Environmental Microbiology and Microbial Ecology Commons^™

The Role Of The Virb Ligand Ctp In The Molecular Mechanism Of Transcriptional Anti-Silencing In Shigella Flexneri, Taylor M. Gerson, Monika M A Karney, Helen Wing

Life Sciences Faculty Research

In bacteria, nucleoid-structuring proteins bind and constrain DNA, often leading to transcriptional silencing. In Shigella spp., the histone-like nucleoid-structuring protein H-NS silences many genes on the large virulence plasmid. Upon a shift to human body temperature, VirB, a DNA-binding protein and key transcriptional regulator of the Shigella virulence cascade, is produced. VirB counteracts H-NS-mediated transcriptional silencing and belongs to a fast-evolving clade of the ParB superfamily. Like other ParB proteins, VirB binds the ligand CTP. While CTP is essential for the anti-silencing activity of VirB, the role of CTP in the mechanism of VirB-dependent anti-silencing has yet to be …

Isolated Bacillus Licheniformis Sp01 From Daqing Oilfield In Reducing Chromium(Iii) Crosslinked Polymer Residue And Enhancing Oil Recovery, Xiao Hui

Student Works (2020-2029)

After polymer gel formation, the residual partially hydrolyzed polyacrylamide (HPAM) and the crosslinker (Cr3+) caused plugging and decreased oil recovery. Microorganisms can degrade HPAM to address the issues, but Cr³⁺ inhibits the process and reduces oil recovery. This study explores the underexamined biodegradation of HPAM and improved oil recovery in the presence of Cr³⁺, offering new perspectives for microbial enhanced oil recovery (MEOR) after polymer gel formation. HPAM and crude oil were innovatively used as the sole nitrogen(N) and carbon(C) sources to isolate the best-growing strain from Daqing Oilfield produced water, identified as Bacillus licheniformis SP01. The oil displacement potential …

Waters At Risk: Preventive Methods Against Cyanobacteria Blooms In Rhode Island, Ryan Boline

CAFE Symposium 2026

This project analyzes the rise of cyanobacteria blooms in Rhode Island freshwater systems and identifies a policy gap in the state’s largely reactive management approach. Drawing on state reports and interviews with environmental experts, it highlights nutrient runoff, climate change, and limited public education as key drivers of bloom severity. To address this gap, I developed a prevention-focused public education poster designed for integration into existing state alert and outreach systems.

Antimicrobial Resistance Of Cultivable Bacteria Isolated From Sorcerer’S Cave In Texas, Jennifer R. Huddleston, David E. Sanderson, Braden J. Smith, Joshua M. Brokaw, Evan M. Babb, Jeffrey T. Wooliscroft

International Journal of Speleology

Studying caves with minimal human contact offers insights into antimicrobial resistance before human influence. In this study, we isolated 315 bacterial strains from Sorcerer’s Cave in Texas and evaluated their resistance to seven common antimicrobials. Under half (41.4%) of the Gram-positive isolates and 68.4% of the Gram-negative isolates were resistant to three or more antimicrobials. The two most common genera identified were Pseudomonas and Bacillus. Compared to bacteria isolated in previous cave studies, Sorcerer’s Cave bacteria exhibited more extensive antimicrobial resistance. This study underscores the importance of minimally disturbed cave environments in advancing our knowledge of antimicrobial resistance present …

Environmental Detection And Genetic Profiling Of Staphylococcus Sp. At Taal Volcano Island, Ray Albert E. La Rosa, Shaun Michael C. Basco, Martin Gabriel Z. Dela Cruz, Iluminada A. Ronio

The Lasallian Journal of Health

Taal Volcano Island’s hydrothermal environment supports extremophilic microbial communities. This study isolated, biochemically characterized, and genetically profiled Staphylococcus sp. from shoreline soils. Soil samples were collected near active vents and cultured on acidified gelatin agar (pH 5.0). Biochemical tests—Methyl Red, Spirit Blue Agar, Motility, and Acrolein—were performed. DNA extraction and 16S rRNA sequencing identified Staphylococcus candidatus, with 99 % sequence similarity to GenBank entries JN794602.1 and KX250303.1. Phylogenetic analysis clustered the isolate with S. ureilyticus, S. cohnii, and S. equorum. The organism’s presence in volcanic soils demonstrates adaptation to acidic, thermophilic conditions and suggests potential applications in bioremediation and enzyme …

