Transcriptional activation of a catB-lacZ chromosomal fusion. β-galactosidase activity is given as relative light units normalized to OD600. For one of the replicate experiments, only the final values are given for clarity. (A) β-galactosidase activity with (closed symbols) or without (open symbols) 2 μM C10-HSL in the following strains: LasR-RhlR-QscR triple-mutant SC24 (squares), SC24ΔpqsR (triangles), SC24ΔtrpE (diamonds), and SC24ΔkynA (circles). The gray symbols in large type represent final values from an independent replicate. (B) β-galactosidase activity of the SC24ΔkynA strain (open symbols), with 0.2 mM anthranilate (gray symbols), and with 0.2 mM anthranilate and 2 μM C10-HSL (black symbols). Circles indicate the final values of an independent replicate.