Bacteriology Commons^™

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 …

Submarine Groundwater Discharge As A Potential Driver Of Bacterial Microbiome Shifts In Nearshore Coral Reef Ecosystems At Black Point, Maunalua Bay, Oahu, Francesca Rasi, Niyam Reddy, Emily Mendoza, Jayla Burson, Florybeth La Valle

Seaver College Research And Scholarly Achievement Symposium

Coral reefs thrive in primarily oligotrophic environments, depending on factors such as temperature and salinity for their stability. While moderate levels of nutrients sustain coral growth, excessive nutrient inputs promote algal blooms which can outcompete corals for space. Over the past century, Maunalua Bay (O'ahu, HI) has experienced dramatic development and increase in population, which has affected the water quality in the nearshore coral reefs of the bay. The main source of dissolved land-based inorganic nutrients in Black Point is submarine groundwater discharge (SGD), which is a chronic freshwater vector that is enriched with nitrates, phosphates, silicates, and more. Because …

A Novel Endolysin Of Phage Persinger Infecting Pseudomonas Aeruginosa: Activity Against Biofilms And Structural Prediction, Layla Abbud

James Madison Undergraduate Research Journal (JMURJ)

Endolysins are proteins that degrade bacterial cell walls. They are encoded on the genome of bacteriophages (viruses that infect and kill bacteria). At the end of the lytic cycle of a bacteriophage, endolysins cut the peptidoglycan layer of the bacterial cell wall, allowing the release of viral progeny. Pseudomonas aeruginosa is a well-known multidrug-resistant human pathogen that causes serious problems, especially in patients diagnosed with cystic fibrosis (CF). One property of P. aeruginosa is the production of biofilms, which is a defense against antibiotics. Previous research has shown that endolysins from bacteriophages can degrade biofilms. The endolysin protein from Persinger, …

Effects Of “Zero Sugar” Energy Drinks On Microbial Proliferation In Relation To The Gastrointestinal Microbiome, Madison Hines

Honors Theses

Energy drinks have rapidly increased in popularity and availability in recent years. With the rise of high-caffeine beverages, complications due to caffeine consumption have become more common in younger populations. The aim of this study was to use controlled laboratory methods to determine the effect of energy drinks on a variety of organisms commonly found in the gastrointestinal (GI) tract. The diverse and dynamic nature of microbes in the gut makes conditions of the GI tract difficult to replicate in a laboratory setting. As an alternative, isolates of bacteria commonly found as normal flora in the GI tract were plated …

Antibiotics And You: A Comprehensive Guide, Brady Haas

Senior Theses

Antibiotic resistance is a rapidly emerging issue within public health. As resistance grows, the effectiveness of traditional antibiotic therapies diminishes while risk of treatment grows. Alongside novel therapies, public knowledge is a strong combatant of the resistance-related risks of antibiotic usage. Through a comprehensive review of current literature, this work serves as an accessible guide to the mechanisms of antibiotics, bacterial resistance, and the challenges related to current antibiotic usage. Additionally, the ability of current policy and emerging novel treatments, such as nanoparticles and bacteriophage therapy, to fight antibiotic resistance is evaluated. This analysis highlights the importance of improving public …

Evolution Of Antibiotic Responses During Chronic P. Aeruginosa Infections In The Human Lung, David Frank Ritz

Dartmouth College Ph.D Dissertations

Typical antibiotic susceptibility testing (AST) of microbial samples is performed in homogeneous cultures in batch environments, which does not account for the highly heterogeneous and dynamic nature of antibiotic responses. The most common mutation found in P. aeruginosa lineages evolved during chronic cystic fibrosis infections in the human lung, a loss of function of repressor MexZ, increases basal levels of multidrug efflux MexXY, but does not increase resistance by traditional minimal inhibitory concentration (MIC) assays. Here, we use single cell microfluidics to show that P. aeruginosa’s response to aminoglycosides is highly heterogeneous, with only a subpopulation of cells surviving exposure. …

In Vitro And In Silico Analysis Of The Antibacterial Activity Of Bioactive Compounds Extracted From Pineapple Peel, Wafa Mohammad Sadik, Iman Tajer Abdullah, Lana Abed Alnajar

Makara Journal of Science

Antibiotic resistance is a critical global challenge that requires the discovery of alternative therapeutic agents. Plants -derived compounds, such as those found in Ananas comosus (pineapple)peel, offer promising antibacterial potential. This study aimed to evaluate the antibacterial activity of pineapple peel extract using both in vitro and in silico approaches. Ethanolic extracts of pineapple peel were fractionated using silica gel chromatography, and the resulting fractions were analyzed by GC-MS. Antibacterial activity was tested against Gram-positive and Gram-negative pathogens using the agar well diffusion method, and the inhibition zones were recorded. Molecular docking was performed to assess the interaction of identified …

Norfolk Flooding And Its Effect On Nutrient And Enterococcus Levels, Malachi R. Stephens

Knowledge and Creativity Expo

Tidal flooding is common in the City of Norfolk, VA due to high rates of sea rise in the region, as well as the region’s subsidence. This has led to increases in flooding at high tide, especially during the spring tide portion of the tidal cycle.  At high tide water from the Elizabeth and Lafayette Rivers can flood the landscape directly or can rise out of storm drains. This floodwater often stays on land for long periods of time and can deliver contaminants back into the rivers. To determine the amounts of nutrients and Enterococcus, a fecal indicator, delivered to …

