Microbiology Commons^™

Evaluating Pfas And Marine Microbial Interactions In Estuarine Sediments With Varying Urbanization And Assessments Of Microbial Responses To Pfos, Zachary J. Padgett

All Theses

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of synthetic chemicals that have become globally distributed due to their extensive use in industrial and consumer products and their extraordinary resistance to environmental degradation. Their persistence and documented toxicity have made them a growing concern in coastal environments, particularly in estuaries where urban runoff, wastewater, and industrial discharges concentrate these compounds. Estuaries are unique in that tidal mixing and interactions with fine-grained sediments and organic matter promote PFAS retention, while the microbial communities living directly within estuarine sediments are positioned where PFAS preferentially accumulate, creating conditions for prolonged exposure and …

Understanding The Potential Sources Of Bacteria And Turbidity Pollution In The Edisto Island Watershed, Brynne Sumner

All Theses

Anthropogenic pollution introduces contaminants, such as pathogenic bacteria and turbidity, into coastal watersheds. These contaminants are the major contributors to water quality impairments in the three sub-watersheds encompassing Edisto Island and the Town of Edisto Beach (hereafter referred to as the Edisto Island Watershed), located within the ACE Basin, South Carolina, USA. With 18 locations impaired for fecal bacteria and 19 for turbidity on the 2024 South Carolina 303(d) list of impaired waters, the Edisto Island Watershed offers valuable insights into the water quality challenges rural coastal communities face.

This study aimed to identify the sources of fecal bacteria and …

Validated Crispr/Cas9 Guide Rnas Targeting Neurodevelopmental Genes In The Tunicate Ciona Robusta, Sydney Popsuj, Tenzin Kalsang, Eduardo D. Gigante

Faculty Articles

The tunicate Ciona robusta provides a powerful and simplified model for dissecting the genetic control of developmental and cell biology. With a larval CNS composed of just over 200 neurons and sensory cells, it has also emerged as a model organism for neurobiology and the development of the nervous system. Although CRISPR/ Cas9-mediated mutagenesis is now routinely used in Ciona as an important technique used to interrogate gene function in diverse biological processes, validated single-guide RNAs (sgRNAs) have yet to be validated for several key neural genes. Here, we report the design and experimental validation of 25 novel sgRNAs targeting …

Mechanism Of Hypothiocyanous Acid Reductase, Morgan L. Fowler

Masters Theses

Hypothiocyanous acid reductase (Har) is a flavin-dependent enzyme that is effective in protecting bacteria from hypothiocyanous acid. HOSCN is an antimicrobial oxidant that is excreted by the mammalian innate immune system during inflammation, targeting and attacking thiols in pathogens. To combat HOSCN, bacteria have developed defense systems, including hypothiocyanous acid reductase. The catalytic mechanism by which Har interacts with its substrates, HOSCN and NADH, is undetermined and requires exploration.

In this study, we characterized the reductive and oxidative half-reactions of E. coli Har (EcHar). We first investigated and characterized wild-type EcHar, showing that Har is extremely efficient in reacting with …

The Aggregation Of Microplastics By Enhancing Extracellular Polymeric Substance Production In Pseudoalteromonas Sp. Ncimb 2021 To Improve Removal Efficiencies In Environmental Matrices, Janelle L. Mercer

All Theses

Microplastics (MP) are ubiquitous in the natural environment and are a growing threat due to their small size and durability. Plastics are released into the environment through improper waste management, wastewater treatment outfalls, industrial spills, agricultural runoff, and landfills. These particles breakdown into secondary MP through degradation pathways. MP, less than 5 mm, require intricate removal techniques from water systems. Filtration techniques, though viable and effective, have implementation constraints due to high cost, maintenance demands, and filter fouling. By integrating coagulation and flocculation processes prior to filtration, MP removal efficiencies can increase, while minimizing operational challenges during filtration. Extracellular polymeric …

Function And Regulation Of Long Polar Fimbriae During Enterohemorrhagic Escherichia Coli Infection, Walter J. Galdamez

Dissertations and Theses (Open Access)

Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen that causes severe gastrointestinal disease and hemolytic uremic syndrome. EHEC employs multiple virulence factors to colonize the host intestine, including the locus of enterocyte effacement (LEE) encoded type III secretion system, intimin, and flagella, yet the role of long polar fimbriae (Lpf) in adhesions and infection remains less well understood. Long polar fimbriae can mediate bacterial attachment to host cells in vitro, yet the regulation and function of its two fimbrial operons, lpf1 and lpf2 in vivo remain poorly understood. Preliminary RNA-seq data from zebrafish infected with EHEC reveal that expression of …

Defining The Role Of Spxa1 And Spxa2 In Group A Streptococcus (Gas), Gretchen Anne Morrison

Dissertations and Theses (Open Access)

Group A Streptococcus (GAS) is a human-restricted pathogen whose global incidence has surged in the post-COVID era. The ability of GAS to shift from a colonizing to invasive phenotype depends on coordinated virulence gene regulation in response to host-imposed stressors. The paralogous global transcriptional regulators, SpxA1 and SpxA2, have emerged as central mediators of these adaptive responses; however, the mechanisms by which these regulators influence both global gene regulation in direct response to external stresses and the host response as a result of regulatory changes remain incompletely understood. Using an integrated multi-omic approach, we define the distinct yet interconnected regulatory …

Mutational Analysis Of Domain Functions In The Yeast Decapping Enzyme Dcp2, Jellisa Ewan, Ambro Van Hoof

Dissertations and Theses (Open Access)

In yeast, the major mRNA decay pathway involves deadenylation of the 3’ poly-A tail, followed by decapping of the 5’ m7Gppp cap and subsequent 5’ to 3’ degradation or 3’ to 5’ degradation. This is carried out by Pan2/Pan3 and Ccr4/Not deadenylases, the decapping enzyme Dcp2, and Xrn1 and  RNA exosome exoribonucleases, respectively. The eukaryotic mRNA decapping enzyme complex, Dcp1/Dcp2, is essential in yeast, and deletion of either gene is lethal. However, the deadenylases that act upstream and the 5’ exoribonuclease that act downstream of the decapping step are not, even though they are all highly conserved with no known …

Tissue-Specific And Sex-Dependent Microbiome Structure In East African Cattle Ticks (Amblyomma Gemma And Rhipicephalus Pulchellus) And Their Bovine Hosts, Dennis Getange, Samson Mukaratirwa, Rua Khogali, Epaphrus Yuko, James Kabii, Joel L. Bargul, Jandouwe Villinger

All Peer-Reviewed Publications

Ticks and their vertebrate hosts share intimate ecological interactions that shape microbial community composition, with implications for tick fitness and pathogen transmission. However, the extent and specificity of tick–host microbial interactions remain poorly understood, particularly in East African tick species. Here, we characterised microbial communities across multiple tissue types from two economically important tick species (Amblyomma gemma and Rhipicephalus pulchellus) and their shared bovine host using 16S rRNA V1-V2 gene sequencing. We profiled haemolymph, midgut, salivary glands, and gonads from individual ticks (25 Am. gemma and 8 Rh. pulchellus), alongside 12 bovine blood samples. Microbiota were dominated by Proteobacteria, Firmicutes, …

Bridging The Gap In Science Research: Preparing Students For College- Level Research In The Sciences, Victoria Helwig, Yaoguang Li

UConn Library Presentations

Many first-year students enter college unprepared to fully engage with scientific literature and academic library resources. Drawing on experiences from academic librarians working with STEM students, this session explores common gaps in science research skills, including navigating databases, identifying scholarly sources, and understanding the structure of scientific literature. Participants will be introduced to practical strategies and classroom-ready activities to better prepare students for college-level research. Discussion questions: What science research skills do students struggle with most when entering college? How can high school instruction better support these skills? Where can librarians and educators collaborate to support student success?

