Microbiology Commons^™

Evaluating Soil Health And Crop Yield In Louisiana Agricultural Systems: Impacts Of Best Management Practices And Prediction Models, Hector J. Mendoza Lagos

LSU Doctoral Dissertations

The adoption of conservation management practices is critical for improving soil health, enhancing nutrient use efficiency, and sustaining crop productivity in row crop systems in Louisiana. This study evaluated the role of conservation agronomic practices, soil biochemical indicators, and machine learning predictive models to improve soil nutrient dynamics, soil health indicators, microbial communities (MC), and crop productivity on a corn (Zea mays L.) research plot scale and in a commercial forty-hectare cotton (Gassypium hirsutum L.)-corn-soybean (Glycine max L.) rotation system in northeast Louisiana. The objectives of the study were to evaluate soil nutrient dynamics and MCs under …

Examining The Ligands, Location, And Function Of Toll-Like Receptor 10, Kiefer Keanu Tam

Master's Theses

Toll-like receptors are a class of innate immune pattern recognition receptors that detect pathogen-associated molecular patterns and regulate downstream inflammatory responses. Toll-like receptor 10 remains the only human TLR whose ligand specificity, cellular localization, and immunological function are not fully defined. Emerging evidence suggests that TLR10 may play an anti-inflammatory role and can heterodimerize with TLR2 to modulate immune signaling. Previous studies from our laboratory demonstrated that stimulation with heat-killed Mycobacterium tuberculosis promotes TLR2-TLR10 heterodimerization and trafficking to the cell surface. In this study, we expanded our ligand panel to include additional gram-positive bacteria, particularly anti-inflammatory probiotic species, to further …

Analysis Of Bacterial Virulence And Resistance In A Model Of Recurrent Uti, Rachel L. Proper

Undergraduate Honors Theses

Urinary tract infection (UTI) is a major women’s health issue, affecting approximately 40% of women during their lifetime. Formation of a biofilm by UTI-causing bacteria poses a major challenge in treatment, as the protection provided by the biofilm hinders both host defenses and antibiotic treatment. Failure to eradicate these infections causes them to become recurrent (rUTI). Previous research indicates that rUTI may be comorbid with a mutation in the SERPINE1 gene, which causes fibrin to accumulate within the body. Literature also indicates that fibrin provides a better scaffold for bacterial attachment and, subsequently, biofilm formation. In this work it was …

Maintaining And Axenizing Live Cyanobacterial Cultures For Bacterial Genome Sequencing, Yufei Wang, Louisa Acquah

SACAD: Scholarly Activities

Harmful cyanobacterial blooms are an

increasing concern in western Kansas, yet the

bloom-forming species in this region remain

poorly characterized. In this study, we

established and maintained axenic

cyanobacterial cultures to support future

genomic and ecological investigations. By

ensuring low contamination levels and stable

growth conditions, this work provides a

foundation for downstream analyses of bloom-

forming cyanobacteria. It contributes to a better

understanding of freshwater ecosystem health

in western Kansas.

Quantifying The Antifungal Properties Of Bacteria Using Cotton Strips, Lily Lofton

Honors Theses

Many bacteria have been known to have antifungal properties. Research has begun to determine how these bacteria can be used to protect cotton and other cellulose-rich textiles. In the present study, standardized cotton strips were inoculated with two different bacterial consortia that have exhibited anti-fungal properties. These strips were then inoculated with the melanized cellulolytic fungi, Chaetomium globosum and Rhinocladiella similis. Similarly, some cotton strips were also inoculated with a non-melanized fungus, Rhodotorula toruloides, which is also thought to be cellulolytic. The tensile strength of cotton strips was measured along with the ergosterol concentrations (fungal biomass) for each cotton strip …

Bio 230 - Microbiology, Sarah Moroianu

Open Educational Resources

This open educational resource (OER) syllabus is designed for BIO 230: Microbiology at Lehman College, City University of New York (CUNY), a single-semester introductory microbiology course for non-biology majors such as Nursing, Dietetics, Health Education, and Physical Education. The course reviews microbial structure, metabolism, genetics, and microbial ecology, with applied emphasis on infectious disease, antimicrobial drugs, host immune defenses, and microbial diseases. The syllabus aligns course content with the freely available OpenStax Microbiology textbook (Parker et al., CC BY 4.0) and reflects accessibility best practices consistent with CUNY guidelines.

