Microbiology Commons^™

Toxicity Analysis Of 2’-Deoxyguanosine-N2-6-Aminopyrene And 2’-Deoxyguanosine-N2-8-Aminopyrene In Escherichia Coli, Emily Janeiro

Honors Scholar Theses

Cancer is a disease that stems from genomic errors that are not corrected properly by cellular repair mechanisms. Errors are more likely to form when organisms are subjected to DNA damage by mutagenic compounds. 1-Nitropyrene, a nitrated polycyclic aromatic hydrocarbon (nitro-PAH), has been shown to be a potent mutagen that causes cancer. Nitro-PAHs can arise from diesel exhaust products in the environment. Out of all nitro-PAHs, 1-nitropyrene is found in largest quantities in the environment. This poses a great need to study its effects biochemically in order to address its toxicity in DNA. Other nitropyrene derivatives, including 1,6-dinitropyrene and 1,8-dinitropyrene, …

Identification And Analysis Of Feather Degrading Bacteria: A Search For Keratinase Genes, Nehal Navali

Honors Scholar Theses

Over two million tons of feather waste is generated annually by the poultry industry, the majority of which goes into landfills due to the difficulty of degrading its major component keratin. Although a portion of feather waste is eliminated via incineration or chemical treatment, the use of Feather Degrading Bacteria (FDB) has been proposed as a cheap and eco-friendly alternative. FDBs have been consistently isolated from the feather microbiome of birds and contain genes coding for the specialized protein keratinase which is able to degrade feathers. By doing so, feather waste, which is rich in nutrients, can be repurposed as …

The Molluscum Contagiosum Virus Targets Host Innate Immune Signaling Networks At Multiple Points Using Viral Proteins Mc160 And Mc163, Catherine D. Suarez

Seton Hall University Dissertations and Theses (ETDs)

The Molluscum Contagiosum Virus (MCV) causes a common skin infection. A member of the Poxviridae family, MCV spreads through skin to skin contact and produces benign skin lesions that persist for months in otherwise healthy individuals. Despite its prevalence, MCV remains understudied, and its pathogenicity is poorly understood. Therefore, a more detailed understanding of MCV-host interactions is of great importance. The MCV genome encodes a variety of immune evasion molecules to antagonize host cell innate immune responses (IIRs). Two such MCV immune evasion molecule are the MC160 and MC163 proteins. MC160 contains two tandem death effector domains (DEDs). DEDs are …

Tobacco Enhances Bacterial-Induced Periodontal Bone Loss In Mice., Mina Iskander

Electronic Theses and Dissertations

Background: Tobacco smoking is the leading environmental risk factor for periodontal diseases. Delineation of the mechanisms underlying tobacco-induced or exacerbated periodontitis is hampered by the lack of an appropriate and reliable animal model. Hypothesis: We hypothesized that Porphyromonas-gingivalis-infected, cigarette smoke-exposed mice would represent reproducible models of acute (ligature model) and chronic (oral gavage model) tobacco-enhanced periodontitis that reflect multiple aspects of the disease noted in human smokers. Methods: In a chronic oral gavage disease model, Balb/c mice (6-8 weeks, 4 groups of n = 6 per group) were exposed to smoke produced by a Teague-10 smoking machine from 1R6F research …

Efforts To Improve Diagnosis Of Bacteraemia By Reducing Blood Culture Contamination In An Emergency Department: Strategies And Outcome, Najma Shaheen, Mohammad Zeeshan, Naima Fasih, Joveria Farooqi, Kausar Jabeen, Seema Irfan

Department of Pathology and Laboratory Medicine

Objective: To assess the strategies and outcome for reducing blood culture contamination in order to improve the diagnosis of bacteraemia.
Methods: The interventional study was conducted at a tertiary care hospital in Karachi from January 1, 2013, to December 31, 2016. The blood culture contamination data related to the first year of the study was taken as the baseline pre-intervention data. Strategies were planned as intervention for improvement by consolidating training and education in the form of dedicated lectures, practising on mannequins and developing in-house video, replacing povidone with 2% chlorhexidine preparation spray plus 70% isopropyl alcohol swabs and inducting …

