Microbiology Commons^™

Development And Characterization Of Novel Sub-Coatings With Polymorphic Brookite Titania Nanoparticles: Enhanced Uv/Vis Photocatalytic Antibacterial And Anticancer Properties, Donna Weinbrenner

All Dissertations

ABSTRACT
Nosocomial and community infections and biofilm formation from bacteria has increased significantly through adaptation combined with overuse of broad spectrum antibiotics. Because the world population continues to escalate, hospitals and long-term managed care will also escalate, thereby increasing transmission of infections, lowering patients' quality of health. Another disease on the rise throughout the world is skin cancer. A treatment modality that would cause less deleterious effects on the patient would be ideal. These two seemingly different issues could be solved with one product. First an inexpensive, safe, and non-selective antimicrobial surface coating would enhance the hospital arena and a …

Sequencing And Functional Analysis Of A Multi-Component Dioxygenase From Pah-Degrading Sphingomonas Paucimobilis Epa505, Renuka Miller

All Dissertations

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic compounds consisting of two or more fused benzene rings. PAHs derive from many different sources including petroleum refining, wood treatment, and coal coking industries. Because of their structural stability and water insolubility, PAHs are extremely resistant to degradation. These compounds are also believed to have mutagenic, carcinogenic, and teratogenic effects. Therefore, there are currently 16 PAH compounds on the EPA's list of priority pollutants.
Many species of bacteria have the ability to breakdown these persistent pollutants. However, bioremediation strategies using these organisms have many unresolved issues. While laboratory experiments can easily demonstrate the …

Kinetic, Mechanistic, And Structural Investigation Of Features Controlling Stereoselectivity Of (R)- And (S)-Hydroxypropyl Com Dehydrogenases From Xanthobacter Autrophicus Strain Py2, Dariusz Adam Sliwa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Enantiopure alcohols are valuable intermediates in fine organic synthesis, in particular for preparation of biologically active compounds. The necessity of preparing single enantiomer drugs in an optically pure form has triggered much research, especially in the pharmaceutical industry. The biocatalytical production of chiral alcohols by alcohol dehydrogenase enzymes is characterized by the asymmetric reduction of the corresponding ketones, usually with high degree of stereoselectivity. The commercial value of the enzymes as stereoselective biocatalysts has been a significant driving force in understanding features that control their mechanism of catalysis and stereoselectivity. This work focuses on two enantiocomplementary dehydrogenase enzymes ((R …

Transcriptional Regulation Of Shigella Virulence Plasmid-Encoded Genes By Virb And Crp, Christopher Thomas Hensley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella flexneri is a species of Gram-negative intracellular pathogens that causes bacillary dysentery in humans. Shigella relies on the precise transcriptional regulation of virulence genes, encoded by a large virulence plasmid, for invasion and infection of human colonic epithelial cells. The transcription of most identified virulence genes are regulated through a cascade controlled by the primary regulator of virulence genes, VirF, and the global transcriptional regulator, VirB. Currently, few studies have addressed how individual Shigella virulence genes are precisely regulated for optimal expression during specific stages of pathogenesis and within the constraints of the regulatory cascade. This work addresses how …

Maporal Hantavirus Β-Integrin Utilization And Sensitivity To Favipiravir, Kristin K. Buys

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hantaviruses are members of the Bunyaviridae family of viruses. Pathogenic hantaviruses are the etiologic agents of hemorrhagic fever with renal syndrome (HFRS), a disease principally endemic in the Old World, and hantavirus pulmonary syndrome (HPS), a disease primarily restricted to the Americas. Maporal virus (MPRLV), a recently isolated hantavirus, has been found to cause disease in hamsters that resembles HPS in humans. However, the virus has not been linked to human cases of HPS. Considerable evidence suggests that β-integrin usage mediating infection may serve to distinguish hantaviruses pathogenic to humans from nonpathogenic, but this receptor usage pattern information is not …

The Immune Inhibitor A1 Protease Of Bacillus Anthracis, Kathryn Pflughoeft

Dissertations and Theses (Open Access)

