Bacteriology Commons^™

Characterisation Of Bacterial Extracellular Polysaccharides (Eps) And Other Complex Carbohydrates With Prebiotic Potential, Padraigin Murphy

Theses

Prebiotics are selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microbiota that confers benefits upon host well-being and health’ It is not the prebiotic by itself but rather the changes induced in microflora composition that is responsible for its effects. Several sources of prebiotic were used in this study, namely extracellular polysaccharides (EPS) originating from Lactic Acid Bacteria (LAB), barley, oat. Laminaria digitata. Laminaria hyperborea and Saccharomyces cerevisiae. EPS-producing LAB were isolated from a wide variety of environmental and gastrointestinal niches. The strains were typed and classified according to their EPS-producing ability …

Characterization Of Photochromogenic Mycobacterium Spp. From Chesapeake Bay Striped Bass Morone Saxatilis, D. T. Gauthier, A. M. Helenthal, M. W. Rhodes, W. K. Vogelbein, H. I. Kator

Biological Sciences Faculty Publications

A large diversity of Mycobacterium spp. has been isolated from striped bass Morone saxatilis in Chesapeake Bay, USA. The new species M. shottsii and M. pseudoshottsii are the dominant isolates, while the classical fish pathogen M. marinum is found much less frequently. M. fortuitum and M. chelonae, other Mycobacterium spp. known to commonly infect fishes, have not yet been aseptically isolated from striped bass within Chesapeake Bay. While M. pseudoshottsii and M. shottsii have been phenotypically and genotypically characterized, other less common mycobacterial isolates have not. In the present study, we describe 17 photochromogenic isolates from Chesapeake …

Western Australia's Biosecurity, Department Of Agriculture And Food, Western Australia, Department Of Environment And Conservation, Western Australia, Department Of Fisheries, Western Australia, Forest Products Commission, Western Australia

Biosecurity published reports

Biosecurity is the protection of the economy, environment and human health from the negative impacts of pests, weeds and diseases, including the management of invasive species if they become established (definition adopted by AusBIOSEC).

This requires steps to prevent the entry of harmful organisms, as well as the timely and efficient management of them if they do enter.

Biosecurity threats range from catastrophic diseases such as Foot and Mouth Disease, which causes rapid and widespread animal deaths, to more subtle and slower spreading problems such as invasive weeds, mussels that foul vessel hulls and fungus-induced dieback disease of trees. These …

Modulation Of Alpha-Subunit Visit-Dg Sequence Residues Ser-347, Gly-351 And Thr-349 In The Catalytic Sites Of Escherichia Coli Atp Synthase., Laura Elaine Brudecki

Electronic Theses and Dissertations

Binding of inorganic phosphate (P_i) in ATP synthase catalytic sites is a crucial step for the synthesis of adenosine-5'-triphosphate (ATP). ATP is the fundamental means of cellular energy in almost every organism, and in order to gain insight into the regulation of ATP catalysis, critical amino acid residues responsible for binding P_i must be identified. Here, we investigate the role of highly conserved α-subunit VISIT-DG sequence residues αSer-347, αGly-351, and αThr-349 in P_i binding. Mutations αS347A/Q, αG351Q, αT349A/D/R, βR182A, and αT349R/βR182A were generated via site directed mutagenesis. Results from biochemical assays showed that αSer-347 is required …

Discovery And Characterization Of An Antibiotic From The Soil Bacterium Bacillus Sp., Thomas S. Barber

Electronic Theses and Dissertations

Many important antibiotics have become nearly obsolete due to the rise of antibiotic resistant pathogens. Rhodococcus, an actinomycete related to the prolific antibiotic producing genus Streptomyces, harbors over 30 genes for secondary metabolism that could be involved in antibiotic production. Several antibiotics have already been reported for Rhodococcus, suggesting the genus may be a good source for new inhibitory compounds. Fifty four soil bacteria were isolated using enrichment culture techniques (including 37 Rhodococcus) and screened for antibiotic producers. BTHX2, a species of Bacillus was found to have activity against Micrococcus luteus and Rhodococcus erythropolis. BTHX2 …

H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at …

Campylobacter Ureolyticus: An Emerging Gastrointestinal Pathogen?, Susan Bullman, Daniel Corcoran, James O'Leary, Brigid Lucey, Deirdre Byrne, Roy D. Sleator

Department of Biological Sciences Publications

A total of 7194 faecal samples collected over a 1-year period from patients presenting with diarrhoea were screened for Campylobacter spp. using EntericBios, a multiplex-PCR system. Of 349 Campylobacter-positive samples, 23.8% were shown to be Campylobacter ureolyticus, using a combination of 16S rRNA gene analysis and highly specific primers targeting the HSP60 gene of this organism. This is, to the best of our knowledge, the first report of C. ureolyticus in the faeces of patients presenting with gastroenteritis and may suggest a role for this organism as an emerging enteric pathogen.

