Table 2.

Regulation of rhlI by PQS and/or C4-HSLa

Signal addedβ-Gal activityb of the following strain containing pLPRI (rhlI′-lacZ)
PAO-R1 (lasR)PDO100 (rhlI)
PQS (50 μM)48,428 ± 7,610141,151 ± 27,930
C4-HSL (5 μM)27,433 ± 1,797136,143 ± 26,227
PQS (50 μM) and C4-HSL (5 μM)125,537 ± 11,596126,468 ± 7,633
None2,380 ± 611123,873 ± 10,798
  • a Cultures were grown for 18 h in the presence of the indicated signal, and β-Gal activity was assayed.

  • b Data are the means for duplicate β-Gal assays from at least three separate experiments and are presented in Miller units ± ςn−1. As a reference for these experiments, we determined that the wild-type P. aeruginosastrain PAO1 containing pLPRI produces 139,797 ± 10,291 U of β-Gal activity.