Show simple item record

dc.contributor.advisorPillai, Suresh D.
dc.creatorLu, Lingeng
dc.date.accessioned2006-10-30T23:24:44Z
dc.date.available2006-10-30T23:24:44Z
dc.date.created2004-08
dc.date.issued2006-10-30
dc.identifier.urihttps://hdl.handle.net/1969.1/4198
dc.description.abstractAutoinducer 2 (AI-2) is a quorum sensing signal employed by bacteria to coordinate their response to environmental stresses. The objective of this study was to determine the relationship between presence of AI-2 molecules, exposure to sub-therapeutic tetracycline, the expression of genes associated with the conjugal transfer of antibiotic resistance plasmids, and the conjugal transfer of these plasmids in Escherichia coli. The studies showed that AI-2 activity increased in Tets E. coli in the presence of tetracycline (2 µg/mL) under both batch and continuous culture conditions. The presence of AI-2 molecules induced tetracycline tolerance development in Tets E. coli. The studies showed that the survival rates of Tets E. coli exposed to AI-2 molecules were significantly higher compared to the cells not exposed to AI-2 molecules or cells that were exposed to only LB (Lauria-Bertani) broth. Molecular analyses using real-time PCR indicate that the expression of at least one conjugation-associated gene (trbC) is increased 9-fold in cells exposed to AI-2 molecules in the presence of sub-therapeutic tetracycline compared to its negative controls. The transconjugation frequency of the plasmid RP4 carrying the tet(A) gene increased between 10-100 fold in the presence of AI-2 molecules. In companion studies, AI-2-like activity was detected in fish, tomatoes, cantaloupes, carrots and milk samples. Interestingly, ground beef and poultry meat contained substances that appear to inhibit AI-2 activity. Collectively, these results highlight the potential importance of bacterial quorum sensing signals such as AI-2 in the response of bacterial cells to environmental stimuli and the possible role of quorum sensing signals in the quality and safety of foods.en
dc.format.extent856918 bytesen
dc.format.mediumelectronicen
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherTexas A&M University
dc.subjectquorum sensingen
dc.subjectAutoinduceren
dc.subjecttetracycline resistanceen
dc.subjectsub-therapeuticen
dc.subjecttransconjugationen
dc.subjectRP4en
dc.subjecttet(A)en
dc.subjectEscherichia colien
dc.subjectfooden
dc.subjectairborne quorum sensingen
dc.subjectmicrofloraen
dc.subjectReal-time PCRen
dc.titleAutoinducer 2-based quorum sensing response of Escherichia coli to sub-therapeutic tetracycline exposureen
dc.typeThesisen
thesis.degree.departmentPoultry Scienceen
thesis.degree.disciplineFood Science and Technologyen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.type.genreElectronic Dissertationen
dc.type.materialtexten
dc.format.digitalOriginborn digitalen


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record