Figure EV1. Very low membrane fluidity in E. coli does not trigger membrane permeabilisation for ortho‐nitrophenyl β‐D‐galactopyranoside (ONPG).

The membrane permeability of ONPG was assessed in strains deficient for the active uptake system LacY simultaneously expressing lacZ from a plasmid‐encoded leaky Ptac promoter (without addition of the inducer IPTG). The graph depicts ONPG hydrolysis rates measured for intact cells upon incubation at 30 and 37°C. In case of the temperature‐sensitive fabA(Ts) strain, growth at the non‐permissive temperature of 37°C was limited to 120 min. As controls, the ONPG conversion rates were measured in strains lacking the lacZ‐expressing plasmid. Note the lack of significant difference in ONPG conversion rates upon strong depletion of unsaturated fatty acids (fabA(Ts) strain at 37°C for 120 min), implying the lack of detectable membrane permeabilisation due to phase separation.

Data information: The graph depicts mean and SD of biological triplicates. The P values represent the results of unpaired, two‐sided t‐tests. Insignificant changes (P > 0.1) are indicated with n.s. Strains used: E. coli Y‐Mel.ΔlacY, UC1098.ΔlacY, Y‐Mel.ΔlacY/pTM30.lacZ‐His2, UC1098.ΔlacY/pTM30.lacZ‐His2.

Source data are available online for this figure.