FIGURE 2.

Schematic representation of the phospholipase plate assay for the identification of quorum sensing inhibitor (QSI) activity. In this test, 18 h cultures are grown either in the presence or absence of QSI, the supernatants harvested and sterile filtered, and then added to the punch holes made in the phospholipid plate. Following an additional 18 h incubation period, the plates are exposed to UV irradiation and photographed. The orange halos indicate the lytic activity of untreated supernatants. Supernatants from QSI-treated cultures would exhibit limited to no lytic effects and no orange halo.