FIG. 5.

Increase of optical density after addition of φ12 endolysin. Unlike the φ11 enzyme, the φ12 endolysin was not able to lyse heat-killed cells of any tested staphylococcal strain. Upon addition of φ12 endolysin (15 μg/ml) we detected an obvious increase of optical density of S. aureus Wood 46 (•), S. aureus Cowan 1 (×), and S. aureus Newman (▴). The protein eluate of empty-vector control (⧫) showed no effect, whereas the control with lysostaphin (▪; 5 μg/ml) lysed all staphylococcal strains.