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Direct Quantitation of the Quorum Sensing Signal, Autoinducer-2, in Clinically Relevant Samples by Liquid Chromatography−Tandem Mass Spectrometry

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journal contribution
posted on 01.08.2009, 00:00 by Shawn R. Campagna, Jessica R. Gooding, Amanda L. May
Quorum Sensing is a type of bacterial cell-to-cell signaling that allows for cell density dependent regulation of gene expression. Many of the behaviors mediated by quorum sensing are critical for bacterial colonization or infection, and autoinducer-2 has been proposed as a universal interspecies signaling molecule that allows multispecies colonies of bacteria, e.g., biofilms or dental plaque, to behave as pseudomulticellular organisms. However, the direct detection of autoinducer-2 has been difficult, leaving the in vivo relevance of this signal in question. Herein we report a liquid chromatography−tandem mass spectrometric technique that enables reproducible, quantitative, and sensitive measurement of the concentration of autoinducer-2 from a variety of sources. This technique was applied to the detection of autoinducer-2 from Escherichia coli and Vibrio harveyi in proof-of-concept studies and was then used to directly measure the concentration of the signal produced by oral bacteria in human saliva.