie restorations is critical to ensuring diverse restored habitats. We compared how microbial communities differed between remnant and restored prairie sites. We also investigated if soil and compost teas could be used to reintroduce microbes to restored prairie soil and if the teas affected native plant establishment. We found significant differences in the levels of bacterial taxa between …

Community Ecology And Disease Dynamics In Pacific Oysters: Unraveling Microbiome-Pathogen Interactions In The Wild, Victoria E. Cifelli

Cal Poly Humboldt theses and projects

In the context of multispecies microbial assemblages, disruptions can occur when there are alterations in host conditions, such as the onset of a disease. Notably, viruses have the potential to reshape a host's microbial community. However, the role of the host's habitat and environment, which could be pivotal in communities with shifting niche space and habitat filters, is often overlooked in host-microbe-pathogen interactions. Recognizing the importance of these factors, I employed a field-based approach to understand microbial community dynamics in the presence of disease. To address the influence of geographical location, I conducted an analysis involving healthy and infected oysters …

Investigating The Effectiveness Of Microplastic Removal And The Relationship Between Microplastics, Bacterial Communities, And Nitrogen Cycling In The Natural Treatment Systems At The Arcata Wastewater Treatment Facility, Fiona Connor

Cal Poly Humboldt theses and projects

This thesis addressed two challenging aspects of microplastic research, including the quantification of microplastics in organic-rich water, and the investigation of how microplastics impact microorganisms and related nutrient-cycling. Two projects were designed and executed to address specific research objectives relating to these broad topics. The first objective was to develop and implement methods to determine the effectiveness of microplastic removal across the natural treatment systems at the Arcata Wastewater Treatment Facility (AWTF). The second objective was to observe how microplastics found in domestic wastewater impact the bacterial communities and nitrogen cycling in freshwater treatment wetland sediment through a bench-scale experiment, …

Fine-Scale Genetic Structure In Rhizosphere Microbial Communities Associated With Chamaecrista Fasciculata (Fabaceae), Mahboubeh Hosseinalizadeh Nobarinezhad, Lisa E. Wallace

Biological Sciences Faculty Publications

Soil microbiota of the rhizosphere are an important extension of the plant phenotype because they impact the health and fitness of host plants. The composition of these communities is expected to differ among host plants due to influence by host genotype. Given that many plant populations exhibit fine-scale genetic structure (SGS), associated microbial communities may also exhibit SGS. In this study, we tested this hypothesis using Chamaecrista fasciculata, a legume species that has previously been determined to have significant SGS. We collected genetic data from prokaryotic and fungal rhizosphere communities in association with 70 plants in an area of …

Understanding Human Gut Bacterial Interactions And Their Role In Colonization Resistance Against Clostridioides Difficile Using Mini-Bioreactor Array And Caenorhabditis Elegans As Model Systems, Achuthan Ambat

Electronic Theses and Dissertations

No abstract provided.

Indigenous Toxin Affects Cell Viability, While An Artificial Proteolytic Queueing Causes The Upregulation Of Specific Genes, Mohammed Salahuddin

Electronic Theses and Dissertations

Studying bacterial physiology is crucial to understand the fundamental mechanisms that govern bacterial growth, survival, and adaptation. This thesis combines two chapters investigating bacterial physiology by studying important cellular processes like bacterial toxin-antitoxin systems and proteolytic pathways. The first chapter involves studying bacterial toxin-antitoxin systems to understand the regulation and function of hypothetical toxin-antitoxin (TA) systems of bacteria and the effects of these TA systems on bacterial growth and survival. The emergence of these genetic modules in bacterial research and the unrevealing of some of their important roles in cell physiology in recent years has drawn much attention in scientific …

Control Of Persistent Environmental Listeria Monocytogenes Using Phenotypic And Genomic Approaches, Bhaswati Chowdhury

Electronic Theses and Dissertations

No abstract provided.

Evaluation Of Welded And Polished Stainless-Steel Surfaces In Supporting Sporeformer Biofilms In Dairy Plants, Taghreed Almalki

Electronic Theses and Dissertations

No abstract provided.

