a–e, 24-point MIC curves of the five SPOCK assay hit strains that were used for follow-up investigation. Overnight cultures were inoculated 1/10,000 into fresh LB media in final volumes of 100 µl in 96-well microtiter plates, and ciprofloxacin was added to the concentrations indicated. Cultures were incubated until untreated control cultures reached stationary phase, and optical density at 600 nm was measured (mean ± range; n = 2 biologically independent experiments). In all panels, wild-type E. coli is shown in blue and mutants are shown in red. Note that no shifts in MIC are observed. f–j, 12-point kill curves of the five strains described above. Cultures were grown to exponential phase (squares) or stationary phase (circles) in LB media in final volumes of 100 µl in 96-well microtiter plates. Ciprofloxacin was introduced at the concentrations noted, and cells were incubated for an additional 24 h prior to plating (mean ± s.d.; n = 2 (exponential phase) or n = 3 (stationary phase) biologically independent experiments). In all panels, wild-type E. coli is shown in blue and mutants are shown in red. Note that little difference in killing is observed between wild-type E. coli and each mutant during exponential phase treatment, whereas significant divergence occurs at stationary phase. LdcA (EMBO J. 18, 4108–4117; 1999), NlpI (Proc. Natl. Acad. Sci. USA 112, 10956–10961; 2015), and YibP (EnvC) (Mol. Microbiol. 52, 1255–1269; 2004) modulate peptidoglycan cross-linking and recycling, whereas OmpR (J. Biol. Chem. 277, 24155–24161; 2002) and YfgL (BamB) (Cell 121, 235–245; 2005) play roles in governing membrane protein composition.