Bacteriology Commons^™

Vibrio Cholerae H-Ns Silences Virulence Gene Expression At Multiple Steps In The Toxr Regulatory Cascade, Melinda B. Nye, James D. Pfau, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

H-NS is an abundant nucleoid-associated protein involved in the maintenance of chromosomal architecture in bacteria. H-NS also has a role in silencing the expression of a variety of environmentally regulated genes during growth under nonpermissive conditions. In this study we demonstrate a role for H-NS in the negative modulation of expression of several genes within the ToxR virulence regulon ofVibrio cholerae. Deletion of hns resulted in high, nearly constitutive levels of expression of the genes encoding cholera toxin, toxin-coregulated pilus, and the ToxT virulence gene regulatory protein. For the cholera toxin- and ToxT-encoding genes, elevated expression in an …

Molecular Evolution Of Insecticidal Spore-Forming Bacteria, John Pool

Honors Theses

Molecular methods are increasingly being used to determine the phylogeny of microorganisms. This research was intended to determine phylogenetic relationships for bacteria of the species Bacillus thuringiensis and other members of the Bacillus cereus group. Each strain was analyzed by its sasp-B gene sequence to determine its species classification and relation to other strains studied. Results of this study indicated that according to the sasp-B gene tree, the species Bacillus thuringiensis is a paraphyletic with respect to both Bacillus cereus and Bacillus anthracis. Some unexpected results and implications for species designations are also discussed.

Kinetic Characterization Of Tetracycline Binding And Release By Demineralized Bone - Dfdba, Orner Kabil

Biological Sciences Theses & Dissertations

The microbial etiology of periodontal diseases has led to widespread research in the development of methods and local delivery systems to increase the efficacy of antibiotic therapy. Several drug delivery systems employing biodegradable and nonbiodegradable carriers have been shown to release antibiotics directly into periodontal pockets. The purpose of this study was to determine the binding and release kinetics of tetracycline by demineralized bone. Further aspects of the study include in vitro evaluation of DFDBA (demineralized freeze-dried bone allografts) as a tetracycline carrier system for periodontal therapy. Experiments were performed which employed different tetracycline concentrations with constant amounts of bone …

Integronlike Structures In Campylobacter Spp. Of Human And Animal Origin, Brigid Lucey, D. Crowley, P. Moloney, B. Cryan, M. Daly, F. O'Halloran, E. J. Threlfall, S. Fanning

Department of Biological Sciences Publications

Resistance to antimicrobial agents used to treat severe Campylobacter spp. gastroenteritis is increasing worldwide. We assessed the antimicrobial resistance patterns of Campylobacter spp. isolates of human and animal origin. More than half (n = 32) were resistant to sulphonamide, a feature known to be associated with the presence of integrons. Analysis of these integrons will further our understanding of Campylobacter spp. epidemiology.

The Global Carbon Metabolism Regulator Crc Is A Component Of A Signal Transduction Pathway Required For Biofilm Development By Pseudomonas Aeruginosa, George A. O'Toole, Karine A. Gibbs, Paul W. Hager, Paul V. Phibbs, Roberto Kolter

Dartmouth Scholarship

The transition from a planktonic (free-swimming) existence to growth attached to a surface in a biofilm occurs in response to environmental factors, including the availability of nutrients. We show that the catabolite repression control (Crc) protein, which plays a role in the regulation of carbon metabolism, is necessary for biofilm formation in Pseudomonas aeruginosa. Using phase-contrast microscopy, we found that a crc mutant only makes a dispersed monolayer of cells on a plastic surface but does not develop the dense monolayer punctuated by microcolonies typical of the wild-type strain. This is a phenotype identical to that observed in mutants …

Genetic And Structural Analyses Of Cytoplasmic Filaments Of Wild-Type Treponema Phagedenis And A Flagellar Filament-Deficient Mutant, Jacques Izard, William A. Samsonoff, Mary Beth Kinoshita, Ronald J. Limberger

Department of Food Science and Technology: Faculty Publications

Unique cytoplasmic filaments are found in the treponeme genus of spirochete bacteria. Their function is unknown, but their location underneath the periplasmic flagellar filaments (PFF) suggests a role in motility and/or cell structure. To better understand these unique structures, the gene coding for the cytoplasmic filaments, cfpA, was identified in various treponemal species. Treponema phagedenis cfpA was 2,037 nucleotides long, and the encoded polypeptide showed 78 to 100% amino acid sequence identity with the partial sequence of CfpA from T. denticola, T. vincentii, and T. pallidum subsp. pertenue. Wild-type T. phagedenis and a …