Expression Of Her-2/Neu In Oral Squamous Cell Carcinoma, Sana Mirza, Naila Hadi, Shahid Pervez, Sultan Zeb Khan, Sameer A. Mokeem, Tariq Abduljabbar, Nawwaf Al-Hamoudi, Fahim Vohra

Department of Pathology and Laboratory Medicine

Background: HER-2/neu is a member of the human epidermal growth factor (HER) family of transmembrane tyrosine kinases, which is significantly associated with the pathogenesis of various cancer types. The aim was to evaluate the expression of HER-2/neu in oral squamous cell carcinoma (OSCC) as a potential biomarker to target antigens for specific immunotherapy in OSCC.
Methods: One hundred and forty histologically diagnosed OSCC cases were identified. Four to five-micrometer thick formalin-fixed, paraffin-embedded tumor sections were stained with Haematoxylin and Eosin (H and E). Histological grade was assessed according to WHO/Broders classification, while tumors were staged according to the American Joint …

Molecular Mechanisms Of Antimicrobial Resistance In Multi-Drug Resistant Enterococci, Ayesha Khan

Dissertations and Theses (Open Access)

Antibiotic resistance is a major global public health threat. Enterococci are recalcitrant, nosocomial pathogens that can be intrinsically resistant to valuable antibiotics, like beta-lactams, or evolve resistance to all existing antimicrobials. The LiaFSR system regulates resistance to cell membrane (CM) stressors like daptomycin (DAP), a front-line drug for multi-drug resistant infections. DAP resistance (DAP-R) in E. faecalis is mediated by CM phospholipid alterations. Emergence of DAP-R often leads to b-lactam resensitization, a phenomenon called the seesaw effect. The molecular mechanism of DAP-R and the seesaw effect are unknown. Here we show that LiaX is a surface exposed protein whose C-terminal …

Synergistic Inhibition Of Resistant Enterobacteriaceae Using A Possible Klebsiella Secreted Bacteriocin With Broad-Spectrum Antibiotic, Andrew Robbins

Undergraduate Honors Theses

Due to the increasing prevalence of multi-drug resistant (MDR) bacteria, it is now important to begin the search for novel means of defending against such resistant infections. Enterobacteriaceae is a clinically relevant family of bacteria that has shown extensive resistance to many antibiotics, especially after biofilm formation. Inhibitory poly-microbial interactions within this family have been observed. It is known that Citrobacter freundii (CF) growth is significantly inhibited by Klebsiella pneumoniae (KP) through a secreted protein. In this study, the potential KP bacteriocin was screened for its inhibitory effects on CF at various phases of biofilm development. The suspected KP bacteriocin …

Reversible Inhibition Of Mycobacterial Dnab Protein Splicing By Zinc, Gabrielle Hardison

Honors College Theses

Inteins are emerging as post-translational regulatory elements, undergoing conditional protein splicing in response to a variety of environmental cues. Inteins are seamlessly removed by self-splicing from exteins, or flanking portions of the host protein, which they interrupt. DnaB of Mycobacterium smegmatis, a helicase essential for replication, harbors two inteins known as DnaBi1 and DnaBi2, each with discrete structural characteristics and insertion positions. DnaBi1 was used here to design a reporter system which links splicing with resistance to the antibiotic kanamycin. We built a construct that strictly requires catalytically active DnaBi1 for survival in the presence of kanamycin and used …

A Comparative Taxonomic And Diversity Study Of Litter-Associated Fungi In Northwest Arkansas Forests, Rajaa Abdulrazzaq Abbas Al Aanbagi

