Figure 2. Lead-binding capacity analyses of MG1363, pGS/MG1363 and pGSMT/MG1363.

The L. lactis strains were grown in GM17 medium with or without erythromycin until the OD₆₀₀ reached 0.4. Then, lead acetate was added to a final concentration of 0.1 mM and the culture was incubated at 30 °C for up to 20 h. The cells were harvested and dried to constant weight. The mass of lead in these dried pellets was evaluated using ICP-OES (n = 3). The parameters are expressed as the means ± S.E.s. The curves represent the lead-accumulating tendency of the recombinant strains at different time points. The capital letter “R” represents the strains grown in the presence of erythromycin.