Microbiology Commons^™

Developing A Microdialysis Sampling-Based Biofilm/Macrophage Co-Culture Model, Alda Diaz Perez

Graduate Theses and Dissertations

The host immune system and bacterial cells are known to interact during the human lifetime. Bacteria secrete a wide variety of signaling molecules, known as quorum sensing (QSC) molecules, that modulate the host immune system. While immune-biofilm interactions involve this chemical signaling network, the mechanisms through which this occurs are not well understood. This work aimed to develop a new method that can be used not only in vitro settings but also in vivo. The microdialysis sampling technique has widely been used in in vitro and in vivo settings in humans, mice, and rats for the collection of neuropeptides, cytokines, …

Phenotypic Characterizations Of Msaabcr Operon Deletion In Staphylococcus Epidermidis Rp62a, Raelyn Williams

Honors Theses

Staphylococcus epidermidis is a human pathogen that is increasingly known for its role in hospital infections associated with implantable medical devices. Antibiotic resistance has become a concerning issue for these infections as this bacteria have various virulence traits that help to evade immune response and antibiotic treatment. Currently, the most effective way to treat S. epidermidis infection is removal of the implant and long-term antibiotic treatment. S. epidermidis causes infection by expressing several protein factors that induce biofilm formation, the bacteria’s primary virulence mechanism. The purpose of this study was to perform the phenotypic characterizations of the msaABCR operon in …

Phosphodiesterase D Is Involved In Bile Resistance In Listeria Monocytogenes, Sophia A. Ali

Honors Theses

Listeria monocytogenes is a deadly foodborne bacterium that is responsible for almost 20% of food-related deaths in the United States. Listeria monocytogenes contaminates ready-to-eat products such as cheese, deli meat, and ice cream. Once ingested, it invades the intestinal lining and can enter the bloodstream, causing listeriosis. There is a gap in the knowledge of the pathogenesis of L. monocytogenes in how it is able to survive in the gastrointestinal tract in the presence of bile, which has bactericidal properties. Previous studies have suggested that the second messenger cyclic-dimeric-GMP may be involved in the regulation of virulence factors of Listeria. …

Implications Of The Evolutionary Past On The Activities Of Virb: A Key Transcriptional Regulator Of Virulence Genes In Shigella Flexneri, Jillian Nicole Socea

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella species are bacterial agents that are the leading cause of diarrheal diseases, the second leading cause of child mortality worldwide. One key protein in Shigella is VirB, a transcriptional regulator of virulence genes that is essential for pathogenicity. VirB functions to antagonize H-NS, a histone-like nucleoid structuring protein that silences many genes found on the large virulence plasmid (pINV). The interplay between H-NS, the silencer, and VirB, the anti-silencer, is fundamental for Shigella virulence. Furthermore, this mechanism of gene regulation appears widespread in many bacteria including other enteric pathogens.

The goal of my dissertation was to explore the activities …

Genomic Analysis Of Paenibacillus Larvae Bacteriophages, Casey Stamereilers

UNLV Theses, Dissertations, Professional Papers, and Capstones

American Foulbrood is the most destructive bacterial infection of the honeybee (Apis mellifera) and is caused by the Gram-positive, spore forming bacterium Paenibacillus larvae. Current treatment methods rely on antibiotics, but antibiotics treatments are experiencing a reduction in efficacy due to the recent rise in antibiotic resistant strains of P. larvae. This has been a major catalyst for exploration of alternative treatment methods. Phage therapy is an alternative treatment method that uses viruses that exclusively infect bacteria, known as bacteriophages (phages), to combat bacterial infections. Several experimental studies have shown that phages P. larvae phages are effective at lysing P. …

Sodium Pyruvate Ameliorates Influenza A Virus Infection In Vitro And In Vivo, Jessica M. Reel

