Image Analysis

The fluorescence intensity of the condensates to cytosol ratio was quantified using ImageJ software. Briefly, the cell shapes were first determined from bright field microscopy images, and the condensates were inferred based on mCherry fluorescence distribution within the cells. Then the confocal images were converted to 8-bit grayscale images and background-subtracted. The mean fluorescence intensity of condensate was determined by the average pixel intensity in the condensate area (I_cond) and the cytosolic region (I_cyto). Then the condensate-to-cytosol intensity ratio was calculated as the mean fluorescence intensity of condensate divided by the mean fluorescence intensity of cytosol (I_cond/I_cyto). For fluorescence distribution analysis, the fluorescence intensity profile along the medial axes of E. coli cell bodies was performed by using the Leica LASX software.

To quantify the cell length, ImageJ software was used to measure the distance of the cell bodies from one pole to the other. In the fields, only visible cells were measured.