Biology Commons^™

Building Genetic And Culturing Tools For The Understudied Soil Bacterium E. Flagellatus, Aaron Butler, Brenda Pratte, Lon Chubiz

Undergraduate Research Symposium

Soil bacteria play essential roles in nutrient cycling, yet many abundant groups remain poorly characterized due to challenges in cultivation and genetic manipulation. One such organism is Edaphobacter flagellatus, a member of the Acidobacteriota frequently detected in soil environments but lacking well-developed experimental tools. To address this limitation, our laboratory has generated a genome-wide mutant library using the Tn5 transposon, enabling random disruption of genes across the population.

This project aims to establish culture conditions necessary to support the use of this library for functional genomic studies. In particular, defined minimal media can impose selective pressures that reveal …

Ecological Drift And Host Filtering Jointly Structure Foliar Endophytes During Ecosystem Development., Caio César Pires De Paula, Petr Macek, Milan Varsadiya, Jakub Borovec, Mehmet A. Balkan, Brett S. Younginger, Daniel J. Ballhorn, Tomáš Picek, Tomáš Hájek, Jan Frouz, Jiří Bárta, Dagmara Sirová

Biology Faculty Publications and Presentations

Foliar endophytes contribute to plant nutrient acquisition, stress tolerance, and pathogen resistance, yet their responses to ecosystem-level processes remain poorly understood. Using a space-for-time substitution design, we investigated bacterial and fungal community dynamics in the foliar endosphere of four phylogenetically distinct plant hosts across a well-characterized successional chronosequence.

Elasmobranchii Oral Microbiome Diversity Within Southeast Florida: Implications Of Shark Zoonotic And Antibiotic Resistant Pathogens Associated With Human Interactions, Amanda Finnefrock

All HCAS Student Capstones, Theses, and Dissertations

Sharks are incredibly common in the Atlantic and Gulf waters surrounding Florida. Despite the prevalent nature of these animals, little research exists on the composition of their microbial communities (or “microbiomes”). Here we aim to determine the microbial makeup of the oral environment of sharks so that we can determine if there are any bacteria of clinical significance to humans, such as being antibiotic-resistant or having elevated capability for pathogenicity. A total of 41 samples were collected from the mouths and teeth of bull, Caribbean reef, great hammerhead, lemon, nurse, and sandbar sharks caught in Southeast Florida using sterile swabs …

Biological Soil Crusts: Effects Of Environmental Change On Dryland Microbes, Mariah T. Patton

Biology ETDs

Climate change is increasing rainfall variability, altering nutrient availability, and causing warming in drylands, which comprise approximately ~36% of Earth's terrestrial surface. These expanding ecosystems contribute the most to interannual variability in the global carbon cycling. Biological soil crusts (biocrusts)—often called the "skin of the Earth"—are critical components of dryland surfaces, consisting of successional microbial communities dominated initially by Cyanobacteria and later by a more diverse composition with other bacteria, archaea, lichen, fungi, and algae. These communities play essential roles in soil aggregation, erosion prevention, and carbon and nitrogen cycling. However, our ability to predict biocrust responses to environmental change …

Imidacloprid Effects On The Survival And Cutaneous Microbiome Of Northern Leopard Frogs, Evelyn Margaret Osterloo

Honors Thesis

Amphibians are experiencing population declines due to habitat loss, climate change, and diseases, particularly chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis. Protection from this fungal infection stems from the cutaneous microbiome. Pesticides have been shown to affect amphibians in a variety of ways, including reducing survival, locomotor performance, and accumulation in body tissues. Pesticides may also lead to changes in the cutaneous microbiome affecting amphibians who rely on these organisms as an anti-Bd defense mechanism. To investigate the effect of imidacloprid, a neonicotinoid insecticide, Northern Leopard frogs (Lithobates pipiens) were subjected to sublethal concentrations (control = …

Weather Conditions Associated With Citrus Canker Incidence Caused By Aw Strain In The Lower Rio Grande Valley Of South Texas, Amit Sharma, Teresa Patricia Feria-Arroyo, George Yanev, Madhurababu Kunta

School of Integrative Biological & Chemical Sciences Faculty Publications

Citrus canker, caused by bacterium Xanthomonas citri subsp. citri (Xcc), affects the citrus industry by making the fruit unmarketable due to unsightly lesions on the fruit. Citrus canker caused by a relatively new AWstrain of Xcc was reported on the citrus trees in the residential areas of the Lower Rio Grande Valley (LRGV) of South Texas. Xcc AW has a limited host range, predominantly affecting limes and a few other citrus species. Previous work has reported prevailing environmental conditions that influence the incidence and spread of the citrus canker caused by the Asiatic A strain. However, no information is available …