Graduate Theses/Dissertations

Pyruvate is produced in duplicate at the end of glycolysis in addition to ATP and NADH. Pyruvate is the metabolite of choice in most cells, whether obtained exogenously or endogenously. Recently we found that the addition of pyruvate’s conjugate base, sodium pyruvate, to cell culture media dampened the immune response to influenza A virus (IAV) infection in cultured innate immune cells. Thus, I decided to investigate the mechanism and potential for treatment of IAV. In vitro using bone marrow derived macrophages that were infected with IAV we found that adding sodium pyruvate to the media decreased immune signaling pathways through …

Suppression Of Inflammation Of Cytokine Following Induced Francisella Tularensis Infection, Nicole Renee Setzu

Open Access Theses & Dissertations

Francisella tularensis is intracellular bacteria which is the causative agent of the disease Tularemia. Highly virulent in both humans and animals, it takes only as few as 10 microorganisms to cause a lethal infection. The bacteria can enter via direct or indirect routes causing the activations of the host innate inflammatory response to ensue. The bacteria invade host dendritic cells and neutrophils but predominately macrophages. This causes a mass inflammatory response resulting in the cytokine storm. Activation of Natural Killer T (NKT) cells has been shown to suppress inflammation in in vivo studies. Development and optimization of an in vitro …

How Historic Shipwrecks Influence Dispersal Of Deep-Sea Microbiomes, Rachel Moseley

Master's Theses

This thesis investigates how historic shipwrecks potentially shape dispersal of deep-sea microbiomes. Processes impacting dispersal of microbiomes around artificial structures in the ocean and how they connect to other deep-sea habitats is unknown. Dispersal processes are explained for some macroorganisms by theories in ecology, specifically the Theory of Island Biogeography and the Wooden Stepping Stone hypothesis. These have not been investigated for microorganisms, and thus this work will probe if they are applicable to microbial biogeography in this habitat. Experiments were conducted to establish new “island-like” features in near proximity (25-125 m) to wooden-hulled historic shipwrecks in the northern Gulf …

The Impact Of Oxygen Availability And Oxidative Stress On Regulation Of Cyclic-Dimeric-Gmp In Listeria Monocytogenes Strain F2365, Anna G. Welch

Honors Theses

Listeria monocytogenes is a gram-positive foodborne pathogen that results in the infectious disease listeriosis. The second messenger molecule cyclic-dimeric-GMP has been found to be responsible for the regulation of expression of many of its virulence factors with diguanylate cyclases and phosphodiesterases regulating the intracellular concentration of cyclic-di-GMP through synthesis and degradation, respectively. This study investigated the possibility that the availability of oxygen is the environmental signal crucial to the regulation of these enzymes. Prior research in our laboratory has demonstrated that the intracellular concentration of cyclic-di-GMP is elevated when exposed to anaerobic conditions. Due to this, it was hypothesized that …

Bioremediation: Breaking Down The Regulations Of Genetically Modified Microorganisms, Lora Katharine Naismith

Texas A&M Law Review

Environmental bioremediation is the use of biological activity to reduce the concentration or toxicity of a pollutant. A rapidly increasing population leads to a consequential increase in industrial waste and pollution, and innovators are researching numerous techniques to degrade these pollutants and prevent their spread into the environment. These techniques are expensive and often result in secondary pollutants, which limits their widespread application. Bioremediation, however, presents a cost-friendly and more efficient way to degrade pollutants with little or no secondary pollutants. This Article explores how scientists can use genetically modified microorganisms (“GMMs”) to target specific hazardous wastes that are otherwise …

Effects On The Human Microbiome: Antibiotics And Other Chemicals, Katherine Moulton

Thinking Matters Student Research Symposium

With skin being the largest organ of the human body, there is a very large surface area for a microbiome to form and live. The human microbiome is composed of different types of bacteria, fungi, and archaea, in different locations of the body. This layer can be greatly affected by daily practices including, hygiene habits, exercise, and antibiotic uses. The major objective of this study is to identify species of the human microbiome from various body sites and test their resistance to major chemicals. To achieve this objective, the mouth, ear, axillary area, hand, belly button, and foot of several …

