Figure 3

Production of secretory SFGFP following varying gene expression levels. Lemo21(DE3) cells harboring a pET-vector with the gene encoding secretory SFGFP were cultured in LB medium at 30°C. The expression of secretory SFGFP was induced with 400 μM IPTG for 4 h. Rhamnose was present as indicated. Lemo21(DE3) harboring an empty expression vector (control) and BL21(DE3) producing secretory SFGFP were included as controls. A The effect of the production of secretory SFGFP following varying gene expression levels on biomass formation was monitored by measuring the A₆₀₀. B The effect of the production of secretory SFGFP following varying gene expression levels on protein yields was monitored as fluorescence per ml of culture. The highest level of fluorescence was set to 100%; the other values were adjusted accordingly. C The localization of secretory SFGFP in Lemo21(DE3) cells cultured in the absence and presence of increasing concentrations of rhamnose was monitored directly in whole cells using fluorescence microscopy. Lemo21(DE3) cells producing cytoplasmic SFGFP (i.e., SFGFP not equipped with a signal sequence) in the absence of rhamnose were included as control.