Serological studies with Agrobacterium radiobacter,A. tumefaciens,and Rhizobium strains

Summary Antisera were prepared against cell material from 3 strains of A. radiobacter and 6 of A. tumefaciens. Agar diffusion and immune absorption techniques revealed 3 antigens common to each strain of these organisms. However, 5 different lipopolysaccharide antigens occurred in the 9 test strains. There was no obvious species differences in the distribution of these antigens. Mannose, and possibly glucuronic acid were immunologically active in one of the lipopolysaccharides.The agrobacterial antisera were further crosstested with antigenic material for 34 strains of Rhizobium. Fast-growing rhizobia showed extensive cross-reaction, but only one of 7 R. lupini strains tested reacted with any antiserum.