Identification Of A Chlorovirus Pbcv-1 Protein Involved In Degrading The Host Cell Wall During Virus Infection, Irina V. Agarkova, Leslie C. Lane, David D. Dunigan, Cristian F. Quispe, Garry A. Duncan, Elad Milrot, Abraham Minsky, Ahmed Esmael, Jayadri S. Ghosh, James L. Van Etten

Nebraska Center for Virology: Faculty Publications

Chloroviruses are unusual among viruses infecting eukaryotic organisms in that they must, like bacteriophages, penetrate a rigid cell wall to initiate infection. Chlorovirus PBCV-1 infects its host, Chlorella variabilis NC64A by specifically binding to and degrading the cell wall of the host at the point of contact by a virus-packaged enzyme(s). However, PBCV-1 does not use any of the five previously characterized virus-encoded polysaccharide degrading enzymes to digest the Chlorella host cell wall during virus entry because none of the enzymes are packaged in the virion. A search for another PBCV-1-encoded and virion-associated protein identified protein A561L. The fourth domain …

The Anti-Sigma Factor Muca Is Required For Viability In Pseudomonas Aeruginosa, Melissa C. Schofield, Daniela Q. Rodriguez, Amanda A. Kidman, Erin K. Cassin, Lia A. Michaels, Elizabeth A. Campbell, Peter A. Jorth, Boo Shan Tseng

Teaching and Learning Faculty Research

During decades-long infections in the cystic fibrosis (CF) airway, Pseudomonas aeruginosa undergoes selection. One bacterial genetic adaptation often observed in CF isolates is mucA mutations. MucA inhibits the sigma factor AlgU. Mutations in mucA lead to AlgU misregulation, resulting in a mucoid phenotype that is associated with poor CF disease outcomes. Due to its ability to be mutated, mucA is assumed to be dispensable for bacterial viability. Here we show that, paradoxically, a portion of mucA is essential in P. aeruginosa. We demonstrate that mucA is no longer required in a strain lacking algU, that mucA alleles encoding for proteins …

Increasing The Frequency Of Periodic Spatial Disturbance Decreases Surface Attachment Protein Expression In Staphylococcus Aureus, Ivana M. Barraza

All HCAS Student Capstones, Theses, and Dissertations

Staphylococcus aureus is an opportunistic pathogen that can cause a variety of acute and chronic illnesses. The severity of these illnesses such as sepsis, necrotizing pneumonia, and toxic shock syndrome is measured through the virulence that S. aureus inflicts on its host. Methicillin-resistant S. aureus (MRSA) is commonly associated with secondary infections and is challenging to treat given the limited selection of antibiotics that are effective against it. Accordingly, novel approaches to reduce S. aureus pathogenicity are required. S. aureus regulates pathogenesis through a cell-to-cell communication system referred to as quorum sensing. Effective communication determines the production of two broad …

Respiratory Pathogens In Patients With Acute Exacerbation Of Non-Cystic Fibrosis Bronchiectasis From A Developing Country, Shayan Shahid, Kausar Jabeen, Nousheen Iqbal, Joveria Farooqi, Muhammad Irfan

Medical College Documents

Bronchiectasis unrelated to cystic fibrosis (non-CF bronchiectasis) has become a major respiratory disease in developing nations. The dilated mucus filled airways promote bacterial overgrowth followed by chronic infection, bronchial inflammation, lung injury and re-infection Accurate pathogen identification and antimicrobial susceptibility allowing appropriate treatment, in turn, may break this vicious cycle. To study the spectrum and antimicrobial spectrum of pathogen yielded from respiratory specimens in adult patients with acute exacerbation of non-cystic fibrosis (CF) bronchiectasis. This cross-sectional study was performed at the pulmonology clinics of the Aga Khan University, Karachi, Pakistan from 2016-2019. Respiratory specimens were collected from adult patients with …

Process Interventions For Improving The Microbiological Safety Of Low Moisture Food Ingredients, Tushar Verma

Department of Food Science and Technology: Dissertations, Theses, and Student Research

