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Fig. 7 | Microbial Cell Factories

Fig. 7

From: High-level production of membrane proteins in E. coli BL21(DE3) by omitting the inducer IPTG

Fig. 7

Production of cytoplasmic SfGFP in BL21(DE3) in the presence and absence of IPTG. BL21(DE3) cells harboring a pET-based sfgfp expression vector were cultured in LB medium at 30 °C in the absence and presence of IPTG (final concentration 0.4 mM IPTG). a To assess SfGFP production levels, we monitored 4 and 24 h after the addition of IPTG fluorescence (relative fluorescence unit, RFU) per milliliter of culture. Biomass formation was monitored by measuring the A600. RFUs/ml per A600 are shown in Additional file 1: Figure S1. b The production of SfGFP per cell was monitored using flow cytometry. Traces of cells cultured in the presence of IPTG are red and traces of cells cultured in the absence of IPTG are black. Cells harvested after 4 h are represented by dotted lines and cells harvested after 24 h are represented by solid lines. The time point at which IPTG was added to the +IPTG cultures was taken as 0 h. c The production of SfGFP in the periplasm (left panel) and in the cytoplasm (right panel) was monitored on-line by measuring GFP fluorescence every 5 min in cells cultured in the presence and absence of IPTG in a 96-well plate in a spectrofluorometer. Traces representing cells cultured in the presence of IPTG are in grey and traces representing cells cultured in the absence of IPTG are in black

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