Microbiology Commons^™

Alpha-Toxin Is Required For Biofilm Formation By Staphylococcus Aureus, Nicky C. Caiazza, George A. O'Toole

Dartmouth Scholarship

Staphylococcus aureus is a common pathogen associated with nosocomial infections. It can persist in clinical settings and gain increased resistance to antimicrobial agents through biofilm formation. We have found that alpha-toxin, a secreted, multimeric, hemolytic toxin encoded by the hla gene, plays an integral role in biofilm formation. The hla mutant was unable to fully colonize plastic surfaces under both static and flow conditions. Based on microscopy studies, we propose that alpha-hemolysin is required for cell-to-cell interactions during biofilm formation.

Production Of Volatile Sulfur Compounds From Inorganic Sulfur By Lactococci, Supriyo Ghosh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Production of volatile sulfur compounds in cheese is associated with desirable flavors. The direct source of these compounds has been assumed to arise from the metabolism of methionine and cysteine. However, the methionine concentration in cheese rises above the amount found in casein during aging, suggesting that alternative sulfur sources are present in milk. This led us to hypothesize that lactococci may acquire sulfur from the inorganic sulfur pool of milk, in addition to methionine and cysteine, to generate volatile sulfur compounds during cheese ripening.

A turbidimetric method to determine total sulfate content in milk samples was developed. The average …

Rapid Detection Of Listeria Monocytogenes, Wim Lippens

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Listeria monocytogenes is a foodbome pathogen that can cause severe illness and even death. It is found in dairy and meat products. The focus is on rapid detection since conventional methods are time consuming (4-5 days). Pre-enrichment steps, as part of those methods, are time consuming. Our objective was to develop a detection system without a pre-enrichment step, giving a final result within 2 to 4 h.

In the concept of "the need for speed," a detection system with an antibody-based capture technique, followed by polymerase chain reaction (PCR), was developed. Glass beads coated with a Listeria polyclonal antibody were …

Determining The Influence Of The Extracellular Proteinase From Brevibacterium Linens On The Metabolism Of Lactococcus Lactis Spp. Lactis Using Functional Genomics, Yi Xie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since the catabolism of amino acids in cheese results in the formation of most volatile flavor compounds, a proper intracellular pool of amino acids must be established in order to produce a desirable flavor production in cheese. Generation of this pool of amino acids requires complex interactions among casein and its derivatives, proteolytic enzymes, and transport systems in the associated bacteria, including lactococci. In this project, we hypothesized that casein hydrolysis by the extracellular proteinases of Brevibacterium linens BL2 modulates the expression profile of proteolytic related genes in Lactococcus lactis spp. lactis IL1403.

In order to monitor the …

Hyaluronate Lyase Gene Of Streptococcus Pyogenes: Molecular Characterization And Regulation, Sheryl Lynne Walton

Theses and Dissertations in Biomedical Sciences

Streptococcus pyogenes causes an assortment of diseases ranging from pharyngitis to necrotizing fasciitis. This bacterium has the ability to elaborate several extracellular products capable of causing tissue damage; one of which is a hyaluronate lyase. Little information is available regarding the regulation of streptococcal hyaluronidase. As such, the expression of hylA in the hyaluronate lyase-producing strain ATCC 10403 and in strains that do not produce detectable enzyme was analyzed by RT-PCR and quantitative PCR. Hyaluronate lyase transcript was detected throughout growth for all strains; however, expression of hylA in the enzymatically inactive strains, 71698 and SF370, was determined …

Real-Time Study Of Multidrug Resistance Mechanism In Pseudomonas Aeruginosa Using Nanoparticle Optics And Single Live Cell Imaging, Sophia Vasou Kyriacou