The recurrence of Salmonella in low moisture foods and the implementation of the FSMA rule requires a need to validate legacy and novel processing technologies. In this dissertation, a legacy thermal (extrusion), a novel thermal (radiofrequency (RF) heating), and a non-thermal (chlorine dioxide) technology, were evaluated as intervention technologies for Salmonella in low moisture foods. The twin-screw extruder was performed at different levels of screw speeds, temperatures, moisture contents, and fat contents to understand the impact of processing conditions on Salmonella inactivation in oat flour. At temperature >65°C, the Salmonella population was below the detection limit. At 55°C, Salmonella reduction …

A Novel Jumbo Phage Phima05 Inhibits Harmful Microcystis Sp., Ampapan Naknaen, Oramas Suttinun, Komwit Surachat, Eakalak Khan, Rattanaruji Pomwised

Civil and Environmental Engineering and Construction Faculty Research

Microcystis poses a concern because of its potential contribution to eutrophication and production of microcystins (MCs). Phage treatment has been proposed as a novel biocontrol method for Microcystis. Here, we isolated a lytic cyanophage named PhiMa05 with high efficiency against MCs-producing Microcystis strains. Its burst size was large, with approximately 127 phage particles/infected cell, a short latent period (1 day), and high stability to broad salinity, pH and temperature ranges. The PhiMa05 structure was composed of an icosahedral capsid (100 nm) and tail (120 nm), suggesting that the PhiMa05 belongs to the Myoviridae family. PhiMa05 inhibited both planktonic and aggregated …

Microbially-Mediated Carbonate Dissolution And Precipitation; Towards A Protocol For Ex-Situ, Cave-Analogue Cultivation Experiments, Vanessa E. Johnston, Andrea Martín-Pérez, Sara Skok, Janez Mulec

International Journal of Speleology

Subterranean calcite dissolution and precipitation are often considered as strictly geochemical processes. The active involvement of microbes in these processes is commonly underestimated in the literature due to general oligotrophic conditions in caves, except in particular cave conditions, such as sulfidic caves and moonmilk deposits, where the presence of microbes likely plays a key role in mineral deposition. Here, we study the possible involvement of microbes from Postojna Cave, Slovenia, in carbonate dissolution (litholysis) and precipitation (lithogenesis). Microbes were sampled from small pools below hydrologically diverse drip sites and incubated on polished limestone tablets at 10 and 20°C for 2 …

Project Alien, Rebecca Mccallin, Madelyn Hoying, Alex Evans, Matthew Nestler, Karli Rae Sutton, Garett Craig, Lucia Secaia Del Cid, Alexander Guy, Rachel Fernandez, Amanda Trusiak, Paige Aley, Ingabire Gakwerere, Nina Dorfner, Maria Mosbacher, Mary Flavin, Selvin Hernandez, Audrey Steen, Benjamin Kazimer

Undergraduate Research and Scholarship Symposium

Project ALIEN is a comprehensive plan to send humans to Mars to look for life on the Martian surface while exploring the viability and adaptability of terrestrial microbes in Martian atmospheric conditions. ALIEN will use a ballistic capture trajectory to get to Mars and stay in aerostationary orbit for a 30-day surface mission, during which two surface crewmembers will perform a variety of experiments to achieve the mission’s goals of Martian microbial discovery within brines of the Gale Crater and terrestrial microbe adaptability and viability to Martian conditions. Experimentation is based on the presumption that Martian microbes are metabolically similar …

Root Exudates Alter The Expression Of Diverse Metabolic, Transport, Regulatory, And Stress Response Genes In Rhizosphere Pseudomonas, Olga V. Mavrodi, Janiece R. Mcwilliams, Jacob O. Peter, Anna Berim, Karl A. Hassan, Liam D.H. Elbourne, Melissa K. Letourneau, David R. Gang, Ian T. Paulsen, David M. Weller, Linda S. Thomashow, Alex S. Flynt, Dmitri V. Mavrodi

Faculty Publications

Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model …