FIGURE 3.

Growth characterization of E. coli MG1655 and E. coli MG1655 ΔrelA, each heterologously expressing the C. glutamicum genes rel_Cg, relH_Cg or relS_Cg, on different solid medium plates. The empty vector pZMP was used as control. All strains were cultivated using initial OD₆₀₀ values of 0.05 in LB-medium for 3 h. The cells were washed and serially diluted in PBS-buffer. 5 μL aliquots of every strain and dilution stage were spotted on LB medium plates (LB), minimal medium plates (MM) and minimal medium plates containing each 1 mM L-serine, L-methionine, and L-glycine (MM+SMG). All solid media plates contained 50 μg mL^-1 kanamycin and 4 g L^-1 glycerol was used as C source for all minimal medium plates. Incubation was carried out at 37°C for 24 h in the case of LB solid medium and 48 h for MM and MM+SMG plates.