Fig. 3: Motility of E. coli as a function of gene expression in minimal medium.
a Flow cytometry measurements of the PfliC-GFP reporter of MG1655 WT (IL28) or Ptac (IL29) strains grown to mid-exponential phase in M9 minimal medium, with either glucose (left) or succinate (right) as the sole carbon source. Labels for different induction levels of Ptac are the same as in Fig. 1b. Flow cytometry histograms of three biological replicates are shown as violin plots in different hues (AU – arbitrary units). Horizontal dashed line indicates threshold PfliC activity level for cellular auto-fluorescence defined as the signal from cells without fluorescent reporter (see also Supplementary Fig. 8). b Dependence of the population-averaged swimming velocity on the median PfliC reporter activity (flow cytometry, FC) for the carbon sources and strains indicated in the table below. Each dot represents an independent culture (biological replicate) for which both expression (PfliC reporter activity) and swimming were determined. Balanced growth experiments were performed with MG1655 WT not carrying pTrc99a (IL182). Flagellar gene expression in Ptac strain was induced as in panel (a), with 0 to 25 µM IPTG in glucose and 0 to 10 µM IPTG in succinate. c Percentage of GFP-positive cells within the population of the indicated E. coli strains (IL28, IL29, IL164, IL165, IL175, and IL217) as a function of median PfliC reporter activity, both measured by flow cytometry as in (a). Each symbol represents an independent culture, with strains and growth conditions indicated in table below. Data are from the batch growth experiments shown in Fig. 1d, (b), Supplementary Fig. 1f, Supplementary Fig. 6b, and Supplementary Fig. 9. Source data are provided as a Source Data file.
