Microbiology Commons^™

Prokaryotic Diversity And Aqueous Geochemistry Of Subsurface Environments Of The Death Valley Regional Flow System, Joshua David Sackett

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation summarizes over four years of effort towards the completion of a Ph.D. in Biological Sciences. The work presented in this document covers a broad range of topics, but a central unifying theme is prokaryotic life in the continental subsurface. The work presented in each chapter relied heavily on cultivation-independent methods for assessing prokaryotic communities, including prokaryotic community structure reconstruction from high-throughput sequencing of 16S rRNA gene libraries and single-cell genome analysis of novel uncultivated bacteria.

Chapter 2 examines the aqueous geochemistry and prokaryotic diversity of Devils Hole, a cavernous limnocrene and sole natural habitat for the critically endangered …

Antibiotic-Resistant Escherichia Coli From Retail Poultry Meat With Different Antibiotic Use Claims, Gregg S. Davis, Kara Waits, Lora Nordstrom, Heidi Grande, Brett Weaver, Katerina Papp, Joseph Horwinski, Benjamin Koch, Bruce A. Hungate, Cindy M. Liu, Lance B. Price

Civil and Environmental Engineering and Construction Faculty Research

Background We sought to determine if the prevalence of antibiotic-resistant Escherichia coli differed across retail poultry products and among major production categories, including organic, “raised without antibiotics”, and conventional. Results We collected all available brands of retail chicken and turkey—including conventional, “raised without antibiotic”, and organic products—every two weeks from January to December 2012. In total, E. coli was recovered from 91% of 546 turkey products tested and 88% of 1367 chicken products tested. The proportion of samples contaminated with E. coli was similar across all three production categories. Resistance prevalence varied by meat type and was highest among E. …

Vancomycin Delays Clindamycin-Induced Fatality In The Hamster Model Of Clostridioides [Clostridium] Difficile Infection, Amelia E. Fox-King, Chrisabelle Mefferd, Jacqueline R. Phan, Nancy O. Nou, Ernesto Abel-Santos, Brian P. Hedlund

LSAMP Poster Presentations

Antibiotics can leave the host gut microbiome susceptible to Clostridioides [Clostridium] difficile colonization and lethal toxin production. For instance, clindamycin-induced susceptibility to C. difficile infection (CDI) results in rapid fatality in hamster models, yet vancomycin has been shown to offer increased survival in hamsters challenged with C. difficile. We aim to develop an antibiotic treatment that will facilitate CDI susceptibility without prompt fatality in hamster models. An antibiotic regimen starting with a continuous vancomycin treatment along with a single clindamycin dosage is thought to reduce the major disruption in the indigenous gut microbiome and prevent clindamycin-induced death. …

Genomic Analysis Of 48 Paenibacillus Larvae Bacteriophages, Casey Stamereilers, Christopher P. Fajardo, Jamison K. Walker, Katterinne N. Mendez, Eduardo Castro-Nallar, Julianne H. Grose, Sandra Hope, Philippos K. Tsourkas

Life Sciences Faculty Research

The antibiotic-resistant bacterium Paenibacillus larvae is the causative agent of American foulbrood (AFB), currently the most destructive bacterial disease in honeybees. Phages that infect P. larvae were isolated as early as the 1950s, but it is only in recent years that P. larvae phage genomes have been sequenced and annotated. In this study we analyze the genomes of all 48 currently sequenced P. larvae phage genomes and classify them into four clusters and a singleton. The majority of P. larvaephage genomes are in the 38–45 kbp range and use the cohesive ends (cos) DNA-packaging strategy, while a minority have genomes …

Transcriptional Silencing And Anti-Silencing Of Virulence Genes In The Bacterial Pathogen Shigella Flexneri: Virb, Dna Supercoiling, And The Histone-Like Nucleoid Structuring Protein, Michael Adam Picker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Transcriptional silencing and anti-silencing affect many aspects of bacterial physiology, including virulence in bacterial pathogens. In Shigella species, a group of gram-negative pathogens that cause bacillary dysentery in humans, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences virulence genes found on the large virulence plasmid while VirB anti-silences these genes. However, the mechanistic details of their interplay are not fully understood. To elucidate their regulatory mechanisms, I use the icsP virulence locus, which shares a long intergenic region with the divergently transcribed ospZ gene (1535 bp from TSS to TSS). Prior to this work, two discrete H-NS binding regions had …

Screening For The Novel Cariogenic Pathogen Scardovia Wiggsiae Among Orthodontic Patients, Adam Whiteley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Screening for the Novel Cariogenic Pathogen Scardovia wiggsiae among Orthodontic Patients

by

Adam Whiteley

Dr. Karl Kingsley, Examination Committee Chair Professor of Biomedical Sciences University of Nevada, Las Vegas School of Dental Medicine

