Fig. 7
Analysis of susceptibility to growth inhibition by zinc intoxication in diverse sequence types of Group B Streptococcus (GBS). GBS strains of varying sequence types (ST-1, black circles; ST-7, squares; ST-12, triangles; ST-17, inverted triangles; ST-19, diamonds; ST-23, open circles) were grown in medium alone or increasing concentrations of zinc chloride (500 μM, 750 μM, 1000 μM, 2500 μM, 5000 μM). Bacterial growth was measured at 24 h post-inoculation as an optical density at 600 nm absorbance (OD600). In medium alone and at 500 and 750 μM concentrations of zinc, no differences in susceptibility were observed. However, at 1000, 2500, and 5000 μM zinc concentrations, ST-1 and ST-7 strains exhibited the highest susceptibility to zinc intoxication than other sequence types. At 2500 μM zinc concentration, ST-17 and ST-19 emerged as the least susceptible strain types. At 5000 μM zinc concentration, ST-19 remained the least susceptible strain type. Statistical significance was determined by one-way ANOVA with Tukey’s post hoc multiple correction (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, n = 3 biological replicates)