Fig. 4

Effects of paraquat and H₂O₂ on P. xenovorans LB400 growth and ROS formation. Strain LB400 grown until exponential growth phase on glucose was exposed to paraquat (PQ) (A) or H₂O₂ (B). Growth was monitored by measuring turbidity at 600 nm. C Paper disks soaked with paraquat or H₂O₂ solutions (1–20 mM) were placed on P. xenovorans LB400 bacterial lawns. Growth inhibition zones around the disks were recorded after 24 h incubation at 30 °C. The dotted line at 6 mm corresponds to the disk diameter and indicates no inhibition. Letters under the error bars indicate significant differences between each concentration of each oxidizing agent. D Exponential glucose-grown cells were exposed to paraquat or H₂O₂. After incubation with HPF, fluorescence was monitored at 515 nm (emission) and 490 nm (excitation). Cells incubated in absence of oxidizing agents were used as control. Letters under the error bars indicate significant differences between treatments in each time. All values were calculated as the mean ± SD of three independent experiments