Microbiology Commons^™

Development Of A Laboratory Based System For Selecting Insect Pathogenic Fungi With Greatest Potential For Success In The Field, Chad Alton Keyser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many insects are important agricultural pests, and active control is necessary to keep them at abeyance. The naturally occurring entomopathogenic fungus Metarhizium is a promising tool to control pest insects, and its use avoids the well-known harmful side effects of chemical pesticides. Thousands of unique isolates of Metarhizium exist throughout the world. These isolates vary widely in their ability to cause infection and to tolerate stressful habitats. The research reported here tests the THESIS: A laboratory-based system can be devised that identifies, from among many Metarhizium isolates, those isolates with the greatest potential for successful biological control of pest insects …

The Hypericum Perforatum Herb As An Antimycobacterial Agent And Its Implications As An Additional Tuberculosis Medication, Trent W. Mortensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An immediate demand exists for new tuberculosis (TB) antibiotics due to the ever-increasing spread of drug-resistant strains. The drug-development process goes through four phases, the first (Phase 0) of which is to demonstrate and investigate drug effectiveness and toxicity. This research investigated the effectiveness of the Hypericum perforatum herb (commonly St. John's wort (SJW)) in its growth inhibition of mycobacteria and its viability effect on human lung cells.

Organic-solvent SJW extracts were effective at inhibiting every nonpathogenic genetically sequenced Mycobacterium isolate currently available (six isolates) in preliminary studies. Quantitative studies of five Mycobacterium isolates showed an order of concentration sensitivity …

Ecology And Relationships Of Rhabdias Spp. (Nematoda: Rhabdiasidae) From North American Amphibians And Reptiles, Gabriel J. Langford

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

Lungworms of the cosmopolitan genus Rhabdias (Nematoda: Rhabdiasidae) are among the most common parasites of amphibians and squamate reptiles. The life cycles, life histories, host specificities, and evolutionary relationships of Rhabdias spp. were studied through examination of their free-living and parasitic stages in amphibians and reptiles. This study found free-living development of anuran lungworms was primarily limited to heterogonic reproduction, whereas snake lungworms primarily reproduced homogonically. Infective anuran lungworms penetrated the skin of frogs and toads; in contrast, snake lungworms penetrated snake esophageal tissue during per os infections. Our molecular phylogeny strongly supported separate clades for anuran and snake lungworms, …

Biogeography And Microhabitat Distribution Of Myxomycetes In High-Elevation Areas Of The Neotropics, Carlos Alonso Rojas-Alvarado

Graduate Theses and Dissertations

Myxomycetes are a group of amoeboid organisms with the capacity of forming fruiting bodies that resemble some macrofungi. The ecology and global distribution of species within the group have been studied only during the last half century. For this reason, a number of questions regarding the nature of the interactions that exist between myxomycetes and their environment still lack the empirical evidence required to obtain complete answers. In the Neotropical region, species assemblages have been moderately well studied, but their biogeography and macroecology have received little attention. In high-elevation areas of this region, the situation is especially precarious, due the …

Host Signaling Response To Adhesion Of Bifidobacterium Infantis, Reed N. Gann

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Investigations of the molecular binding partners of the probiotic bacterium Bifidobacterium longum subspecies infantis (B. infantis) and the pathogen Salmonella enterica subspecies enterica serovar Typhimurium LT2 (Salmonella ser. Typhimurium) found that these two very different bacteria bind gangliosides. However, these organisms lead to completely different host health outcomes when present in the gut. B. infantis is the founding microbial population in the intestinal tract of breast-fed infants. S. typhimurium is the most important food-borne pathogen that results in humans. This study used an in vitro gut epithelial cell model to examine the host cellular response to adhesion …

Survival Of Mycoplasma Species In Recycled Bedding Sand And Possible Implications For Disease Transmission To Ruminants, Anne E. Justice-Allen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mycoplasmas are a group of bacteria which are small in size, lack a cell wall, and have small genomes in comparison to other bacteria. The members of the group that are pathogenic utilize several mechanisms to evade the host's immune system. These processes affect surveillance and control mechanisms such as serologic testing and vaccination. Many of these organisms cause diseases of livestock, which heavily impact production parameters such as weight gain, milk yield, and egg production. Mycoplasmas also cause disease in people.

