Detection and analysis of quorum-quenching enzymes against acyl homoserine lactone quorum-sensing signals.

Many Gram-negative bacterial pathogens employ N-acyl homoserine lactones (AHLs) quorum-sensing signals for regulation of various biological functions. Several types of AHL-inactivating enzymes, also known as quorum-quenching enzymes, have been unveiled in recent years. These enzymes seem to play important roles in microbial physiology and ecology and hold promising potential in biotechnology. This unit describes methods based on a simple diffusion plate assay for qualitative detection and quantitative measurement of AHL-inactivating enzyme activity. The qualitative detection method is suitable for rapid and large-scale screening and identification of quorum-quenching enzymes. Furthermore, HPLC methods are provided for accurate determination of whether the quorum-quenching enzyme is a lactonase or an acylase. The unit also presents concise background information on the quorum-quenching enzymes identified from various sources, including bacterial and mammalian species.