A Vibrio Cholerae Lysr Homolog, Aphb, Cooperates With Apha At The Tcpph Promoter To Activate Expression Of The Toxr Virulence Cascade, Gabriela Kovacikova, Karen Skorupski

Dartmouth Scholarship

We describe here a new member of the LysR family of transcriptional regulators, AphB, which is required for activation of the Vibrio cholerae ToxR virulence cascade. AphB activates the transcription of the tcpPH operon in response to environmental stimuli, and this process requires cooperation with a second protein, AphA. The expression of neither aphA or aphB is strongly regulated by environmental stimuli, raising the possibility that the activities of the proteins themselves may be influenced under various conditions. Strains of the El Tor biotype of V. cholerae typically exhibit lower expression of ToxR-regulated virulence genes in vitro than classical strains …

An Extracellular Protein Produced By Staphylococcus Hominis Strain Αm With Antimicrobial Activity Against Mycobacterium Spp, Sandra May Jacobsen

Biological Sciences Theses & Dissertations

The inhibitory activity exhibited by Staphylococcus hominis strain αM toward Mycobacterium species was examined. These studies included determining the conditions that maximized inhibitory agent production, analyzing characteristics of the agent, determining the time of agent production, ascertaining plasmid possession and the role of plasmids in the production of this inhibitory agent, and ascertaining the antimicrobial activity of other strains of S. hominis. On solid and in liquid media, S. hominis strain αM exhibits a unique inhibitory activity toward Mycobacterium species that is not demonstrated by Staphylococcus epidermidis or other S. hominis strains. Maximum agent production and recovery was …

Insertional Inactivation Of Treponema Denticola Tap1 Results In A Nonmotile Mutant With Elongated Flagellar Hooks, Ronald J. Limberger, Linda L. Slivienski, Jacques Izard, William A. Samsonoff

Department of Food Science and Technology: Faculty Publications

The treponemal fla operon is comprised of numerous motility-related genes; however, the initial gene of this operon, tap1, has no known function. A recently developed system to generate specific mutants in Treponema denticola was utilized to determine if Tap1 was essential for motility. T. denticola tap1 and flanking DNA were identified, cloned, and sequenced, and a suicide plasmid that contained tap1 interrupted with an erythromycin resistance cassette (ermF and ermAM) was constructed. Because of potential polar effects from this cassette, a second plasmid that contained tap1 interrupted with a modified erythromycin resistance cassette that lacked the putative ermF transcription …

Genetic And Transcriptional Analyses Of The Vibrio Cholerae Mannose-Sensitive Hemagglutinin Type 4 Pilus Gene Locus, Jane W. Marsh, Ronald K. Taylor

Dartmouth Scholarship

The mannose-sensitive hemagglutinin (MSHA) of the Vibrio cholerae O1 El Tor biotype is a member of the family of type 4 pili. Type 4 pili are found on the surface of a variety of gram-negative bacteria and have demonstrated importance as host colonization factors, bacteriophage receptors, and mediators of DNA transfer. The gene locus required for the assembly and secretion of the MSHA pilus has been localized to a 16.7-kb region of the V. cholerae chromosome. Sixteen genes required for hemagglutination, including five that encode prepilin or prepilin-like proteins, have been identified. Examination of MSHA-specific cDNAs has localized two promoters …

Identification And Characterization Of Spcu, A Chaperone Required For Efficient Secretion Of The Exou Cytotoxin, Viviane Finck-Barbançon, Timothy L. Yahr, Dara W. Frank

Dartmouth Scholarship

In recent studies, we have shown that Pseudomonas aeruginosa strains that are acutely cytotoxic in vitro damage the lung epithelium in vivo. Genetic analysis indicated that the factor responsible for acute cytotoxicity was controlled by ExsA and therefore was part of the exoenzyme S regulon. The specific virulence determinant responsible for epithelial damage in vivo and cytotoxicity in vitro was subsequently mapped to the exoU locus. The present studies are focused on a genetic characterization of the exoU locus. Northern blot analyses and complementation experiments indicated that a region downstream of exoU was expressed and that the expression of this …

The Seca Subunit Of Escherichia Coli Preprotein Translocase Is Exposed To The Periplasm, Jerry Eichler, William Wickner

Dartmouth Scholarship

SecA undergoes conformational changes during translocation, inserting domains into and across the membrane or enhancing the protease resistance of these domains. We now show that some SecA bound at SecYEG is accessible from the periplasm to a membrane-impermeant probe in cells with a permeabilized outer membrane but an intact plasma membrane.

