Biochemical changes in Bifidobacterium bifidum var. pennsylvanicus after cell wall inhibition. IX. Metabolism and release of cellular lipids in the presence of antibiotics.

Inhibiton of cell wall synthesis caused simultaneously an increase in cellular phospho-and glycolipids and a marked release of these compounds to the medium. The composition of the cellular and the released glyco-and phospholipids was almost the same. Antibiotics, which inhibit cell wall synthesis, did not influence glycolipid composition, but increased the relative and absolute amounts of disphosphatidylglycerol and its lysoderivatives. Incorporation and chase experiments demonstrated a considerable stimulation of phospholipid metabolism, and of diphosphatidylglycerol synthesis especially. Release of lipids was not accompanied by loss of cellular protein. Omission of Tween 80 from the medium decreased the release by about 50% and increased the relative amounts of the phosphogalactolipids in the cells and in the culture fluid. Inhibitors of protein synthesis and valinomycin caused a decrease in cellular lipidphosphorus content, and a relative increase of the phosphogalactolipids. No release of lipids was observed under these conditions.