Bacteriology Commons^™

Characterization Of Lps As A Virulence Factor In Burkholderia Cepacia During Plant And Human Infection, Jack Klahr, Elizabeth Danka

Biology Senior Theses

Burkholderia cepacia is a gram-negative bacterium first characterized as the causative agent of sour skin in onion crops. More recently, B. cepacia has become a clinical concern as an opportunistic pathogen that can colonize the upper respiratory tract of cystic fibrosis patients and increase mortality in these patients. Infection is exacerbated by the intrinsic resistance to antibiotics found in this genus of organisms. Additional virulence factors help the bacteria persist in the host during infection. However, few of these factors have been described. In this work, we characterized a putative virulence factor that was first identified through an onion infection …

Causes And Consequences Of Lasr Mutant Selection In Pseudomonas Aeruginosa Populations, Dallas L. Mould

Dartmouth College Ph.D Dissertations

Change is the only constant in life, and these changes, though random in nature, can have consequences. Quorum sensing is heterogeneous in phenotype and prone to negative selection. In P. aeruginosa, the regulator LasR is frequently non-functional in phylogenetically diverse isolates. Through repeated experimental evolution and mathematical modeling, we show that differences in growth enable lasR mutant evolutionary success and this requires a system enabling metabolic choices, known as carbon catabolite repression (or catabolite repression). The differences in catabolite repression between wild type and lasR mutants enable altered metabolite preferences, and the resulting differences in metabolic states enable intraspecies …

A Critical Assessment Of The Role Of Clpxp-Mediated Proteolysis In The Development And Differentiation Of Chlamydia Trachomatis, Nicholas A. Wood

Theses & Dissertations

Chlamydia trachomatis, an obligate intracellular human pathogen, is the etiological agent of the most commonly reported bacterial sexually transmitted infection and the leading cause of preventable infectious blindness worldwide. In adapting to an intracellular niche, Chlamydia has evolved to eliminate superfluous genes from its chromosome. Despite its highly reduced genome, Chlamydia undergoes a complex developmental cycle in which the bacteria differentiate between two functionally and morphologically distinct forms: the infectious, non-replicative elementary body (EB) and the non-infectious, replicative reticulate body (RB). An EB initiates infection by binding to and inducing uptake into a host cell. Within the cell, the EB …

Effect Of Temperature On The Microbiome Of A Laboratory Reared Colony Of Haemaphysalis Longicornis Ticks, Brianna Mitchell

Poster Presentations

Honors research poster.

Haemaphysalis longicornis is a species of tick native to eastern Asia, including eastern China, Japan, eastern Russia, and Korea. To date, it has invaded and has now established its existence in Australia, New Zealand, and several of the Pacific Islands. This species of tick has recently been introduced to the United States, having a confirmed sighting in November 2017 on a sheep farm in New Jersey and since establishing populations in 18 states along the east coast and Appalachia. Based on the existing locations of H. longicornis in its native regions, as well as in the United …

Diagnosis Of Urinary Tract Infections And Rapid Molecular Characterization Of Antibiotic Resistance, Mohammed Harris

All Dissertations

Urinary tract infections (UTIs) are one of the most common infectious clinical entities in both community and hospital settings. They have a broad range of clinical severity yet inflict large epidemiological burden of morbidity and mortality on patients and the healthcare system with billions of dollars in cost of treatment. Understanding what methods are optimal for diagnosing UTIs are critical to mitigate the marked impact and cost of these infections.

Chapter 1 and 2 in this work surveys the broad array of diagnostic modalities for UTIs and highlights their advantages and limitations in the context of the current standard of …

Role Of Pseudomonas Aeruginosa Exoenzymes S, T, And Y In The Modulation Of Intrinsic Apoptosis In Pulmonary Microvascular Endothelial Cells, Andrea M. Vavrinek

Honors Theses

P. aeruginosa is the most common cause of ventilator-associated pneumonia in ICU patients. P. aeruginosa uses a type III secretion system to inject exoenzymes S, T, U, and Y into host cells, exhibiting unique effects. Pulmonary microvascular endothelial cells (PMVECs) are used to evaluate cellular changes caused by exoenzymes. ExoY infection of PMVECs leads to cell rounding but does not lead to cell death, unlike ExoS/T. The current study evaluated the exoenzyme-induced modulation of intrinsic apoptosis in endothelial cells. Strain PAK, producing ExoS, T, and Y, was compared to isogenic strains expressing either S, SY, T, TY, Y, or none …

The Stringent Response In Pseudomonas Aeruginosa Influences The Phenotypes Controlled By The Gac/Rsm System, Michael Shawn Hooker

Electronic Theses and Dissertations

Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen that causes acute and chronic infections. Infection is typically initiated via motile and virulent strains. After exposure to stressors, acute infections make both genotypic and phenotypic switches to a chronic, sessile strain. This is due to intricate regulatory networks directing gene expression in response to stressors. One network, GacA/GacS, has been established to control virulence factors. The stringent response of bacteria is mediated by alarmones produced primarily by RelA which responds to starvation.

