ABSTRACT
Bacterial envelopes consist of a number of structures of varying complexity, including membranes and cell walls of different types. These structures maintain cell shape and protect the bacteria against osmotic shock. The envelopes of Gram-negative bacteria consist of three layers: the outer membrane, the peptidoglycan layer, and the plasma membrane. The fact that B. bifidum var. pennsylvanicus requires human milk for growth prompted several investigators to undertake studies on the biosynthesis of the cell wall of the organism. The biosynthesis of the bifidobacterial cell wall peptidoglycan can be inhibited by a number of antibiotics, such as penicillin, Vancomycin, Bacitracin, and d-cycloserine. There are apparently two kinds of teichoic acid-like substances present in bifidobacteria: a true teichoic acid involving mannitol and a glycerol-containing substance. The glycerol-type teichoic acid-like substances of bifidobacteria have been investigated by two groups with different results.