Chemistry & Biochemistry Theses & Dissertations

This thesis centers on the study of the xenobiotic efflux system in Pseudomonas aeruginosa, which is a ubiquitous bacterium. It resists many structurally and functionally diverse substrates due to expression of Mex-extrusion pumps, including MexAB-OprM, MexCD-OprJ, MexEF-OprN and MexXY-OprM systems. Despite extensive research, the structure and mechanism of multidrug resistance is unclear (1-9). For example, (i) how do MexA, MexB and OprM proteins assemble to extrude antibiotics? (ii) What is the antibiotic susceptibility of MexA, MexB, and OprM proteins? (iii) How do substrates cross the outer membrane of P. aeruginosa? (iv) Where are antibiotics accumulated inside the cell? This thesis …

An Analysis Of Microbial Contamination In Military Aviation Fuel Systems, Harold W. Graef

Theses and Dissertations

Military aviation fuel systems can be an ideal environment for microorganisms. Microbial growth in hydrocarbon fuel systems arises because of the impracticality of keeping fuel tanks sterile and the inevitable presence of water from condensation. Microbial contaminants in aviation fuel systems are a concern because of their potential to degrade the fuel, accelerate tank corrosion, and threaten flight safety. This research addresses the concern of using more environmentally friendly Fuel System Icing Inhibitors (FSII), which are also biocidal. Are significant levels of microorganisms growing in military aviation fuel systems, and if so, are there any common variables? Forty aviation fuel …

Prevalence Of Bacteria Of Division Tm7 In Human Subgingival Plaque And Their Association With Disease, Mary M. Brinig, Paul W. Lepp, Cleber C. Ouverney, Gary C. Armitage, David A. Relman

Faculty Publications, Biological Sciences

Members of the uncultivated bacterial division TM7 have been detected in the human mouth, but little information is available regarding their prevalence and diversity at this site. Human subgingival plaque samples from healthy sites and sites exhibiting various stages of periodontal disease were analyzed for the presence of TM7 bacteria. TM7 ribosomal DNA (rDNA) was found in 96% of the samples, and it accounted for approximately 0.3%, on average, of all bacterial rDNA in the samples as determined by real-time quantitative PCR. Two new phylotypes of this division were identified, and members of the division were found to exhibit filamentous …

Comparison Of Methods For Dna Isolation From Food Samples For Detection Of Shiga Toxin-Producing Escherichia Coli By Real-Time Pcr, Loree C. Heller, Carisa R. Davis, K. Kealy Peak, David Wingfield, Andrew C. Cannons, Philip T. Amuso, Jacqueline Cattani

Bioelectrics Publications

In this study, food samples were intentionally contaminated with Escherichia coli O157:H7, and then DNA was isolated by using four commercial kits. The isolated DNA samples were compared by using real-time PCR detection of the Shiga toxin genes. The four kits tested worked similarly.

Life-History Evolution And The Microevolution Of Intermediary Metabolism: Activities Of Lipid-Metabolizing Enzymes In Life-History Morphs Of A Wing-Dimorphic Cricket, Anthony J. Zera, Zhangwu Zhao

Anthony Zera Publications

Although a considerable amount of information is available on the ecology, genetics, and physiology of life-history traits, much more limited data are available on the biochemical and genetic correlates of life-history variation within species. Specific activities of five enzymes of lipid biosynthesis and two enzymes of amino acid catabolism were compared among lines selected for flight-capable (LW[f]) versus flightless (SW) morphs of the cricket Gryllus firmus. These morphs, which exist in natural populations, differ genetically in ovarian growth (100–400% higher in SW) and aspects of flight capability including the size of wings and flight muscles, and the concentration of triglyceride …

Rhamnolipid Surfactant Production Affects Biofilm Architecture In Pseudomonas Aeruginosa Pao1, Mary E. Davey, Nicky C. Caiazza, George A. O'Toole

Dartmouth Scholarship

In response to certain environmental signals, bacteria will differentiate from an independent free-living mode of growth and take up an interdependent surface-attached existence. These surface-attached microbial communities are known as biofilms. In flowing systems where nutrients are available, biofilms can develop into elaborate three-dimensional structures. The development of biofilm architecture, particularly the spatial arrangement of colonies within the matrix and the open areas surrounding the colonies, is thought to be fundamental to the function of these complex communities. Here we report a new role for rhamnolipid surfactants produced by the opportunistic pathogen Pseudomonas aeruginosa in the maintenance of biofilm architecture. …