Bacillus anthracis, an organism ubiquitous in the soil and the causative agent of anthrax, utilizes multiple mechanisms to regulate secreted factors; one example is the activity of secreted proteases. One of the most abundant proteins in the culture supernates of B. anthracis is the Immune Inhibitor A1 (InhA1) protease. Here, I demonstrate that InhA1 modulates the abundance of approximately half of the proteins secreted into the culture supernates, including substrates that are known to contribute to the ability of the organism to cause virulence. For example, InhA1 cleaves the anthrax toxin proteins, PA, LF, and EF. InhA1 also targets …

Stress-Induced Targeting Of Molecular Chaperones In The Yeast Saccharomyces Cerevisiae, Hugo Tapia

Dissertations and Theses (Open Access)

The eukaryotic stress response is an essential mechanism that helps protect cells from a variety of environmental stresses. Cell death can result if cells are not able to properly adapt and protect themselves against adverse stress conditions. Failure to properly deal with stress has implications in human diseases including neurodegenerative disorders and distinct cancers, emphasizing the importance of understanding the eukaryotic stress response in detail. As part of this response, expression of a battery of heat shock proteins (HSP) is induced, which act as molecular chaperones to assist in the repair or triage of unfolded proteins. The 90-kDa HSP (Hsp90) …

Characterization Of The Agrobacterium Tumefaciens Virb2 Pilin Of The Virb/D4 Type Iv Secretion System, Jennifer Kerr

Dissertations and Theses (Open Access)

The Agrobacterium tumefaciens VirB/D4 type IV secretion system (T4SS) delivers oncogenic T-DNA and effector proteins to susceptible plant cells. This leads to the formation of tumors termed Crown Galls. The VirB/D4 T4SS is comprised of 12 subunits (VirB1 to VirB11 and VirD4), which assemble to form two structures, a secretion channel spanning the cell envelope and a T-pilus extending from the cell surface. In A. tumefaciens, the VirB2 pilin subunit is required for assembly of the secretion channel and is the main subunit of the T-pilus. The focus of this thesis is to define key reactions associated with the T4SS …

Agrobacterium Virb10 Contributions To Type Iv Substrate Secretion, T-Pilus Biogenesis, And Outer Membrane Pore Formation, Isaac Garza

Dissertations and Theses (Open Access)

The VirB/D4 type IV secretion system (T4SS) of Agrobacterium tumefaciens functions to transfer substrates to infected plant cells through assembly of a translocation channel and a surface structure termed a T-pilus. This thesis is focused on identifying contributions of VirB10 to substrate transfer and T-pilus formation through a mutational analysis. VirB10 is a bitopic protein with several domains, including a: (i) cytoplasmic N-terminus, (ii) single transmembrane (TM) α-helix, (iii) proline-rich region (PRR), and (iv) large C-terminal modified β-barrel. I introduced cysteine insertion and substitution mutations throughout the length of VirB10 in order to: (i) test a predicted transmembrane topology, (ii) …

Vertical Transmission Of West Nile Virus In Culex Spp. Mosquitoes Of Clark County, Nevada, Vivek K. Raman

UNLV Theses, Dissertations, Professional Papers, and Capstones

West Nile Virus (WNV) is an RNA arbovirus that cycles between mosquitoes and birds, but also infects and causes disease in humans, horses and other vertebrate species. Although most infections are asymptomatic, WNV has emerged as the most common cause of epidemic meningoencephalitis in North America and the leading cause of arboviral encephalitis in the United States.