Analysis Of The Atypical Temperature Dependence And Conformational Changes During Turnover Of A Lactobacillus Chlorogenic Acid Esterase, Nathaniel Carl, Yianni Tsigaris, Dan Ji, Nora K. Anpree, Kellie K. Omori, Cedric P. Owens

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Many bacterial chlorogenic acid esterases (ChlEs) exhibit atypical temperature behavior, featuring activities that barely change with temperature and activity maxima that fall below the thermal denaturation point. This work focuses on a ChlE from Lactobacillus helveticus (Lh–ChlE), which has a flat temperature dependence. First, it was determined that conformational changes during Lh–ChlE turnover are not rate-limiting and that the overall rate depends on the chemical step at all temperatures. Next, Lh–ChlE’s temperature dependence was investigated using a conformational equilibrium model that assumes the existence of a temperature-dependent equilibrium between an active and an inactive conformation and an activation heat capacity …

De Novo Pyrimidine Synthesis Controls Germinal Center B Cell And Plasma Cell Fates And Systemic Autoimmunity, Julia L. Weber, Tien Bui, Keomonyroth Nuon, Adam J. Fike, Sophia M. Crocker, Kristen N. Bricker, Anju Maharjan, Wujuan Zhang, Aaron R. Goldman, Sathi Babu Chodisetti, Ziaur S. M. Rahman

Department of Microbiology and Immunology Faculty Papers

Whether and how pyrimidine metabolites promote systemic autoimmunity is unknown. Here, metabolomics and 15N-amide glutamine tracing show enhanced flux through de novo pyrimidine synthesis in systemic lupus erythematosus (SLE)-prone B cells. Temporal inhibition of pyrimidine synthesis dampens SLE-prone but not foreign antigen-specific germinal center (GC), plasma cell (PC), and antibody responses. Uridine monophosphate synthase (UMPS) conditional deletion, however, reveals a B cell-intrinsic requirement of de novo pyrimidine synthesis in foreign antigen-driven and SLE-prone GC, PC, and antibody responses and kidney immune complex deposition. Metabolomics, mitochondrial stress test, metabolic flow cytometry, glycolytic rate assay, and RNA sequencing highlight the importance of …

Systemic Infection Of Beauveria Bassiana In A Stranded Endangered Green Turtle Chelonia Mydas: A Case Report, Ming-An Tsai, I-Chun Chen, Tsung-Hsien Li

The Thai Journal of Veterinary Medicine

The green turtle (Chelonia mydas) is the most frequently encountered marine turtle species in Taiwan. This study describes the postmortem findings of a juvenile green turtle with injuries to the right foreflipper that was rescued off the Taiwan coast and died after 3 months in rehabilitation. Necropsy revealed large, yellow, multifocal caseous lesions involving the right foreflipper, spleen, liver, kidneys, and lungs. Fungal infection of Beauveria bassiana was confirmed by culture, morphological and molecular characterization, phylogenetic analysis, and histopathological examination. This report provides evidence that B. bassiana is associated with a systemic fungal infection which can be fatal …

In Vivo Expression Profiling Of Listeria Monocytogenes Internalins (Inlf, Inlp, Inlj) And Their Corresponding Host Receptors (Vim, Afdn, Muc2) Using A Rabbit Ligated Intestinal Loop Model, Nawar Al-Janabi, Nadhim Mushtaq Hashim Al-Bderee, Zahraa M. Madania, Mohanad Jawad Kadhim

Karbala International Journal of Modern Science

Listeria monocytogenes is a Gram-positive pathogen that causes severe infections, particularly in immunocompromised individuals. Internalin genes are important virulence factors that facilitate the bacterium's invasion of host cells. This research aimed to quantify in vivo expression of selected internalin genes (inlF, inlP, and inlJ) and their corresponding host receptors (VIM, AFDN, and MUC2) during L. monocytogenes infection. To achieve this aim, a rabbit ligated intestinal loop model was constructed comprising two intestinal loops. The first loop was injected with 1 mL of L. monocytogenes (1 × 10⁷ CFU/mL), while the second loop was injected with 1 mL of PBS as …

Pharky, Phedro, Phractured, And Stagephright: Complete Genome Sequences Of Four Ek2 Cluster Microbacterium Phages, Susan M. R. Gurney, Medha Gupta, Deeksha Reddy, Gloria Zacharias, Aleda S. Jomy, Carly J. Smith, Matthew T. Mcdonald, Brett M. Condon

Student Papers, Posters & Projects

We report the complete genome sequence of four Microbacterium phages, Pharky, Phedro, Phractured, and StagePhright, isolated using the bacterial host Microbacterium foliorum from soil samples collected in Philadelphia. All four phages are genetically very similar and contain a gene of unknown function, which is uncommon in the EK2 cluster.

