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http://hdl.handle.net/10400.7/187

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Browsing BS - Artigos by Subject "Anti-Bacterial Agents"

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  • Manipulation of the Quorum Sensing Signal AI-2 Affects the Antibiotic-Treated Gut Microbiota
    Publication . Thompson, Jessica Ann; Oliveira, Rita Almeida; Djukovic, Ana; Ubeda, Carles; Xavier, Karina Bivar
    The mammalian gut microbiota harbors a diverse ecosystem where hundreds of bacterial species interact with each other and their host. Given that bacteria use signals to communicate and regulate group behaviors (quorum sensing), we asked whether such communication between different commensal species can influence the interactions occurring in this environment. We engineered the enteric bacterium, Escherichia coli, to manipulate the levels of the interspecies quorum sensing signal, autoinducer-2 (AI-2), in the mouse intestine and investigated the effect upon antibiotic-induced gut microbiota dysbiosis. E. coli that increased intestinal AI-2 levels altered the composition of the antibiotic-treated gut microbiota, favoring the expansion of the Firmicutes phylum. This significantly increased the Firmicutes/Bacteroidetes ratio, to oppose the strong effect of the antibiotic, which had almost cleared the Firmicutes. This demonstrates that AI-2 levels influence the abundance of the major phyla of the gut microbiota, the balance of which is known to influence human health.
    2015-03-24Journal article Open access Show more
  • Synthesis and biological activity of a potent optically pure autoinducer-2 quorum sensing agonist
    Publication . Ascenso, Osvaldo S.; Torcato, Inês M.; Miguel, Ana Sofia; Marques, João C.; Xavier, Karina B.; Ventura, M. Rita; Maycock, Christopher D.
    Quorum sensing (QS) regulates population-dependent bacterial behaviours, such as toxin production, biofilm formation and virulence. Autoinducer-2 (AI-2) is to date the only signalling molecule known to foster inter-species bacterial communication across distantly related bacterial species. In this work, the synthesis of pure enantiomers of C4-propoxy-HPD and C4-ethoxy-HPD, known AI-2 analogues, has been developed. The optimised synthesis is efficient, reproducible and short. The (4S) enantiomer of C4-propoxy-HPD was the most active compound being approximately twice as efficient as (4S)-DPD and ten-times more potent than the (4R) enantiomer. Additionally, the specificity of this analogue to bacteria with LuxP receptors makes it a good candidate for clinical applications, because it is not susceptible to scavenging by LsrB-containing bacteria that degrade the natural AI-2. All in all, this study provides a new brief and effective synthesis of isomerically pure analogues for QS modulation that include the most active AI-2 agonist described so far.
    2019-04Journal article Open access Show more