Figure 4.

Serum represses 3OC₁₂-HSL and C₄-HSL production during early phases (A) but enhances 3OC₁₂-HSL, C₄-HSL, and HHQ/PQS production during late phases (B) of growth. PAO1 was grown in either LB or LB/S. Samples were collected at early and late phases, autoinducers were extracted from the supernatant and their levels were determined as described in Experimental Procedures. Values represent the means of three independent experiments ± SEM; ***P < 0.001; **P < 0.01; *P < 0.05; ns, not significant.