Some Characters of Rhizobium Strains from Tropical Legumes

SUMMARY: Twelve strains of Rhizobium sp. from wild and cultivated leguminous plants growing in the Belgian Congo were examined. All were bacillary or filamentous, weakly Gram-positive, and produced occasional retractile, heat-resistant spores; all grew alternatively in the form of very tiny, Gram-negative rods with polar flagella (if motile), and without spores. Botanical evidence suggests that the host plants are primitive members of the family Leguminosae, and if the characters of these strains of Rhizobium are also to be regarded as primitive, this evidence supports the view that Rhizobium is related to Azotobacter and the Bacillaceae.