Bacteriology Commons^™

Sara Of Staphylococcus Aureus Binds To The Sara Promoter To Regulate Gene Expression, Ambrose L. Cheung, Koren Nishina, Adhar C. Manna

Dartmouth Scholarship

The 375-bp sarA open reading frame is driven by three promoters, P1, P3, and P2. Using gel shift and DNase I footprinting assays, we found that SarA binds to two 26-bp sequences and one 31-bp sequence within the P1 and P3 promoters, respectively. Together with the results of transcription analyses, our data indicate that SarA binds to its own promoter to down-regulate sarA expression.

Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder

Articles

Sol–gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating. The incorporation of a silver salt into a sol–gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained …

Characterization Of Mazfsa, An Endoribonuclease From Staphylococcus Aureus, Zhibiao Fu, Niles P. Donegan, Guido Memmi, Ambrose L. Cheung

Dartmouth Scholarship

The mazEF homologs of Staphylococcus aureus, designated mazEF(sa), have been shown to cotranscribe with the sigB operon under stress conditions. In this study, we showed that MazEF(Sa), as with their Escherichia coli counterparts, compose a toxin-antitoxin module wherein MazF(Sa) leads to rapid cell growth arrest and loss in viable CFU upon overexpression. MazF(Sa) is a novel sequence-specific endoribonuclease which cleaves mRNA to inhibit protein synthesis. Using ctpA mRNA as the model substrate both in vitro and in vivo, we demonstrated that MazF(Sa) cleaves single-strand RNA preferentially at the 5' side of the first U or 3' side of the second …

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan Culbertson, Jaymie Krone, Erastus Gatebe, Norbert Furumo, Steven Daniel

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan J. Culbertson, Jaymie Krone, Erastus Gatebe, Norbert C. Furumo, Steven L. Daniel

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Jaymie Krone, Norbert Furumo

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

Antimicrobial Activity Screening Of Recombinant And Synthetic Varasin A Defensin From The Hard Tick Dermacentor Variabilis Against Various Bacteria, Julia A. Sharp

Biological Sciences Theses & Dissertations

Hematophagous arthropods, such as ticks and mosquitoes, rely on their innate immune system for defense against pathogens ingested in a blood meal as well as those acquired through injury. In response to pathogen recognition, the production of antimicrobial peptides, such as defensin, is typically upregulated. Varisin, a defensin, is thought to be a key component in the immunocompetence of the hard tick D. variabilis against Borrelia burgdorferi, the causative agent of Lyme disease. To study the antimicrobial effects of varisin, recombinant varisin was expressed by both insect cells and E coli. Purification of the protein followed by enterokinase treatment yielded …

A Serratia Marcescens Oxyr Homolog Mediates Surface Attachment And Biofilm Formation, Robert M. Q. Shanks, Nicholas A. Stella, Eric J. Kalivoda, Megan R. Doe

Dartmouth Scholarship

OxyR is a conserved bacterial transcription factor with a regulatory role in oxidative stress response. From a genetic screen for genes that modulate biofilm formation in the opportunistic pathogen Serratia marcescens, mutations in an oxyR homolog and predicted fimbria structural genes were identified. S. marcescens oxyR mutants were severely impaired in biofilm formation, in contrast to the hyperbiofilm phenotype exhibited by oxyR mutants of Escherichia coli and Burkholderia pseudomallei. Further analysis revealed that OxyR plays a role in the primary attachment of cells to a surface. Similar to what is observed in other bacterial species, S. marcescens OxyR …

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven Daniel, G. Hartman, E. Wagner, M. Plewa

Faculty Research & Creative Activity

No abstract provided.

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa

Faculty Research & Creative Activity

No abstract provided.

Bifa, A Cyclic-Di-Gmp Phosphodiesterase, Inversely Regulates Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Sherry L. Kuchma, Kimberly M. Brothers, Judith H. Merritt, Nicole T. Liberati, Frederick M. Ausubel, George A. O'Toole

Dartmouth Scholarship

The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in swarming motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner …

Crystal Structure Of The Vibrio Cholerae Quorum-Sensing Regulatory Protein Hapr, Rukman S. De Silva, Gabriela Kovacikova, Wei Lin, Ronald K. Taylor, Karen Skorupski, F. Jon Kull

Dartmouth Scholarship

Quorum sensing in Vibrio cholerae involves signaling between two-component sensor protein kinases and the response regulator LuxO to control the expression of the master regulator HapR. HapR, in turn, plays a central role in regulating a number of important processes, such as virulence gene expression and biofilm formation. We have determined the crystal structure of HapR to 2.2-Å resolution. Its structure reveals a dimeric, two-domain molecule with an all-helical structure that is strongly conserved with members of the TetR family of transcriptional regulators. The N-terminal DNA-binding domain contains a helix-turn-helix DNA-binding motif and alteration of certain residues in this domain …

Conservation Of The Sos Operon, Umudc, In Acinetobacter Species, Ching-Li Lin

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Ching-Li Lin on May 1, 2007.