To study the effect of the stringent response on the virulence switch. A series of experiments were run in both …

Inhibiting Survival Of Salmonella During Desiccation Through The Use Of Naturally Occurring Signals, Joseph Headrick

Electronic Theses and Dissertations

A rising problem in agriculture is the increase of antibiotic-resistant Salmonella cases associated with chicken eggs, which transmit infection to humans. To counter this, new approaches to combat Salmonella in chickens and desiccated on eggshells are vital in the prevention of human foodborne illness. Disrupting signaling pathways with naturally occurring compounds provides a potential novel avenue for prevention of Salmonella infections, as this would disrupt sensing of these environments and inhibit subsequent optimal gene expression. Starting with signals identified in previous studies, salicylic acid was found to inhibit Salmonella desiccation survival on both eggshells and plastic. To expand upon this, …

Determining The Effects Of Maternal Adiposity On Preterm Neonatal Microbiome And Short Chain Fatty Acid Profiles, Dalton James, William A. Clark Phd, Kristy L. Thomas

Undergraduate Honors Theses

The gut microbiota and its metabolites have vast impacts on the human digestive system, immune system, and health outcomes. Short chain volatile fatty acids (SCVFAs) present in feces can be representative of the interactions of the microbiota present in the gut. Low microbiota diversity in the human gut is highly associated with obesity and adverse health outcomes. Furthermore, the maternal microbiome has a direct impact on neonatal microbiota through various pathways such as environment, skin flora, breast milk composition, and vaginal secretions. This study is aimed to further understand the associations between various factors (maternal adiposity, gestational time, length of …

Development, Optimization, And In Vitro/In Vivo Evaluation Of Azelaic Acid Transethosomal Gel For Antidermatophyte Activity, Ali Nasr, Noha Badawi, Yasmine Tartor, Nader Sobhy, Ali Nasr

Pharmacy

Treatment of dermatophytosis is quite challenging. This work aims to investigate the antidermatophyte action of Azelaic acid (AzA) and evaluate its efficacy upon entrapment into transethosomes (TEs) and incorporation into a gel to enhance its application. Optimization of formulation variables of TEs was carried out after preparation using the thin film hydration technique. The antidermatophyte activity of AzA-TEs was first evaluated in vitro. In addition, two guinea pig infection models with Trichophyton (T.) mentagrophytes and Microsporum (M.) canis were established for the in vivo assessment. The optimized formula showed a mean particle size of 219.8 ± 4.7 nm and a …

The Effects Of Specialized Pro-Resolving Mediator Lipoxin A4 On Pseudomonas Aeruginosa Biofilms And Interactions With Monocytes, Julianne M. Thornton

Graduate School of Biomedical Sciences Theses and Dissertations

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen known as a major cause of hospital-acquired secondary infections, commonly causing chronic respiratory infections in immunocompromised individuals, especially those with cystic fibrosis, and often found in wound infections. P. aeruginosa uses the quorum sensing pathway to readily form protective biofilms, which reduce the efficacy of antibiotics and access by host immune cells to eradicate the pathogen. Specialized pro-resolving mediators (SPMs) are lipids endogenously produced by the host immune response to infection to aid in infection resolution. One SPM, Lipoxin A4 (LxA4), has been shown to be a robust quorum sensing inhibitor.

The …

Investigating The Antibacterial And Immunomodulatory Properties Of Lactobacillus Acidophilus Postbiotics, Rachael M. Wilson

Graduate School of Biomedical Sciences Theses and Dissertations

Probiotics are nonpathogenic microorganisms that have been extensively studied for their ability to prevent various infectious, gastrointestinal, and autoimmune diseases. The mechanisms underlying these probiotic effects have not been elucidated. However, we and other researchers have evidence suggesting that probiotic bacteria secrete metabolites that are antimicrobial and anti-inflammatory. As such, we developed a methodology to collect the secreted metabolites from a probiotic bacterium, Lactobacillus acidophilus, and tested this cell free filtrate (CFF) both in vitro and in vivo. Using this CFF, we have demonstrated that L. acidophilus secretes a molecule(s) that has specific bactericidal activity against the opportunistic pathogen, Pseudomonas …

Protocol To Identify The Core Gene Supported By An Essential Gene In E. Coli Bacteria Using A Genome-Wide Suppressor Screen, Isao Masuda, Ya-Ming Hou

Department of Biochemistry and Molecular Biology Faculty Papers

We describe here a genome-wide screening approach to identify the most critical core reaction among a network of many that are supported by an essential gene to establish cell viability. We describe steps for maintenance plasmid construction, knockout cell construction, and phenotype validation. We then detail isolation of suppressors, whole-genome sequencing analysis, and reconstruction of CRISPR mutants. We focus on E. coli trmD, which encodes an essential methyl transferase that synthesizes m1G37 on the 3'-side of the tRNA anticodon. For complete details on the use and execution of this protocol, please refer to Masuda et al. (2022).

