Characterization of rhizobia that nodulate native legume trees from Uruguay

This report describes some biochemical and genetic characteristics of seven rhizobial isolates that nodulate legume trees Inga uragüensis, Prosopis nigra, Acacia caven, Erythrina crista-galli and Enterolobium contortisiliquum, native to Uruguay. Based on specific growth rates, carbon source utilization and acid production the isolates could be assigned to the fast-growing group of rhizobia. The analysis of plasmid content showed that from seven isolates examined, three contained a single plasmid of approximately 220 Mda, two harboured two plasmids with molecular weight < 220 Mda and no plasmid was detected in the remaining isolates. All the isolates examined showed a distinguishable protein profile using one-dimensional SDS-PAGE. This technique could distinguish one isolate from another. Hybridization studies using R. leguminosarum hup probe did not indicate hup genes in any of the isolates examined.