%0 Journal Article %A McClean, Kay H. %A Winson, Michael K. %A Fish, Leigh %A Taylor, Adrian %A Chhabra, Siri Ram %A Camara, Miguel %A Daykin, Mavis %A Lamb, John H. %A Swift, Simon %A Bycroft, Barrie W. %A Stewart, Gordon S. A. B. %A Williams, Paul %T Quorum sensing and Chromobacterium violaceum: exploitation of violacein production and inhibition for the detection of N-acylhomoserine lactones %D 1997 %J Microbiology, %V 143 %N 12 %P 3703-3711 %@ 1465-2080 %R https://doi.org/10.1099/00221287-143-12-3703 %K N-acylhomoserine lactones %K Chromobacterium violaceum %K bioassay %K violacein %K quorum sensing %I Microbiology Society, %X Quorum sensing relies upon the interaction of a diffusible signal molecule with a transcriptional activator protein to couple gene expression with cell population density. In Gram-negative bacteria, such signal molecules are usually N-acylhomoserine lactones (AHLs) which differ in the structure of their N-acyl side chains. Chromobacterium violaceum, a Gram-negative bacterium commonly found in soil and water, produces the characteristic purple pigmen violacein. Previously the authors described a violacein-negative, mini-Tn5 mutant of C. violaceum (CV026) in which pigment production can be restored by incubation with supernatants from the wild-type strain. To develop this mutant as a general biosensor for AHLs, the natural C. violaceum AHL molecule was first chemically characterized. By using solvent extraction, HPLC and mass spectrometry, a single AHL, N-hexanoyl-L-homoserine lactone (HHL), was identified in wild-type C. violaceum culture supernatants which was absent from CV026. Since the production of violacein constitutes a simple assay for the detection of AHLs, we explored the ability of CV026 to respond to a series of synthetic AHL and N-acylhomocysteine thiolactone (AHT) analogues. In CV026, violacein is inducible by ail the AHL and AHT compounds evaluated with N-acyl side chains from C4 to C8 in length, with varying degrees of sensitivity. Although AHL compounds with N-acyl side chains from C10 to C14 are unable to induce violacein production, if an activating AHL (e.g. HHL) is incorporated into the agar, these long-chain AHLs can be detected by their ability to inhibit violacein production. The versatility of CV026 in facilitating detection of AHL mixtures extracted from culture supernatants and separated by thin-layer chromatography is also demonstrated. These simple bioassays employing CV026 thus greatly extend the ability to detect a wide spectrum of AHL signa molecules. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-143-12-3703