[Carboyydrates localization on ultrathin sections of "Brucella" and "Escherichia" cells in smooth (S) and rough (R) phase (author's transl)].

Carbohydrates localization on ultrathin sections of Brucella abortus, melitensis and Excherichia coli cells has been studied by the periodic acid thiocarbohydrazide-silver proteinate (PATAg) and phosphotungstic acid (PTA) methods. Carbohydrates are mainly localized on the cell envelope of Brucella and Escherichia but there are several differences between these two bacteria. The differences are discussed and a Brucella polysaccharide envelope model is proposed. The PATAg method gives the same silver grain deposits on Brucella S and R and Escherichia S and R. The phosphotungstic acid method differenciates Brucella S and R cells by lack of contrast on the outer leaflet of the outer membrane of the latter, but does not differenciate E. coli S or R cells. The Brucella outer membrane contains less polysaccharides than that of E. coli. There is a seemingly symetric distribution of polysaccharide in the Brucella outer membrane as compared to an asymetric distribution in E. coli. The peptidoglycan of Brucella reacts strongly as compared with that of E. coli. The polysaccharides present a dispersed pattern in Brucella cytoplasm, whereas in E. coli they appear as dense, strongly reactive clusters very close to the cytoplasmic membrane.