Characterization Of Metal-Regulated Genes In Pseudomonas Fluorescens, Melanie Pearson

Honors Theses

One side effect of today's industrialized world is increased levels of heavy metals in the environment. Many of these metals are necessary for biological function as trace elements, but at higher concentrations are toxic. Other metals, such as cadmium, are not beneficial at any level, and have only deleterious effects on living organisms. Cadmium is primarily thought to interfere with normal biological function of proteins. Human exposure to cadmium appears to primarily damage the kidneys, but may also affect the liver, lungs, immune system, and central nervous system. Bacteria, however, have developed several methods for handling toxic heavy metals: cation …

Cellular Responses In Escherichia Coli To Lethal And Sublethal Doses Of Ozone, Indira Ruth Komanapalli

Loma Linda University Electronic Theses, Dissertations & Projects

Ozone is a major component of photochemical smog. High levels of this pollutant, sufficient to affect human health are found in many urban areas worldwide. Though limited studies in humans are supported by extensive findings from animal experiments, a difficulty in interpreting the results of these experiments has lead to an ambiguity on the biochemical mechanism of ozone toxicity. To elucidate the mechanism by which ozone causes cell damage and eventual cell death we conducted a comprehensive study using Escherichia coli K-12 as a model.

Studies on the comparative inactivation of bacteriophage lambda (λ), Escherichia coli, and Candida albicans …

Cyclic Amp And Its Receptor Protein Negatively Regulate The Coordinate Expression Of Cholera Toxin And Toxin-Coregulated Pilus In Vibrio Cholerae, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Insertion mutations in two Vibrio cholerae genes, cya and crp, which encode adenylate cyclase and the cyclic AMP (cAMP) receptor protein (CRP), respectively, derepressed the expression of a chromosomal cholera toxin (CT) promoter-lacZ fusion at the nonpermissive temperature of 37 degrees C. In the classical biotype strain O395, the crp mutation increased the production of both CT and toxin-coregulated pilus (TCP) in vitro under a variety of growth conditions not normally permissive for their expression. The most dramatic increase in CT and TCP was observed with the crp mutant in Luria-Bertani (LB) medium pH 8.5, at 30 degrees C. El …

Biotransformation Of Bile Acids, Cholesterol And Steroids. Chapter 13 In: The Ecology And Physiology Of Gastrointestinal Microbes. Vol. 1, New York, Chapman And Hall., Stephen Baron, Phillip B. Hylemon

Biology Faculty Scholarship

No abstract provided.

Miscellaneous Publication No 33/93 - Virulent Footrot A Farmer's Guide To Eradication, Department Of Agriculture, Western Australia

Animal production and livestock published reports

The first thing to understand about virulent footrot is that it can occur on any farm in the medium to high rainfall zone. Persons who regularly buy and sell sheep have a greater risk, but even closed breeding flock properties are at risk from stray sheep.

People often associate footrot with properties managed by inefficient farmers. This is a false belief. Many good farmers have found the disease in their sheep, including high profile studs.

Footrot can strike anywhere and often without warning.

The important thing to remember is that once it is found, getting to know and understand the …

The Distribution And Occurrence Of Aerobic Heterotrophic Antimicrobic-Producing Bacteria Isolated From The Lower Chesapeake Bay, Linda Lea Gilmer

Biological Sciences Theses & Dissertations

Three different estuarine microenvironments in the lower Chesapeake Bay were investigated for the occurrence and geographical distribution of antimicrobic-producing bacteria. Samples were taken from the water column, fish skin, and algal surfaces. A total of 1472 bacterial isolates were assayed for antimicrobial activity against fungal, Gram-negative and Gram-positive bacterial test organisms. Of the total bacterial isolates assayed, 5. 2% were active antimicrobic producers. Algal surf aces were shown to have a higher incidence of antimicrobic-producing bacteria than the water column or fish skin. No antimicrobic activity was demonstrated by bacteria isolated from the flounder fish skin. The majority of the …

The Expression And Regulation Of The Hsdk Genes Of Escherichia Coli K-12, Ainu Parkash

