Fig. 4.

Haemolytic activities of S. pneumoniae wild type and mutants strains. (A) Bacterial cells were fractionated into cell wall or cytoplasm fractions (as indicated) and two-fold serial dilutions were incubated with 2% sheep RBCs in replicates of three. The control was assay buffer only. No pellet was considered to be 100% lysis. Vertical lines show the detection endpoints of 50% lysis. (B) Quantitative haemolytic data of the absorbance (A₄₉₀) values of the first 50% lysis endpoint and the corresponding WT or mutant absorbance value at the same dilution. Therefore, absorbance values for cell wall and cytoplasmic fractions were taken at dilution factors 128 and 64, respectively. The dotted line represents the limit of detection. *P < 0.05. (n = 3). (C) Haemolytic activities of S. pneumoniae TIGR4, mutants and complemented strains after contact (sedimentation with sheep RBCs; black bars) or non-contact (incubation with sheep RBCs without sedimentation; white bars). P values: * <0.1, ** <0.05. No statistical significance to the wild type (NS) is also indicated. (n = 3).