Biofilm Architecture Determines Proliferation Of Phages And Plasmids, James B. Winans

Dartmouth College Ph.D Dissertations

This thesis explores how biofilm architecture determines the spread and ecological consequences for the bacteria-dependent genetic elements phages and plasmids. Using Escherichia coli and Vibrio cholerae as model microbes, and the genetic elements T7 phages, λ phages, and conjugative plasmid pED208, we investigate how spatial structure influences phage infection dynamics, plasmid transfer, and interbacterial interactions within biofilms. We show that densely packed biofilms can protect sensitive bacteria from phage exposure and modulate competitive outcomes between obligately lytic and temperate phages. We find that entirely different outcomes can coöccur within microns of each other dependent on biofilm structure. We also demonstrate …

A Bacillus Pumilus Isolate With Promising Antimycobacterial Properties, Cody M. Pfaff

SACAD: Scholarly Activities

The emergence of multidrug-resistant bacterial pathogens, particularly Mycobacterium tuberculosis, highlights the urgent need for new antimicrobial agents. Tuberculosis remains one of the world’s deadliest infectious diseases, claiming over a million lives annually and posing increasing challenges due to the thick, lipid-rich, acid-fast cell wall of Mycobacterium species that renders them naturally resistant to many antibiotics. In this study, a soil sample collected from the Campus of Fort Hays State University yielded a bacterial isolate exhibiting strong antimicrobial activity. Initial screening against Escherichia coli MM294 showed a 10 mm inhibition zone, and subsequent testing identified the isolate as Bacillus pumilus …

Antimicrobial Activity Of Violacein Extracted ​ From Janthinobacterium Lividum​, Catherine M. Brownhill-Slatore

Scripps Senior Theses

Abstract

Antibiotic-resistant bacteria have been a threat since the discovery of antibiotics. The increased rise of antibiotic-resistant bacteria has created an immediate need for new antibiotics. Violacein, a purple bisindole pigment produced by Janthinobacterium lividum, has been shown to be a promising new antibiotic. Its efficacy has not been completely demonstrated, and this project aims to further investigate the effectiveness of violacein as an antibiotic. To do this, a minimum inhibitory concentration (MIC) test was conducted. Violacein was grown, extracted, purified, and tested across concentrations ranging from 1.0 to 500.00 µg/mL to cover values well above and below previously cited …

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 …

Coordinating The Layers: Regulation Of Peptidoglycan Synthesis And Cell Wall Assembly In Mycobacterium Smegmatis By Murj And Pgfa, Karen Emmanuella Samaga-De-Tembiwa

Biology Dissertations

The mycobacterial cell envelope consists of three covalently linked layers whose synthesis must be coordinated to maintain structural integrity during polar growth. While the biosynthetic enzymes for each layer are well characterized, the molecular mechanisms that coordinate synthesis across layers have remained poorly understood. This thesis investigates two essential transmembrane proteins, PgfA and MurJ, that regulate peptidoglycan metabolism in Mycobacterium smegmatis and provide new insight into how mycobacteria synchronize cell wall assembly.

