a Two E. coli strains were used: strain 1 constitutively expresses a yellow fluorescent protein (mVenus) and carries a plasmid with the ampicillin resistance cassette (cyan AmpR in the plasmid magnification) and a red fluorescent protein (RFP), mCherry (magenta), under the control of the trc promoter, an hybrid of the trp and lac promoters. Strain 2 constitutively expresses a red fluorescent protein (mKate2Hyb) and carries a plasmid with the ampicillin resistance cassette. b Proteome allocation of the two strains at different concentration of IPTG in the medium. When strain 1 grows in the presence of IPTG, a fraction φiRFP of the strain’s proteome is allocated for the expression of the RFP mCherry, thus reducing the fraction Φ1 allocated for metabolism and growth. The proteome allocation of strain 2, instead, is not affected by the presence of IPTG. c The two strains were co-cultured in minimal medium at different IPTG concentrations, they were diluted daily into fresh medium and their relative abundance was measured at every transfer via flow cytometry.