Analysis Of The Clear Plaque Phenotype Of The Bacteriophage Hk75, Phani Chandrika Kunapuli

Masters Theses & Specialist Projects

The growth of bacteriophage HK75 is inhibited by specific mutations in the zinc binding domain of the host RNA polymerase beta prime subunit. It shares this rare property with bacteriophage HK022 and other phages that use RNA mediated antitermination to promote early gene expression. Recent genomic analysis of HK75 and HK022 has confirmed the relatedness of these two phages and place HK75 in the lambdoid family of bacteriophages. Lambdoid phages are temperate and can adopt a lytic or lysogenic lifestyle upon infection of a suitable host. However, HK75 only forms clear plaques and thus appears to be defective in its …

Staphylococcus Aureus Virulence Factors Synthesis Is Controlled By Central Metabolism, Yefei Zhu

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

Staphylococcus aureus is a versatile pathogen that can survive in diverse host environments. This versatility depends on its ability to sense nutrients and respond by modulating gene expression, including the synthesis of virulence determinants. In addition to its ability to synthesize virulence factors, the capacity of S. aureus to form biofilms is an important mediator of virulence in certain infections. Biofilms are a complex aggregation of bacteria commonly encapsulated by an adhesive exopolysaccharide matrix (polysaccharide intercellular adhesin; PIA). To study S. aureus biofilm formation, we assessed the metabolic requirements of S. aureus growing in a biofilm and …

Deletion Of The Cel48s Cellulase From Clostridium Thermocellum, Daniel G. Olson, Shital A. Tripathi, Richard J. Giannone, Jonathan Lo, Nicky C. Caiazza, David A. Hogsett, Robert L. Hettich, Adam M. Guss, Genia Dubrovsky, Lee R. Lynd

Dartmouth Scholarship

Clostridium thermocellum is a thermophilic anaerobic bacterium that rapidly solubilizes cellulose with the aid of a multienzyme cellulosome complex. Creation of knockout mutants for Cel48S (also known as CelS, S(S), and S8), the most abundant cellulosome subunit, was undertaken to gain insight into its role in enzymatic and microbial cellulose solubilization. Cultures of the Cel48S deletion mutant (S mutant) were able to completely solubilize 10 g/L crystalline cellulose. The cellulose hydrolysis rate of the S mutant strain was 60% lower than the parent strain, with the S mutant strain also exhibiting a 40% reduction in cell yield. The cellulosome produced …

The Human Oral Microbiome, Floyd E. Dewhirst, Tuste Chen, Jacques Izard, Bruce J. Paster, Anne C. R. Tanner, Wen-Han Yu, Abirami Lakshmanan, William G. Wade

Department of Food Science and Technology: Faculty Publications

The human oral cavity contains a number of different habitats, including the teeth, gingival sulcus, tongue, cheeks, hard and soft palates, and tonsils, which are colonized by bacteria. The oral microbiome comprises over 600 prevalent taxa at the species level, with distinct subsets predominating at different habitats. The oral microbiome has been extensively characterized by cultivation and culture-independent molecular methods such as 16S rRNA cloning. Unfortunately, the vast majority of unnamed oral taxa are referenced by clone numbers or 16S rRNA GenBank accession numbers, often without taxonomic anchors. The first aim of this research was to collect 16S rRNA gene …

Growth Of Lactic Acid Bacteria: Influence Of Protocooperation, Bacteriophage Infection, And Prebiotic Carbohydrates, Caitlin D. Goin

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

Lactic acid bacteria are a vital part of the fermented food industry and are the subject of much interest and research. Industry is especially interested in using modern molecular approaches to maintain and improve selected strains; several industrial uses could be improved by closer investigation, namely the protocooperation of S. thermophilus and L. bulgaricus, the role of CRISPRs in phage resistance, and the utilization of prebiotic carbohydrates. Questions such as what genes and pathways are shared during milk fermentation between S. thermophilus and L. bulgaricus, when and what genes are active during bacteriophage infection, and how and where …

Isolation Of A Siderophore Produced By Methicillin-Resistant Staphylococcus Aureus Strain H372., Rachel Elizabeth Presswood

Electronic Theses and Dissertations

Iron is necessary for many cellular processes such as the electron transport chain and gene regulation. However, most iron on earth is found in insoluble iron-hydroxide complexes. In addition, iron is tightly sequestered in the human body by proteins such as transferrin, making it unavailable for pathogens. In order to overcome these limitations bacteria have evolved siderophores. Siderophores are low molecular weight compounds that bind ferric iron with a high affinity. Staphylococcus aureus is an important human pathogen that is known to produce at least four siderophores, and these siderophores contribute to its virulence. S. aureus strain H372 was found …

Antibiotic Resistance In Bacillus Subtilis As Affected By Transcriptional Derepression And The Stringent Response, Brandon Eisinger, Ronald E. Yasbin, Eduardo A. Robleto

Undergraduate Research Opportunities Program (UROP)

