RT Journal Article SR Electronic(1) A1 Thornhill, Starla G. A1 Kumar, Manish A1 Vega, Leticia M. A1 McLean, Robert J. C.YR 2017 T1 Cadmium ion inhibition of quorum signalling in Chromobacterium violaceum JF Microbiology, VO 163 IS 10 SP 1429 OP 1435 DO https://doi.org/10.1099/mic.0.000531 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000531