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 …

Molecular Techniques: A Project-Based Undergraduate Laboratory, Ming-Mei Chang

Milne Open Textbooks

This book can be read online at: milnepublishing.geneseo.edu/molecular-techniques

Molecular biology, examining the structures and functions of nucleic acids and proteins, is crucial to advancing biological science and improving human life, particularly in agriculture and medicine. Advances in the field can transform a crop to resist disease or uncover clues to fight illness by manipulating DNA. Techniques for molecular biology research and applications have advanced rapidly over the past decades, and undergraduates need hands-on experiences in this vital field of science. This text provides a structured approach to learning and practicing those techniques, covering DNA, RNA, and protein across five modules …

Oral Streptococcus And Vitamin B12 Deficiency In E-Cigarette Users: A Microbial–Nutrient–Neurotransmitter Axis Linking To Mood Disturbances, Maryam Sabah Naser, Ali Jabbar Abd Al-Hussain Alkawaz, Ali Abbas Hashim Almusawi, Ali Jalil Obaid, Hasanain Ayed Mohammed Al-Khafaji, Reihaneh Sabbaghzadeh

Karbala International Journal of Modern Science

Background: With the rising popularity of e-cigarettes, questions have emerged regarding their broader influence on oral ecology, nutrient absorption, and psychological health. Disruptions in the oral microbiome may alter vitamin B12 dynamics. This, in turn, may indirectly influence serotonin biosynthesis and mood regulation.

Methods: An observational cross-sectional study involved 150 young adults segregated into groups of 50 each as vapers, smokers, or non-users. Streptococcus sanguinis and vitamin B12 metabolism-related variable statuses methylmalonic acid and holotranscobalamin were quantified in samples, along with inflammatory markers interleukin-6, kynurenine/tryptophan ratio, and serotonin. Statistical techniques, including ANOVA and the Kruskal-Walli’s test, correlation, and serial mediation …

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 …

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 …

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 …

Population Genomics And Evolution Of Pseudomonas Aeruginosa, Samara T. Choudhury

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is a Gram-negative bacterium ubiquitous in diverse environments and an opportunistic pathogen in humans. It is a leading cause of chronic lung infections in cystic fibrosis patients and of hospital-acquired pneumonia and sepsis. With a large flexible genome and abundant mobile genetic elements, P. aeruginosa exhibits high levels of antimicrobial resistance (AMR), making it a significant public health threat. Evolutionary processes such as homologous recombination, and horizontal gene transfer generate extensive genomic diversity in this species and facilitate the spread of resistance genes. In this dissertation, I investigate the genetic and evolutionary factors shaping P. aeruginosa population structure …

Regional Oceanographic Controls On Water Column Nitrogen Fixation In Northern Australian Waters, Douglas G. Capone, Ajit Subramaniam, Yubin Raut, Joseph P. Montoya, Margaret R. Mulholland, Rachel Ann Foster, Miles Furnas, Edward J. Carpenter

OES Faculty Publications

Large blooms of the diazotrophic cyanobacteria, Trichodesmium, have been re-ported along the north coast of Australia and are readily evident in remote sensing images. During a research cruise in November 1999, we sampled from Townsville to Broome, examined Trichodesmium population densities and their rates of carbon and N₂ fixation alongside microscopy-based cell counts of them and other cyanobacte-rial diazotrophs. Additionally, we also enumerated the picophytoplankton community using flow-cytometry, measured bulk chlorophyll concentrations, carbon and N₂ fixation rates, and water column hydrography, enabling comparison of diazotrophic and picophytoplankton functional groups across the system. Agglomerative hierarchical clustering analysis of physicochemical oceanographic …

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 …

Requirement Of Prepiilin Peptidase Activity For Variovorax Paradoxus Eps Flp/Fap Pilus Assembly, Jenny L. Lanthripp

Electronic Theses, Projects, and Dissertations

Variovorax paradoxus is a Gram-negative aerobic bacterium present in both soil and the human oral microbiome. This species contributes to biotransformation of xenobiotics and promotes plant growth. Interestingly, although the genome of strain EPS lacks the flagellum operon annotated in strain S110, the microbe remains motile, and flagella can be observed microscopically. To investigate this unexpected phenotype, motility mutants were enriched from a Tn5 mutant library using a liquid culture settling strategy. A total of 122 isolates were screened for motility defects, and 57 exhibited significantly reduced motility compared to the wild type. Rescue cloning revealed that over 60% of …

Functional Analysis Of Ftsa-Mediated Recruitment Of Ftsk In Escherichia Coli, Abbigale Perkins

Dissertations and Theses (Open Access)

Bacterial cytokinesis requires precise coordination between cytoplasmic and periplasmic components of the divisome to ensure that membrane constriction and chromosome segregation occur in synchrony. The actin-like protein FtsA plays a central role in this process by tethering FtsZ to the membrane and recruiting downstream division proteins. Despite its essential function, the mechanisms by which FtsA coordinates divisome activation and the recruitment of late-acting proteins remain incompletely defined. To address this, the role of FtsA in activating septal synthesis and recruiting the DNA translocase FtsK was examined using mutational analysis in Escherichia coli.

The FtsA^{M96E R153D} variant, which has …