Light and Scanning-Beam Electron Microscopy of Wall-Defective Staphylococcus aureus Induced by Lysostaphin

Abstract

The serial morphological changes of Staphylococcus aureus after exposure to lysostaphin (one unit per ml) in hypertonic culture medium containing 5% NaCl were studied over an 8-hr period at 37 C. S. aureus stained gram-negative almost instantaneously upon contact with lysostaphin. Many cells were lysed, but wall-defective staphylococci with corrugated surface were detected as early as 5 min by use of scanning-beam electron microscopy. Wall-defective staphylococci enlarged progressively with increasing periods of incubation. The absorbance of the lysostaphin-treated culture decreased significantly by 2 min, remained stationary for 2 hr, and then progressively increased. The number of vegetative colony-forming units decreased progressively with increasing periods of incubation) whereas the number of

Roles of mannosylerythritol lipid-B components in antimicrobial activity against bovine mastitis-causing Staphylococcus aureus

“…Moreover, these structures were completely different from those of damaged S. aureus treated with lysostaphin, which specifically disrupts the cell wall of S. aureus (Fig. 5 b) (Watanakunakorn et al 1971 ). These results suggest that the effect of MEL-B on the inhibition of the growth of S. aureus may not be due to the disruption of the overall bacterial structure.…”

Morphology and Ultrastructure of Staphylococcal L Colonies: Light, Scanning, and Transmission Electron Microscopy

“…NaCl, which was buffered to pH 7.2 with potassium phosphate buffer and air dried as previously described (5,13), had a gross morphology which corresponded to that observed with LM. They were difficult to study at high magnification, however, because the individual cells were indistinct and tolerated the primary electron beam poorly.…”

“…In the present study, portions of a 24-hr broth culture of a lysostaphin-induced, cell wall-free, stable L-phase variant of Staphylococcus aureus (AH24H) were inoculated onto plates of hypertonic agar medium (5,(12)(13)(14). After incubation periods of from 6 hr to 5 days, colony-containing agar blocks were removed for study by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).…”