Abstract
Antisera to 50 S ribosomal subunits of five strains of Agrobacterium were developed and tested for specificity against ribosomes from various bacterial species in immunodiffusion gels. Two methods of ribosome extraction were compared. When crude ribosomes from 34 Agrobacterium and four Rhizobium strains were tested against the five antisera, heterogenous precipitation patterns with multiple bands were produced. In contrast, when purified ribosomes from these strains were tested against the five antisera, a single precipitin band developed that was common to all 38 strains, showing that 50 S ribosomal subunits of Agrobacterium and Rhizobium are serologically identical. The five antisera did not react with species outside the rhizobiaceae and were therefore specific to the Agrobacterium-Rhizobium group. Any of these antisera could be used in diagnostic tests to determine if an unknown isolate belonged to the Agrobacterium-Rhizobium group.