Bacterial cells under conditions of starvation or prolonged non-lethal selective pressures accumulate mutations in highly transcribed genes. This process is part of cellular programs to increase genetic diversity in conditions of stress, also known as stationary phase or stress-induced mutagenesis. This experiment investigated mutation frequencies for antibiotic resistance as affected by the stringent response. The stringent response is a global cellular process that initiates at the cessation of growth and mediates changes in gene expression that repress synthesis of ribosome components. We used Bacillus subtilis strains that differ in RelA proficiency. The relA gene controls the synthesis of (p)ppGpp, the …

Examination Of Germination Receptors Of B. Subtilis And B. Megaterium, Shruti Patel, Alessio Luinetti, Ernesto Abel-Santos, Eduardo Robleto

Undergraduate Research Opportunities Program (UROP)

Many bacterial species including those in the Bacilli group form spores as a mechanism to survive harsh conditions such as extreme temperature, radiation, chemicals, and nutrient starvation. By forming spores, they can remain metabolically dormant for an extended period and revert to their vegetative form when environment becomes favorable. This resumption of metabolism and growth is marked by a process called germination that is triggered by exogenous nutrients such as amino acids, sugars, and nucleotides. The (Ger) germination receptors that are postulated to respond to these germinants, in the case of B. subtilis and B. megaterium, are a complex of …

Evaluation Of Virb Binding Site Contribution To The Regulation Of The Icsp Promoter In Shigella Flexneri, Juan C. Duhart, Maria I. Castellanos, Helen J. Wing

Undergraduate Research Opportunities Program (UROP)

Shigella species are gram-negative, rod-shaped bacteria that are closely related to Escherichia coli. Virulent Shigella spp. are intracellular pathogens that invade, replicate and spread through epithelial cells of the lower intestine and cause bacillary dysentery in humans. This disease is characterized by a robust inflammatory response that results in fever, abdominal pain, and bloody diarrhea (3). According to the CDC, approximately 14,000 cases are reported each year in the United States alone. This number however, does not reflect the actual incidence of this disease as many cases go unreported. The molecular pathogenesis of these bacteria lies in the large virulence …

The Small Regulatory Rna Ryhb Regulates Icsa Expression In Shigella Flexneri, Nick Egan, Helen J. Wing

Undergraduate Research Opportunities Program (UROP)

Shigella flexneri is a gram negative non-motile, non-spore forming, rod-shaped bacterium responsible for bacillary dysentery in humans. The master regulator, VirF, initiates a cascade of virulence gene activation by acting as a transcription factor for the gene encoding the global regulator, VirB (1). Production of VirB is also negatively regulated by the regulatory small RNA (sRNA), RyhB 2). Regulatory sRNAs are untranslated RNA molecules involved in the regulation of both transcription and translation. RyhB, a 90 nt sRNA, was first identified in E. coli and subsequently found in all Shigella species. In Shigella this sRNA is maximally expressed in response …

Transcriptional Regulation Of The Shigella Flexneri Icsp Promoter: Silencing And Anti-Silencing By H-Ns And Virb, Dustin Harrison

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella species are gram-negative intracellular pathogens that cause bacillary dysentery in humans. Many genes required for virulence of Shigella are carried on a large 230 kb plasmid and many of these are under the transcriptional control of the histone-like nucleoid structuring protein (H-NS) and by the major virulence regulator VirB. At the non-permissive temperature of 30⁰C, H-NS represses transcription, while at 37⁰C VirB alleviates this repression. This mechanism of gene regulation has been coined "silencing/anti-silencing" and is commonly found in many important bacterial pathogens including Salmonella spp. and Yersinia spp. The icsP gene, encoded by the Shigella virulence plasmid, is …

Probiotic Therapy - Recruiting Old Friends To Fight New Foes, Roy D. Sleator

Department of Biological Sciences Publications

Against a backdrop of increasing antibiotic resistance, and the emergence of new and evolving pathogens, clinicians are increasingly forced to consider alternative therapies - probiotics are one such alternative.

Constraint-Based Model Of Shewanella Oneidensis Mr-1 Metabolism: A Tool For Data Analysis And Hypothesis Generation, Grigoriy E. Pinchuk, Eric A. Hill, Oleg V. Geydebrekht, Jessica De Ingeniis, Xiaolin Zhang, Andrei Osterman, James H. Scott

Dartmouth Scholarship

Shewanellae are gram-negative facultatively anaerobic metal-reducing bacteria commonly found in chemically (i.e., redox) stratified environments. Occupying such niches requires the ability to rapidly acclimate to changes in electron donor/acceptor type and availability; hence, the ability to compete and thrive in such environments must ultimately be reflected in the organization and utilization of electron transfer networks, as well as central and peripheral carbon metabolism. To understand how Shewanella oneidensis MR-1 utilizes its resources, the metabolic network was reconstructed. The resulting network consists of 774 reactions, 783 genes, and 634 unique metabolites and contains biosynthesis pathways for all cell constituents. Using constraint-based …