FIG 10.

Autolysis and membrane permeability in S. aureus glucosaminidase mutants. Triton X-100 (0.05%) or buffer alone was added to mid-exponential-phase cultures (A₆₀₀ of 0.5) of S. aureus suspended in 50 mM phosphate buffer (pH 7.5). Turbidity at A₆₀₀ was monitored over 3 h and plotted as the A₆₀₀ of lysostaphin-inoculated staphylococci of buffer alone at each time point. Autolysis, as determined by reduction of turbidity, was compared between the wild-type, atl, and sagB strains (A). (B) Autolysis in 0.05% Triton X-100 was assessed in the wild-type (pOS1), sagB(pOS1), and sagB(psagB) strains. (C) Propidium iodide staining of bacteria was used to assess membrane permeability. One milliliter of culture (A₆₀₀ of 0.5) was fixed with paraformaldehyde and subsequently stained with SYTO 9 for total cells and with propidium iodide to assess membrane integrity. SYTO 9-positive cells were analyzed for propidium iodide positivity using flow cytometry. Data from triplicate samples of 10,000 cells are presented. Statistical significance was assessed by one-way ANOVA with Bonferroni's multiple comparison test. ns, not significant.