Graduate Theses and Dissertations

Fungi are taxonomically the most species-rich group of organisms on the earth, ecologically occupy distinctive niches and interact with diverse other organisms throughout their biogeographic distributions and functionally play key roles through their various lifestyles. Plant litter, in particular, is a keystone component in ecosystems and provides heterogeneous microhabitats for the often overlooked litter-decomposing fungi and other organisms on the floor of temperate deciduous forests. Litter fungi involve indirect interactions with the plant, soil and whole food web network. However, the community structure and functions of litter-associated fungi as well as patterns of species richness distributed across various litter microhabitats …

Draft Genome Sequences Of Two Extensively Drug-Resistant Strains Of Acinetobacter Baumannii Isolated From Clinical Samples In Pakistan, Sara Lomonaco, Matthew A. Crawford, Christine Lascols, Debra J. Fisher, Kevin Anderson, David R. Hodge, Segaran P. Pillai, Stephen A. Morse, Erum Khan, Molly A. Hughes, Marc W. Allard, Shashi K. Sharma

Department of Pathology and Laboratory Medicine

Infections in immunocompromised patients that are caused by extensively drug-resistant (XDR) Acinetobacter baumannii strains have been increasingly reported worldwide. In particular, carbapenem-resistant A. baumannii strains are a prominent cause of health care-associated infections. Here, we report draft genome assemblies for two clinical XDR A. baumannii isolates obtained from hospitalized patients in Pakistan.

Identification Of Genome-Linked Bacillus Bacteriophage Proteins, Katherine Dyer

Honors Program Theses

Small viruses that can infect bacteria, called bacteriophages, can be found in the soil. These viruses are being examined as a potential treatment against bacterial infections when antibiotics are not available or non-effective. Before viruses can be used as a medical treatment, they must be studied extensively. Previous attempts to sequence the terminal end of the genome of a bacteriophage QCM-11 (Quartz-Crystal-Microbalance-11: Q11) resulted in error. It is thought that a covalently bound protein may be attached to Q11’s DNA, blocking sequencing of the genome from the 5’ end. Proteins bound to the DNA of phages is not unheard of, …

The Influence Of G4 Dna Structures On Stationary Phase Mutagenesis In Bacillus Subtilis, Tatiana Ermi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Until the late 1980’s it was widely understood that bacterial variance emerges randomly during growth. Research that followed has convincingly shown evidence for mutations arising in non-growing conditions, a phenomenon known as stationary-phase mutagenesis. In Bacillus subtilis, an elegant mutagenic mechanism has been elucidated in non-growing cells that biases mutations to transcribed regions of a subpopulation. One interesting possibility is that mutations can be further biased to hotspots within genes through alternate DNA structures known as non-B DNA. Non-B DNA have been linked to genomic instability and disease in humans, lesser is known about its role in bacteria. Here we …

Rapid Detection Of Toxin-Producing Cyanobacteria, Timothy Alba

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lake Mead provides drinking water to millions of people in Nevada, California, and Arizona. In 2015, the Southern Nevada Water Authority detected the cyanobacteria-produced toxin microcystin in the lake for the very first time. This toxin is lethal in large doses, and in small doses it causes a myriad of serious health effects. Detecting microcystin directly is a time-consuming and expensive process that requires liquid chromatography tandem mass spectrometry or immunological analyses, which require a full day or more to process samples. In order to provide water managers with the methodology for a toxin monitoring plan, this work developed a …

The Significance Of Mfd And Oxidative Damage In Stationary-Phase Mutagenesis In Bacillus Subtilis, Holly Anne Martin

UNLV Theses, Dissertations, Professional Papers, and Capstones

The process of stationary-phase mutagenesis, also known as adaptative or stress-induced mutagenesis, is a phenomenon where bacterial cells accumulate mutations in non-replicative conditions. This process has mainly been studied in Escherichia coli and Bacillus subtilis; however, the underlying mechanisms found in each of these systems differ. Here, I use B.msubtilis to study previously understudied aspects of stationary-phase mutagenesis. In this dissertation, I describe work that has led to three major discoveries which are described below.

