Thirty-one strains of two new genomic species (genomic species 1 and 2) of rhizobia isolated from root nodules of and originating from various locations in France were compared with reference strains of rhizobia by performing a numerical analysis of 64 phenotypic features. Each genomic species formed a distinct phenon and was separated from the other rhizobial species. A comparison of the complete 16S rRNA gene sequences of a representative of genomic species 1 (strain R602sp) and a representative of genomic species 2 (strain H152) with the sequences of other rhizobia and related bacteria revealed that each genomic species formed a lineage independent of the lineages formed by the previously recognized species of rhizobia. Genomic species 1 clustered with the species that include the bean-nodulating rhizobia, , and , and branched with unclassified rhizobial strain OK50, which was isolated from root nodules of in Japan. Genomic species 2 was distantly related to all other species and related taxa, and the most closely related organisms were and several species. On the basis of the results of phenotypic and phylogenetic analyses and genotypic data previously published and reviewed in this paper, two new species of the genus and , are proposed for genomic species 1 and 2, respectively. Each species could be divided in two subgroups on the basis of symbiotic characteristics, as shown by phenotypic (host range and nitrogen fixation effectiveness) and genotypic data. For each species, one subgroup had the same symbiotic characteristics as biovar phaseoli and biovar phaseoli. The other subgroup had a species-specific symbiotic phenotype and genotype. Therefore, we propose that each species should be subdivided into two biovars, as follows: biovar gallicum and biovar phaseoli; and biovar giardinii and biovar phaseoli.


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