PROTOPLAST MEMBRANE OF STREPTOCOCCUS FAECALIS

Abstract

The membrane fraction of Streptococcus faecalis (ATCC 9790) was isolated and purified, by a variety of procedures, from cultures that were grown under closely controlled conditions of physiological age and nutrition. The most satisfactory method required the use of lysozyme-to-cell ratios below 0.01 and the intermediate formation of protoplasts in osmotically protective media. Amino acid analyses of three of the membrane preparations indicated a characteristic and constant, but not unusual, pattern; 42% of the membranes from threonine

The membrane lipids of Halobacterium halobium

“…This value is similar to the change in composition of the protoplast membrane ofStreptococcu8faecali8 between exponential-and stationary-growth phases in a medium limited by valine (Shockman, Kolb, Bakay, Conover & Toennies, 1963); the lipid content of the S. faecalis membrane was 28-40%.…”

pH‐dependent changes in density of plasma membranes of growing Mycoplasma laidlawii cells

“…Changes in the lipid to protein ratio have been recorded in several microbial and animal cell membranes during various physiological phases of growth [13][14][15] or after selective inhibition of membrane protein or lipid synthesis [11,16]. The present results show that the pH of the growth medium has a pronounced effect on the lipid to protein ratio in M. laidlawii membranes.…”

Bacterial phosphatides and natural relationships.

“…The omithine-containing lipid in the phospholipid fraction of Rhodopseudomonas spheroides showed no radioactivity when the cells were grown on P32 and therefore also appears not to be a phospholipid (34). (77); and in Streptococcus faecalis, 28 to 40% (87), 21% (45), and 30.4% (104). Furthermore, studies indicate that most of the lipid of the cell is concentrated in the membrane.…”