Figure 2.

A novel signal induces lasB in P. aeruginosa. Strain PAO-R1 (lasR⁻) (pTS400) (A) or strain PAO-JP3 (lasR⁻, rhlR⁻) (pTS400) (B) was grown in the presence of culture supernatant extracts from the following P. aeruginosa strains: PAO1 (wild type), PAO-JP2 (lasI⁻, rhlI⁻), PAO-JP2 (pECP39), or PAO-JP2 (pUCP22). After 18 h of growth, β-gal activity was assayed and is presented in Miller units +/− SDⁿ⁻¹. (Note: A control culture with no extract added produced 8 Miller units of β-gal activity.) Data represent the means of duplicate assays performed during three separate experiments.