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven Daniel, Bryan Culbertson, Norbert Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

Membrane Association And Multimerization Of Tcpt, The Cognate Atpase Ortholog Of The Vibrio Cholerae Toxin-Coregulated-Pilus Biogenesis Apparatus, Shital A. Tripathi, Ronald K. Taylor

Dartmouth Scholarship

The toxin-coregulated pilus (TCP) is one of the major virulence factors of Vibrio cholerae. Biogenesis of this type 4 pilus (Tfp) requires a number of structural components encoded by the tcp operon. TcpT, the cognate putative ATPase, is required for TCP biogenesis and all TCP-mediated functions. We studied the stability and localization of TcpT in cells containing in-frame deletions in each of the tcp genes. TcpT was detectable in each of the biogenesis mutants except the ΔtcpT strain. TcpT was localized to the inner membrane (IM) in a TcpR-dependent manner. TcpR is a predicted bitopic inner membrane protein …

Bactericidal Effects Of Cold Plasma Technology On Geobacillus Stearothermophilus And Bacillus Cereus Microorganisms, Angela Dawn Morris

Dental Hygiene Theses & Dissertations

Non-equilibrium atmospheric pressure plasma, also known as cold plasma, is a state of matter that consists of a mix of neutral and charged particles. Plasma generates chemically reactive species and ultraviolet radiation making them useful in decontamination applications (Kong & Laroussi, 2003). Research regarding the inactivation of gram-positive bacteria, such as Bacillus atrophaeus, by cold plasma has been studied by Laroussi et al. (2003); however, there is limited research regarding the germicidal effectiveness of cold plasma on the microorganisms Geobacillus stearothermophilus and Bacillus cereus. The purpose of this study was to determine if cold plasma technology inactivates heat …

Inverse Regulation Of Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, Judith H. Merritt, Kimberly M. Brothers, George A. O'Toole

Dartmouth Scholarship

We previously reported that SadB, a protein of unknown function, is required for an early step in biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa. Here we report that a mutation in sadB also results in increased swarming compared to the wild-type strain. Our data are consistent with a model in which SadB inversely regulates biofilm formation and swarming motility via its ability both to modulate flagellar reversals in a viscosity-dependent fashion and to influence the production of the Pel exopolysaccharide. We also show that SadB is required to properly modulate flagellar reversal rates via chemotaxis cluster IV (CheIV cluster). …

Staphylococcal Cassette Chromosome Mec And Panton-Valentine Leukocidin Characterization Of Methicillin-Resistant Staphylococcus Aureus Clones, Shannon M. Moroney, Loree C. Heller, Jesse Arbuckle, Monica Talavera, Ray H. Widen

Bioelectrics Publications

Staphylococcal cassette chromosome mec (SCCmec) types and Panton-Valentine leukocidin (PVL) gene carriage were compared among suspected community-associated methicillin-resistant Staphylococcus aureus MRSA (CA-MRSA) and health care-associated MRSA (HA-MRSA) isolates. CA-MRSA isolates carried the SCCmec type IV complex, and most were PVL positive. The HA-MRSA isolates carried the SCCmec type II complex and did not harbor the PVL genes.

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven Daniel, Christine Pilsl, Harold Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

Sulfur-Oxidizing Bacteria In Soap Lake (Washington State), A Meromictic, Haloalkaline Lake With An Unprecedented High Sulfide Content, Dimitry Y. Sorokin, Mirjam Foti, Holly C. Pinkart, Gerard Muyzer

All Faculty Scholarship for the College of the Sciences

Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium, which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 10⁷ cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups …

Evaluation Of Four Novel Broad-Host-Range Antimicrobial Agents., Jiahui Guo

Theses

The overall objective of this thesis was to evaluate the antimicrobial effects of four novel broad-host-range antimicrobial agents. The first was a milk-derived lipoprotein developed by Westgate Biologicals with the support of Enterprise Ireland. This lipoprotein which was designated LactiSAL, was evaluated against a wide range of bacterial species associated with humans. Essentially, the LactiSAL was incorporated at a variety of concentrations into agar media, which were appropriate for cultivation of the different genera. Agars were examined for colony formation, after which it was possible to quantify the minimal inhibitory concentration for each genus. Subsequently, LactiSAL was incorporated at levels …

Genetic Microheterogeneity And Phenotypic Variation Of Helicobacter Pylori Arginase In Clinical Isolates, Justin Hovey, Emily Watson, Melanie Langford, Ellen Hildebrandt, Sangeetha Bathala, Jeffrey Bolland, Domenico Spadafora, George Mendz, David Mcgee

School of Biological Sciences: Faculty Publications

Background: Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid.

Results: The degree of variation in arginase was explored at the DNA sequence, enzyme activity and protein expression levels. To this end, arginase activity was measured from 73 minimally-passaged clinical isolates and six laboratory-adapted strains …

Assessment Of Key Parameters To Achieve Bacteria Transformability In E. Coli And A. Tumefaciens, Zach Regelin

Honors Program Theses

ln this project, growth and transformability of E. coli and A. tumefaciens were investigated. The growth of the bacterial species was monitored under different key parameters including: the strain of the bacteria, the inoculum source (a fresh plate or frozen glycerol stock), and the media type. Growth was monitored by measuring the optical density (OD). Using E. coli strains Dh5a and CdB\ it was determined that the strain, the media type, and the amount of inoculum had a great effect on the growth but the source of the inoculum had little effect. For A. tumefaciens, the strain and the media …