Analytical Approaches for the Identification of Quorum Sensing Molecules

Chemical communication in bacteria relies on the production, release, and detection of small molecules called autoinducers (AIs) that regulate gene expression in a cell-density-dependent manner (quorum sensing, QS). QS not only serve as intraspecies but also in interspecies communication. Furthermore, the clinical significance of interkingdom crosstalk between bacteria and human host is becoming more and more evident. Typically, signal molecules are produced at a very low concentration and their detection requires highly sensitive techniques. Biosensors have allowed fast screening of microorganisms for AI production; however, for their specific identification, the gold choice are mass spectrometry-based methodologies, coupled with either gas or liquid chromatography. Sample extraction, cleanup, and preconcentration greatly improve autoinducer identification from complex matrices allowing reliable quantification. The present chapter provides an overview on the most recent and advanced analytical approaches to identify and quantify these bacterial chemical messages with a special focus on N-acyl-L-homoserine lactones (AHLs/Acyl-HSLs).