Antibiotic Resistance Trends In Coliform Bacteria Of Kittitas County Waters, Kaitlyn Holbrook, Bella Blasingim, Cruz Veronica Guillen Mejia, Holly Pinkart

Journal of the Symposium of University Research and Creative Expression

Project Mentor(s): Holly Pinkart, PhD

Since the mid-1900s, antibiotics have been developed to help fight against bacterial pathogens. However, bacteria can evolve rapidly and have evolved resistance to many types of antibiotics. Using coliform bacteria collected from waters around Kittitas County, BIOL 323 students at Central Washington University have identified a variety of antibiotic-resistant bacteria in Kittitas County streams and canals. Antibiotic resistance was measured from 2014-2019 and compared to data collected in 2024. This study focuses on three antibiotics, ampicillin, kanamycin, and trimethoprim-sulfamethoxazole. In the past (2014-2019) we saw no change in the trend of antibiotic resistance in collected …

Plant-Microbe Interactions Across Scales: Diversity, Disease, And Stress In Herbaceous Plant Communities, Philippa Tanford

Arts & Sciences Graduate Student Theses and Dissertations

Plants interact consequentially with microbes spanning mutualism to pathogenicity, with broader effects on large-scale plant community structure. These plant communties, in turn, shape below and aboveground microbial communities through a variety of mechanisms. However, plant diversity-microbial diversity relationships remain broadly inconsistent across environments and among different plant and microbial assemblages. In my dissertation, I work to bridge some of these gaps in plant-microbial ecology in three experimental chapters assessing relationships between plant diversity and microbial diversity, including the influence of belowground-aboveground microbiome interactions, the influence of drought stress, and incorporating different spatial and experimental scales. First, I explore the microbial …

Isolation And Characterization Of Siderophore(S) From Pseudomonas Mosselii, Casey J. Stophel

Electronic Theses and Dissertations

Iron is essential for growth of most microorganisms. It functions as an important cofactor in many important biological processes. However, iron found in soil is rendered insoluble and unavailable to microorganisms for use. To overcome this, many bacterial species produce siderophores, a small organic molecule that has high affinity for iron. Siderophores allow for bacterial cells to obtain otherwise insoluble iron. Pseudomonas mosselii, a Gram negative bacterium, was isolated from a local soil sample. P. mosselii was found to produce siderophore(s) under iron restricted environment, however, they have not been characterized. Therefore, it was of interest to isolate, purify and …

Chaperone-Usher Pathway Pili Adhesin Conformations And Inhibitors In Urinary Tract Infections, Edward Lopatto

Arts & Sciences Graduate Student Theses and Dissertations

Antibiotic resistant bacteria are becoming increasingly difficult-to-treat resulting in increased morbidity and mortality, especially for common infections such as urinary tract infections (UTIs). Globally, UTIs afflict over 400 million people a year. Numerous different gram-negative and gram-positive bacterial species cause UTIs, including uropathogenic Escherichia coli (UPEC), Klebsiella pneumoniae, and Acinetobacter baumannii. Many of these bacterial species are listed as pathogens of urgent concern by the Center for Disease Control due to the dangerous rise and prevalence of antibiotic resistance necessitating development of new therapeutic measures. Bacteria utilize adhesin factors, such as chaperone-usher pathway (CUP) pili to gain a foothold in …

Resistant & Persistent Bacterial Cells, Jean-Louis Bru

Open Educational Resources

An activity on the difference between resistant & persistent bacterial cells. This activity aims to build on the pre-lecture materials about resistant bacterial cells, so that students can make a connection toward persistent cells. In both cases, they make antibiotics less effective.

Learning Objectives

Recognize the importance of antibiotics in fighting bacterial infections. Understand how bacterial species become antibiotic resistant. Determine the difference between resistant and persistent bacterial cells.

Social and Collaborative

Students work together on this in-class activity in groups of 2-4 (3, ideally). Each student will have one of the following roles: encourager, recorded, investigator, and time keeper. …

Propelling Whole-Cell Biosensor Creation By Leveraging Gene Fusion To Assemble Synthetic Functional Transcription Factors For The Detection Of Biomarkers, Samuel J. Verzino

Theses and Dissertations

Biosensors are analytical devices that leverage biological modules for the detection of molecules of interest. As customizable tools designed to aid in a wide array of diagnostics, these instruments are rapidly advancing the field of synthetic biology. While varied in their construction and purpose, biosensors are ultimately concerned with converting a physicochemical stimulus into a detectable signal. Among the many existing variants, whole-cell biosensors (WCBs) stand out due to their versatility and engineering potential. WCBs are a type of biosensor in which a physiologically active cell sustains an array of biomolecular elements - receptors, transporters, regulators, etc. - capable of …

