CONTRIBUTION OF CELL SURFACE TO SALT TOLERANCE OF STAPHYLOCOCCUS AUREUS

STUDIES BY FREEZE-ETCHING METHOD

Abstract

The role of cell surface in a haloresistant mechanism of S. aureus was analyzed by freeze-etching method. Our comparative studies were carried out on S. aureus cultivated in 0.5% NaCl containing medium (Normal-Staph) and in 10% NaCl containing medium (10%-Staph), as they were or were treated with L-11 enzyme (cell wall lytic enzyme obtained from Flabobacterium sp.).
1. As shown in photographs of non-treated and enzyme-treated cells, both the cell size and cell wall thickness of 10%-Staph increased to about 1.5 times Normal-Staph.
2. When Normal-Staph was exposed to L-11 enzyme, there occurred a gradual decrease in the OD. In the case of 10%-Staph, the OD showed a down-slope with a shoulder which rose in OD once at about 10 minutes after incubation.
3. The surface pattern of plasma membrane of Normal-Staph appeared to be made up of closely arranged spherical subunits. But in the case of 10%-Staph, the spherical subunits were indistinct and appeared to be sparsely located.