Exploring Alkaline Protease Activity Of Bacillus Strain Isolated From Sidon Dumpsite Lebanon, Zahra Farroukh, Dalia El-Badan, Jamilah Borjac

BAU Journal - Science and Technology

Proteases are crucial hydrolytic enzymes present in all organisms, performing essential physiological and industrial tasks. This study was conducted to screen and isolate protease-producing bacteria from soil and water samples collected from Sidon dumpsite in Lebanon. Bacterial samples were cultured onto skim milk agar medium to identify the alkaline protease-producing ones. In this study, we report on the partial purification and characterization of one of the isolated alkaline protease-producing bacteria. The bacterium was identified as Bacillus subtilis Z3 based on 16S rRNA sequencing. The molecular weight of the partially purified protease was approximately 55 kDa, estimated by sodium dodecyl sulphate …

Bacterial Community Function In Pitcher Plant Leaves As An Experimental And Mathematical Model Of Functional Dynamics, Amelia Jackson

Cal Poly Humboldt theses and projects

This work looks at two different sites with differing abiotic factors in measures of altitude, temperature and precipitation. The site with higher altitude, larger temperature range, and lower precipitation, located in Plumas National Forest (Quincy, CA), had a flat BEF trend that suggests functional redundancy The site with lower altitude, more moderate temperatures, and higher precipitation located in Six Rivers National Forest (Gasquet, CA), also had a flat BEF trend. These abiotic factors could correlate to the significantly different bacterial compositions between sites. The second portion of this work is modeling the host antagonist relationship between Eyxra moths and their …

Combining Crispr And Nanoasv To Uncover The Rare Bacterial Communities Of The Human Oral Microbiome, Gilma Ruth Sevilla Alvarez

Master's Projects

Studying the oral microbiome is vital because its health implications are not contained to the mouth. Cariogenic bacteria cause tooth demineralization and oral microbes that translocate to extra-oral organ systems are linked to conditions like Alzheimer’s disease, heart disease, diabetes, and cancer. Some of these pathogens belong to the most abundant phyla in the oral cavity: Bacillota, Pseudomonadota, Bacteroidota, Actinomycetota, Spirochaetota, and Fusobacteriota, which together comprise 94% of the oral microbiome. This project uses CRISPR-Cas9 to deplete sequences from highly abundant phyla and the Eubacteria domain, enriching the remaining 6% of rarer taxa. Paired with NanoASV for single-nucleotide resolution, this …

Surveillance Of A Novel Vesivirus Discovered In An Urban Mephitis Mephitis Population, Amanda E. Diggins

Honors Theses and Capstones

Caliciviridae is a family of non-enveloped, positive-sense, single stranded RNA viruses, including eleven defined genera that contain important pathogens of humans and animals. Within the Caliciviridae family, the genus Vesiviridae includes feline calicivirus, a leading cause of upper respiratory disease in cats, and vesicular exanthema of swine virus, a historical disease of domestic swine that has now been implicated in several marine mammal vesicular diseases, one of which has been confirmed zoonotic. Urban landscapes create a unique environment for rapid intra- and interspecies transmission of viruses. Clustered resources attract high-density populations of synanthropic wildlife species, increasing spatial overlap and heightening …

Investigating Microbe-Mediated Temperature Tolerance In Lemna Minor, Matthew Thomas Farbaniec

Honors Theses and Capstones

Temperature limits plant growth and survival more than many other environmental variables, and increases in the frequency of extreme hot or cold weather events pose significant challenges for plant growth and crop yields. Previous studies have shown that bacteria, fungi, and other microorganisms associated with plants ( i.e., the plant microbiome) can influence host response to temperature stress. These same microbes have their own temperature tolerances. We investigated whether microbial temperature tolerance correlates with plant resilience using an aquatic plant model, Lemna minor, and isolates derived from its microbiome. Microbial isolates were assessed at −10°C, 4°C, and 32°C for …

