Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"Acid Stress"”.
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Structural and Functional Studies on the Escherichia coli Inducible Lysine Decarboxylase: Linking the Acid Stress and Stringent Responses
The Escherichia coli acid stress response allows the survival of cells over a wide range of pH challenges: down to pH 2.0 with the extreme acid stress response and down to pH 4.0 – 5.0 with the mild acid stress response. The cell employs a number of different acid stress response systems, including …
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Effects of heat and acid stress on bacterial populations of beef, and on susceptible and multi-antimicrobial resistant Salmonella isolated from beef
… provided cross-protection against low-pH or heat stress. Results of studies evaluating methods to improve microbiological quality of chilled beef carcasses, subprimal cuts, and fabrication table surfaces, suggested reduced antimicrobial efficacy (≤ 1 log CFU/100 cm2 reduction) of steam-vacuuming …
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Elucidation of weak organic acid resistance mechanisms in non-Saccharomyces yeast: a case study of Zygosaccharomyces parabailii and Kluyveromyces marxianus
… including bulk chemicals such as organic acids. However, efficient and economically viable production of organic acids has to face problems related to low productivity/titer and toxicity of the final product. Therefore, the exploration of yeast biodiversity to exploit unique native …
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Ecology of acidification and recovery in Welsh upland streams
This study investigates the current impact of acid deposition on the structure and function of benthic communities in streams of contrasting pH in mid-Wales, UK, and examines barriers to biological recovery across the sites. The results of field surveys across 30 streams revealed sustained effects …
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Characterisation of stress responses in Lactobacillus paracasei and Bifidobacterium animalis (syn. lactis)
… a study of the nature of the responses to stress, particularly acid stress, in Lactobacillus paracasei and Bifidobacterium anitnalis (syn. lactis). The aims of the study were validate the identification of the bacteria being studied, to determine the nature of their stress responses and …
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Autoinducer-2-based quorum sensing of foodborne pathogenic bacteria under food related conditions
… under aerobic conditions. Under heat (55°C) and acid stress (pH 3.0 or 3.5), surviving cell counts of Salmonella were not different (P≥0.05) in the presence and absence of AI-2 activity, indicating that AI-2-based quorum sensing of Salmonella may not be involved in heat and acid stress response. …
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Characterization of The Ato Gene Family In Alternative Carbon Metabolism
… process that should be inhibited in the normally acidic phagolysosome. We have shown that <em>C. albicans</em> induces germination by neutralizing the phagolysosome. To better understand this process we compared transcript profiles of cells in conditions that promote<em> </em>alkalinization <em>in …
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Metabolic engineering of microorganisms for the overproduction of fatty acids
<p>Fatty acids naturally synthesized in many organisms are promising starting points for the catalytic production of industrial chemicals and diesel-like biofuels. However, bio-production of fatty acids in microbial hosts relies heavily on manipulating tightly regulated fatty acid biosynthetic …
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Characterization of Deoxycholate-Responsive Genes Utilized by Brucella abortus 2308 During Oral Infection
… abortus subjected to deoxycholate, a host bile acid encountered by bacteria during oral infection. Gene deletion strains of B. abortus were then created and tested for susceptibility to pH and bile acid stress, along with their ability to invade and replicate within macrophages. If the genes of …
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Understanding the physiological role of the small RNA RydC
… shown to stabilize cfa (cyclopropane fatty acid synthase) mRNA, resulting in higher levels of cyclopropane fatty acids in the cell membrane. Here, we show that additional sRNAs, ArrS and CpxQ, also directly regulate cfa post-transcriptionally. RydC and ArrS act through masking an RNase E …
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Influence of Physiological State, Prolonged Dry Storage, and Passage through Simulated Digestion on the Survival and Gene Expression of Salmonella enterica sv. Tennessee
… also improve survival to desiccation and gastric stresses. The purpose of this study was to quantify the effect of physiological state (planktonic versus biofilm) and prior exposure to desiccation on Salmonella survival and gene expression after passage through an in-vitro digestion model. Cells …
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Acid adaptation of Escherichia coli O157:H7 in fermented goat milk
… study was undertaken to determine the effect of acid adaptation on the survival and growth of Escherichia coli in broth and fermented goat milk. In the first phase of the study, acid resistance of E. coli O157:H7 strain UT 10 and E. coli ATCC 25922 was determined in brain heart infusion broth at …
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RNA regulatory elements and translational control
… at four time points after application of acid stress. The project characterized changes in the expression of genes encoding complexes involved in virulence, and response to low pH. Furthermore, a ribosome profile of the *Cowpea mosaic virus*, a model plant RNA virus, was obtained during an …
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The Convergence of Metabolism and Virulence Factor Regulation on Streptococcus pyogenes Pathogenesis
… both the production of ATP and protection from acid stress.</p><p>To further investigate the arc operon's contribution to the fitness of bacteria in a soft tissue environment we examined the influence of arginine catabolism on pathogenesis. Analysis of several mutants defective in catabolism …
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The Unconventional Amino Acid Starvation Response of the Malaria Parasite, Plasmodium falciparum
… cell hemoglobin, salvaging the released amino acids for its own use. However, human hemoglobin does not contain the amino acid isoleucine, which is one of the most prevalent amino acids in the parasite's proteome. Since P. falciparum cannot synthesize isoleucine, it must acquire this amino acid …
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Effects of environmental and physiological stress on the functionality of probiotic microorganisms
… exposure to environmental and physiological stress conditions could affect some functional properties for the selection of probiotic microorganisms. The study was focused on two commercial strains of Bifidobacterium animalis ssp. lactis and two non-commercial Bifidobacterium strains, namely …
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Exploration of the transcriptomes and functional contributions of Listeria monocytogenes plasmids during food production-associated stress conditions
… when cells were exposed to FPE-associated stress conditions. Much is known of the chromosomally-encoded molecular mechanisms of L. monocytogenes that increase tolerance to FPE-associated stress conditions. However, our understanding of the stress response roles of L. monocytogenes plasmids …
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The effect of pH and dissolved organic carbon on the growth kinetics of Ac. cupricumulans JTC3 and L. ferriphilum HT pertinent to the BIOX® process
… archaea including the iron-oxidizer, Acidiplasma cupricumulans JTC3. In this study, the effect of physicochemical factors, such as pH and temperature, and the presence of dissolved organic carbon on the growth and ferrous iron oxidation kinetics of these two microorganisms were …
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Funktionelle Analyse und Charakterisierung des Gpr1-Proteins in der Hefe Yarrowia lipolytica
In der Hefe Yarrowia lipolytica führen Mutationen im GPR1-Gen zu Essigsäuresensitivität. Die Deletion dieses Genes hat demgegenüber keinen Effekt auf den Phänotyp. In dieser Arbeit wurde das Gpr1-Protein näher charakterisiert. Es zeigte sich, dass GPR1-Mutantenstämme wesentlich schneller Acetat …
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Combinatorial search strategies for the metabolic engineering of microorganisms
… and increase the flux through the aromatic amino acid biosynthetic pathway. The resulting strains, P1 and P2, exhibited L-tyrosine production levels of 358 mg/l and 418 mg/l, respectively, thus establishing an already high base line for this study. In a parallel investigation, we also worked on …