Selecting time points for analysing the heterologous proteome fraction (φ_H). The images compare different criteria for selecting time points to analyse the heterologous proteome fraction in five different E. coli strains containing the DE3 system, |$BL21\ {lacI}^{OV}$|⁠, BLR, |$BLR\ {lacI}^{OV}$|⁠, |$MG1655$|⁠, and |$MG1655\ {lacI}^{OV}$|⁠. Cells co-transformed with pACYCDuet for the additional expression of LacI are indicated as |$\mathrm{lacI}^{OV}$|⁠. (a) Specific fluorescence accumulation over 12 h of cultivation after induction. The markers indicate the point of maximum specific fluorescence, |${\varphi }^{\text{max}}_\text{H}$|⁠. (b) Specific growth vs. time; the markers indicate the maximum specific growth rate for each culture, and the dotted line is a visual aid to identify the time at which it occurs. (c) Specific fluorescence accumulation for the first 2.5 h of cultivation after induction by 1 mM IPTG. The markers indicate the maximum specific growth rate for each culture, and the dotted lines indicate the time and the value of the specific fluorescence at these points.