Changes in the antigenic properties of Azospirillum brasilense lipopolysaccharide, induced by addition of tris-(hydroxymethyl)-aminomethane into the culture medium

Addition of tris-(hydroxymethyl)-aminomethane (Tris) into the culture medium of Azospirillum brasilense sp245 changes the antigenic properties of the lipopolysaccharide (LPS) isolated from the external membrane of the bacteria. LPS preparations from the bacteria grown in the presence of Tris have been analyzed by immunodiffusion, using monospecific antibodies. The disappearance of the precipitation band corresponding to one of the two O-specific polysaccharides of the LPS (O-PS) and changes in the electrophoretic profile have been revealed. However, only minor differences in absorption spectra of products of O-PS I reaction with phenol/sulfuric acid have been demonstrated between the bacteria grown under standard conditions and in the presence of Tris.