Diversity, Genomics And Antimicrobial Resistance Of Coagulase-Negative Staphylococcus: A Literature Review, Kathleen Okeefe

Electronic Theses & Dissertations (2024 - present)

Members of the gram-positive bacterial genus Staphylococcus have historically been classified into coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS). This classification is based on the ability of clotting of plasma by the coagulase enzyme, which converts fibrinogen to fibrin. CoNS species are ubiquitous commensals that frequently colonize the skin and mucosal surfaces. They are also opportunistic pathogens implicated in many human and animal infections. The evolutionary history of CoNS has generally been overlooked because of the historical lack of recognition for their clinical importance and poor taxonomic sampling. They are often perceived as being less or non-pathogenic, especially compared to …

The Effect Of Sars-Cov-2 On Bacterial Diversity And Abundance In Community Wastewater, Joshua Lambert

Graduate Theses, Dissertations, and Problem Reports (ETD)

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) enters human respiratory cells through binding of its spike (S) protein to the ACE-2 receptor, which is highly expressed in lung cells, but is also found in over 150 other cell types encompassing major organs including GI enterocytes. SARS-CoV-2 causes gut dysbiosis in infected individuals and patients with COVID-19 and also coincides with lower alpha diversity of the individual’s gut microbiome. Certain gut microbiome-associated genera are lower in abundance in COVID-19 patients including Lachnospira, Prevetolla, Roseburia, Bifidobacterium, and Faecalibacterium while genera such as Bacteroides, Enterococcus and Proteobacteria are increased during a SARS-CoV-2 …

Characterizing The Francisella Tularensis Universal Stress Protein, Benjamin Girardo

Theses & Dissertations

Francisella tularensis is an extremely virulent pathogen responsible for the zoonotic disease tularemia. F. tularensis employs various defense mechanisms to survive and persist under diverse environmental and host-induced stress conditions. Despite its significance, the full spectrum of stress factors that enable F. tularensis persistence remain inadequately understood. In many bacterial species, universal stress proteins (Usp) play a crucial role in managing adverse conditions. The aim of this study was to elucidate the role of Usp in F. tularensis as a means of clarifying the stress response mechanisms of this pathogen. The F. tularensis Usp is encoded by a single, highly …

Study On The Seasonal Endobacterial Profile Of Avicennia Officinalis, Focusing On Core Bacterial Consortia Within Mangrove Pneumatophores, Devi R R, Vinod Prabhakar

Karbala International Journal of Modern Science

Microhabitats are smaller pockets of ecosystems with unique conditions and they serve as major contributors of species richness. Mangrove plants offer a diverse array of such microhabitats (rhizosphere, phyllosphere, endosphereetc), and the inhabitant bacteria benefit the host by providing better salinity tolerance, faster and better nutrient mobilization, protection from phytopathogens and assistance in seed germination. Identification of such beneficial bacteria,their growth requirementsandmetabolism, willhave direct application in the field of agriculture and ecosystem restoration. Hence in this study, effort has been made to elucidate the seasonal numerical and compositional profile of pneumatophore bacterial consortia of Avicennia officinalis, from the mangrove …

Antibiotic-Resistant Gram-Negative Bacteria In A Local Wastewater Treatment Plant In North Georgia, Nou Moua, Lindsay Mccuen, Sarah White, Swapna Bhat, Margi Flood, Jeanelle Morgan

Georgia Journal of Science

Antibiotics are some of the most essential lifesaving drugs currently available to us against infectious diseases. Several pathogens are developing resistance to these drugs and many have become resistant to multiple antibiotics. Such multi-drug resistance is becoming a global issue and has been found in many environments including wastewater treatment plants (WWTPs). In this study, we sampled a local WWTP for antibiotic-resistant bacteria. This WWTP is in North Georgia and runs directly into Lake Lanier, which is the main source of drinking water for the Atlanta area as well as a popular spot for water recreation. We obtained treated and …

A Careful Examination Of The Parameters Impacting The Study Of Plant/Bacteria Interactions, Caroline Victoria Royals

Theses and Dissertations

Our laboratory has been studying how different Caulobacter strains impact Arabidopsis plant growth. While reading papers published by other laboratories, I noticed inconsistencies in the methods used by different plant/bacteria interaction studies. For example, a variety of different variables have been used for defining a bacterium as Plant Growth Promoting (PGP). To establish a baseline, I conducted longitudinal studies that examined the impact of bacteria on all phases of a plant’s life. I found that individual Caulobacter wild type strains impact different aspects of plant growth. In addition, I continuously encountered problems with within and between pot variation in plant …