Damped Oscillating Phosphoryl Transfer Reaction In The Cyanobacterial Circadian Clock, Hye In Jang, Pyonghwa Kim, Yongick Kim

Chemistry Faculty Research

Most organisms have circadian clocks to ensure the metabolic cycle to resonate with the rhythmic environmental changes without “damping,” or losing robustness. Cyanobacteria is the oldest and simplest form of life that is known to harbor this biological intricacy. Its KaiABC-based central oscillator proteins can be reconstituted inside a test tube, and the post-translational modification cycle occurs with 24 h periodicity. KaiC’s two major phosphorylation sites, Ser-431 and Thr-432, become phosphorylated and dephosphorylated by interacting with KaiA and KaiB, respectively. Here, we mutate Thr-432 into Ser to find the oscillatory phosphoryl transfer reaction damps. Previously, this mutant KaiC was reported …

Enrichment Media Selection And Co-Culture Potential Among Exoelectrogen Bacteria Vary With Ecological Factors, Nur Syafira Khoirunnisa, Syaiful Anwar, Untung Sudadi, Dwi Andreas Santosa

Makara Journal of Science

Staphylococcus saprophyticus ICBB 9554 and Citrobacter freundii ICBB 9763 are exoelectrogen bacteria applied as microbial fuel cells (MFC). We selected enrichment media for both these exoelectrogen bacteria, characterized their synergistic traits, and evaluated the growth conditions under different ecological factors. In this study, different enrichment media, such as those containing sugar, molasses, and palm sugar (2, 4, and 6% w/v) were tested for S. saprophyticus ICBB 9554. Meanwhile, technical sodium acetate (NaAc), commercial vinegar 25%, and cider vinegar (5, 10, and 15 mM acetate concentration) were tested for C. freundii ICBB 9763. Both the exoelectrogen bacteria were tested for the …

Tools For Quantifying Bacterial Motility Using Digital Holographic Microscopy As Applied To Studying The Simulated Microgravity Environment, Jacqueline Marie Acres

Dissertations and Theses

Digital holographic microcopy (DHM) is a label-free technique that has gained attention in recent years as a tool for volumetric imaging. One application of DHM is for the study of microbial motility with the advantage being that organisms may freely move within their environment. Images created from DHM are in the form of holograms. Holograms are time recordings showing XY information with the Z information contained within. Z information can be retrieved from the holograms directly through a variety of numerical techniques or through reconstruction. Datasets generated from DHM are large and processing remains a challenging task. Here, we show …

Fish Farming Wastewater Treatment Using Algae-Cyanobacterial Inocula, Yolanys Aranda

Graduate Industrial Research Symposium

Fish is one of the most important nutrient sources of the human diet, and its low-cost aquaculture production is advantageous. During processing, large quantities of organic and inorganic nutrients are produced. Discharging fish farming wastewater to the environment without proper treatment can support harmful algal growth. Therefore, aquaculture effluent must be treated prior to discharge to the receiving waters. In this study, six different cyanobacteria and algae species, including Chlorococcumminutum, Porphyridiumcruentum, Chlorella vulgaris, Microcystis aeruginosa, Chlamydomonas reinhardtii, and Fischerellamuscicola were studiedto treatfish aquaculture wastewater, using mix-culture bacteria as the inoccolum. All samples were incubated for 21 days. Parameters such as …

Investigating The Diversity Of Wolbachia Across The Spiny Ants (Polyrhachis), Jenna L. Webb, Leland C. Graber, Manuela O. Ramalho, Corrie S. Moreau

Biology Faculty Publications

Among insects, Wolbachia is an exceedingly common bacterial endosymbiont with a range of consequences of infection. Despite the frequency of Wolbachia infection, very little is known about this bacteria's diversity and role within hosts, especially within ant hosts. In this study, we analyze the occurrence and diversity of Wolbachia across the spiny ants (Polyrhachis), a large and geographically diverse genus. Polyrhachis samples from throughout the host genus' phylogenetic and biogeographical range were first screened for single infections of Wolbachia using the wsp gene and Sanger sequencing. The multilocus sequence typing (MLST) scheme was then used on these singly infected samples …

Conformational Rearrangements In The Sensory Rcsf/Omp Complex Mediate Signal Transduction Across The Bacterial Cell Envelope, Sarah Rosemarie Lach Phd

Dissertations and Theses (Open Access)

Timely detection and repair of envelope damage are paramount for bacterial survival. The Regulator of Capsule Synthesis (Rcs) stress response is a complex signaling cascade that monitors gram-negative cell envelope integrity and can transduce the stress signals across the multilayered envelope to regulate gene expression in the cytoplasm. The outer membrane (OM) lipoprotein RcsF is the sensory component, but how RcsF functions remains elusive. RcsF interacts with the β-barrel assembly machinery (Bam) complex, which assembles RcsF in complex with OM proteins (OMPs), resulting in RcsF’s partial cell surface exposure. RcsF can also interact with the periplasmic domain of the negative …

The Immunomodulating Effects Of Delta-9 Tetrahydrocannabinol (Thc) And Cannabidiol (Cbd) In The Context Of Infection, Rose D. Goodman, Kate Rouse, Victor Jimenez

Annual Research Symposium

No abstract provided.