FIG. 1.

Viability and phospholipid hydrolysis of S. aureus treated with a sublethal dose of PLA2. [1-¹⁴C]oleate-labeled S. aureus RN450 Lyt+ (A and B) and Lyt− (C and D) were treated with 50 ng (Lyt+) or 150 ng (Lyt−) of PLA2 per ml in RPMI- 1640 supplemented with 0.3% BSA, 10 mM HEPES (pH 7.4), and 1 mM CaCl₂. At the indicated times, samples were removed to measure phospholipid degradation (A and C) and viability (B and D), as described in Materials and Methods. The results represent the mean and standard error of the mean of three or more independent determinations (∗, P ≤ 0.01 by Student's t test). The error bars are masked by the symbols. Open squares, bacteria alone; solid squares, bacteria plus PLA2.