Extraction of violacein from Chromobacterium violaceum provides a new quantitative bioassay for N-acyl homoserine lactone autoinducers

J Microbiol Methods. 2000 Mar;40(1):47-55. doi: 10.1016/s0167-7012(99)00136-0.


Fatty acyl homoserine lactones (AHLs) are used as extracellular quorum sensing signals by a variety of gram-negative bacteria. By activating proteins belonging to the LuxR family of transcriptional regulators, these signal metabolites allow population density-dependent gene regulation within a species, as well as interspecies communication among different bacteria. The experimental detection of AHLs is important in the identification of quorum sensing capabilities in bacteria. Chromobacterium violaceum is a gram-negative bacterium that produces the purple pigment violacein in response to the presence of the AHL N-hexanoyl homoserine lactone (C6HSL). The mini-Tn5 mutant strain C. violaceum CV0blu is deficient in the production of this signal molecule but retains the ability to synthesize violacein in response to the presence of C6HSL and a variety of other short-chain AHLs. We have developed a quantitative bioassay that measures the amount of violacein produced by this strain in response to the presence of different concentrations of various AHL molecules. This new assay provides a means of quantifying the amount of a given AHL present in a bacterial culture and can be used to measure differences in AHL production among different strains or different batch cultures of a given species.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 4-Butyrolactone / analogs & derivatives*
  • 4-Butyrolactone / metabolism
  • Biological Assay*
  • Chromatography, High Pressure Liquid
  • Chromobacterium / genetics
  • Chromobacterium / growth & development
  • Chromobacterium / metabolism*
  • Culture Media, Conditioned
  • Indoles / isolation & purification
  • Indoles / metabolism*
  • Signal Transduction


  • Culture Media, Conditioned
  • Indoles
  • homoserine lactone
  • 4-Butyrolactone
  • violacein