Reversible Metabolic Swelling of Bacterial Protoplasts* T

In a previous communication (I) it was reported that the cell walls of Streptococcus fecalis (ATCC 9790) were susceptible to digestion by lysozyme. This finding subsequently allowed the preparation of protoplasts from these organisms by treatment of whole cells with lysozyme and the use of high concentrations of sucrose as the impermeantl substance necessary for osmotic stabilization. Further investigations led to the observation that addition of relatively small amounts of glucose to suspensions of these protoplasts produces a reversible swelling as indicated by a marked progressive fall in turbidity which eventually reverses spontaneously and returns to its initial value. It is to be noted that the reversible swelling in this case is not elicited by deliberate changes in extracellular osmotic pressure as described for BaciZZus megaterium protoplasts (2) (or other osmotically sensitive bodies), but rather by a concentration of metabolite which does not contribute significantly to the extracellular osmotic pressure, hence the term “reversible metabolic swelling.” This paper reports a study of the phenomenon of reversible swelling particularly with regard to the roles of glycolysis and specific cations.