FIG 4 .

Determination of viable cell titers of S. aureus and B. subtilis wild-type strains (WT) and their ΔmurQ mutants grown in LB medium with or without MurNAc. Wild-type and ΔmurQ mutant cells of S. aureus and B. subtilis were grown in LB medium in the absence (left two bars in each graph) or presence of 0.2% MurNAc. Bacterial cultures were diluted appropriately in 0.9% NaCl solution in 96-well plates and plated on LB agar. Viable cells were determined by counting CFU/ml (×10⁸) at mid-exponential (4 h for S. aureus and 4.5 h for B. subtilis), transition (8 h and 10 h, respectively), and stationary (24 h, 48 h, and 72 h) phases. Data are presented as the mean values ± SEM from three independent biological replicates and were analyzed for statistical significance with the nonpaired t test. A P value of <0.05 was determined as statistically significant (*, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001; ns, nonsignificant).