Microbiology Commons^™

Evaluating Soil Health Changes Following Cover Crop And No-Till Integration Into A Soybean (Glycine Max) Cropping System In The Mississippi Alluvial Valley, Alexandra Gwin Firth

Theses and Dissertations

The transition of natural landscapes to intensive agricultural uses has resulted in severe loss of soil organic carbon (SOC), increased CO₂ emissions, river depletion, and groundwater overdraft. Despite negative documented effects of agricultural land use (i.e., soil erosion, nutrient runoff) on critical natural resources (i.e., water, soil), food production must increase to meet the demands of a rising human population. Given the environmental and agricultural productivity concerns of intensely managed soils, it is critical to implement conservation practices that mitigate the negative effects of crop production and enhance environmental integrity. In the Mississippi Alluvial Valley (MAV) region of Mississippi, USA, …

Optimized Selenium Status, Gut Microbiota, And Type 2 Diabetes, Ying-Chen Huang

Theses and Dissertations

We have previously demonstrated that long-term dietary Se deficiency in old Terc^-/- mice with humanized telomeres induces type-2 diabetes and exacerbates age-dependent increases in the abundance of A. muciniphila and Lachnospiraceae, which are related to obesity and metabolic syndromes. The objectives of this dissertation are: 1) to determine the minimum intake of Se required for type 2 diabetes prevention in middle-aged mice; 2) to evaluate the efficacy of A. muciniphila and R. torques (a Lachnospiraceae family member) to intervene dietary Se deficiency-induced type 2 diabetes and the underlying mechanisms; 3) to assess sex differences in the responses to …

Identification Of Pneumococcal Membrane Proteins Involved In Colonization/Biofilm Formation And Cognate Host Cellular Receptors, Yoonsung Hu

Theses and Dissertations

Colonization is prerequisite for infection and transmission of Streptococcus pneumoniae, or pneumococcus. Currently available pneumococcal conjugate and pneumococcal polysaccharide vaccines can provide protection against a limited number of capsular serotypes. Implementation of vaccines has decreased the frequency of invasive pneumococcal disease and their colonization rates, but only in a serotype-dependent manner. This has led to serotype replacement in pneumococcal ecology and increased invasive disease caused by non-vaccine serotypes. Development of conserved protein-based vaccine that can provide protection against all pneumococcal serotypes is needed. Numerous surface proteins are conserved in all serotypes, and some are known to be involved in …

The Impact Of Iaa And Tryptophan On Microcystis Bloom Community Dynamics, Hunter R. Baylous

Masters Theses, 2020-current

Microcystis aeruginosa is a freshwater cyanobacterial species that degrades freshwater and brackish ecosystems due to its capacity to form toxic cyanobacterial harmful algal blooms (cyanoHABs). There both abiotic and the biotic factors that exacerbate the presence of cyanoHABs. Current research is looking at the microbial interactions that occur between microbes and phytoplankton. Microbes interact with cyanobacteria in the phycosphere, where nutrients are exchanged between the two. Understanding the chemical currencies exchanged can help to show interactions that are beneficial for cyanoHAB formation A key player in the growth promotion of cyanoHABs is hypothesized to be auxins, which are synthesized by …

Characterization Of A Helicobacter Pylori Small Rna By Rt-Pcr, Roxanne Mcpeck, Andrea Castillo

2022 Symposium

Helicobacter pylori, a bacterial gastric pathogen infecting approximately 50% of the human population, produces gastritis, ulcers, and gastric cancers. Colonizing the inhospitable and fluctuating environment in the stomach requires tight genetic control. However, H. pylori lacks many genetic regulatory elements present in other bacteria to control gene expression. Instead, over 200 small RNAs (sRNAs; noncoding RNAs shorter than 300 nucleotides) have been found in this bacterium, but few have been fully characterized. Of those, many are antisense to virulence genes. Characterizing these sRNAs is important in understanding the mechanisms of molecular genetics and potentially supporting medical management of this …

Eskape Pathogens: The Clinical Prevalence And Molecular Mechanisms Of Antibiotic Resistance, Anusha Attre

Honors Scholar Theses

The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are the leading cause of all nosocomial, or healthcare-associated (HAI), infections (Navidinia, 2016). The purpose of this research study is to determine the burden of ESKAPE infections on healthcare and study the antibiotic resistance in these high-risk pathogens to provide direction for researchers to develop new antimicrobial innovations to reduce ESKAPE infectivity and improve patient outcomes. To study the burden of ESKAPE infections, this review analyzes the current statistics explaining the clinical prevalence of each pathogen in causing HAIs. Additionally, each pathogen is …