First in B. subtilis, Mfd is important for stationary-phase mutagenesis and its mutagenic function at regions of the genome that are transcriptionally upregulated has been …

Development Of In Vitro Models To Study The Rapid Extraintestinal Dissemination Of Salmonella., Adarsh Gopinath

Electronic Theses and Dissertations

Salmonella appears in the bloodstream of mice in as little as 15 minutes after oral inoculation and establishes persistent colonies in the spleen and liver. While its pathway to blood is undetermined, this phenomenon is dependent on the activity of Salmonella pathogenicity island 2 (SPI-2) coded type III secretion system (T3SS) and CD18+ phagocytes. We hypothesize that dendritic cells associated with the basal face of the gut epithelium, that are naturally migratory and known to sample for luminal antigens directly transport Salmonella to the bloodstream. This process comprises of at least two phases, dissociation and reverse transmigration. We define dissociation …

The Release, Transport, And Utilization Of Phosphorus From Bed-Sediments: A Study Of A Eutrophic Littoral Cove On Beaver Lake In Northwest Arkansas, James A. Mccarty

Graduate Theses and Dissertations

Eutrophication of surface waters not only impacts the environment but also water treatment processes, the most significant of which is from the effects of algae. During peak algal growth in many southern U.S. reservoirs, inflows that bring nutrients are at an annual minimum, and phosphorus released from bed-sediments is trapped in the hypolimnion. Littoral areas, described as the most productive zone of the lake, may be a possible source of phosphorus that fuels algal growth in the reservoir. I studied an isolated shallow cove in the War Eagle Creek arm of Beaver Lake in Northwest Arkansas to measure, quantify, and …

Effects Of Light, Nutrients, And Salts On Microbial Biofilm Productivity And Detrital Processing In Aquatic Mesocosms, Bethanie Brooke Howard-Parker

Graduate Theses and Dissertations

Anthropogenic activities associated with urbanization, agriculture, and resource extraction continue to increase to support increasing needs of the growing population. These activities increase the amounts of pollutants entering freshwater streams and put aquatic ecosystems at structural and functional risk. Aquatic microbes play an important role in detrital processing in streams as a key linkage in moving carbon from detrital stocks into aquatic food webs. My research investigates the effects of light, nutrients, and salts on detrital microbes and decomposition in freshwaters using a mesocosm approach. In chapter one, I modified a current priming effect (PE) hypothesis model to include light …

Soil Microbial Diversity And Litter Decomposition Increase With Time Since Land Use Disturbance In Tropical Montane Forests Of Malaysian Borneo, Renee Sniegocki

Graduate Theses and Dissertations

Logging and forest conversion are occurring at alarming rates in the tropical forests of Southeast Asia. These disturbances alter soil chemistry, microbial diversity, and disrupt carbon cycling through shifts in litter decomposition. Direct links between microbial diversity and soil properties such as pH are well established; however, the indirect impacts of logging and forest conversion on microbial diversity and litter decomposition are poorly understood. We used surface (5 cm) soil to assess soil physicochemical properties, next-generation DNA sequencing to assess soil microbial diversity, and standardized litterbags to assess litter decomposition stabilization at five sites along a land use disturbance gradient …

Evaluation Of Microbiome On Chicken Necrotic Enteritis And Growth Performance, Mussie Abraha

Graduate Theses and Dissertations

Necrotic enteritis (NE) has re-emerged following restriction of antimicrobial usage and costs $6 billion every year worldwide. The primary objective of the studies was to evaluate prevention and treatment of NE using a microbiota metabolic product, secondary bile acid deoxycholic acid (DCA), in drinking water. Day-old birds were tagged and placed in floor pens. In experiments 1 and 2, the birds were infected with Eimeria maxima (Em) at d 18 and C. perfringens at d 23 and 24 and the birds were euthanized at d 26. In experiment 3, birds were infected with Eimeria at d 20 and C. perfringens …