Loma Linda University Electronic Theses, Dissertations & Projects

The DNA restriction and modification (R-M) genes in bacteria play a defensive role in the organism, offering protection to the host from invaders such as bacteriophages. The expression of these genes in E. coli K-12 had not previously been studied due to the complexity of the EcoK R-M enzymes. The use of lacZ gene fusion techniques allowed studies of the expression of the hsdK genes for the first time. Operon fusions of Mu(/ac) to the hsdK genes show that the two hsdK promoters, p _res and p _mod, are weak (50 Miller units) and that …

New Technique Joins The Fight Against Footrot, Laurie Depiazzi, Mike Palmer, David Pitman

Journal of the Department of Agriculture, Western Australia, Series 4

The diagnosis of footrot in sheep and goats is not an easy task. Two main techniques are used for diagnosis - inspection of diseased feet on a farm and laboratory testing of bacteria isolated from foot scrapings. The interpretation of the results obtained by these methods requires a good understanding of the various forms of footrot.

A new laboratory technique has halved the time taken to detect those strains of the bacterium, Bacteroides (Dichelobacter) nodosus, that cause each form of the disease.

Concentration Of Leukotrienes B4 And C4 In Human Periradicular Lesions, Elisabetta Cotti

Loma Linda University Electronic Theses, Dissertations & Projects

The 5-lipoxygenase metabolites of arachidonic acid such as leukotrienes (LT) B₄ and C₄, are potent mediators of inflammation. The purpose of this investigation was to determine the concentrations of LTB₄ and LTC₄ in human periradicular lesions. Specimens from asymptomatic and symptomatic patients were obtained and immediately frozen in liquid nitrogen. Periradicular tissues from unerupted third molars as well as chronically inflamed gingival tissues were also obtained, frozen and were used as negative and positive controls respectively. The concentrations of LTB₄ and LTC₄ were determined by the reverse phase high pressure liquid chromatography. Representative …

Characterization Of Hsd::Mudx128 Operon Fusion Mutant Of Escherichia Coli K-12, Marjorie Ann T. Reyno

Loma Linda University Electronic Theses, Dissertations & Projects

The study of the regulation of gene expression in complex genes can be facilitated by the use of operon fusions which place a well characterized lacZ gene under the control of a promoter of interest. An hsd::MudX128 operon fusion mutant of E. coli K-12 isolated by Prakash (1986) was observed to have a high β-galactosidase activity (1000 units), ten to twenty times higher than other hsd::MudX mutants. This β-galactosidase activity was suppressed to a very low level (25 units) by the introduction of an F’ plasmid, F'101, which carries the 98 min to 2 min region of the …

Interactions Between Aquatic Chromogenic Bacteria And Pathogenic Vibrio Spp., John Louis Harris

Biological Sciences Theses & Dissertations

Interactions between populations inhabiting an ecosys­tem are responsible, in large part, for determining which species coexist in that ecosystem. In this study, interac­tions between selected Vibrio species, V. alginolyticus and V. anguillarum, and marine heterotrophic, chromogenic bac­teria in aquatic microcosms were investigated. The ultimate goal of this project was to evaluate the feasibility of ex­ ploiting competitive interactions as a means to biologically control growth of the pathogenic marine bacteria, V. alginolyticus and V. anguillarum. In the majority of ex­periments (14/16), if chromogenic species were allowed to develop stable populations before a Vibrio spp. was intro­duced into a …

The Effects Of Certain Oral Bacteria On The In Vitro Growth Of Bacteroides Gingivalis, Steven G. Morrow

Loma Linda University Electronic Theses, Dissertations & Projects

The effect of nine gram positive and grain negative cocci and bacilli, which are indigenous to the oral cavity, on the in vitro growth of Bacteroides gingivalis was examined in this study. A pure culture of B. gingivalis is was obtained from the American Type Culture Collection. The nine oral test organisms were Streptococcus mitis, Streptococcus mutans, Streptococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus, Corynebacteriurn hofmanii, Lactobacillus acidophilus, Branhamella catarrhalis, and Escherichia coli. The effect on the growth of B. gingivalis of the nine test organisms was evaluated on a solid medium by use of …

A Study Of Transferable Antibiotic Resistance In Enteric Bacteria, Charles H. Regeski