Mycoplasma spp. can cause mastitis, metritis, pneumonia, and arthritis. The currently documented routes of transmission of Mycoplasma spp. …

Bacillus Cereus And Bacillus Anthracis Germination Kinetics: A Michaelis-Menten Approach, Helen Luu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bacillus species are rod-shaped, gram-positive bacteria that are capable of producing endospores. In this dormant stage, the endospores can persist in hostile physical and chemical environments. Once conditions become favorable, the spores germinate into actively dividing cells, vegetative cells. Germination is a crucial step for the pathogenicity of the Bacilli in affecting a host organism.

Our study applies mathematical approaches to spore germination to determine whether the binding of one germinant will affect the binding of another germinant. We pursued this approach with two different species, B. cereus and B. anthracis, both pathogenic organisms. B. cereus is a widely known …

Host-Pathogen Interactions Of Secreted And Surface Staphylococcus Aureus Factors, Vanessa Vazquez

Dissertations and Theses (Open Access)

Staphylococcus aureus is an opportunistic bacterial pathogen that can infect humans and other species. It utilizes an arsenal of virulence factors to cause disease, including secreted and cell wall anchored factors. Secreted toxins attack host cells, and pore-forming toxins destroy target cells by causing cell lysis. S. aureus uses cell-surface adhesins to attach to host molecules thereby facilitating host colonization. The Microbial Surface Components Recognizing Adhesive Matrix Molecules (MSCRAMMs) are a family of cell-wall anchored proteins that target molecules like fibronectin and fibrinogen. The Serine-aspartate repeat (Sdr) proteins are a subset of staphylococcal MSCRAMMs that share similar domain organization. Interestingly, …

Molecular Basis Of Corynebacterium Diphtheriae Virulence And Infection In The Caenorhabditis Elegans Model Host, Melissa M. Broadway

Dissertations and Theses (Open Access)

Corynebacterium diphtheriae is the causative agent of cutaneous and pharyngeal diphtheria in humans. While lethality is certainly caused by diphtheria toxin, corynebacterial colonization may primarily require proteinaceous fibers called pili, which mediate adherence to specific tissues. The type strain of C. diphtheriae possesses three distinct pilus structures, namely the SpaA, SpaD, and SpaH-type pili, which are encoded by three distinct pilus gene clusters. The pilus is assembled onto the bacterial peptidoglycan by a specific transpeptidase enzyme called sortase. Although the SpaA pili are shown to be specific for pharyngeal cells in vitro, little is known about functions of the three …

Modified Method For The Microbial Enumeration Of High Fat Foods, Robert Valerio

All Theses

Foods of high fat content, such as peanut butter and ground beef, can be of particular interest to food microbiologists due to their role in harboring microorganisms that lead to spoilage and/or foodborne illnesses. In previous studies on raw poultry rendering materials, Glenn (2006) determined standard phosphate buffer serial dilutions produced erratic microbial enumeration results. As the material contained high fat, it was
hypothesized that the immiscibility of fat in the aqueous buffer caused the errors. This could occur by fat globules entrapping microorganisms in foods. Upon serial dilution with aqueous buffers, the fat globules may not be evenly dispersed …

Functional Characterization Of Mat1-1-Specific Mating-Type Genes In The Homothallic Ascomycete Sordaria Macrospora Provides New Insights Into Essential And Nonessential Sexual Regulators, V. Klix, M. Nowrousian, C. Ringelberg, J. J. Loros

Dartmouth Scholarship

Mating-type genes in fungi encode regulators of mating and sexual development. Heterothallic ascomycete species require different sets of mating-type genes to control nonself-recognition and mating of compatible partners of different mating types. Homothallic (self-fertile) species also carry mating-type genes in their genome that are essential for sexual development. To analyze the molecular basis of homothallism and the role of mating-type genes during fruiting-body development, we deleted each of the three genes, SmtA-1 (MAT1-1-1), SmtA-2 (MAT1-1-2), and SmtA-3 (MAT1-1-3), contained in the MAT1-1 part of the mating-type locus of the homothallic ascomycete species Sordaria macrospora. Phenotypic analysis of deletion mutants revealed …