Homocysteine Thiolactone From Translation Proofreading Is An Endogenous Ligand For Cell-Cell Signaling By The Receptor Sdia, Lorenzo Eugenio Leiva, Roberto A. Zúñiga, Gregory J. Phillips, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Several widespread mechanisms enable cellular communication and coordinate the behavior of bacterial populations. The modules responsible for cellular communication are often found in matching pairs: an enzyme that synthesizes a signal molecule and a specific receptor that decodes it. A notable exception is Escherichia coli SdiA, a homolog of known N-acyl-homoserine lactone (AHL) receptors, for which no corresponding AHL synthase exists. SdiA is an orphan receptor that enables cross-talk by sensing AHLs from other bacterial species. In this work, we investigated whether homocysteine thiolactone (HTL), an AHL-like molecule arising from a proofreading reaction of methionyl tRNA synthetase (MetRS) to correct …

Understanding The Effects Of Simulated Microgravity On Staphylococcus Epidermidis And Escherichia Coli In Co-Culture, Emma Costa, Mitchell K. Villafania, Makaila Olson, Kareigh N. Gammon, Hugo Castillo

Beyond: Undergraduate Research Journal

With the popularity of space travel increasing, it is important to understand the effects of microgravity on microbial communities as alterations on bacterial interactions can occur. Staphylococcus epidermidis and Escherichia coli are bacteria that are commonly found within human microbiomes. S. epidermidis is a cocci-shaped gram-positive bacterium that is part of the human skin microbiome. However, it can gather on sites of open skin and enter the body leading to an infection. E. coli is a rod-shaped gram-negative bacterium that can be found in the human gut microbiome. The pathogenic strains of E. coli have the potential to cause harmful …

Effectiveness Of Organic Amendments In Enriching Nitrogen In Compost Produced From Organic Fractions Of Market Waste Generated In Dar Es Salaam, Tanzania, Amani Bilula, Ally Mahadhy, Anthony Manoni Mshandete, Amelia Kivaisi

Tanzania Journal of Science

Low nitrogen (N) content remains a key limitation of compost derived from urban organic waste. This study evaluated the effectiveness of selected plant-based organic amendments in enhancing nitrogen content and improving compost quality. Four plant- based organic amendments, Leucaena leucocephala (BN01), Commelina benghalensis (BN02), Morus alba (BN03), and Helianthus annuus (sunflower) cake (BN04), were incorporated into market waste compost at ratios of 1:0.06:0.04, 1:0.06:0.25, and 1:0.06:0.5 (organic waste: sawdust: amendment). Composting was conducted using a 4 × 3 factorial design with three replicates per treatment (n = 36). Temperature, moisture, and pH were monitored throughout the composting period. Total nitrogen, …

Birds Of A Tether Flock Together: Examining Centromere Tethering And Chromosome Segregation In Caulobacter Crescentus, Jake Dwyer, Simon Kruczak, Rodrigo Arana-Garrido, Paola Mera

MICRO-CCS student projects

Introduction:

Chromosome segregation is essential for all domains of life. Caulobacter crescentus is a key model for studying this process. It divides asymmetrically into two morphologically distinct cells. Proteins can be seen directly with fluorescent tags.

Research done on Caulobacter can apply to many different bacteria. The ParABS system is integral to chromosome segregation in Caulobacter.

ParS – DNA sequence on the chromosome

ParB – CTP-binding protein that specifically recognizes parS

ParA – ATP-binding protein that non-specifically binds DNA and provides the force for segregation.

PopZ – Polar tethering protein via interactions with ParB.

TipN - Polar protein that …

Has Plant Domestication Compromised Plant Defensive Chemistry? Aphid Induced Stress In Tomatoes, Nhi Do, Satinderpal Kaur, Minxing Zhu, Esther N. Ngumbi

MICRO-CCS student projects

Tomato plants have natural defensive mechanisms.

Direct: Phenolics are secondary metabolites that can protect the plant by intoxicating the herbivores and/or producing strong repulsive odors.