Microbial Communities In The Guana Tolomato Matanzas National Estuarine Research Reserve: An Assessment Of The Responses Of Spartina Alterniflora Epiphytes To Nitrogen Enrichment, And A Characterization Of Benthic Cyanobacterial Diversity, Anne C. Hurley

UNF Graduate Theses and Dissertations

Elevated nitrogen and phosphorus inputs from anthropogenic sources, which can lead to significant increases in algal biomass and changes in algal community composition, poses a serious threat to estuarine ecosystems worldwide. While numerous studies have addressed the impacts of nutrient enrichment on epiphytic algae in seagrass habitats, few have investigated potential nutrient-driven changes to epiphytes on emergent salt marsh plants, such as Spartina alterniflora. Epiphytic microalgae on S. alterniflora play an important role in food availability in salt marsh ecosystems, and epiphytic nitrogen-fixing cyanobacteria also provide an important source of nitrogen for salt marsh consumers. The first study included …

Effect Of Soil Ph And Indigenous Bacterial Populations In Selecting Rhizobial Endophytes Within Soybean Root Nodules, Brianne Danielle Edwards

Graduate Theses/Dissertations

Soybean plants fulfill most of their nitrogen requirement by developing symbiotic associations with four different rhizobial genera, including Bradyrhizobium, Sinorhizobium, Mesorhizobium, and genus Rhizobium. In general, members of Bradyrhizobium and Sinorhizobium have been reported as dominant root nodule endophytes under acidic soils and alkaline soil conditions, respectively. So far, it is unknown whether the selection of rhizobial endophytes is regulated by their ability to survive under different soil pH or driven by host plants regardless of their relative abundance in soil. This study was focused on the assessment of the potential role of soil pH in …

Screening For Compounds That Affect Innate Immune Memory In Macrophages, Intan Mukti Pratiwi

Chulalongkorn University Theses and Dissertations (Chula ETD)

Innate immunity, the first line of defense against pathogens, is characterized by a rapid response, limited specificity, and lack of memory for future insults. However, recent evidence indicates that components of innate immunity, such as monocytes, macrophages, and natural killer cells, exhibit memory-like responses, known as trained immunity. Trained immunity involves metabolic reprogramming and epigenetic modifications to regulate the expression of inflammation-related genes. Dysregulation of trained immunity can lead to diseases, making it a novel therapeutic target. In this study, the effects of synthetic saccharides derived from the cell wall of Mycobacterium tuberculosis and synthetic cannabinoids on innate immune memory …

Development Of Duplex Loop-Mediated Isothermal Amplification (Dlamp) For Detection Of Carbapenem Antibiotic-Resistant Genes Kpc And Ndm, Nindi Syahputri Lubis

Chulalongkorn University Theses and Dissertations (Chula ETD)

Carbapenems are regarded as a last-resort option for treating a wide range of Gram-positive and Gram-negative bacterial infections. Unfortunately, the prevalence of carbapenem-resistant genes has been on the rise among patients. Some factors contribute to this trend, including prolonged hospital stays, prior antibiotic usage, inappropriate or insufficient antibiotic treatment, and contamination through wounds or feces. The emergence of carbapenem-resistant (CR) genes gained significant attention, particularly after 2005. These CR genes are frequently carried on mobile genetic elements such as plasmids or transposons, enabling their transmission to other bacteria. Klebsiella pneumoniae carbapenemase (KPC) and New delhi metallo-β-lactamase (NDM) stand out as …

Distribution Patterns Of Allorhizobium Vitis In Missouri Vineyards And Non-Vineyard Soils, Jacquelyn M. Wray

Graduate Theses/Dissertations

Crown gall disease causes significant economic loss to the grape and wine industry. Preventive strategies are most effective for mitigating the loss of grapevines in vineyards, as there is no known cure for this disease. The bacterium Allorhizobium vitis carrying a tumor-inducing (Ti) plasmid is the causative agent. A. vitis bacteria live systemically in the grapevine before causing visible symptoms and can survive in residual plant tissues and soil for more than two years. Diagnostic methods have been developed to detect A. vitis bacteria in grapevines and soil. However, more reliable, specific, and high-throughput diagnostics are still needed for screening …