Extended Data Fig. 4: Impermeable molecules within the cell wall after lysis cause residual turgor pressure.

a, Increasing detergent concentration caused an approximately proportional increase in the mean cell-wall contraction upon lysis and the mean total contraction in E. coli MG1655 cells. Each point represents one experiment. The number of cells for each experiment is given in Supplementary Table 2. b, Representative DAPI-stained E. coli cells before (left) and after (right) lysis shown in phase contrast and epifluorescence, demonstrating that DNA is not retained in the lysed cells. The experiment was performed once. c, Representative E. coli cells expressing a fluorescent protein fusion to the S2 ribosomal protein before (left) and after (right) lysis shown in phase contrast and epifluorescence, demonstrating that ribosomes are not retained in lysed cells. The experiment was performed once. d, Representative E. coli cells expressing cytosolic GFP before (left) and after (right) lysis shown in phase contrast and epifluorescence, demonstrating that GFP is not retained in lysed cells. The experiment was performed once. e, Representative E. coli cells expressing a fluorescently tagged version of MreB after lysis shown in phase contrast (left), epifluorescence (centre) and in overlay (right), demonstrating that MreB is retained within most lysed cells, but that cells with weak phase density after lysis retain low levels of MreB (arrows). f, Cumulative fluorescence intensity of MreB–sfGFP versus the average phase-contrast intensity within the cell after lysis (n = 162 cells). Cells with higher phase density have lower intensity. g, Cell-wall contraction upon lysis versus average phase-contrast intensity within the cell after lysis (n = 46 cells). h, Total contraction during plasmolysis and lysis versus average phase-contrast intensity within the cell after lysis (n = 46 cells).