Indirect: VOCs, Volatile Organic Chemicals, are gas phase signals that attract the predators of the attacking herbivore to the plant.

Domestication of plants may chemically alter these defenses by prioritizing fruit production over defensive traits.

We hypothesize that wild/ancient tomato plants would have a greater quantity of volatiles and increased concentration of leaf total phenolics compared to cultivated tomatoes during aphid herbivory.

How Does High-Oil Sorghum Change Potential Extracellular Enzyme Activity Across Soil Depth Profiles Under Drought Conditions?, Krystal Monique Role, Rounak Patra, Wendy Yang

MICRO-CCS student projects

Transgenic oil sorghum reallocates photosynthate-carbon (C) into vegetative lipids, accumulating nonstructural lipids in both shoot and root tissues. Altered plant C allocation and root lipid accumulation may shift root exudate chemistry, belowground C inputs, and microbial nutrient demand throughout the soil profile. While aboveground productivity in high-oil sorghum is well-characterized, its belowground impacts on soil microbial enzyme activity and exchangeable cation dynamics, especially across soil horizons under drought stress remain unknown.

Project objective was to find out how transgenic high oil sorghum (Tx-HO1) influences CNP acquiring extracellular enzyme activities and soil exchangeable cation dynamics across soil horizons under drought and …

Investigation Of Biological Denitrification Inhibition By Specific Anthocyanins, Kristin Palazzo, Holly Anderson, Aislinn Geedey, Angela Kent

MICRO-CCS student projects

Nitrogen fertilizers are applied to corn fields to support high crop yields, but some nitrogen is lost through microbial denitrification, producing nitrous oxide (N2O), a potent greenhouse gas. Some plants produce certain flavonoids that can suppress microbial denitrification, a trait known as biological denitrification inhibition (BDI). Maize produces flavonoids in the form of anthocyanins, including cyanidin-3-glucoside (C3G), the major anthocyanin produced by maize.

The goals of this project were to determine whether C3G:

is produced in maize roots

inhibits microbial denitrification

Recovering Plasmid-Id Barcoded Strains Of Sinorhizobium Meliloti From A Native Soil Microbiome, Kenny Sacks, Hannah Murray, Katy Heath

MICRO-CCS student projects

Introduction

Legume-Rhizobia Mutualism: Nitrogen is an essential nutrient for plant growth. Plants can’t produce nitrogenous compounds. Rhizobia fix atmospheric nitrogen gas into bioavailable forms. Rhizobia form a nutrient exchange mutualism with leguminous plants.

Project description

Can our bacteria persist within the rhizosphere and into the nodule when faced with native microbial competitors? The Medicago-Sinorhizobium mutualism is used as a model system. Survival of strains post competition is difficult to measure due to identical 16S rRNA sequences and similar marker genes. Plasmid-ID barcoding sequences may provide a way of testing strains against a community.

Soil Microbiome Effect On Seedling Diseases And High Throughput Isolate Identification, Annalaysia Smith, Mara Krone, Santiago Mideros

MICRO-CCS student projects

The soil microbiome has a substantial effect on disease suppression. Organic farming is a practice used to create a more diverse microbiome which can create disease suppression. Different agricultural practices such as fertilization and rotation system are known to affect the microbiome (Schlatter et al 2017). Therefore, it is important to study the effects of different microbiomes on disease suppression. Furthermore, methods are necessary for quantifying the effect of disease suppression on specific pathogen populations. To do this, it is important to properly identify the pathogens.

Objectives:

1. Test if different nitrogen treatments cause variations in organic soils disease suppression. …

Effects Of Varying Ph Levels On Prophenoloxidase Activity And Hemocyte Recruitment In Daphnia Dentifera, Yusra Siddiqi, Carla Caceres

MICRO-CCS student projects

Anthropogenic activities and natural processes are responsible for changing the pH of freshwaters which can impact aquatic life. D. dentifera is a keystone species found in midwestern lakes that is susceptible to a parasitic yeast called Australozyma monospora. A. monospora spores puncture the Daphnia gut into the hemolymph and begin using the host’s resources. Invertebrate immunity is under researched.