Metagenomic Analysis Of Antarctic Microbial Communities, David Michael Robinson

Biology ETDs

The research presented in this dissertation focuses on microbial roles in biogeochemical cycling in Antarctic aquatic environments. The major objective of my research was to examine the impact of biotic and abiotic pressures on nutrient cycling in microbially dominated systems. I used three perennially ice covered lakes in the McMurdo Dry Valleys (MDVs) along with subglacial lakes Whillans and Mercer as natural case studies. The MDVs are located in Victoria Land, East Antarctica and have been studied since 1993 as part of the McMurdo Long Term Ecological Research Project. Viruses in the MDVs were shown to be seasonally abundant and …

Evolution And Adaptation To Temperature In Thermotogota, Anne Amelia Farrell

Dartmouth College Ph.D Dissertations

Life thrives across incredibly diverse environmental conditions, yet most organisms are restricted to growing within a narrow range around their optimum growth temperature (OGT). The evolutionary events leading to changes in OGT are poorly understood, and it is uncertain if specific genes are required to thrive at a particular temperature. The bacterial phylum Thermotogota is an excellent model for the evolution of OGT. It comprises mesophilic, thermophilic, and hyperthermophilic members that collectively grow between 20°C and 90°C.

In this work, I analyze the history of OGT in the Thermotogota phylum and show how horizontal gene transfer contributes to the evolution …

Novel Microbiological Medium Developed For The Isolation Of Bacteria Associated With Estuarine Anemones, Parker K. Lund, Catalina Cuellar-Gempeler

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

Out of the nearly one trillion species of microbiota estimated to inhabit Earth only ten thousand have been cultured in the laboratory. Culturing continues to play a vital role in determining the physiology and ecologic function of individual bacteria in microbial communities and for microbes associated with host organisms one of the major challenges is developing microbiological media that mimics the bacteria’s natural environment enough to promote growth. Here, we target bacteria associated with the estuary anemones Diadumene lineata and Metridium senile by developing a novel medium that uses anemone tissue as the sole source of nutrients. We further measured …

Drought Legacy Interacts With Wildfire To Alter Soil Microbial Communities In A Mediterranean Climate-Type Forest, Anna J. M. Hopkins, Aaron J. Brace, Jess L. Bruce, J. Hyde, J. B. Fontaine, L. Walden, W. Veber, K. X. Ruthrof

Research outputs 2022 to 2026

Mediterranean forest ecosystems will be increasingly affected by hotter drought and more frequent and severe wildfire events in the future. However, little is known about the longer-term responses of these forests to multiple disturbances and the forests' capacity to maintain ecosystem function. This is particularly so for below-ground organisms, which have received less attention than those above-ground, despite their essential contributions to forest function. We investigated rhizosphere microbial communities in a resprouting Eucalyptus marginata forest, southwestern Australia, that had experienced a severe wildfire four years previously, and a hotter drought eight years previously. Our aim was to understand how microbial …

Seasonal Soil Moisture Thresholds Inhibit Bacterial Activity And Decomposition During Drought In A Tallgrass Prairie, Nathan P. Lemoine, Michelle L. Budny, Ethan Rose, Jane Lucas, Christopher Marshall

Biological Sciences Faculty Research and Publications

Soil moisture reductions during drought often inhibit soil microbial activity and inhibit decomposition rates by reducing microbial biomass or by altering microbial communities. Evidence suggests that soil water must drop below a critical threshold to inhibit microbial activity. Thus, it is likely that the seasonal timing of drought will determine the extent to which belowground processes are adversely impacted by drought. Specifically, the effects of drought might be minimal during cool, wet periods typical of late spring but dramatic during hot summer months with high evapotranspiration rates that lower soil moisture levels below the critical threshold. Here, we present results …

Persistence Of Wastewater-Associated Antibiotic Resistant Bacteria In River Microcosms, Aoife P. Mahaney

Theses and Dissertations

The spread of antibiotic-resistant bacteria (ARB) associated with wastewater is a significant environmental concern, but little is known about the persistence and proliferation of these organisms in receiving water bodies after discharge. To address this knowledge gap, we performed a series of microcosm experiments in which river water was amended with either untreated or treated wastewater, and the abundance of viable ciprofloxacin-, Bactrim-, and erythromycin-resistant bacteria was monitored for 72 hours.

