Fig. 2

BgaB activities of five plasmids with the Pgrac01 promoter in E. coli. The bacterial cells were grown in LB medium at 37 °C to the mid-logarithmic growth phase. Then, the culture was split into two subcultures and was further incubated in the absence of IPTG (0 mM) and the others induced with 1 mM IPTG. Samples were taken immediately after addition of IPTG (0 h) and 2 and 4 h later (2, 4 h). The β-galactosidase activity was measured in all samples and expressed as MUG units ×10⁴