Quorum sensing (QS) is a mechanism adopted by bacteria to regulate expression of genes according to population density. N-acylhomoserine lactones (AHLs) are a type of QS signalling molecules commonly found in Gram-negative bacteria which have been reported to play a role in microbial spoilage of foods and pathogenesis. In this study, we isolated an AHL-producing Hafnia alvei strain (FB1) from s...

Cell-cell communication is also known as quorum sensing (QS) that happens in the bacterial cells with the aim to regulate their genes expression in response to increased cell density. In this study, a bacterium (L8A) isolated from dental plaque biofilm was identified as Citrobacter amalonaticus by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Its...

In many species of bacteria, the quorum sensing mechanism is used as a unique communication system which allows them to regulate gene expression and behavior in accordance with their population density. N-Acylhomoserine lactones (AHLs) are known as diffusible autoinducer molecules involved in this communication network. This finding aimed to characterize the production of AHL of a bacterial str...

In Chromobacteium violaceum, the purple pigment violacein is under positive regulation by the N-acylhomoserine lactone CviI/R quorum sensing system and negative regulation by an uncharacterized putative repressor. In this study we report that the biosynthesis of violacein is negatively controlled by a novel repressor protein, VioS. The violacein operon is regulated negatively by VioS and positi...

The Rhodococcus erythropolis strain W2 has been shown previously to degrade the N-acylhomoserine lactone (AHL) quorum-sensing signal molecule N-hexanoyl-L-homoserine lactone, produced by other bacteria. Data presented here indicate that this Gram-positive bacterium is also capable of using various AHLs as the sole carbon and energy source. The enzymic activities responsible for AHL inactivation...

Acylhomoserine lactone (AHL) synthases act as chemical communication signals or pheromones in Gram-negative bacteria and regulate diverse physiological events in a cell density-dependent manner. The recent crystal structure determination of EsaI, a key enzyme in this pathway, shows that the AHL synthase superfamily members adopt the fold of the N-acetyltransferase superfamily. We suggest, by th...

A Gram-positive, rod- or coccoid-shaped and N-hexanoyl-l-homoserine lactone-degrading bacterial strain, A2-4(T), was isolated from a soil in Korea, and its taxonomic position was investigated by using a polyphasic approach. Strain A2-4(T) grew optimally at pH 7.0-8.0 and 30 degrees C without NaCl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain A2-4(T) is most closel...

N-Acylhomoserine lactone (AHL)-degrading enzyme, AiiM, was identified from the potato leaf-associated Microbacterium testaceum StLB037. In this study, we cloned eight aiiM gene homologues from other AHL-degrading Microbacterium strains. The similarity of the chromosomal locus of the aiiM gene is associated with the phylogenetic classification based on 16S rRNA. Degenerate PCR revealed that the ...

In Aeromonas hydrophila, the ahyI gene encodes a protein responsible for the synthesis of the quorum sensing signal N-butanoyl-L-homoserine lactone (C4-HSL). Inactivation of the ahyI gene on the A. hydrophila chromosome abolishes C4-HSL production. The exoprotease activity of A. hydrophila consists of both serine protease and metalloprotease activities; in the ahyI-negative strain, both are sub...