Increase In Isolation Of Extended Spectrum Beta Lactamase Producing Multidrug Resistant Non Typhoidal Salmonellae In Pakistan., Kauser Jabeen, Afia Zafar, Seema Irfan, Erum Khan, Vikram Mehraj, Rumina Hasan

Department of Pathology and Laboratory Medicine

Background:Increasing resistance to quinolones and ceftriaxone in non typhoidal Salmonellae is a global concern. Resistance to quinolone and 3rd generation cephalosporin amongst non typhoidal Salmonellae (NTS) from Pakistan has been reported in this study.

Methods:

Retrospective analysis of laboratory data was conducted (1990-2006). NTS were isolated and identified from clinical samples using standard microbiological techniques. Antimicrobial susceptibility testing was performed by Kirby Bauer. Extended spectrum beta lactamase production (ESBL) was detected using combined disc method. Ciprofloxacin sensitivity was detected by nalidixic acid screening method. Minimum inhibitory concentration (MIC) of ciprofloxacin was determined by agar dilution method. Statistical analysis was …

Effects Of Mold Exposure On Immune Cells, Katrin Gorham

Honors Projects in Science and Technology

The relationship between exposure to mold spores and human disease is only beginning to be understood. While evidence exists of strong correlations between moldy environments and allergic and infectious diseases, the relationship between exposure to specific species and human immune responses to them is not fully understood. This paper seeks to clarify this relationship by analyzing the effects of exposing murine immune cells to volatile organic compounds (VOCs) produced by different mold species. Mold species studied include Stachybotrys alternans; tests performed include cell viability studies and immunoassays. Results have implications for further research and treatment of mold-related diseases.

Section Abstracts: Biology With Microbiology And Molecular Biology

Virginia Journal of Science

Abstracts of the Biology with Microbiology and Molecular Biology Section for the 88th Annual Meeting for the Virginia Academy of Science, May 20-21, 2010, James Madison University, Harrisonburg, VA.

A V3 Loop-Dependent Gp120 Element Disrupted By Cd4 Binding Stabilizes The Human Immunodeficiency Virus Envelope Glycoprotein Trimer, Shi-Hua Xiang, Andrés Finzi, Beatriz Pacheco, Kevin Alexander, Wen Yuan, Carlo Rizzuto, Chih-Chin Huang, Peter D. Kwong, Joseph Sodroski

Nebraska Center for Virology: Faculty Publications

Human immunodeficiency virus (HIV-1) entry into cells is mediated by a trimeric complex consisting of noncovalently associated gp120 (exterior) and gp41 (transmembrane) envelope glycoproteins. The binding of gp120 to receptors on the target cell alters the gp120-gp41 relationship and activates the membrane-fusing capacity of gp41. Interaction of gp120 with the primary receptor, CD4, results in the exposure of the gp120 third variable (V3) loop, which contributes to binding the CCR5 or CXCR4 chemokine receptors. We show here that insertions in the V3 stem or polar substitutions in a conserved hydrophobic patch near the V3 tip result in decreased gp120-gp41 association …

Pichia Insulana Sp. Nov., A Novel Cactophilic Yeast From The Caribbean Free, Philip F. Ganter, Gianluigi Cardinali, Kyria Boundy-Mills

Biology Faculty Research

A novel species of ascomycetous yeast, Pichia insulana sp. nov., is described from necrotic tissue of columnar cacti on Caribbean islands. P. insulana is closely related to and phenotypically very similar to Pichia cactophila and Pichia pseudocactophila. There are few distinctions between these taxa besides spore type, host preference and locality. Sporogenous strains of P. insulana that produce asci with four hat-shaped spores have been found only on Curaçao, whereas there was no evidence of sporogenous P. cactophila from that island. In addition, sequences of the D1/D2 fragment of the large-subunit rDNA from 12 Curaçao strains showed consistent differences from …