We present evidence that PgfA functions as a bifunctional regulator that links peptidoglycan metabolism to the availability of trehalose monomycolate (TMM), a key mycolic acid precursor. Through epistasis …

A Comparison Of White-Light And Monochromatic Led Sources For Antimicrobial Photodynamic Inactivation Of Staphylococcus Aureus, Emily Simmons

The Journal of Purdue Undergraduate Research

Drug-resistant bacteria are an ongoing public health crisis for which alternative treatments are needed. One alternative is antimicrobial photodynamic inactivation (aPDI), which uses potent photosensitizers and light irradiation to damage the bacteria. Our standard light source used in aPDI is a single-wavelength light source at 405-nm; however, we evaluated a white-light source for similarities in the resulting aPDI activities. This is done by comparing aPDI experiments using S. aureus and its methicillin-resistant strains (MRSA) conducted with either the white LED light source or the 405-nm LED light source. Statistical analysis using t-tests revealed no significant differences in the aPDI activities …

Comparative Analysis Of Taproot And Fibrous Root System Microbiomes Under Flooding Stress, Natalie S. Kozlowski, Leighanna Jake

Humboldt Journal of Microbiology

There has been increased interest in understanding how the microbiomes of vascular plants respond to flooding stress and, many studies have focused on monocotyledonous plants with fibrous root systems. This leaves a gap in knowledge of dicotyledonous plants with taproot systems, as previous studies have been in the context of flooding to cropland affecting major food crops which are often monocotyledonous plants with fibrous root systems. Since the structural and functional differences between these root systems may influence microbial community stability and response to flooding conditions, a study looking at both is long overdue As such, this study aims to …

Enhancing Preparedness: A Genetic Study Of Sar-Cov-2 And Other Microbial Public Health Threats In Wastewater From A College Town, Christian N. Hutchinson

Master's Theses

Problem

The SARS-CoV-2 (COVID-19) pandemic revealed both the systemic vulnerabilities of our healthcare system as well as the importance of timely, localized data for informing public health responses. Traditional testing approaches were essential but often failed to capture the full extent of viral spread, especially in those with mild or asymptomatic conditions that relied on at home testing. This underreporting hindered effective allocation of resources and made developing effective intervention strategies difficult. We also realized the potential for wastewater surveillance to be applied to tracking antimicrobial resistance gene markers. Taken together, this approach should have important implications for improving public …

Hot Spring Associated Infectious Diseases In The Great Basin And Southwest, Matthew Bentz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Like all bodies of freshwater, natural hot springs can harbor pathogenic microorganisms that carry the threat of infectious disease. The unique chemistry, increased temperature, and popularity for bathing may alter the risk profile of hot springs compared to other natural bodies of water. Despite this risk, the role of hot springs as a reservoir for infectious diseases remains understudied, particularly within the context of regional public health. Nevada and the Great Basin/Southwest have increasingly promoted hot springs for the purposes of tourism, and they share a strong link to the cultural heritage of the region. The unknown risk profile and …

Impacts Of Land Development On Soil Microdiversity And Antibiotic Production, Dennis Guillen Castro, Robert Garcia, Jonathan Castro, Davida Smyth

Masters Theses (Archived)

The impact of land development on soil microbial diversity and antibiotic production is critical due to industrial expansion and the scarcity of effective antibiotics. Low Impact Development (LID) aims to preserve ecosystems, but its effectiveness in maintaining microbial diversity is uncertain. This study compares soil samples from nine sites: undisturbed (UD), residential (RD), and Madla Greenway (GW) within the VIDA development area and Texas A&M University-San Antonio campus. Isolated microbes were screened for antibiotic production and genetically characterized. Preliminary findings indicate that UD sites harbor greater microbial abundance, and a higher proportion of antibiotic-producing microbes compared to GW and RD …

Investigation Into The Microbiome Of Blow Fly Eggs Using Microseqtm Id, Samantha S. Davis, Drusilla Sheridan, Jennifer Rosati

