Article

Bacterial quorum sensing in pathogenic relationships.

University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
Infection and Immunity (Impact Factor: 4.16). 10/2000; 68(9):4839-49. DOI: 10.1128/IAI.68.9.4839-4849.2000
Source: PubMed

ABSTRACT Bacteria were for a long time believed to exist as individual cells that sought primarily to find nutrients and multiply. The discovery of intercellular communication among bacteria has led to the realization that bacteria are capable of coordinated activity that was once believed to be restricted to multicellular organisms. The capacity to behave collectively as a group has obvious advantages, for example, the ability to migrate to a more suitable environment/better nutrient supply and to adopt new modes of growth, such as sporulation or biofilm formation, which may afford protection from deleterious environments. The "language" used for this intercellular communication is based on small, self-generated signal molecules called autoin- ducers. Through the use of autoinducers, bacteria can regulate their behavior according to population density. The phenom- enon of quorum sensing, or cell-to-cell communication, relies on the principle that when a single bacterium releases autoin- ducers (AIs) into the environment, their concentration is too low to be detected. However, when sufficient bacteria are present, autoinducer concentrations reach a threshold level that allows the bacteria to sense a critical cell mass and, in response, to activate or repress target genes. Most of the bac- teria thus far identified that utilize quorum-sensing systems are associated in some way with plants or animals. The nature of these relationships can be either amicable, as characterized by symbiotic bacteria, or adversarial, as seen with pathogenic bac- teria. There are numerous bacteria that have components of a quorum-sensing system for which the phenotype regulated re- mains an enigma. Similarly, there are bacteria known to reg- ulate a specific phenotype via quorum sensing for which one or more of the regulatory components have thus far eluded iden- tification. In this review we give examples of pathogenic rela- tionships, focusing on organisms for which many of the facets of their quorum-sensing systems have been elucidated.

1 Bookmark
 · 
150 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pantoea stewartii is known to be the causative agent of Stewart's wilt, which usually affects sweet corn (Zea mays) with the corn flea beetle as the transmission vector. In this work, we present the whole-genome sequence of Pantoea stewartii strain M009, isolated from a Malaysian tropical rainforest waterfall. Copyright © 2015 Tan et al.
    Genome Announcements 01/2015; 3(1).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We reconstructed the first genome-scale metabolic network of the plant pathogen Pectobacterium carotovorum subsp. carotovorum PC1 based on its genomic sequence, annotation, and physiological data. Metabolic characteristics were analyzed using flux balance analysis (FBA), and the results were afterwards validated by phenotype microarray (PM) experiments. The reconstructed genome-scale metabolic model, iPC1209, contains 2,235 reactions, 1,113 metabolites and 1,209 genes. We identified 19 potential bactericide targets through a comprehensive in silico gene-deletion study. Next, we performed virtual screening to identify candidate inhibitors for an important potential drug target, alkaline phosphatase, and experimentally verified that three lead compounds were able to inhibit both bacterial cell viability and the activity of alkaline phosphatase in vitro. This study illustrates a new strategy for the discovery of agricultural bactericides. Copyright © 2014. Published by Elsevier B.V.
    FEBS Letters 12/2014; · 3.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial epiphytes isolated from marine eukaryotes were screened for the production of quorum sensing inhibitory compounds (QSIs). Marine isolate KS8, identified as a Pseudoalteromonas sp., was found to display strong quorum sensing inhibitory (QSI) activity against acyl homoserine lactone (AHL)-based reporter strains Chromobacterium violaceum ATCC 12472 and CV026. KS8 supernatant significantly reduced biofilm biomass during biofilm formation (-63%) and in pre-established, mature P. aeruginosa PAO1 biofilms (-33%). KS8 supernatant also caused a 0.97-log reduction (-89%) and a 2-log reduction (-99%) in PAO1 biofilm viable counts in the biofilm formation assay and the biofilm eradication assay respectively. The crude organic extract of KS8 had a minimum inhibitory concentration (MIC) of 2 mg/mL against PAO1 but no minimum bactericidal concentration (MBC) was observed over the concentration range tested (MBC > 16 mg/mL). Sub-MIC concentrations (1 mg/mL) of KS8 crude organic extract significantly reduced the quorum sensing (QS)-dependent production of both pyoverdin and pyocyanin in P. aeruginosa PAO1 without affecting growth. A combinatorial approach using tobramycin and the crude organic extract at 1 mg/mL against planktonic P. aeruginosa PAO1 was found to increase the efficacy of tobramycin ten-fold, decreasing the MIC from 0.75 to 0.075 µg/mL. These data support the validity of approaches combining conventional antibiotic therapy with non-antibiotic compounds to improve the efficacy of current treatments.
    Marine Drugs 01/2014; 13(1):1-28. · 3.51 Impact Factor

Preview

Download
4 Downloads
Available from