Responses of <i>wggR</i> to AHLs.

<p><b>A.</b> Average activity [fluorescence/OD₅₉₅] of the <i>wggR-gfp</i> reporter pMG310 in <i>S. meliloti</i> Rm8530 (wild type), MG32 (<i>sinI</i>) and MG32 pVO190 (vector control). <b>B.</b> Average activity of <i>wggR-gfp</i> (on pMG310) in MG32 grown on 0.4% agar and 20-fold-diluted LB medium plates with dilutions of AHLs (from left to right) C_16:1-, 3-oxo-C_16:1-, C₁₄-, and oxo-C₁₄-HSL. Fluorescence of the MG32 pMG310 reporter in the negative control (solvent only) was 7,995±646. For the assays, bacteria were collected from colonies after 3 days of incubation on soft agar plates. Average of three biological replicas within a representative experiment are shown. All essays were repeated at least twice with reproducible results. Error bars denote standard deviations. <b>C.</b> Fluorescent images of colonies formed by MG32 pMG310 on soft agar containing different kinds and amounts of AHLs (as indicated at the bottom of the image).