Methods for Analysis of Bacterial Autoinducer‐2 Production

Abstract The quorum‐sensing signal molecule autoinducer‐2 (AI‐2) is produced by over 50 diverse bacterial species and controls many different processes, including antibiotic production, biofilm formation, and virulence. AI‐2 production often varies according to growth phase, media conditions, and the presence of specific factors. This unit describes a biological assay for AI‐2 activity produced by a bacterial strain of interest. The assay employs an AI‐2 reporter strain, Vibrio harveyi BB170, which produces light in response to AI‐2. In the first stage of the assay, culture fluids of the bacterial strain of interest are collected over a time course of growth and filtered to remove cells. In the next stage, these culture fluids are mixed with BB170, and the light produced in response to AI‐2 in the culture fluids is measured using a luminometer. BB170 is exquisitely sensitive to AI‐2, and therefore, even low amounts of AI‐2 can be detected using this bioassay.