The Development Of A Global Shoreland Information Database May Help Determine The Appropriate Bacteria And Nutrient Technology Needed To Remediate Oil Contaminated Shorelands, Tiffany Ann Veeder

Honors Projects

The use of oil and its derivative products is well known world-wide. The benefits of oil are many and its products, for example, range from gasoline used in our automobiles to its use in plastics, building products, and medical supplies. Oil spill hazards associated with oil extraction, production, and transportation can have devastating impacts on the environment and local economies. When oil spills happen in the water, for instance, major shorelands are placed at risk of significant harm. As oil contaminates shorelands, the impacts can range from killing sea creatures and seabirds to destroying entire ecosystems. To help mitigate the …

Antibiotic-Resistant Bacteria In Freshwater Crayfish, Colby Finch

Honors Theses

The presence of antibiotic-resistant bacteria is increasing in natural aquatic environments. Alongside this, organisms that live in these ecosystems are increasingly harboring antibiotic-resistant bacteria. In this study, I analyzed the capacity for the crayfish species Procambarus vioscai paynei to harbor antibiotic-resistant bacteria. Crayfish, as well as water and sediment, were sampled from a pond at the University of Mississippi Field Station. The guts of crayfish were plated on TSA agar, as well as agar containing vancomycin, erythromycin, penicillin, tetracycline, or ciprofloxacin. Following incubation, counts of bacteria were determined. Selected bacterial isolates were tested for multiple antibiotic-resistance. Bacterial isolates were also …

A Comparison Of Heterotroph Isolation And Sequencing Methods From Various Cyanobacterial And Algal Microbiomes, Victoria Starks

Honors Theses

Cyanobacteria have provided a vast, new source of natural products to be utilized in drug development. Because of their non-axenic nature, cyanobacteria typically have an abundance of symbiotic heterotrophs living in association with them. These bacteria can play significant roles in the survival of its cyanobacterial host as well as provide the potential production of unique compounds. The possibility of unknown natural products is only increased by the flexible nature of these bacteria, as altering its environmental state can change the activity of biosynthetic pathways and even activate novel production. Our research team’s intent is to isolate cyanobacterial strains from …

Metagenome-Wide Associations And Metabolic Modeling To Predict The Biomarkers For Colorectal Cancer, Nagavardhini Avuthu

Theses & Dissertations

Colorectal cancer (CRC) is the most common malignancy and the second most common cause of cancer-related deaths in the world. It is a multifactorial disease mediated by genetic, environmental, and lifestyle factors. Over time, the accumulation of genetic and epigenetic changes results in the activation of oncogenes and deactivation of tumor suppressor genes in the colon and rectal region which finally leads to tumor development. The gut microbiome is the main factor linking the effects of diet and environmental factors to host metabolism. Several studies showed the dysbiosis of gut microbiota in CRC patients with an increased proportion of pathogenic …

Gut Commensals Modulate Siv/Shiv Pathogenesis And Therapeutics, Samuel Johnson

Theses & Dissertations

Despite significant advancements in combination antiretroviral therapy (cART), ongoing inflammation in the brain and gut remain two of the most significant hurdles in the health of people living with human immunodeficiency virus (HIV). Additionally, a viral reservoir in each compartment inhibits cure efforts by allowing rapid viral rebound following cART interruption. Emerging understanding of the gut-brain axis (GBA) implicates each compartment in the modulation of the other in a complex bi-directional interaction mediated by vagus innervation, circulating lymphocytes, and microbiome composition and biproducts. Using multiple models of the simian (and simian-human) immunodeficiency virus (SIV/SHIV) and therapeutic intervention, I present how …

Detecting Potentially Neurotoxic Pseudo-Nitzschia Species In The Grand Strand Area, Chesney Price

Honors Theses

Pseudo-nitzschia is a globally distributed diatom genus which contains 26 neurotoxin (domoic-acid) producing species. In shallow coastal waters these diatoms are associated with both the development of harmful algal blooms and the bio-accumulation of toxins in shellfish that can impact human health. Pilot data recovered in 2018 indicated the presence of multiple species of Pseudo-nitzschia, including domoic-acid producing taxa. We hypothesize that we will recover a similar species diversity using multiple sampling dates during the summer of 2021. Environmental DNA (eDNA) samples taken from the public shellfish harvesting area waters at Huntington Beach State Park (SC) over a two month …

