Figure 2. Growth inhibition of E. coli cells by dye-tagged LL37 peptides.

(A) Sample phase contrast and fluorescent time-lapse images of an E. coli cell treated with a lethal dosage of the dye-tagged LL37 peptides (5-FAM-LC-LL37). Phase contrast images show inhibition of growth and slight shrinkage of the cell after a brief growth period. The fluorescent channel shows the distribution, translocation and retention of the peptides. (B) Abrupt transition in the fluorescent signal of 383 cells that occur over a span of more than 30 min. The black line corresponds to the sample shown in panel A. The fluorescence intensity histogram is depicted for different time points on the right. (C) The instantaneous growth rate of individual cells collapse on each other when plotted in referenced to the peptide translocation point. The average behavior (white line) of the collapse shows that the translocation happens shortly after the inhibition of growth and shrinkage of the cell. The shaded area denotes the standard deviation. (D) The two dimensional distribution of instantaneous growth rate and fluorescent signal from all time points depict well-separated clusters referring to a binary response of the cells to the peptides.