Postnatal Human Herpesvirus 8 And Human Immunodeficiency Virus Type 1 Infection In Mothers And Infants From Zambia, Brad P. Brayfield, Saul Phiri, Chipepo Kankasa, Jubra Muyanga, Hamakwa Mantina, Geoffrey Kwenda, John T. West, Ganapati Bhat, Dave B. Marx, Winslow Klaskala, Charles D. Mitchell, Charles Wood

Nebraska Center for Virology: Faculty Publications

The specific route and timing of human herpesvirus (HHV) 8 infection in regions where Kaposi sarcoma is endemic are not known. HHV-8 infection and any risk factors that may be associated with HHV-8, including human immunodeficiency virus (HIV) type 1 infection, were monitored during the 12-month post-delivery period for 416 mothers and 485 infants from Lusaka, Zambia. HHV-8 incident infection rates during this period were 3.2 and 5.3 infections/100 person-years for infants and mothers, respectively. HHV-8 infection among infants was not associated with HHV-8 or HIV-1 infection in the mother. Among the HHV-8–positive infants, 2 of 12 tested were found …

Meiotic And Mitotic Phenotypes Conferred By The Blm1-1 Mutation In Saccharomyces Cerevisiae And Msh4 Suppression Of The Bleomycin Hypersusceptibility, Georgia Anyatonwu, Ediberto Garcia, Ajay Pramanik, Marie Powell, Carol Wood Moore

Publications and Research

Oxidative damage can lead to a number of diseases, and can be fatal. The blm1-1 mutation of Saccharomyces cerevisiae confers hypersusceptibility to lethal effects of the oxidative, anticancer and antifungal agent, bleomycin. For the current report, additional defects conferred by the mutation in meiosis and mitosis were investigated. The viability of spores produced during meiosis by homozygous normal BLM1/BLM1, heterozygous BLM1/blm1-1, and homozygous mutant blm1-1/blm1-1 diploid strains was studied and compared. Approximately 88% of the tetrads derived from homozygous blm1-1/blm1-1 mutant diploid cells only produced one or two viable spores. In contrast, just one tetrad among all BLM1/BLM1 and BLM1/blm1-1 …

Rapid Prion Neuroinvasion Following Tongue Infection, Jason C. Bartz, Anthony E. Kincaid, Richard A. Bessen

Nebraska Center for Virology: Faculty Publications

Food-borne transmission of prions can lead to infection of the gastrointestinal tract and neuroinvasion via the splanchnic and vagus nerves. Here we report that the transmission of transmissible mink encephalopathy (TME) is 100,000-fold more efficient by inoculation of prions into the tongues of hamsters than by oral ingestion. The incubation period following TME agent (hereinafter referred to as TME) inoculation into the lingual muscles was the shortest among the five nonneuronal routes of inoculation, including another intramuscular route. Deposition of the abnormal isoform of the prion protein, PrP^Sc, was first detected in the tongue and submandibular lymph node …

Transcriptional Control Of The Opp Operon In Clostridium Difficile, S. Lindsey Davis

Inquiry: The University of Arkansas Undergraduate Research Journal

As a serious expense for both the hospital and the patient, nosocomial infections create a burden on the health care industry that is not easily overcome. Among the infections commonly contracted in the hospital environment, those associated with the Clostridium difficile bacterium account for millions of cases each year. Largely due to the nature of C. difficile infection as a response to the disruption of the normal flora of the colon caused by antibiotic activity, no completely effective treatment for this condition has been identified. It is this problem that forms the foundation for research devoted to the development of …

Regulation Of Type 1 Diabetes By A Self-Mhc Class Ii Peptide: Role Of Transforming Growth Factor Beta (Tgf-Beta)., Bhagirath Singh, R Mukherjee, P Chaturvedi, Babita Agrawal