Microbial Community Structure In Global Soils, Matthew Jabro

CMC Senior Theses

Soil harbors the most diverse microbial communities on Earth, yet whether predictable community types exist across biomes and whether taxonomic composition encodes habitat of origin remain open questions at global scale. This thesis addresses both questions by applying unsupervised clustering and supervised classification to transformed 16S ribosomal RNA (rRNA) amplicon profiles from two independent datasets: the global topsoil survey of Bahram et al. (193 samples) and the Earth Microbiome Project (EMP) soil subset of Thompson et al. (2,209 samples). Application of a sample clustering method based on a mixture of Gaussian Graphical Models (MixGGM) identified 19 clusters in the topsoil …

Characterizing Gut Microbial Communities And Symbiont-Mediated Detoxification In Herbivorous Insects, Rachel C. Vargas

Biology Dissertations

Insect gut bacteria are vital contributors to host physiology, yet the broader prevalence and fitness implications of symbiont-mediated detoxification remain poorly understood. This thesis investigates these dynamics across three research chapters. Chapter 1 uses 16S rRNA sequencing to characterize how grasshopper gut microbial communities vary across species, dietary breadths, and gastrointestinal segments. Chapter 2 evaluates the detoxification capacity of over 150 bacterial isolates from diverse herbivores against the plant allelochemicals phenethyl isothiocyanate, rutin, and chlorogenic acid to determine if host dietary specialization predicts microbial metabolic ability. Finally, Chapter 3 employs fitness bioassays to test whether inoculating generalist herbivores with detoxifying …

Exploring The Link Between Soil Microbes, And Land Use Through A One Health Lens, Yaw A. Antwi

Master's Theses or Doctor of Nursing Practice

The diversity of microbes within the soil plays an essential role in soil ecosystem

functioning. However, these microbes may also serve as environmental reservoirs for antibiotic resistance genes. The study examined the diversity of bacteria that are found in soil across Rural/Agricultural and Rural/Nonagricultural landscapes within some selected counties in Kansas and its associated antibiotic resistance genes taxa. A total of twenty-four soil samples was collected and analyzed using 16S rRNA gene amplicon sequencing which targeted the V3-V4 regions. Statistical analysis revealed that the alpha diversity metrics (Chao1 richness and Shannon evenness) showed no significant difference in microbial structure (p=0.693, …

Lead Biosorption By Oceanobacillus Profundus Kbz 3-2: Strategies For Bioremediation Systems In Kabwe, Danielle S. Desmarteau

Scripps Senior Theses

Lead contamination remains a significant global public health concern, particularly in Kabwe, Zambia, the site of a former lead mining operation. Bioremediation, which utilizes biological materials and processes to remove environmental contaminants, represents a promising approach for addressing lead pollution. However, the development of effective bioremediation systems requires a detailed understanding of the mechanisms underlying metal removal and the feasibility of implementation in low-resource settings. Oceanobacillus profundus KBZ 3-2, a bacterium isolated from Kabwe mine waste, has demonstrated the ability to remove lead from aqueous environments. This study proposes to investigate the mechanism of lead biosorption by this organism, …

Pipeline Corrosion And Relevant Microbial Influence, Renee E. Bamberger

Williams Honors College, Honors Research Projects

This study investigated the role of microbial activity and oxygen availability in the corrosion of carbon steel pipelines with a focus on microbially influenced corrosion (MIC). Sediment collected from Old Woman Creek, Ohio, was used to simulate natural soil conditions, and carbon steel coupons were incubated under four treatments: nonsterile oxic, nonsterile anoxic, autoclaved oxic, and autoclaved anoxic over 85 days. Corrosion was assessed through mass loss measurements and the analysis of pH, sulfate, chloride, and dissolved iron concentrations. The greatest mass loss was observed in autoclaved oxic conditions, contrary to the initial hypothesis that microbial activity would greatly enhance …

Environmental Monitoring In Shallow Lakes: Public Health Threats In Urban Waters, Kyleigh E. Johnson

