FIG. 2.

Susceptibility of E. faecalis peptidoglycan to hen egg white lysozyme. Representative samples of peptidoglycan (approximately 0.5 mg/ml) in 50 mM sodium phosphate buffer (pH 6.0) were incubated at 25°C with 200 μg/ml (final concentration) of lysozyme, and the decrease in OD₆₆₀ was monitored with time. The percentage of peptidoglycan solubilized was determined by comparison with the amount solubilized in an appropriate control to which lysozyme was not added. Peptidoglycans were isolated from E. faecalis ATCC 19433 grown to the mid-exponential phase (▴), the stationary phase (•), and the VBNC state (▪). ⧫, control (de-O-acetylated E. faecalis peptidoglycan prepared by incubation in 40 mM NaOH for 2 h).