Both types of wastewater amendments increased the initial abundance of ARB compared to microcosms containing only river water. The increase was greatest with untreated wastewater, but that effect decreased …

Quantitative Shotgun Proteomic Analysis Of Bacteria After Overexpression Of Recombinant Spider Miniature Spidrion, Masp1, Kathryn P. Randene

University of the Pacific Theses and Dissertations

Spider silk has extraordinary mechanical properties, displaying high tensile strength, elasticity, and toughness. Given the high performance of natural fibers, one of the long-term goals of the silk community is to manufacture large-scale synthetic spider silk. This process requires vast quantities of recombinant proteins for wet-spinning applications. Attempts to synthesize large amounts of native size recombinant spidroins in diverse cell types have been unsuccessful. In these studies, we design and express recombinant miniature black widow (Latrodectus hesperus) MaSp1 spidroins in bacteria that incorporate the NTD and CTD, along with varying numbers of codon-optimized internal block repeats. Following spidroin overexpression, we …

The Investigation Of The Antimicrobial And Biofilm-Disrupting Properties Of Synthesized Hemibastadin Derivatives, Antonio Harvey, Andrew A. Yeagley

Longwood Senior Thesis Proposal

We want to investigate structural changes to the core hemibastadin structure while attempting to make these derivatives biologically safer. Since these modifications have never been done before, we will need to design a synthesis of these new molecules. Due to the nature of the molecules (dimers), a divergent synthesis that allows for the creation of both halves simultaneously seems most appropriate. A successful synthesis of these compounds will allow us to further investigate these derivatives for their antimicrobial and biofilm-disrupting properties.

Pathogenicity Of Acinetobacter Calcoaceticus, Kaitlan A. Sullivan

MUSC Theses and Dissertations

Acinetobacter is a genus of gram-negative bacteria that have been appearing frequently in hospitals contributing to infections in the blood, lungs, urinary tract, and other parts of the body. It infects patients with weakened immune systems that are placed on ventilators, after the use of catheters, or have any other open wounds produced by prolonged hospital stays. This genus of bacteria is problematic due to its high probability of becoming resistant to multiple classes of antibiotics. Thus, we are determining the pathogenicity of clinical isolates of Acinetobacter calcoaceticus using the organism Caenorhabditis elegans as a model.

We are testing …

Synthesis, Characterization And Antimicrobial Properties Of Mixed-Ligand Complexes Of Some Metal(Ii) Ions With Barbituric Acid And 1,10-Phenanthroline Ligands, Kayode Taiwo Ishola, Oluwabiyi James Olaoye, Mary Adelaide Oladipo, Omobola Ajibike Odedokun, Oyebanji Oluseun Aboyeji

Tanzania Journal of Science

Many pathogenic organisms have developed resistance to many antibiotics, which leads to an increase in the spread of many microbial infections. There is an urgent need to find more effective drugs to curb widespread transmission. Hence, this study synthesized and evaluated the antimicrobial activities of mixed-ligand complexes of Cu(II), Co(II), Ni(II), Mn(II), and Zn(II) ions with barbituric acid and 1,10 phenanthroline ligands in effort to find more effective antibiotics. The complexes were characterized using elemental analysis, metal analysis, melting points, solubility tests, and spectroscopic analyses (IR and UV-visible). The antimicrobial activities of the complexes were evaluated against two gram-positive bacteria …

Cell Division In Mycobacteria: The Role Of Sepiva, Angela H. Freeman

Biology Dissertations - Archive

Today, about a quarter of the world’s population are infected with Mycobacterium tuberculosis (Mtb) and therefore, are at risk of developing tuberculosis (TB) disease. Tuberculosis, on average, takes about six months to treat, and even longer for those with drug resistant Mtb infections (World Health Organization, 2022). Extended treatment times for these infections are caused by the inherent tolerance to antibiotics conveyed by mycobacteria’s distinct cell wall. Mycobacteria have a wide variety of cell wall regulators that help the cell adapt to stress, such as antibiotics. By understanding how these regulators work, we can learn how mycobacteria evade killing by …

Detection And Capture Of Nitrogen Fixing Bacteria From Soil And Roots Using Plant Specific Lectins, Alana Horton

Natural Sciences and Mathematics | Biological Sciences Master's Theses

Diazotrophs increase plant productivity by providing ammonia directly to plants in the rhizosphere or through association with the roots (Sun et al., 2021). Leveraging diazotrophs can aid in the reduction or application of harmful synthetic nitrogen fertilizers. This thesis aims to use plant root proteins, or lectins, to more rapidly recover viable diazotrophs that are likely to associate with crops. In this study, lectins, are used to recover bacteria from bulk soil by taking advantage of the binding relationship between lectins and bacterial cell surface polysaccharides. When commercially-available lectins were used with a magnetic pulldown to separate the lectin, bacterial …