FORMATION OF TWO TYPES OF OSMOTICALLY FRAGILE BODIES FROM STREPTOCOCCUS FAECALIS VAR. LIQUEFACIENS

Abstract

Osmotically fragile bodies which may be true protoplasts of the group D Streptococcus faecalis var. liquefaciens have been produced by use of a lytic enzyme derived from phage-infected cultures of the group D S. faecalis var. zymogenes. These bodies may be held in 1.1 M sucrose and are lysed almost quantitatively upon removal into water at room temperature or at 37 °C. The phage-associated lysin, in the presence of 0.7 M cysteine, causes almost complete lysis of the sensitive organism by the end of 1 hour at 37 °C and effects complete removal of cell-wall materials (rhamnose-containing moieties and phage-receptor sites) in that time.Osmotically fragile bodies which may be termed spheroplasts of S. faecalis var. liquefaciens have been produced by the use of lysozyme on cells previously grown in penicillin (5 units/ml). Lysis to the extent of 50% in 1 hour at 37 °C occurs in the aqueous suspensions, whereas 17% sucrose with 0.2% MgSO4∙7H2O or 0.2% MgSO4∙7H2O alone effects almost complete stabilization. The stabilized bodies are lysed almost quantitatively upon removal to water at 56 °C. Cell-wall material containing rhamnose remains on these forms, indicating that they are spheroplasts rather than protoplasts.