The Impact Of Processing Body Proteins On An Adenovirus Infection, La`Quita Randolph

Biology Theses

Adenovirus is a nonenveloped, double-stranded DNA virus that contains a 36 Kbp genome. The E4 ORF3 region of its genome consists of an E4 11k protein that can reorganize host cell components by relocalizing cellular proteins. One such cellular component is the cytoplasmic processing body, which consists of proteins involved in translational repression of mRNA and mRNA degradation. During an adenovirus infection, processing body proteins Ddx6 and Pat1b have been shown to colocalize and form aggresomes. Aggresomes induced by E4 11k are specific to the adenovirus serotype 5 (Ad 5). In this study, cytoplasmic Pat1b foci were observed and quantified …

Cdk8 Kinase Module Modifies Expression Of Specific Translation-Related Proteins Before And After Stress, Brittany Friedson, Katrina Cooper

Rowan-Virtua Research Day

Translation is tightly coupled to growth status. Efficient protein synthesis is necessary for cell growth in nutrient rich environments, while global translation inhibition combined with selective translation of stress-responsive mRNAs helps limit growth in times of stress. Environmental stress cues which inhibit the nutrient-sensing complex TORC1 are known to reduce general translation, but how does the cell alter protein synthesis machinery to adapt to these conditions? A few mechanisms to promote cell survival in nitrogen starvation include post-translational modification and selective degradation of specific mRNA-binding translation factors, as well as inhibition of activators of genes whose products are required for …

Comparative Transcriptomic Study Between Cyanobacteria That Contain Chlorophyll D And Those That Lack Chlorophyll D, Fernanda Montoya

Honors Capstones

All cyanobacteria, which perform oxygenic photosynthesis on Earth, contain the photosynthetic pigment chlorophyll a (Chl a) that absorbs light in the violet and red region of the visible spectrum. Cyanobacteria of the Acaryochloris species, however, contain the rare photosynthetic pigment chlorophyll d (Chl d) that absorbs light in the far-red region. Chl d’s ability to absorb light in this region allows it to avoid competing with other photosynthetic organisms for light. Creating a photosystem that uses Chl d in plants would be of great use for agricultural land optimization, but requires knowledge of the biosynthetic pathways of …

Effect Of Mycorrhizae Inoculation On The Growth And Success Of Three Taxodium Distichum Hybrids In Saline - Impacted Coastal Soils, Elif Ilhan

Electronic Theses and Dissertations

In 2008, Galveston Island was severely impacted by Hurricane Ike, resulting in high salt deposition in the soil and groundwater. This caused a loss of many native plant species. A study was initiated to determine effective ways to promote the growth conditions of three bald cypress genotypes (Taxodium distichum var distichum and Taxodium distichum var mexicanum crosses) in salt-affected soils. The treatments applied were mycorrhizae inoculation, fertilizer application, and a combination of mycorrhizae inoculation and fertilizer application. A total of sixty (60) trees planted in plots of three rows and divided into five randomized replication blocks of four treatments …

An Analysis Of The Effects Of Temperature And Other Environmental Factors On Microorganismal Productivity Within Aquatic Ecosystems Using Long-Term Data From Various Lter And Ilter Sites, Andrew Dorbu

Theses and Dissertations

Global climate change is a phenomenon resulting in more extreme weather patterns and species diversity loss. In this study, I explore the impacts of climate change on regional patterns of microbial productivity. Variation in microbial productivity was explained using temperature, salinity, and dissolved oxygen as predictors in regression models with data from the LTER and iLTER network of sites that ranged from the poles to the equator. I found a positive relationship between temperature and productivity. Antarctica and Arctic sites exhibited the strongest positive relationships supporting prior research demonstrating temperature as one of the driving forces of productivity change in …

Systems Biology Approach To Functionally Assess The Clostridioides Difficile Pangenome Reveals Genetic Diversity With Discriminatory Power, Charles J Norsigian, Heather A Danhof, Colleen K Brand, Firas S Midani, Jared T Broddrick, Tor C Savidge, Robert A Britton, Bernhard O Palsson, Jennifer K Spinler, Jonathan M Monk

Faculty, Staff and Students Publications

Combatting Clostridioides difficile infections, a dominant cause of hospital-associated infections with incidence and resulting deaths increasing worldwide, is complicated by the frequent emergence of new virulent strains. Here, we employ whole-genome sequencing, high-throughput phenotypic screenings, and genome-scale models of metabolism to evaluate the genetic diversity of 451 strains of C. difficile. Constructing the C. difficile pangenome based on this set revealed 9,924 distinct gene clusters, of which 2,899 (29%) are defined as core, 2,968 (30%) are defined as unique, and the remaining 4,057 (41%) are defined as accessory. We develop a strain typing method, sequence typing by accessory genome (STAG), …

