@article{mbs:/content/journal/micro/10.1099/mic.0.000531, author = "Thornhill, Starla G. and Kumar, Manish and Vega, Leticia M. and McLean, Robert J. C.", title = "Cadmium ion inhibition of quorum signalling in Chromobacterium violaceum", journal= "Microbiology", year = "2017", volume = "163", number = "10", pages = "1429-1435", doi = "https://doi.org/10.1099/mic.0.000531", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000531", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "biofilm formation", keywords = "quorum sensing", keywords = "Chromobacterium violaceum", keywords = "heavy metals", keywords = "non-competitive inhibition", abstract = "Single-celled bacteria are capable of acting as a community by sensing and responding to population density via quorum signalling. Quorum signalling in Chromobacterium violaceum, mediated by the luxI/R homologue, cviI/R, regulates a variety of phenotypes including violacein pigmentation, virulence and biofilm formation. A number of biological and organic molecules have been described as quorum signalling inhibitors but, to date, metal-based inhibitors have not been widely tested. In this study, we show that quorum sensing is inhibited in C. violaceum in the presence of sub-lethal concentrations of cadmium salts. Notable Cd2+-inhibition was seen against pigmentation, motility, chitinase production and biofilm formation. Cd-inhibition of quorum-signalling genes occurred at the level of transcription. There was no direct inhibition of chitinase activity by Cd2+ at the concentrations tested. Addition of the cognate quorum signals, N-hexanoyl homoserine lactone or N-decanoyl homoserine lactone, even at concentrations in excess of physiological levels, did not reverse the inhibition, suggesting that Cd-inhibition of quorum signaling is irreversible. This study represents the first description of heavy metal-based quorum inhibition in C. violaceum.", }