Microbiology Commons^™

Virulence Factors Of The Group A Streptococci And Genes That Regulate Their Expression, Wayne Hines

Biological Sciences Faculty Publications

Group A streptococci produce a wide variety of extracellular (cell-associated and released) virulence factors. The function of these factors varies and includes roles in adhesion, spreading, tissue destruction, immune system evasion, and cell toxicity. How these factors are regulated with regard to one another is important for this organism's ability to bring about the variety of diseases this microbe is capable of causing. Therefore, along with the multitude of virulence factors, there are a number of regulatory systems that regulate, either directly or indirectly, the production of these factors and therefore influence the pathogenesis of group A streptococcal infections.

A Survey Of Antibiotic Resistance Among Coliform Bacteria Isolated From The Missouri River, Sara E. Mcdonnell, Amy M. Treonis

Biology Faculty Publications

The prevalence of antibiotic resistant microorganisms in the environment is not well known but could represent a challenge to maintaining public health in the future. Fecal waste from livestock facilities, where antibiotics are routinely used, is recognized as a significant source of pollution to surface waters in the United States. We collected water from the Missouri River across a winter to spring seasonal change in order to survey the density of coliform bacteria. We tested bacterial isolates for resistance to penicillin, tetracycline, ampicillin, erythromycin, and ciprofloxacin. Coliform density in Missouri River water generally was high throughout the study (0-405 cfu …

Identification And Characterization Of A Nontypeable Haemophilus Influenzae Putative Toxin-Antitoxin Locus, Dayle A. Daines, Justin Jarisch, Arnold L. Smith

Biological Sciences Faculty Publications

Background: Certain strains of an obligate parasite of the human upper respiratory tract, nontypeable Haemophilus influenzae (NTHi), can cause invasive diseases such as septicemia and meningitis, as well as chronic mucosal infections such as otitis media. To do this, the organism must invade and survive within both epithelial and endothelial cells. We have identified a facilitator of NT(Hi) survival inside human cells, virulence-associated protein D (vapD_Hi, encoded by gene H10450). Both vapD_Hi and a flanking gene, H10451, exhibit the genetic and physical characteristics of a toxin/antitoxin ( TA) locus, with VapD_Hi serving as the …

Isolation And Characterization Of Mycobacteria From Striped Bass Morone Saxatilis From The Chesapeake Bay, Martha W. Rhodes, Howard Kator, Ilsa Kaattari, David Gauthier, Wolfgang Vogelbein, Christopher A. Ottinger

Biological Sciences Faculty Publications

Mycobacteriosis in striped bass Morone saxatilisof Chesapeake Bay, USA, was first diagnosed in 1997 based on the presence of granulomatous inflammation and acid-fast bacteria in skin and spleen. To confirm histopathology, bacteriological detection and identification of mycobacteria were begun using splenic tissue from fish with and without skin ulcerations. On the basis of initial studies using a variety of selective and nonselective media, decontamination, homogenization and incubation conditions, a simple and quantitative recovery method using aseptic necropsy of splenic tissue was developed. Optimal recovery was obtained by spread-plating homogenates on Middlebrook 7H10 agar with incubation for 3 mo at …

Characterization Of Spy1600 A Putative Hyaluronidase Gene In Group A Streptococci, Karin M. Berling

Biological Sciences Theses & Dissertations

Group A Streptococci (GAS), also known as Streptococcus pyogenes, can cause a variety of human diseases ranging from asymptomatic to life threatening. Exactly how a single type of organism is able to inflict such a multitude of diseases remains to be fully understood. One possibility includes the large number of secreted virulence factors expressed by the organism. The recent sequencing of three streptococcal genomes has indicated the existence of several previously unknown genes, some of which may encode possible virulence factors. Among these is Spy1600, which based on its sequence similarities has been proposed to encode a hyaluronidase, a …

The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski

Dartmouth Scholarship

Activation of the tcpPH promoter on the Vibrio pathogenicity island by AphA and AphB initiates the Vibrio cholerae virulence cascade and is regulated by quorum sensing through the repressive action of HapR on aphA expression. To further understand how the chromosomally encoded AphA protein activates tcpPH expression, site-directed mutagenesis was used to identify the base pairs critical for AphA binding and transcriptional activation. This analysis revealed a region of partial dyad symmetry, TATGCA-N6-TNCNNA, that is important for both of these activities. Searching the V. cholerae genome for this binding site permitted the identification of a second one upstream of a …

Isolation And Characterization Of Thermophilic, Calcium-Precipitating Bacteria Form Calcite Deposits At Yucca Mountain, Terry Ann Else, Curtis R. Pantle, Penny S. Amy, Mark P. Buttner, Amy J. Smiecinski

Publications (YM)

