Polyphasic taxonomy of symbiotic Rhizobia from wild leguminous plants growing in Egypt

About 20 strains of rhizobia from wild legumes were characterized based on numerical analysis of phenotypic characteristics, nodulating ability, fatty acid methyl esters (FAME) and SDS-PAGE profiles of whole cell proteins. FAME analysis revealed that palmitic, stearic and arachidonic acids were detected in most of wild-legume rhizobia. The strains were classified into 9 clusters and one heterogeneous group. There was both agreement and disagreement with the clustering data based on phenotypic analysis and FAME analysis. Four strains were grouped together in the same cluster based on both methods. SDS-PAGE revealed that the rhizobial strains exhibited protein profiles with peptide bands ranging from 5-19 band per profile and showed molar mass of 110-183 kDa. Numerical analysis of protein bands was compared with clustering of phenotypic analysis. