Figure 2.

Group B Streptococcus (GBS) biofilm regulatory protein A (BrpA) contributes to cellular chain length, buoyancy, pigmentation, and acid tolerance. A, Bright-field images of wild-type (left) and ΔbrpA (center) strains in mid-log–phase growth, taken at 630× original magnification. Scale bar = 10 µm. Quantification of the chain length is shown at right, with data analyzed via the 2-tailed Mann-Whitney U test (n = 50). Median values with 95% confidence intervals are displayed. Experiments were performed twice independently, with representative images and combined data shown. B and C, Visualization of stationary-phase cultures (B) or colonies (C) grown for 18 hours at 37°C in Todd-Hewitt broth (THB) or on THB agar plates, respectively. D, Growth curves of GBS strains in THB at specified pH values. Independent replicates (n = 3) are shown, with lines indicating mean values ± standard errors of the mean. Data were analyzed using 2-way repeated measures analysis of variance with the Tukey multiple comparisons test. ****P < .0001.