FIG. 6.

Effect of the amino acid stringent response on the production of 3-oxo-C₁₂-HSL. Bioassays for 3-oxo-C₁₂-HSL extracted from the culture supernatants of the wild-type strain PAO1 (A), the relA mutant strain PAΩR3 (B), and the complemented strain PAΩR3(pLFR2) (C) were performed. Strains were grown in MOPS medium either in the absence (open squares) or in the presence of 200 (open circles) or 500 (closed squares) μM SHX as described in Materials and Methods. Shown are the means (± SDs) of three (A) and two (B and C) independent experiments performed in triplicate.