Multiple resistance factors collectively promote inoculum-dependent dynamic survival during antimicrobial peptide exposure in Enterobacter cloacae
Fig 6
PhoPQ, Rcs, and OmpT are collectively required for cecB resistance.
Overnight cultures were diluted (A) 10-fold into fresh LB containing 20 μg/mL cecB, and cells were grown at 37°C for 24 hours. OD600 measurements were taken every 5 minutes. Bars at each point represent standard deviation (n = 3). (B) Cultures were diluted 100fold into fresh medium with or without cecropin; samples were taken at indicated timepoints to quantify colony forming units (CFU) per mL. Error bars represent standard deviation (n = 3). (C) Mid-exponential phase cells were placed on 0.8% agarose pads containing indicated amounts of cecropin and incubated at 37°C. Representative, cropped time frames are shown. (D) Percentage of cells that divided during the time lapse, grouped by drug concentration (0, 10, 20, 200 μg/mL). Cells are binned by birth frame, i.e., the frame of the time lapse during which the cell was first identified by SuperSegger [85]. Blue represents cells that underwent a successful division event throughout the course of the timelapse, red indicates cells which did not divide. Missing bars indicate that the initial population of cells was unable to divide.