Theses and Dissertations

Lakes are an integral part of urban and suburban communities, providing ecological, recreational, and public health benefits. Many of these lakes are located in densely populated areas and are subject to urban influences on water quality. Algal toxins and Escherichia coli are two common recreational concerns. Algal toxins come from harmful algal blooms that are influenced by nutrient availability and temperature, while bacteria are often introduced through run-off and animal waste. Sampling every 3-4 weeks from May-October 2025 allowed for the assessment of seasonal patterns and site-specific differences across nine lakes in the Richmond area. The highest bacterial concentrations appeared …

The Ecological Consequences Of Horizontal Transmission Of Symbionts, Bibek Singh Parajuli

Biology Dissertations

Most multicellular organisms depend on their microbial symbionts for various functions, such as digestion, nutrient supplementation, pesticide degradation, and defense. While many insects acquire their symbionts vertically from their parents, thousands of species of true bugs (Hemiptera) across different families acquire their microbial symbiont, Caballeronia, from the environment each generation. Acquiring symbionts from the environment (horizontal transmission) has various ecological consequences for the host. In this study, I used the bug-Caballeronia model 1) to understand whether the free-living symbionts benefit from association with multicellular hosts, 2) to evaluate whether host specialization on symbiont strains varies across taxonomic levels, …

Effects Of Fermented Soybean Products On The Human Gut Microbiome, Microbial Metabolism, And Host Physiology, Shannon Moncier

Biology Dissertations

Fermented soybean products (FSPs) contain soybean-derived substrates, fermentation-associated microorganisms, and bioactive compounds that may interact with the human gut microbiome and host physiology. However, despite the growing interest in FSPs, longitudinal human studies specifically evaluating traditional Korean-FSPs (K-FSPs), particularly among United States-based populations, remain limited. The objective of this work was to evaluate the effects of three K-FSPs, including Cheonggukjang, Gochujang, and Doenjang, on host physiological responses, gut microbial community structure, predicted microbial functional potential, and fecal butyrate responses in healthy adults. Three independent dietary intervention cohorts were conducted using FSP formulations produced either by traditional artisan methods (Product A) …

Remediation Impacts Metal Concentrations And Metal Tolerant Bacteria In Soils Of The Missouri Tri-State Mining District, Ophelia R. Pettington

Graduate Theses/Dissertations

After over 100 years of Zn and Pb mining in the Tri-State mining district (TSMD), former mines continue to be sources of metals. Metal contaminated soils can be remediated using plant-microbe interactions. Plants manipulate their microbiome and recruit microbes to increase metal tolerance. Remediating bacteria are site-specific and identifying native microbes can accelerate remediation efforts. Studies relating microbes and metal concentrations in remediated areas in the TSMD are scarce. I collected root and bulk zone soils associated with Andropogon virginicus from remediated and non-remediated sites in Webb City, MO. I used 16S rRNA gene amplicon sequencing to evaluate the bacterial …

Exploring The Application Of Wastewater Monitoring To Determine The Prevalence And Diversity Of Influenza On The Campus Of West Virginia University, Lakyn Renee Sanders

Graduate Theses, Dissertations, and Problem Reports (ETD)

Influenza viruses (IV) affect populations globally, with the World Health Organization (WHO) estimating that IV are responsible for an estimated 3-5 million infections and 290,000 – 650,000 deaths annually^1–3. More specifically, the 2019-2020 IV season is associated with an estimated 38 million illnesses and 22,000 deaths in the United States alone⁴. IV are rapidly spread between individuals through direct contact with infected individuals, contaminated surfaces, or aerosolized virus particles². Traditional IV infection monitoring relies on clinical screening of patients presenting influenza-like symptoms, commonly through the use of multi-target panel tests such as the BioFire …

Exploring The Interplay Of Operational Conditions, Microbial Communities, And Water Quality In Drinking Water Ozone-Biofiltration, Kara Yvonne Cunningham

Graduate Theses, Dissertations, and Problem Reports (ETD)

