Table 3.

Effect of rpoS mutation on P. aeruginosa PAO1 exoproductsa

ExoproductActivity in strain:% Relative activity
PAO1 (RpoS+)SS24 (RpoS)
Exotoxin A1,302 ± 46660 ± 2050.7
Elastase161 ± 6126 ± 278.6
LasA protease0.587 ± 0.0020.518 ± 0.01488.3
Phospholipase C33.45 ± 0.6532.97 ± 0.8298.6
Pyocyanin0.3470.716206.3
Pyoverdine0.5110.755147.7
  • a Exotoxin A activity is measured in counts per minute per 10 μl of supernatant. Elastase activity is measured as the increase in A 495minute−1 gram of protein−1. LasA protease activity is measured as the rate of decrease inA 595 minute−1 milligram of protein−1. Phospholipase C activity is measured as the increase in OD405 minute−1 milligram of protein−1. The pyocyanin level was measured as OD695 and the pyoverdine level was measured as OD460 following excitation at OD400 (see Materials and Methods for details). The relative activity was calculated as follows: (activity of the rpoS mutant/activity of the parent) × 100. Values are means ± standard deviations.