Identification Of Genetic Elements Involved In Alcaligenes Faecalis’ Inhibitory Mechanism Against Polymicrobial Species, Abigail Mathis

Undergraduate Honors Theses

The rise of antibiotic resistance in common human pathogens and the lack of development of novel therapeutic treatments has created a threat to global health. A unique source for potential novel treatments are from microorganisms, particularly within the complex, antagonistic polymicrobial interactions that take place in microbial communities. These unique mechanisms utilized by microorganisms to fight each other could potentially identify novel therapeutic targets for use at a clinical level, however, there is a lack of research in this area to determine its applicability. Alcaligenes faecalis is a Gram-negative bacterium that seldom causes human disease and has been observed in …

Elevated Levels Of External Cysteine Inhibit Nitrogen Fixation By The Methanogenic Archaeon Methanosarcina Acetivorans, Regan Massey

Biological Sciences Undergraduate Honors Theses

Methanogens are nitrogen fixing and methane producing archaea that play a key role in the cycling of carbon and nitrogen on earth. The global carbon and nitrogen cycle is vital to all life which makes the methanogen a primary organism of study. Methanogens are the only archaea capable of fixing nitrogen, and in order to do so, methanogens use a vital enzyme called the nitrogenase which fixes dinitrogen (N2) to ammonia (NH3). Expanding our understanding on metabolic processes of methanogens allows us to understand their environmental impact and advance their use in biotechnological applications. Methanosarcina acetivorans is the model used …

Identification Of Critical Points For Bacterial Contamination In The Microbrewery Environment, Alex Ryan Thompson

All Theses

There are 8,884 craft breweries producing over 23 million barrels of beer in the United States as of 2020. These 23 million barrels of craft beer account for 12.3% of the United States beer consumption in 2020. The American craft beer industry is substantial and needs to protect its product from bacterial contamination.

Overall, beer is a microbially stable product. Beers pH, ethanol levels, CO₂ concentrations, the presence of hop-derived antimicrobial compounds, and low levels of O₂ make beer a highly unfavorable environment for most bacterial species. Furthermore, the brewing process, which involves heat treatments and chemical sanitizers …

Studying The Lysine Acetylation Of Aconitase Isozymes In E. Coli, Sara Ottinger

Chemistry & Biochemistry Undergraduate Honors Theses

The contents of this thesis have been modified from the publication “Araujo J, Ottinger S, Venkat S, Gan Q and Fan C (2022) Studying Acetylation of Aconitase Isozymes by Genetic Code Expansion. Front. Chem. 10:862483”. Though studies have found multiple lysine sites in which acetylation takes place in Escherichia Coli aconitase, acetylation’s effects on the enzyme’s activity have yet to be studied. Aconitase is the dehydratase-hydratase found in the citric acid and glyoxylate cycles responsible for the reversible isomerization of citrate to isocitrate via cis-aconitate intermediate. There are two isoforms of aconitase in E. coli: AcnA and AcnB. In …

Dynamics Of The Supragingival Dental Plaque Microbiome And Its Implications In Early Childhood Caries (Ecc), Lauren O'Connell

All Dissertations

Early childhood caries (ECC) is one of the most common chronic diseases worldwide and remains a serious public health crisis in developing countries and socioeconomically disadvantaged communities. Caries is a complex polymicrobial, sugar-driven disease caused by interactions between the biofilm and tooth surface. While there is a general understanding of the microbial processes driving dental caries development and progression, the microbiota associated with the initiation and progression of dental caries have yet to be fully characterized. The most-studied species associated with tooth health and disease are the oral streptococci. Nevertheless, there are still large gaps in our knowledge of the …

Mycobacteriosis Of Striped Bass (Morone Saxatilis) In Virginia Tributaries Of The Chesapeake Bay, Joshua S. Mcgilly

Biological Sciences Theses & Dissertations

Mycobacteriosis was first documented in Chesapeake Bay striped bass (Morone saxatilis) in 1997 after fish exhibited emaciation and skin lesions. Since it was first identified, studies of mycobacteriosis in the mainstem of the Chesapeake Bay (2003-2007) and the Rappahannock River (2005-2012) have shown high disease prevalence and disease-associated mortality. Until this study, no current prevalence data existed from the Rappahannock River, and no published prevalence data existed for the James River, leaving a gap in our understanding of this disease in major Chesapeake Bay tributaries. We began gathering mycobacteriosis prevalence data from an existing survey collecting striped bass …