Calcite deposits, composed of a mixture of calcium carbonate and silicon dioxide, were found in fractures and small cavities within the welded tuff of Yucca Mountain. This research investigation involves determining the presence of thermophilic, calciumprecipitating bacteria within these deposits. The possible existence of thermophilic bacteria may help to resolve the issue of whether these calcite deposits formed from precipitation of dissolved calcium carbonate in rain water transported from the overlying soil environment or as a result of upwelling of geothermally-heated waters transported from below the mountain. Evidence for microbially-influenced calcite precipitation in these deposits is indicated by the presence …

Decoupling Between Bacteria And The Surf-Zone Diatom Asterionellopsis Glacialis At Cassino Beach, Brazil, Paulo C. Abreu, Leonardo R. Rorig, Virginia Garcia, Clarisse Odebrecht, Bopaiah Biddanda

Peer-reviewed scientific publications

The surf-zone diatom Asterionellopsis glacialis (Castracane) Round attains extremely high abundances (up to 109 cells l–1) and chl a concentrations (up to 1.5 mg chl a l–1), forming darkbrown patches in Cassino Beach, southern Brazil. Several lines of evidence from this study indicate a decoupling between A. glacialis and heterotrophic bacteria. For instance, despite the high abundance of diatoms, associated high levels of chl a and rates of dissolved organic carbon (DOC) production by A. glacialis, bacterial abundance at Cassino Beach was extremely low (0.03 to 0.7 × 106 cells ml–1) compared to the nearby estuarine waters, adjacent coastal waters …

Crystal Structure Of The Sars Protein From Staphylococcus Aureus, Ronggui Li, Adhar C. Manna, Shaodong Dai, Ambrose L. Cheung, Gongyi Zhang

Dartmouth Scholarship

The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sarA and agr). One of these determinants, protein A (spa), is activated by sarS, which encodes a 250-residue DNA-binding protein. Genetic analysis indicated that the agr locus likely mediates spa repression by suppressing the transcription of sarS. Contrary to SarA and SarR, which require homodimer formation for proper function, SarS is unusual within the SarA protein family in that it contains two homologous halves, with each half sharing sequence similarity to SarA and SarR. Here we report the 2.2 Å …

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 …

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.

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 …

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 …

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.

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. …

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

Seton Hall University Dissertations and Theses (ETDs)

No abstract provided.

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 …

Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor

Dartmouth Scholarship

The AraC homolog ToxT coordinately regulates virulence gene expression in Vibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with the tcpA promoter and investigated the mechanism of ToxT-dependent transcriptional activation at tcpA. Deletion analysis showed that a region from −95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to −63. A collection of point mutations generated by error-prone PCR revealed two small regions required …

Microbial Cellulose Utilization: Fundamentals And Biotechnology, Lee R. Lynd, Paul J. Weimer, Willem H. Van Zyl, Isak S. Pretorius

Dartmouth Scholarship

Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial …

Affinity Purification And Characterization Of E. Coli Molecular Chaperones, Seung-Hee Nam

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The molecular chaperones are a group of proteins that are effective in vitro and in vivo folding aids and show a well documented affinity for proteins lacking tertiary structure.

Heat-induced Escherichia coli BL21 cell lysate (10 mg protein) was applied to immobilized ɑ-casein (45 mg/g beads) or β-casein (30 mg/g beads) column. After removing a majority of nonspecifically bound proteins with 1 M NaCl, the molecular chaperones were eluted with cold water, 1 mM Mg-ATP, or 6 M urea. Western analysis identified five Escherichia coli molecular chaperones including DnaK, DnaJ, GrpE, GroEL, and GroES. Among samples, ATP eluates showed the …

Tryptophan Catabolism In Brevibacterium Linens Bl2, Madhavi Ummadi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent studies suggest aromatic amino acid catabolism by starter lactococci and flavor adjunct bacteria have a significant impact on off-flavor development during Cheddar cheese ripening. We hypothesized that a flavor adjunct bacterium, Brevibacterium linens BL2, produces off-flavor compounds from aromatic amino acid metabolism that will have a detrimental impact on cheese flavor.

The mechanism of tryptophan (Trp) catabolism in Brevibacterium linens BL2, was investigated in a chemically defined medium during incubation in laboratory conditions (no carbohydrate, pH 6.50, 220 rpm, 25°C) and cheese-like conditions (no carbohydrate, 4% NaCl, static incubation, l5°C). In laboratory conditions, metabolic studies and enzyme assays confirmed …

Comparison Of Tnf-A Levels Produced By Macrophages Treated With Brucella Abortus And Escherichia Coli Lps, Tajie Harris

Honors Capstones

Capstone submitted as a graduation requirement for the BSU Honors Program.

