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. 2019 Mar 7;116(14):7021–7026. doi: 10.1073/pnas.1819801116

Fig. 1.

Fig. 1.

Production of C4-HSL, pyocyanin, and protease by the LasR− mutant clinical isolate E80 and E80 RhlRI− mutant. (A) Relative levels of C4-HSL in P. aeruginosa E80 (black squares), PAO1 (black circles), and a PAO1 LasR− mutant (white circles) at different times during cell growth. Levels are normalized to the maximum amount of C4-HSL in PAO1 cultures. The data are means ± SD (bars) of four independent experiments. (B) Relative pyocyanin levels of the indicated strain. The pyocyanin levels produced by strain PAO1 are defined as 100%. Pyocyanin was measured after 24 h of growth in LB-Mops broth. Data represent means and SDs of six replicates. (C and D) Protease production on casein agar. High levels of extracellular proteases result in a zone of clearing around a colony, with a white zone of partial casein degradation at the periphery of the zone of clearing. The PAO1 LasR mutant and the E80 RhlRI mutant produce relatively little protease, as indicated by the lack of a zone of clearing. There is only a small zone of partial casein digestion. The images are of colonies after about 30 h of incubation.