DIVERSITY OF PARTIAL 16S RIBOSOMAL-RNA SEQUENCES AMONG AND WITHIN STRAINS OF AFRICAN RHIZOBIA ISOLATED FROM SCACIA AND PROSOPIS

To assess tile phylogenetic diversity of fast-growing rhizobium strain s isolated from root nodules of Acacia senegal and Prosopis chilensis trees growing in Sudan and Kenya, a 230-nucleotide segment of the 16S ribosomal RNA gene was sequenced from each oi thirty strains. Twelve d ifferent sequences were found: four were identical to those of previou sly described species, eight were novel. Sequence comparisons indicate d that une strain belonged to the Rhizobium huakuii phylogenetic branc h, while the rest were Sinorhizobium, as they were close to S. (Rhizob ium) meliloti, S. fredii, S. teranga and S. saheli. isolates from Acac ia and from Prosopis Often had the same sequence, but the sequence typ e was not very well correlated with the phenotypic characteristics det ermined previously for these strains. One isolate had two 16S rRNA seq uences, differing at six positions, in approximately equal copy number . The type strain of S. saheli was also shown to have two different se quences.