[Ultrastructural investigations on anionic surface sites of Brucella canis (author's transl)].

Anionic sites on the surface of Brucella canis were visualized in the electron microscope by staining with positively charged ferric oxide hydrosols in acetic acid (AI-reagent), or propanoic acid (PI-reagent), and with a polycationic ferritin derivative. With the AI-reagent, single or small aggregates of ferric oxide particles were bound to the cell surface of Br. canis, whereas, with the lipophilic PI-reagent, the microorganisms were heavily stained with focal aggregates of iron granules. The polycationic ferritin label was uniformly distributed over the entire cell surface of Br. canis. The ferritin label was not bound on the surface of the organisms after prior treatment with trichloroacetic acid or methanolic hydrochloric acid. Treatment with aqueous acetone, chloroform/methanol, diethyl ether, sodium deoxycholate, pronase, lysozyme, hyaluronidase, and sodium periodate neither influenced the morphology of the Brucella nor diminished their ionic binding sites. Our results indicate that the anionic sites on the cell surface of Br. canis may be carboxyl and phosphate groups of lipopolysaccharides.