FIG. 1.

Opr86 is essential for viability. (A) PAO1 and a conditional opr86 mutant (PS186) grown on LB agar at 37°C in the absence or the presence of IPTG overnight. (B) Growth curves of PAO1 (squares) and PS186 in the presence (circles) and absence (triangles) of 100 μM IPTG. Initially, PS186 was cultured with IPTG. At the 5-h growth point, cells were diluted to an OD₆₀₀ of 0.01, and then IPTG was added to one sample of PS186 but not to the other. At the 9-h growth point, cells were diluted to an OD₆₀₀ of 0.01 in the presence or absence of IPTG again. PAO1 was also cultured and diluted without adding IPTG. The results presented are representative of three independent experiments. (C) The survival rate of PS186 without IPTG. PS186 was cultured without IPTG in the same way described for panel B and plated to an LB plate with (black) or without (white) 100 μM IPTG at hourly intervals after the 9-h growth point. The results are expressed as the mean CFU/ml and SD from three replicates. Similar results were obtained in two independent experiments.