Type 4 Pilus Biogenesis And Type Ii-Mediated Protein Secretion By Vibrio Cholerae Occur Independently Of The Tonb-Facilitated Proton Motive Force, Niranjan Bose, Shelley M. Payne, Ronald K. Taylor

Dartmouth Scholarship

In Vibrio cholerae, elaboration of toxin-coregulated pilus and protein secretion by the extracellular protein secretion apparatus occurred in the absence of both TonB systems. In contrast, the cognate putative ATPases were required for each process and could not substitute for each other.

Cyanonews (Vol. 17, No. 1, 2002), Jeff Elhai

CyanoNews

CyanoNews was a newsletter that served the cyanobacteriological community from 1985 to 2003, with content provided by readers (sort of a blog before there were blogs). The newsletter reported new findings from the lab, summaries of recent meetings (often provided by graduate students and post-docs entering the field), positions sought or available, life transitions, a compendium of recent cyanobacteria-related articles, and other items of interest to those who study cyanobacteria.

Characterization Of Host-Bacteria Interactions Contributing To Group B Streptococcus Colonization, Jennifer Marie Smith

Theses, Dissertations and Capstones

Group B streptococcus (GBS) is the leading cause of life-threatening bacterial infections during the first three months of life. GBS is also a frequent cause of maternal postpartum infections. Both types of infections stem from maternal vaginal and/or rectal colonization with GBS in the perinatal period. Limited information is available concerning how the colonization process occurs and what role the host immune system may play in the establishment of persistent colonization by GBS. The complex interactions between the immune system and GBS normally should end in clearance of the bacteria. However, since colonization by GBS occurs in a large number …

Effects Of Nonequilibrium Atmospheric Pressure Plasmas On The Heterotrophic Pathways Of Bacteria And On Their Cell Morphology, Mounir Laroussi, J. Paul Richardson, Fred C. Dobbs

OES Faculty Publications

To date, most research on the interaction of nonequilibrium, atmospheric pressure plasma discharges with bacteria has concentrated on the germicidal effects. Therefore, published results deal mainly with killing efficacy and little attention is given to physical mechanisms and biochemical pathways and their potential alterations when cells of microorganisms are exposed to the plasma. In this letter, an attempt to investigate the effects of plasma exposure on the biochemical pathways of bacteria is presented. In addition, using electron microscopy, we investigate if any gross morphological changes take place when cells are exposed to a lethal dose of plasma. We are testing …

Development Of A Genomic Approach For The Study Of A Coryneform Bacterial Collection., Carole Feurer

Theses

In the last few years, genomics has profoundly changed research in the biological sciences and in particular in microbiology. Recent studies have demonstrated that comparative genomics is a powerful approach contributing to a deeper understanding of the evolution of microorganisms. Bacterial collections are important resources of microorganisms, however, the potential that genomics has to offer remains to be realised as it is still virtually absent in any study involving strain collections. This feature thus framed the experimental objectives for this study, whose aim was to define the most comprehensive way to apply genomic based methods (high throughput sequencing and bioinformatics) …

Aerobic Biodegradation Of Methyl Tert-Butyl Ether By Aquifer Bacteria From Leaking Underground Storage Tank Sites, S. R. Kane, H. R. Beller, T. C. Legler, C. J. Koester, Holly C. Pinkart, R. U. Halden, A. M. Happel

All Faculty Scholarship for the College of the Sciences

The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-¹⁴C]MTBE was mineralized to¹⁴CO₂. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely …

Development Of An Electrotransformation Technique For Streptococcus Iniae And Preliminary Characterization Of The Hemolysin Associated With This Bacterium, Kimberly Ann Hahn

Biological Sciences Theses & Dissertations

Streptococcus iniae is a gram-positive organism responsible for causing disease in both freshwater as well as saltwater fish. Every year fisheries lose fish by the tons due to diseases caused by this organism. In 1991, the first reported human case of disease associated with this organism was described. Since this initial case, there have been numerous other reported cases of S. iniae infections. This organism is a catalase negative, facultatively anaerobic organism that produces a capsule and when plated onto blood agar demonstrates β-hemolytic activity.

In this study, the relationship between the hemolysin produced by S. iniae and the lactate …

Identification Of The Polar Flagellum Genes In Azospirillum Brasilense, Enid Thanna Mckinley

Loma Linda University Electronic Theses, Dissertations & Projects

Azospirillum brasilenser, a nitrogen fixing rhizobacterium, can colonize plant roots and increase the yield of economically important cereals, such as rice and grasses. This organism has a mixed pattern of flagellation: a single polar flagellum for motility in liquid medium and lateral flagella which might be involved in motility across the root surface and or attachment to the root hairs of plants. Flagella dictate A. brasilense chemotactic ability and motility, which plays an important role in colonization of plant roots. However, nothing is known about the genes that code for the polar flagellum. To study the polar flagellum, different mutants …