Farnesol Signaling In Candida Albicans, Melanie L. Langford

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

Candida albicans is a polymorphic fungus that causes a range of disease in humans, from mucosal infections to systemic disease. Its ability to cause disease is linked to conversion between yeast and filamentous forms of growth, and the first quorum-sensing molecule discovered in an eukaryote, farnesol, blocks this transition. In C. albicans, farnesol also kills mating-competent opaque cells, inhibits biofilm formation, protects the cells from oxidative stress, and can be a virulence factor or protective agent in disseminated and mucosal mouse models of infection, respectively. While much emphasis has been placed on determining its effect on C. albicans morphology, …

Cd1d-Dependent B-Cell Help By Nk-Like T Cells Leads To Enhanced And Sustained Production Of Bacillus Anthracis Lethal Toxin-Neutralizing Antibodies, T. Scott Devera, Lindsay M. Aye, Gillian A. Lang, Sunil K. Joshi, Jimmy D. Ballard, Mark L. Lang

Bioelectrics Publications

The current Bacillus anthracis vaccine consists largely of protective antigen (PA), the protein of anthrax toxin that mediates entry of edema factor (EF) or lethal factor (LF) into cells. PA induces protective antibody (Ab)-mediated immunity against Bacillus anthracis but has limited efficacy and duration. We previously demonstrated that activation of CD1d-restricted natural killer-like T cells (NKT) with a CD1d-binding glycolipid led to enhanced Ab titers specific for foreign antigen (Ag). We therefore tested the hypothesis that activation of NKT cells with the CD1d ligand (alpha-galactosylceramide [alpha-GC]) at the time of immunization improves PA-specific Ab responses. We observed that alpha-GC enhanced …

Role Of Flgt In Anchoring The Flagellum Of Vibrio Cholerae, Raquel M. Martinez, Brooke A. Jude, Thomas J. Kirn, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Flagellar motility has long been regarded as an important virulence factor. In Vibrio cholerae, the single polar flagellum is essential for motility as well as for proper attachment and colonization. In this study, we demonstrate that the novel flagellar protein FlgT is involved in anchoring the flagellum to the V. cholerae cell. A screen for novel colonization factors by use of TnphoA mutagenesis identified flgT. An in-frame deletion of flgT established that FlgT is required for attachment, colonization, and motility. Transmission electron microscopy revealed that while the flgT mutant is capable of assembling a phenotypically normal flagellum, …

An Assessment Of The Antioxidant And Antimicrobial Activity Of Six Species Of Edible Irish Seaweeds, Sabrina Cox, Nissreen Abu-Ghannam, Shilpi Gupta

Articles

Six species of edible Irish seaweeds; Laminaria digitata, Laminaria saccharina, Himanthalia elongata, Palmaria palmata, Chondrus crispus and Enteromorpha spirulina were screened for potential bioactivity. Extraction of secondary metabolites was carried out using different solvents to determine antioxidant and antimicrobial properties of the dried extracts. The total phenolic contents of dried methanolic extracts were significantly different (p < 0.05). H. elongata exhibited highest phenolic content at 151.3 mg GAE/g of seaweed extract and also had the highest DPPH scavenging activity (p < 0.05) with a 50% inhibition (EC50) level at 0.125μg/ml of extract. H. elongata also had the highest total tannin and total flavonoid contents (p < 0.05) of 38.34 mg CE/g and 42.5 mg QE/g, respectively. Antimicrobial activity was determined using a microtitre method which allowed detection of bacterial growth inhibition at low levels. All methanolic seaweed extracts inhibited the food spoilage and food pathogenic bacteria tested; Listeria monocytogenes, Salmonella abony, Enterococcus faecalis and Pseudomonas aeruginosa, except C. crispus extracts. It was found that dried methanolic extracts of red and green seaweeds had significantly lower antimicrobial activity than the brown species; H. elongata had the highest antimicrobial activity with up to 100% inhibition. In the studied work, the antimicrobial activity of red and green seaweed extracts significantly increased when ethanol and acetone were used as extraction solvents (p < 0.05). Inhibition of E. faecalis with C. crispus extracts increased from 39.28 to 100% when ethanol and acetone were applied as solvents.