Bacterial quorum sensing in pathogenic relationships

Division of General Medicine, University of Rochester, Rochester, New York, United States
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.

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    ABSTRACT: Abstract can be found at the end of the PhD thesis
    01/2013, Degree: PhD, Supervisor: Hans Nauwynck
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    ABSTRACT: Gram negative phytophatogen bacteria perform quorum sensing by using N-acylhomoserine lactone signal to regulate the expression of virulence factor genes. One of strategy to inactivate quorum sensing by degrading the signal molecules using AHL lactonase encoded by aiiA gene. This study was conducted to characterize bacteria producing AHL lactonase from agriculture lands. Isolation of AHL degrading bacteria was done on 11 sampels of rhizosphere soils from Java, Indonesian agriculture lands. AHL degrading activities of bacterial isolates were tested using Chromobacterium violaceum as a bioindicator. AHL degrading bacterial isolates were indentified based on morphology and 16S rRNA gene. Verification of AHL lactonase existence was done by amplification of aiiA gene (using BTF and BTR primers). A total of 161 bacterial isolates were isolated from rhizosphere soils, six of them could degrade AHL. Analysis of 16S rRNA gene sequences showed that the isolates had 100% similarity with Serratia marcescens By2Root2 (BKS-1 isolate), Bacillus aquimaris JB306 (BKS-8), B. marisflavi GN28 (BGR-7), B. altitudinis NIOT-BARREN23 (CMS-4), B. aquimaris JP44SK28 (JBR1-3) and B. axarquiensis CHMS1B6 (JBR2-16), respectively. The aiiA gene amplification showed that all isolates were successfully amplified with PCR product of 750 bp. BLAST-X analysis of aiiA gene showed that AHL lactonase of BKS-1 was closely related with AHL lactonase B. cereus group, BKS-8 with AHL lactonase Bacillus sp. MBG09, BGR-7 with AHL lactonase Bacillus sp. MBG12, CMS-4 and JBR1-3 were closely related with AHL lactonase B. cereus, JBR2-16 with AHL lactonase B. firmus with 99%, 92%, 97%, 94%, 98%, and 99% of maximum identity, respectively. Phylogenetic analysis based on amino acid sequences of AHL lactonase (AiiA) showed that AHL lactonase from the six isolates had similarity with AHL lactonase of B. cereus, B. weihenstaphenensis, B. thuringiensis, B. subtilis and B. firmus, respectively. This finding indicated new information of quorum quenching bacteria that B. aquimaris, B. marisflavi, B. altitudinis, B. axarquiensis and S. marecescens had AHL lactonase encoded by aiiA gene and they might have potential application to degrade AHL of plant pathogenic bacteria.
    Advances in Environmental Biology 05/2015; 9(8):140-148.
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    Central-European Journal of Immunology 01/2013; 3:310-316. DOI:10.5114/ceji.2013.37752 · 0.36 Impact Factor


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