Fig. 4.
Comparison of the induced expression level with P43′-riboE1 and three strong promoters from B. subtilis. a SDS-PAGE analysis of GFP controlled by the constitutive promoters PsrfA, PaprE, P43 and by the theophylline-induced element P43′-riboE1. The BSG11 strain was activated by 8-mM theophylline for 24 h prior to sampling for SDS-PAGE. b Fluorescence intensity representing the relative expression level was driven by three constitutive promoters as well as by the P43′-riboE1 element after induction by 8-mM theophylline for total 31 and 24-h culture periods, respectively. The GFP fluorescence was measured in triplicates and the data were shown in mean ± SD