Microbiology & Immunology Publications

The present study was undertaken to analyze the regulatory T cells generated in response to class I derived self-I-A beta(g7) (54-76) peptide. It was observed T cells from young unprimed type 1 diabetes (T1D) prone NOD mice did not respond to self-I-A beta(g7) (54-76) peptide although T cells from primed young NOD mice showed a strong response. T cells from young unprimed BALB/c mice responded to self-I-A beta(d) (62-78) peptide. However, a breakdown of tolerance to these peptides was observed with age in both the strains. Culture supernatant from I-A beta(g7) (54-76) peptide-primed cells secreted large amounts of TGF-beta and …

Humboldt Journal Of Microbiology: Volume 6, Number 1- May 2003, Press Humboldt

Humboldt Journal of Microbiology

No abstract provided.

Structural Analyses Of Phycodnaviridae And Iridoviridae, Alan A. Simpson, Narayanasamy Nandhagopal, James L. Van Etten, Michael G. Rossmann

Nebraska Center for Virology: Faculty Publications

The Phycodnaviridae, Iridoviridae and related viruses, with diameters of 1500±2000 A Ê , are formed from large trigonal arrays of hexagonally close-packed capsomers forming the faces of icosahedra [Yan et al. (2000), Nature Struct. Biol. 7, 101-103; Nandhagopal et al. (2002), Proc. Natl Acad. Sci. USA, 99, 14758-14763]. Caspar and Klug predicted that such structures could be assembled from hexameric capsomers [Caspar & Klug (1962), Cold Spring Harbor. Symp. Quant. Biol. 27, 1-24], as was subsequently found in numerous icosahedral viruses. During the course of evolution, some viruses, including the virus families …

Developing Methods For The Rapid Molecular Assessment Of Aquatic Microbial Communities, Traci D. Hudson

Theses, Dissertations and Capstones

Molecular investigations of microbial community structure and dynamics involve costly and time-consuming methods. This approach is limiting when rapid assessment and detection of microbial organisms are needed. In aquatic environments, especially freshwater environments which may be used as a water source, rapid detection of pathogenic microbes is essential. Likewise, monitoring for the presence or absence of various functional genes can be used to indicate the type of microbial community present in the environment of interest. Therefore, the aim of this study was to develop and optimize methods necessary for the rapid assessment of freshwater microbial community structure and dynamics. Primers …

Functional Implications In Apoptosis By Interferon Inducible Gene Product 1-8d, The Binding Protein To Adenovirus Preterminal Protein, Insil Joung, Peter C. Angeletti, Jeffrey A. Engler

Nebraska Center for Virology: Faculty Publications

Adenovirus (Ad) precursor to the terminal protein (pTP) plays an essential roles in the viral DNA

replication. Ad pTP serves as a primer for the synthesis of a new DNA strand during the initiation

step of replication. In addition, Ad pTP forms organized spherical replication foci on the nuclear

matrix (NM) and anchors the viral genome to the NM. Here we identified the interferon inducible

gene product 1-8D (Inid) as a pTP binding protein by using a two-hybrid screen of a HeLa cDNA

library. Of the clones obtained in this assay, nine were identical to the Inid, a 13-kDa polypeptide …

Dara, The Antirestriction Protein Of Bacteriophage P1, Priti R. Vemulapalli

Seton Hall University Dissertations and Theses (ETDs)

No abstract provided.

Use Of Irradiated And Formalin-Fixed Trichomonas Vaginalis To Examine Protective Immune Responses In The Mouse Intraperitoneal Model, Terryl L. Hostetler, James J. Daly, Timothy J. O'Brien, Max L. Baker

Journal of the Arkansas Academy of Science

Gamma irradiated Trichomonas vaginalis was used to initiate a protective immune response in mice by intraperitoneal inoculation using host mortality as the measure of virulence. Irradiated trichomonads of a virulent strain gave some immune protection but no more so than the use of formalin-fixed, virulent trichomonads. A formalin-fixed virulent strain combined with complete Freund's adjuvant (CFA) gave complete protection. Metabolically produced antigens do not appear to be important in conferring protective immunity in these experiments. A common laboratory strain of T. vaginalis (ATCC 30001) was used as an avirulent control. It gave no protection against a virulent strain. Combining CFA …

