Establishing a quantitative definition of quorum sensing provides insight into the information content of the autoinducer signals in Vibrio harveyi and Escherichia coli.

Extracellular autoinducer concentrations in cultures of Vibrio harveyi and Escherichia coli were monitored by liquid chromatography-tandem mass spectrometry to test whether a quantitative definition of quorum sensing could help decipher the information content of these signals. Although V. harveyi was able to keep the autoinducer-2 to cell number ratio constant, the ratio of signal to cell number for V.