Undergraduate Research

There is little published research characterizing the microbiome associated with blow fly eggs and how they may affect the colonization behaviors of certain blow fly species. Once deposited, blow fly eggs are rapidly introduced to a diverse range of microorganisms, which can vary depending on the species of blow fly, the environment, and the decomposition stage of the substrate (Junqueira et al., 2017). Since blow flies are among the first insects to colonize decomposing remains, the microbial communities present on their eggs could serve as key indicators of the decomposition stage at the time of egg-laying, thus providing a potential …

Biological Reduction Of Perchlorate In Martian Regolith Simulant Using Azospira Oryzae, Brianna Bernhardt

Honors Program: Senior Projects (Public)

Establishing a sustainable human presence on Mars will require in-situ resource utilization (ISRU) to reduce costly and inefficient resupply missions. Despite containing many of the requirements for agriculture, Martian regolith is contaminated with toxic levels of perchlorate (ClO₄^-), threatening human health and agricultural success. Biological remediation using perchlorate-reducing bacteria offers a promising approach to address these challenges. This study investigated the perchlorate-reducing ability of Azospira oryzae, a facultative anaerobe capable of converting ClO₄^- to chloride (Cl^-) through dissimilatory respiration. A. oryzae was cultured in Martian regolith simulant (MGS-1) amended with 0.0%, 0.5%, …

Bacterial Microbiomes In Different Depths Of Sand At The Mississippi Gulf Coast, Hays S. Roth

Honors Theses

Microbial communities in sand play essential roles in their ecosystems, yet little is known about how bacterial diversity and function vary across different sand depths. This study investigated bacterial microbiomes at varying depths (0, 10, 20, 30, and 40 cm) on Biloxi East Beach, on the Mississippi Gulf Coast, using 16S rRNA gene sequencing and assays of extracellular enzyme activity. 11,161 amplicon sequence variants (ASVs) were identified across all samples, with the most abundant bacterial phyla being Planctomycetota, Gammaproteobacteria, and Bacteroidota. Depth had a significant impact on bacterial community composition, with surface layers having more diverse bacterial communities. Microbial diversity …

Neutrophil Inflammatory Death Regulation By Bacterial Type Iii Secreted Effectors, Arianna D. Reuven

Dartmouth College Ph.D Dissertations

Yersinia and Pseudomonas use a T3SS to secrete effectors into host cells that inhibit phagocytosis and modulate immune responses, such as inflammasome activation. Inflammasomes promote the activation of the proinflammatory protease caspase-1. The activation of an inflammasome sensor in response to a signal or ligand initiates the assembly of the inflammasome leading to activation of caspase-1 which cleaves GSDMD and pro-inflammatory cytokines IL-1β and IL-18 into their mature forms. As neutrophils are recruited in large quantities to sites of infection, they are excellent candidates to drive inflammasome dependent responses. Neutrophils have been shown to produce multiple inflammasomes, like pyrin and …

The Isolation And Characterization Of Acidovorax And Brevundimonas Bacteriophages With Preliminary Biocontrol Study On Arabidopsis Thaliana, Minh Quynh N. Vu

Senior Theses

As antibiotic-resistance becomes an increasing global concern, researchers are looking for alternatives to combat phytopathogenic rhizobacteria – one of which is through the application of phage biocontrol. To elucidate the complex tripartite relationships between phage, bacteria and plant interactions, nine novel phages were isolated from potential phytopathogenic strains of Acidovorax (RBW13) and Brevundimonas (RBW18). These phages were isolated from root samples obtained from the Rocky Branch Creek and the Broad River located in Columbia, SC. Using Pulsed-Field Gel Electrophoresis (PFGE), we identified seven “medium sized” phages (~40 kbp), one “large-sized” phage (~200 kbp), and one “small-sized” phage ( < 25 kbp). Three phages were determined to be lambda-like due to their “ladder-building” patterns on PFGE. Although spot-tests revealed that all phages seemed to have broad host ranges that spanned over multiple genera, plaque-formations must be observed in future experiments to determine if these phages can infect their hosts productively. Preliminary in planta experiments were performed on Arabidopsis thaliana …