Mosquitoes of the genus Culex are the most active vectors of WNV in North America. Approximately 85% of human WNV infections in the United States occur in late summer with a peak number of cases in August and September. Vertical transmission is defined …

In Vitro Boosting And Expansion Of Tumor Infiltrating Killer T Cells, Chunlei Mei

All Theses

Immune cell tumor infiltration represents one of the mechanisms that the immune system responds to tumor cells. The tumor infiltrated immune cells include lymphocytes (TIL), dendritic cells (DCs), macrophages, and natural killer (NK) cells. Although TILs have been extensively studied in order to develop adoptive transfer based immunotherapies, how to effectively isolate, culture, and in vitro boosting the killer cells from TILs remains a challenge. Meanwhile, OK-432, a heat and penicillin-treated lyophilized preparation of the low-virulence strain of Streptococcus pyogenes, has been shown to exhibit immunomodulatory activities and potential antitumor therapeutic function, including the activation of DCs, neutrophils, macrophages, lymphocytes, …

Effects Of Diabetic State And Gender On Pro-Inflammatory Cytokine Secretion By Human Macrophages Infected With Burkholderia Pseudomallei, Annette J. Blam

Theses and Dissertations

Burkholderia pseudomallei is a gram-negative opportunistic soil pathogen that causes the life-threatening disease melioidosis. It is endemic in Northern Australia and Southeast Asia but can be found throughout many other regions in the world. Diabetes mellitus is a predisposing risk factor for infection with this organism and it has been demonstrated that diabetic males are particularly susceptible to severe infection. Previous research suggested that monocytes isolated from the whole blood of diabetic males demonstrated a decreased ability to produce the proinflammatory cytokines IL-1β and IL-8. We hypothesized that monocyte-derived macrophages from diabetic males would also secrete lower levels of pro-inflammatory …

Aminoglycoside Resistance Of Pseudomonas Aeruginosa Biofilms Modulated By Extracellular Polysaccharide, Wajiha Khan, Steve P. Bernier, Sherry L. Kuchma, John H. Hammond, Fariha Hasan, George A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa is an opportunistic pathogen that produces sessile communities known as biofilms that are highly resistant to antibiotic treatment. Limited information is available on the exact role of various components of the matrix in biofilm-associated antibiotic resistance. Here we show that the presence of extracellular polysaccharide reduced the extent of biofilm-associated antibiotic resistance for one class of antibiotics. Minimal bactericidal concentration (MBC) for planktonic and biofilm cells of P. aeruginosa PA14 was measured using a 96 well microtiter plate assay. The MBC of biofilm-grown ΔpelA mutant, which does not produce the Pel polysaccharide, was 4-fold higher for tobramycin and …

Neonatal Mortality And Prevalence Of Practices For Newborn Care In A Squatter Settlement Of Karachi, Pakistan: A Cross-Sectional Study., Afsheen Ayaz, Sarah Saleem

Department of Pathology and Laboratory Medicine

Background: During the past two decades there has been a sustained decline in child and infant mortality, however neonatal mortality has remained relatively unchanged. Almost all neonatal deaths (99%) occur in developing countries, where the majority are delivered at homes. Evidence suggests that these deaths could be prevented by simple, inexpensive practices and interventions during the pregnancy, delivery and postnatal period. In Pakistan over the last decade extensive efforts have been made by the international donors and government to implement these practices. However, limited attempts have been made to explore if these efforts have made a difference at the grass …

Virulence Of An Emerging Respiratory Pathogen, Genus Pandoraea, In Vivo And Its Interactions With Lung Epithelial Cells, Gillian Herbert, Anne Costello, Lydia Fabunmi, Kirsten Schaffer, Kevin Kavanagh, Emma M. Caraher, Máire Callaghan, Siobhan Mcclean

Articles

Pandoraea species have emerged as opportunistic pathogens among cystic fibrosis (CF) and non-CF patients. Pandoraea pulmonicola is the predominant Pandoraea species among Irish CF patients. The objective of this study was to investigate the pathogenicity and potential mechanisms of virulence of Irish P. pulmonicola isolates and strains from other Pandoraea species. Three patients from whom the P. pulmonicola isolates were isolated have since died. The in vivo virulence of these and other Pandoraea strains was examined by determining the ability to kill Galleria mellonella larvae. The P. pulmonicola strains generally were the most virulent of the species tested, with three …

Dna Barcoding In The Red Algal Order Gelidiales: Comparison Of Coi With Rbcl And Verification Of The "Barcoding Gap", D. Wilson Freshwater, Kelly Tudor, Katie O'Shaughnessy, Brian Wysor