Experimental Mycobacteriosis In Striped Bass Morone Saxatilis, D. T. Gauthier, M. W. Rhodes, W. K. Vogelbein, H. Kator, C. A. Ottinger

Biological Sciences Faculty Publications

Striped bass Morone saxatilis were infected intraperitoneally with approximately 10⁵ Mycobacterium marinum, M. shottsii sp. nov., or M. gordonae. Infected fish were maintained in a flow-through freshwater system at 18 to 21°C, and were examined histologically and bacteriologically at 2, 4, 6, 8, 17, 26, 36 and 45 wk post-infection (p.i.). M. marinum caused acute peritonitis, followed by extensive granuloma development in the mesenteries, spleen and anterior kidney. Granulomas in these tissues underwent a temporal progression of distinct morphological stages, culminating in well-circumscribed lesions surrounded by normal or healing tissue. Mycobacteria were cultured in high numbers from …

Potentiation Of Trail-Induced Apoptosis In Primary Effusion Lymphoma Through Azidothymidine-Mediated Inhibition Of Nf-[Kappa]B, Subrata K. Ghosh, Charles Wood, Lawrence H. Boise, Abdul M. Mian, Vadim V. Deyev, Gerold Feuer, Ngoc L. Toomey, Nicole C. Shank, Lisa Cabral, Glen N. Barber, William J. Harrington

Nebraska Center for Virology: Faculty Publications

The survival of viral mediated lymphomas depends upon constitutive nuclear factor kappa B (NF-[kappa]B) activity. AIDS-related human herpesvirus type 8–associated primary effusion lymphoma (PEL) responds poorly to chemotherapy and is almost invariably fatal. We have previously demonstrated that the antiviral combination of interferon alpha (IFN-[alpha]) and azidothymidine (AZT) induces apoptosis in PEL cell lines. We therefore used these agents as therapy for an AIDS patient with PEL. The patient had a dramatic response, with complete resolution of his malignant effusion in 5 days. In PEL cells, the death receptor ligand known as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is markedly …

Epitope Mapping And Characterization Of A Novel Cd4-Induced Human Monoclonal Antibody Capable Of Neutralizing Primary Hiv-1 Strains, Shi-Hua Xiang, Liping Wang, Mariam Abreu, Chih-Chin Huang, Peter D. Kwong, Eric Rosenberg, James E. Robinson, Joseph Sodroski

Nebraska Center for Virology: Faculty Publications

Human immunodeficiency virus (HIV-1) enters target cells by binding its gp120 exterior envelope glycoprotein to CD4 and one of the chemokine receptors, CCR5 or CXCR4. CD4-induced (CD4i) antibodies bind gp120 more efficiently after CD4 binding and block the interaction with the chemokine receptor. Examples of CD4i antibodies are limited, and the prototypes of the CD4i antibodies exhibit only weak neutralizing activity against primary, clinical HIV-1 isolates. Here we report the identification of a novel antibody, E51, that exhibits CD4-induced binding to gp120 and neutralizes primary HIV-1 more efficiently than the prototypic CD4i antibodies. The E51 antibody blocks the interaction of …

Animal Anti-Apoptotic Genes Ameliorate The Loss Of Turgor In Water-Stressed Transgenic Tobacco, Tala Awada, D. D. Dunigan, M. B. Dickman

Nebraska Center for Virology: Faculty Publications

Nicotiana tabacum L. ‘Glurk’ plants were transformed with antiapoptotic animal genes [chicken Bcl-xl; nematode CED-9; chicken Bcl-xl(GA) a mutant of Bcl-xl; and a 3’ non-coding region of human Bcl-2, referred to as 161-1]. Our objectives were to determine whether plant transformation with anti-apoptotic genes ameliorates drought tolerance in tobacco plants by subjecting the plants to a dry-down period. The non-transformed Glurk and the transgenic Glurk harboring G115, which expresses β-glucuronidase, served as controls. Transformation of tobacco plants with animal anti-apoptotic genes significantly impacted the rates of photosynthesis (A) and stomatal conductance (g_s), but not to the same extent …