Describing The Effect Of Thin Layer Sediment Placement On Coastal Microbial Communities Using Foraminifera Diversity, Elizabeth B. Billings

Senior Honors Projects

Salt marshes are rich ecosystems that play an important role in aquatic food systems and prevent erosion while also providing essential habitats for wildlife. Climate change has resulted in rising sea levels and erosion of these coastal wetlands. Thin Layer Sediment Placement (TLP) is a restoration effort being implemented to mitigate the effects of climate change on coastal ecosystems. The TLP process raises elevation of the marsh and provides substrates for vegetative growth by spraying dredged sediment over existing marsh. The impacts of TLP on microbial populations is not widely understood, therefore metrics are required to study the effects of …

Characterization Of The Role Of The Replicase And Quasispecies Diversity In Flaviviral Evolution And Host Adaptation, Haley Caldwell

Legacy Theses & Dissertations (2009 - 2024)

Flaviviruses include several emerging and re-emerging arboviruses that cause millions of infections each year. Although relatively well-studied, much remains unknown regarding the mechanisms and means by which these viruses adapt to different hosts and rapidly alternate between hosts. Different aspects of flaviviral biology impact host switching, viral fitness, and the generation of viral diversity during genome replication by the NS3 and NS5 proteins. Together these factors may impact host plasticity.

Temporal And Spatial Comparison Of Pseudo-Nitzschia Species Composition And Domoic Acid In Narragansett Bay, Rhode Island And The Northeast U.S. Shelf, Isabella Church, Bethany D. Jenkins

Senior Honors Projects

Diatoms are unicellular algae that make up a significant portion of phytoplankton biomass at the base of marine food webs. Narragansett Bay (NB), RI is home to several species of the diatom genus Pseudo-nitzschia (P-n), some of which are known to cause harmful algal blooms through the production of the potent neurotoxin domoic acid (DA). This toxin can lead to Amnesic Shellfish Poisoning in humans through the consumption of affected shellfish. Although the presence of P-n has been well established in NB for over 50 years, DA levels have only recently become a problem, with shellfish harvest closures …

Native And Non-Native Ant Impacts On Soil Microbes, Hannah A. Stewart

Biology Theses

Organisms produce chemical weapons for defense, but target organisms can develop resistance. In their introduced range, non-native species may bring “novel weapons” against which native organisms have not co-evolved resistance. The invasive European fire ant (Myrmica rubra) may have brought antimicrobial secretions to the Northeastern United States that are novel weapons against native fungal and bacterial soil organisms. I hypothesized that M. rubra would better inhibit seed pathogens resulting in greater emergence of native myrmecochorous Viola sororia seeds and, as a side effect, more strongly inhibit arbuscular mycorrhizal fungi than a native seed dispersing ant (Aphaenogaster picea …

Nitrogen Availability In Dune Systems And Its Effect On Root Fungal Endophyte Communities., Haley E. Sage

College of Arts & Sciences Senior Theses

As global change persists, changes in resource availability can influence plant-microbe interactions. To understand how resource availability can influence these interactions and species diversity, I focused this research on how varying nitrogen (N) levels affect root endophyte communities in the plant species Ammophila breviligulata, an ecosystem engineer in the dune system. I analyzed the relationship between nitrogen addition and microbial community composition across 60 plots treated with three nitrogen addition levels (control, low, and high) in a long-term experimental field site in the Lake Michigan dunes. I identified Ammophila breviligulata's root endophyte community after creating a culture collection and …

Functional Characterization Of A Putative Alternative Oxidase In Sporisorium Reilianum F. Sp. Zeae., Emma A Lamb

College of Arts & Sciences Senior Theses

Sporisorium reilianum is a pathogenic basidiomycete fungus with two formae speciales, each capable of infecting corn (SRZ) or sorghum (SRS), respectively. This fungus is also a dimorphic variety, meaning it can switch between its haploid, yeast-like sporidia and diploid teliospore stages over the course of its life cycle (Schirawski). When S. reilianum is found in a haploid state and conditions are favorable, it will mate with a compatible non-self mating type to begin filamentous growth and proliferation in the plant host (Zhao). S. relianum, like most fungi, utilizes the four classical components of the electron transport chain to produce …