Arts & Sciences Faculty Publications

Mitochondria-encoded COI and plastid-encoded rbcL sequences were used to assist with the identification or "barcoding" of a variety of red algal species. The rbcL locus has been extensively analyzed within the Gelidiales and general levels of intraspecific and interspecific sequence divergences are established. Complementary COI and rbcL data sets were compared to explore the utility of COI for Gelidiales species identification and verify the presence of a barcoding gap between closely related species. There was no difference between the two loci in the clustering of specimens into species, but the COI sequences were more variable than rbcL and exhibited a …

Chronic Gastritis And Helicobacter Pylori: A Histopathological Study Of Gastric Mucosal Biopsies, Mohammad Yawar Yakoob, Akbar Shah Hussainy

Department of Pathology and Laboratory Medicine

The aim of this study was to observe the histological features of chronic gastritis and associated effects due to Helicobacter pylori infection in 176 randomly selected antral biopsy specimens of chronic gastritis cases. The specimens were reviewed for the presence or absence of H.pylori. The activity (neutrophilic infiltration) of gastritis and the presence or absence of mucosa-associated lymphoid tissue (MALT) were also noted. Chi-square test (Pearson value) was used to analyze categorical variables. H.pylori was detected in 110 (62.5%) cases of chronic gastritis. There was a significant association between H.pylori infection and activity of chronic gastritis (p=0.002). Lymphoid aggregates were …

Detection Of Poliovirus By Icc/Qpcr In Concentrated Water Samples Has Greater Sensitivity And Is Less Costly Using Bgm Cells In Suspension As Compared To Monolayers, Helene B. Balkin, Aaron B. Margolin

Molecular, Cellular & Biomedical Sciences

The integrated cell culture quantitative reverse transcriptase PCR (ICC/qRT-PCR) method is used in our lab to detect enteroviruses in environmental waters. Typically we utilize monolayers of 3 cell lines; buffalo green monkey kidney (BGM), human colonic carcinoma (CACO-2) and African rhesus monkey kidney (MA104) with the intent of providing one or more permissive hosts to a wide range of enteroviruses. In this study the BGM cell line was used to compare poliovirus infectivity in conventional monolayer cultures to BGM cells in suspensions. Propagated virus was subsequently amplified by qRT-PCR. Our PCR data showed lower cycle threshold (Ct) values in the …

Deletion Of The Cel48s Cellulase From Clostridium Thermocellum, Daniel G. Olson, Shital A. Tripathi, Richard J. Giannone, Jonathan Lo, Nicky C. Caiazza, David A. Hogsett, Robert L. Hettich, Adam M. Guss, Genia Dubrovsky, Lee R. Lynd

Dartmouth Scholarship

Clostridium thermocellum is a thermophilic anaerobic bacterium that rapidly solubilizes cellulose with the aid of a multienzyme cellulosome complex. Creation of knockout mutants for Cel48S (also known as CelS, S(S), and S8), the most abundant cellulosome subunit, was undertaken to gain insight into its role in enzymatic and microbial cellulose solubilization. Cultures of the Cel48S deletion mutant (S mutant) were able to completely solubilize 10 g/L crystalline cellulose. The cellulose hydrolysis rate of the S mutant strain was 60% lower than the parent strain, with the S mutant strain also exhibiting a 40% reduction in cell yield. The cellulosome produced …

Growth Of Lactic Acid Bacteria: Infuence Of Protocooperation, Bacteriophage Infection, And Prebiotic Carbohydrates, Caitlin D. Goin

School of Biological Sciences: Dissertations, Theses, and Student Research

Lactic acid bacteria are a vital part of the fermented food industry and are the subject of much interest and research. Industry is especially interested in using modern molecular approaches to maintain and improve selected strains; several industrial uses could be improved by closer investigation, namely the protocooperation of S. thermophilus and L. bulgaricus, the role of CRISPRs in phage resistance, and the utilization of prebiotic carbohydrates. Questions such as what genes and pathways are shared during milk fermentation between S. thermophilus and L. bulgaricus, when and what genes are active during bacteriophage infection, and how and where …