Identification Of Novel Domains Within Sox-2 And Sox-11 Involved In Autoinhibition Of Dna Binding And Partnership Specificity, Matthew S. Wiebe, Tamara K. Nowling, Angie Rizzino

Nebraska Center for Virology: Faculty Publications

Sox transcription factors play key regulatory roles throughout development, binding DNA through a consensus (A/T)(A/T)CAA(A/T)G sequence. Although many different Sox proteins bind to this se-quence, it has been observed that gene regulatory elements are commonly responsive to only a small subset of the entire family, implying that regulatory mechanisms exist to permit selective DNA bind-ing and/or transactivation by Sox family members. To identify and explore the mechanisms modu-lating gene activation by Sox proteins further, we compared the function of Sox-2 and Sox-11. This led to the discovery that Sox proteins are regulated differentially at multiple levels, including trans-activation, protein partnerships …

Duration Of Infection And Proportion Of Pigs Persistently Infected With Porcine Reproductive And Respiratory Syndrome Virus, Robert W. Wills, Alan R. Doster, Judith A. Galeota, Jung-Hyang Sur, Fernando A. Osorio

Nebraska Center for Virology: Faculty Publications

Understanding the dynamics of porcine reproductive and respiratory syndrome virus (PRRSV) persistence in individual pigs is essential to the development of successful control programs. The objectives of this study were to investigate the proportion of inoculated pigs that become persistently infected with PRRSV and the duration of their infection. Additionally, different diagnostic techniques that detect persistent infections were compared. Twenty-eight 35-day-old pigs were inoculated with PRRSV. Serum and tonsil biopsy samples were collected on days 0, 7, 14, and 28 and then approximately monthly thereafter until day 251 post-inoculation (p.i.). Tonsil, lymph node, and lung samples were collected following euthanasia …

The Coat Protein Of Turnip Crinkle Virus Suppresses Posttranscriptional Gene Silencing At An Early Initiation Step, Feng Qu, Tao Ren, Thomas Jack Morris

Nebraska Center for Virology: Faculty Publications

Posttranscriptional gene silencing (PTGS), or RNA silencing, is a sequence-specific RNA degradation process that targets foreign RNA, including viral and transposon RNA for destruction. Several RNA plant viruses have been shown to encode suppressors of PTGS in order to survive this host defense. We report here that the coat protein (CP) of Turnip crinkle virus (TCV) strongly suppresses PTGS. The Agrobacterium infiltration system was used to demonstrate that TCV CP suppressed the local PTGS as strongly as several previously reported virus-coded suppressors and that the action of TCV CP eliminated the small interfering RNAs associated with PTGS. We have also …

Eight Gram-Negative Bacteria Are 10,000 Times More Sensitive To Cationic Detergents Than To Anionic Detergents, Soumitra Rajagopal, Nicole Eis, Kenneth Nickerson

Kenneth Nickerson Papers

In liquid culture, eight typical Gram-negative bacteria were ca. 10,000-fold more sensitive to cationic detergents than to the anionic detergent sodium dodecyl sulfate. Cetyltrimethylammonium bromide (CTAB) was inhibitory at concentrations ranging from 0.0006% to 0.01%. Four pseudomonads able to form biofilms were ca. 1000-fold more resistant to CTAB on Luria–Bertani agar plates than they were in liquid culture. A lasI mutant of Pseudomonas aeruginosa was only able to tolerate 0.1% CTAB on Luria–Bertani agar plates but could tolerate 5% CTAB when supplemented with homoserine lactone containing culture supernatants.

En culture liquide, huit bactéries Gram négatif typiques étaient ca. 10,000 fois …