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Title Autoinducer 2-based quorum sensing response of Escherichia coli to sub-therapeutic tetracycline exposure
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Date Accessioned
University/Publisher Texas A&M University
Abstract Autoinducer 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 ????g/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.
Subjects/Keywords quorum sensing; Autoinducer; tetracycline resistance; sub-therapeutic; transconjugation; RP4; tet(A); Escherichia coli; food; airborne quorum sensing; microflora; Real-time PCR
Contributors Pillai, Suresh D. (advisor)
Language en
Country of Publication us
Record ID handle:1969.1/4198
Repository tamu
Date Retrieved
Date Indexed 2017-09-06
Issued Date 2006-10-30 00:00:00

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…4 Sub-therapeutic antibiotic administration in animals ………………. 4 Tetracycline resistance development in enteric bacteria …………..... 6 Bacterial quorum sensing …………………………………………… 9 III AUTOINDUCER 2-BASED RESPONSE INDUCES TETRACYCLINE TOLERANCE IN…

…32 33 35 37 46 ix CHAPTER IV Page AUTOINDUCER 2 (AI-2) PRODUCTION IN ENTERIC BACTERIA IN RESPONSE TO SUB-THERAPEUTIC ANTIBIOTIC EXPOSURE ………………………………………....... 50 Overview………………………………………………………………. Introduction…

…Materials and Methods………………………………………………… Results…………………………………………………………………. Discussion……………………………………………………………... V AUTOINDUCER 2 (AI-2)-BASED QUORUM SENSING PROMOTES trbC GENE EXPRESSION AND CONJUGAL TRANSFER OF tet(A) GENE IN RESPONSE…

…VI 74 75 77 85 92 AUTOINDUCER-2 (AI-2)-LIKE ACTIVITY ASSOCIATED WITH FOODS AND ITS INTERACTION WITH ORGANIC ACIDS USED AS FOOD ADDITIVES………………….. 96 Overview………………………………………………………………. Introduction……………………………………………………………. Materials and…

…114 115 117 119 124 x CHAPTER VIII Page SUMMARY……………………………………………………….. 128 Autoinducer 2-based response induces tetracycline tolerance in Escherichia coli under sub-therapeutic exposure………………………………………………………….... Autoinducer AI-2 activity in…

Autoinducer 2(AI-2)-like activity associated with foods and its interaction with organic acids used as food additives……………………………………………………… A non-indole-based airborne quorum sensing molecule can confer tetracycline tolerance in physically separated…

…function as a “single unit”, allowing them to withstand environmental stresses and host defense mechanisms. Autoinducer molecules act upon specific sets of target genes through different regulatory mechanisms, resulting in the modulation of a number of…

…x28;Lee and Morrison, 1999; Steinmoen et al., 2002) and conjugal transfer of plasmids (Oger and Farrand, 2002), are associated with bacterial quorum sensing. Bacterial autoinducer molecules. A class of small molecular weight molecules is…

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