Loma Linda University Electronic Theses, Dissertations & Projects

A group of 48 enteric bacteria was selected from a total of 170 at Loma Linda University Medical Center because of resistance to three or more antibiotics. They were examined to see if any of the antibiotic resistances were transferred by conjugation to either of two recipient bacteria. These were a restrictionless, antibiotic sensitive, azide resistant mutant of Escherichia coli K 12 designated E. coli 1228 and a similar phenotypic strain of Salmonella typhimurium LT2 designated LB 5000. Forty-three transferred one or more antibiotic resistances to either or both recipients, a frequency of 25.3% of the total bacteria and 89.6% …

Dispelling Some Myths About 'Dermo', J R. Edwards

Journal of the Department of Agriculture, Western Australia, Series 4

There are a lot of misconceptions and myths about dermatophilosis, a disease which can kill young lambs, affect wool quality, make shearing difficult and make sheep susceptible to fly strike.

One misconception is perpetuated by the incorrect use of the name mycotic dermatitis, which implies that a fungus causes the disease. This is not so.

The disease is caused by the bacteria Dermatophilus congolensis, which attacks the sheep's skin and eventually forms a lesion or scab in the wool, and so is better called dermatophilosis, 'dermo' or 'lumpy wool'.

Veterinary Epidemiologist at the Albany Regional Office, J.R. Edwards, discusses …

New Developments In Footrot Control, R B. Richards, L. J. Depiazzi, R. V. R. Gwynn

Journal of the Department of Agriculture, Western Australia, Series 4

The eradication policy for footrot in sheep adopted by the Western Australian Department of Agriculture has produced an overall decline in the number of properties with the disease.

Our knowledge of the disease has improved substantially as a result of the research conducted at the Slabany Regional Veterinary Laboratory in recent years. Laboratory tests now sssist stock inspectors and veterinary officers to distinguish between different forms of footrot and to quarantine and eradicate accordingly.

The recent discovery of more effective foot-bathing solutions by officers of the Victorian Department of Agriculture will greatly assist further eradication procedures.

Western Australia's sheep industry …

Petroleum-Utilizing Bacteria: The Biological Line Defense Against Oil Pollution, Steven W. Sokolowski

Biological Sciences Theses & Dissertations

A silica gel-petroleum (SGP) medium was developed which is reliable, approximately the same cost as that of the corresponding agar-based petroleum medium, and can be made sufficiently firm to use in streaking or the spread-plate technique. Advantages of the medium include: the incorporation of all of the major ions of seawater in accordance with Dittmar's Law (the salinity of which can easily be varied from 0 to 35 parts per thousand); a wide workable pH range (5.5 to 11.6); negligable pH drift(~ 0.2 pH units after 166 days); the elimination of all but negligable amounts of syneresis, the ability to …

The Development Of Techniques For The Enumeration Of Selected Pathogenic Bacteria In Lynnhaven Estuarine Sediments, Mark T. Frank

Biological Sciences Theses & Dissertations

Methodologies for the improved recovery of selected pathogenic bacteria from estuarine sediments were investigated. Laboratory and field studies were conducted to document the sensitivity of the techniques for isolating Salmonella species, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Vibrio parahaemolyticus-like organisms were enriched in a seawater yeast extract broth and isolated from Thiosulfate Citrate Bile Salts Sucrose plated media. Enrichment procedures with and without elevated temperatures and subsequent transfers to selective and differential plated media have been examined for the isolation of Salmonella species and P. aeruginosa. These pathogens were initially assayed for utilizing primary enrichments of asparagine …

Cell Mediated Immunity By Cytotoxicity Assay And The Effect Of Corynebacterium Parvum And Radiation On Mice Bearing Herpes-Induced Tumors, Robert B. Stagg

Loma Linda University Electronic Theses, Dissertations & Projects

Cell mediated immune (CMI) cytotoxic reactivity of Balb/c mice against H238 cells, a Herpes simplex virus (HSV) Type 2 - induced sarcoma, was measured by the ¹²⁵IUdR release assay. The Balb/c mouse response to the growing HSV-induced tumor, treated with radiation and , was measured by survival rate, tumor growth and immune cytotoxicity of spleen and peritoneal exudate cells (PEC) as determined by ¹²⁵IUdR release assay. Subcutaneous (s.c.) inoculation of 1 x 10⁶ H238 cells (high dose) produced progressive tumor growth while s.c. inoculation of 1 x 10⁴ H238 cells (low dose) produced no tumors. A …