Ensuring reliable access to safe drinking water is a growing global challenge as water utilities face variable source water quality driven by population growth, land‑use change, and climate change impacts. To address these challenges, utilities are implementing advanced treatment technologies designed to improve reliability under variable source water conditions. Ozone-biofiltration has emerged as a treatment approach that can reduce a wide range of natural and anthropogenic contaminants. However, despite its increased use, there is limited insight into the biological processes shaping filter function or how they respond to operational and environmental changes. Advances in molecular microbiology and high-throughput sequencing now …

Plant Invasion Patterns In Understory And Soil Microbial Communities Of North Central West Virginia Mixed Hardwood Forests, Isabelle Marie Uganski

Graduate Theses, Dissertations, and Problem Reports (ETD)

Invasive plants alter forest ecosystems by reducing species richness, habitat heterogeneity, and nutrient cycling as they rapidly displace native plants. Invasive plant composition can influence soil health through altering soil microbial associations and communities. By studying the mechanisms in which invasives alter above- and below-ground communities, we can better understand whole-ecosystem impacts and inform management decisions. This study examined the relationships between co-occurring invasion on above and belowground communities of mixed hardwood forests of north central West Virginia. Despite distinctive associations with aboveground characteristics (native diversity, native tree regeneration, and leaf litter density) we detected limited changes to soil microbial …

The Influence Of Localized Water Quality On Eastern Oysters (Crassostrea Virginica) And Their Internal Microbiome Under Changing Environmental Conditions, Jessie Rivera Lafreniere

College of Graduate Studies: Theses & Dissertations

Oysters are found ubiquitously in estuaries along the Georgia coast, where marsh morphology and large daily tidal fluctuations create dynamic and stressful conditions to which oysters may be locally adapted. Based on water quality data from the Sapelo Island National Estuarine Research Reserve, it is evident that changing climatic conditions are rapidly causing shifts in water quality that may be adversely affecting oyster health, especially as ocean acidification alters the carbonate buffering capacity, increasing the amplitude of daily pH variations. Importantly, the rate of change of conditions are not uniform within estuaries, varying on spatial and temporal scales. The symbiotic …

Regulation And Localization Of Urease In Sporosarcina Pasteurii: Implications For Coastal Protection, Amar Kosovac

UNF Graduate Theses and Dissertations

Coastal erosion is a persistent problem exacerbated by global warming. As the climate changes, the southeastern coast is likely to experience an increased frequency and intensity of storms, which can significantly damage the coastline. The coast is crucial as it serves as a habitat for numerous animals, supports tourism, and underpins infrastructure. Microbially induced calcite precipitation (MICP) is a novel method to enhance erosion resistance in sandy soils using the non-pathogenic bacterium Sporosarcina pasteurii. S. pasteurii produces urease to catalyze urea into bicarbonate, which drives the precipitation of calcium carbonate. Maximal expression of urease is a limiting factor for …

Assessing The Impact Of Storing Water Samples At Ambient Temperature On Plankton Metabarcoding, Stephanie N. Lievano

Honors Undergraduate Theses

Increasing incidence of Harmful Algal Blooms (HABs) has led to fish kills, air quality hazards, and economic impacts. One economic impact is on tourism, one of the main sources of Florida’s income, where billions of dollars are lost to such events. The Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute (FWC-FWRI), with the help of collaborators, collects water samples from across the state for HAB monitoring. These samples are stored at ambient temperature for up to 24 hours which could directly affect data analyses. Here, in collaboration with FWRI-FWC, I investigated whether this storage technique affects plankton …

Quantifying Amendment Impact On Microbial Respiration Rate, Qwynn Starrwalker

Honors Undergraduate Theses

Wetlands play a critical role in the global carbon cycle by acting as carbon sinks, where the flooded anaerobic conditions cause slow microbial respiration compared to other soils. Comparatively more carbon is stored in the soil as organic matter than is released as carbon dioxide (CO₂). Making wetland pools of soil organic matter less available to microbes for respiration could reduce overall atmospheric CO₂ and slow global warming. This study examined the effect of kaolinite, goethite, and lime on microbial respiration rates in wetland soils under alternating hydrologic conditions. Homogenized soil from a cypress dome was separated …