Fig. 4
Online measurement of biomass and Plk-eGFP formation. Scattered light intensity as a measure for biomass (first column) and eGFP fluorescence intensity (second column) over time of culture of E. coli BL21(DE3) uAA-eGFP cultures. Four process parameters were varied individually: (a, b) Plk concentration cplk = 0–70 mM; (c, d) time of Plk addition tplk = 4–2 h (e, f) IPTG concentration cIPTG = 0–500 μM (g, h) and time of IPTG addition tIPTG = 4 – 12 h. If not varied, parameters were fixed at cPlk = 10 mM, tPlk = 4 h, cIPTG = 200 μM and tIPTG = 4 h respectively. No Plk and no IPTG was added to cultures designated as ‘non-induced’ (dark grey). Small down-pointing arrows indicate the time of Plk and IPTG supplementation and large vertical arrows indicate trends in eGFP fluorescence after 32 h