Figure 2.

Production of QS signals by bacteria isolated from marine holobionts. Bacterial cultures were extracted twice with half volumes of ethyl acetate acidified with glacial acetic acid (4 ml l⁻¹), and concentrated by rotary evaporation. Samples were spotted on reverse-phase C₁₈ Si TLC plates, developed with 60:40 methanol:water and overlaid with a suspension of the Agrobacterium tumefaciens NTL1 pZLR4 AHL reporter in soft agar with X-Gal. Synthetic AHL standards (all from Sigma) were similarly subjected to the bioassay-coupled thin-layer chromatography.