DNA-DNA hybridization study of Bradyrhizobium strains

DNA-DNA hybridizations were performed between Bradyrhizobium strains, isola ted mainly from Faidherbia albida and Aeschynomene species, as well as Brad yrhizobium reference strains. Results indicated that the genus Bradyrhirobi um consists of at least 11 genospecies, I to XI, The genospecies formed fou r subgeneric groups that were more closely related to each other (> 40% DNA hybridization) than to other genospecies (< 40% DNA hybridization) : (i) g enospecies I (Bradyrhilobium japonicum), III (Bradyrhizobium liaoningense), IV and V; (ii) genospecies VI and VIII; (iii) genospecies VII and IX; and (iv) genospecies II (Bradyrhizobium elkanii), X and XI. Photosynthetic Aesc hynomene isolates were found to belong to at least two distinct genospecies in one subgeneric group, DNA-DNA hybridization data are compared with data from amplified fragment length polymorphism analysis and 16S-23S rDNA spac er sequence analysis.