M9 minimum medium

Wild type and ∆aroA Escherichia coli K1 E11 strains were grown for 48 h at 37 °C on M9 minimum medium (Sigma, France) with or without the addition of 40 µg/ml tryptophan, 40 µg/ml tyrosine, 40 µg/ml phenylalanine. A third condition with the addition of 2 times the amino acids was added. During this period, bacterial growth was measured by Optical Density.

For genetic engineering, E. coli cells were incubated in Lysogeny broth (LB) supplemented, when required, with 100 μg/ml ampicillin (Sigma-Aldrich), 50 μg/ml kanamycin (Sigma-Aldrich), or 34 μg/ml chloramphenicol (Sigma-Aldrich) for plasmid selection, or with 25 μg/ml kanamycin, 20 μg/ml chloramphenicol, or 0.2% sucrose for selection of the genomic insertions of gene cassettes. For imaging strains with fluorescent foci with LacI fusions, we grew cells in liquid M9 minimum medium (Fluka Analytical) supplemented with 2 mM MgSO₄, 0.1 mM CaCl₂, 0.4% glycerol (Sigma-Aldrich), and 0.01% protein hydrolysate amicase (PHA; Fluka Analytical). For imaging other strains, we grew cells either in liquid M9 minimum medium supplemented with 2 mM MgSO₄, 0.1 mM CaCl₂, 0.4% glucose (Sigma-Aldrich), and 0.25% PHA, or in LB medium. For imaging, overnight cultures were back diluted into the fresh medium described above to an OD (600 nm, same below) of 0.01 in falcon tubes until an OD of 0.4–0.6 for M9 medium with 0.25% PHA and LB, and OD of 0.1 for M9 medium with 0.01% PHA. The growth conditions for the FtsZ complementation assay are as described in Osawa and Erickson (2005) (link). 0.002% arabinose was used for the induction of ectopic FtsZswTagRFP-T fusion from the plasmids in the presence of the endogenous ftsZ.