Research objective: How will different pH impact prophenoloxidase (proPO) activity and hemocyte recruitment in Daphnia dentifera?

Screening A Random Hile Mutant Library To Characterize Hild Regulation In Salmonella, Danista Kannah, Gracious Donkor, James M. Slauch

MICRO-CCS student projects

Salmonella is a leading cause of gastrointestinal diseases globally. It utilizes a type three secretion system (T3SS) encoded on Salmonella Pathogenicity Island 1 (SPI1) to invade host intestinal epithelial cells during infection.

HilE directly regulates HilD via a direct protein-protein interaction. The Slauch lab identified two HilD variants, A141V and A141T, which are blind to HilE. These variants activate hilA expression even in the presence of HilE, indicating that the binding of HilE to these mutants is compromised.

Hypothesis: Performing random mutagenesis of hilE could lead to changes at the protein level which could compensate for the loss of interaction …

Fungal Diversity In Lespedeza Cuneata Roots, Gwendolyn Happ, Sophia Mcdade, Anthony Yannarell

MICRO-CCS student projects

Background

• Plants form a relationship with fungi that can be beneficial or harmful
• Fungi may grow on the plant surface, within plant tissues, or around roots
• Plants release compounds that invite fungi to their roots and chemicals  that can diminish unwanted fungi

Why Lespedeza cuneata? 

• Invasive that competes with native plants and damages biodiversity within plant and animal communities
• Alters soil microbiome
• Expansive seed bank and deep root system
• Understanding its microbiome can help in understanding invasive species success and ecology

Efficacy And Evolutionary Dynamics Of 222 Nm Far-Uvc Against Vibrio Cholerae, Kadicha Madakimova, Angus Wu, Nkrumah Grant

MICRO-CCS student projects

The Far-UVC light at 222 nm wavelength (UV222) is one of the emerging methods of disinfection of bacteria in public spaces such as hospitals and labs.

• Does not penetrate human skin and does not cause harm to eyes making it a safer alternative to conventional UV systems.

• Primarily targets proteins preventing regrowth and repair pathways.

However, the potential for bacterial adaptation following sublethal UV222 exposure remains largely unknown.

Central question: How does QS transcriptional state influence the efficacy and resistance profile of V. cholerae to UV222 nm irradiation?

Hypothesis: Qurom-sensing transcriptional state determines V. cholerae susceptibility to UV222 nm UV …

A Tale Of Two Symbionts: Comparative Cellular Localization Of Two Manipulative Rickettsiella Strains In A Spider, Kaitlyn Costanza, Thea Bliss, Matthew Doremus

MICRO-CCS student projects

Many arthropods harbor maternally transmitted endosymbionts that manipulate host reproduction to increase their transmission. One such manipulation is cytoplasmic incompatibility (CI), in which embryos produced by infected males and uninfected females fail to develop.

Rickettsiella has recently been discovered to cause CI in Mermessus fradeorum. Two geographically distinct Rickettsiella strains infect this spider: R1 causes strong CI, whereas R2 causes weaker CI.

Hypothesis: H1: Both Rickettsiella strains will localize within or near developing sperm cells in the testes. H2: The stronger R1 strain will exhibit more consistent localization within infected adult reproductive tissues than the weaker R2 strain.

Identification Of Conditionally Essential Genes Required For Salmonella Enterica Serovar Typhimurium Adaptation To The Chicken Cecal Extract Through Ex Vivo Modeling And Transposon Insertion Sequencing, Deborah Bukola Olubanjo

Graduate Theses and Dissertations

Salmonella enterica serovar Typhimurium (S. Typhimurium) remains a major foodborne pathogen associated with chicken, where it can persist in the intestinal tract without overt disease and contribute to zoonotic transmission. The chicken cecum represents a complex ecological niche shaped by microbial competition, host-derived substrates, short-chain fatty acids, oxygen limitation, extracellular components, and diverse metabolic gradients. Although transposon insertion sequencing (Tn-seq) has been widely used to define bacterial fitness determinants, limited work has examined genome-wide adaptation of S. Typhimurium in chicken ceca-derived ex vivo systems that preserve key features of the avian cecal environment. This dissertation investigated conditionally essential genes required …