Fig. 3

The mechanisms by which erythromycin and 16-membered ring macrolides induce ermB expression are different. A-D Mutation of the tenth codon of ermBL to other amino acids. β-Galactosidase activity and disk diffusion assays of the activation of the lacZα reporter in response to Ery and 16-membered ring macrolides in vivo. Miller units of β-galactosidase activity are shown on the Y-axis. The number on the top of each bar represents the fold change in beta-gal activity between the antibiotic and DMSO group. The error bars correspond to the SEM of three independent experiments. All the β-Galactosidase activity of antibiotics group compared to DMSO group is significantly. P < 0.05; (unpaired two-tailed Student’s t test). B β-Galactosidase activity assay and disc diffusion assay of ermB’ truncated mutants exposed to erythromycin, spiramycin and tylosin. Miller units of β-galactosidase activity are shown on the Y-axis. The number on the top of each bar represents the fold change in beta-gal activity between the antibiotic and DMSO group. The error bars correspond to the SEM of three independent experiments. All the β-Galactosidase activity of antibiotics group compared to DMSO group is significantly. P < 0.05; (unpaired two-tailed Student’s t test)