The recent discovery of a novel cariogenic pathogen Scardovia wiggsiae has led many scientists and oral health researchers to re-evaluate and re-examine existing saliva repositories to determine the prevalence among patient populations. Recent efforts at this institution have used existing saliva samples to determine the prevalence among both adults and pediatric patients. These studies have revealed this organism may be found in approximately one-quarter of all samples …

Evaluation Of The Antimicrobial Activity Of Endophytic Bacterial Populations From Chinese Traditional Medicinal Plant Licorice And Characterization Of The Bioactive Secondary Metabolites Produced By Bacillus Atrophaeus Against Verticillium Dahliae, Osama A. A. Mohamad, Li Li, Jin-Biao Ma, Shaimaa Hatab, Lin Xu, Jian-Wei Guo, Bakhtiyor A. Rasulov, Yong-Hong Liu, Brian P. Hedlund, Wen-Jun Li

Life Sciences Faculty Research

Endophytic bacteria associated with medicinal plants possess unique strategies that enhance growth and suvival of host plants, many of which are mediated by distinctive secondary metabolites. These bacteria and their secondary metabolites are important subjects for both basic and applied research aimed at sustainable agriculture. In the present study, 114 endophytic strains isolated from the wild ethnomedicinal plant Glycyrrhiza uralensis (licorice) were screened for their in vitro antimicrobial activities against common fungal pathogens of tomato (Fusarium oxysporum f. sp., Fulvia fulva, Alternaria solani), cotton (Fusarium oxysporum f. sp. Vesinfectum, Verticillium dahliae), pomegranite (Ceratocystis fimbriata), Cymbidinium (Colletotrichum gloeosporioides), and Tsao-ko (Pestalotiopsis …

A Biofilm Matrix-Associated Protease Inhibitor Protects Pseudomonas Aeruginosa From Proteolytic Attack, Boo Shan Tseng, Courtney Reichhardt, Gennifer E. Merrihew, Sophia A. Araujo-Hernandez, Joe J. Harrison, Michael J. Maccoss, Matthew R. Parsek

Life Sciences Faculty Research

Pseudomonas aeruginosa produces an extracellular biofilm matrix that consists of nucleic acids, exopolysaccharides, lipid vesicles, and proteins. In general, the protein component of the biofilm matrix is poorly defined and understudied relative to the other major matrix constituents. While matrix proteins have been suggested to provide many functions to the biofilm, only proteins that play a structural role have been characterized thus far. Here we identify proteins enriched in the matrix of P. aeruginosa biofilms. We then focused on a candidate matrix protein, the serine protease inhibitor ecotin (PA2755). This protein is able to inhibit neutrophil elastase, a bactericidal enzyme …

Genomic Expansion Of Magnetotactic Bacteria Reveals An Early Common Origin Of Magnetotaxis With Lineage-Specific Evolution, Wei Lin, Wensi Zhang, Xiang Zhao, Andrew P. Roberts, Greig A. Paterson, Dennis A. Bazylinski, Yongxin Pan

Life Sciences Faculty Research

The origin and evolution of magnetoreception, which in diverse prokaryotes and protozoa is known as magnetotaxis and enables these microorganisms to detect Earth’s magnetic field for orientation and navigation, is not well understood in evolutionary biology. The only known prokaryotes capable of sensing the geomagnetic field are magnetotactic bacteria (MTB), motile microorganisms that biomineralize intracellular, membrane-bounded magnetic single-domain crystals of either magnetite (Fe3O4) or greigite (Fe3S4) called magnetosomes. Magnetosomes are responsible for magnetotaxis in MTB. Here we report the first large-scale metagenomic survey of MTB from both northern and southern hemispheres combined with 28 genomes from uncultivated MTB. These genomes …

Nevada Desert Dust With Heavy Metals Suppresses Igm Antibody Production, Deborah E. Keil, Brenda J. Buck, Dirk Goossens, Brett Mclaurin, Lacey Murphy, Mallory Leetham-Spencer, Yuanxin Teng, James E. Pollard, Russell Gerads, Jamie C. Dewitt

Geoscience Faculty Research

Systemic health effects from exposure to a complex natural dust containing heavy metals from the Nellis Dunes Recreation Area (NDRA) near Las Vegas, NV, were evaluated. Several toxicological parameters were examined following lung exposure to emissive dust from three geologic sediment types heavily used for recreational off-road activities: yellow sand very rich in arsenic (termed CBN 5); a shallow cover of loose dune sand overlying a gravelly subsoil bordering dune fields (termed CBN 6); and brown claystone and siltstone (termed CBN 7). Adult female B6C3F1 mice were exposed by oropharyngeal administration to these three types of geogenic dusts at 0.01–100 …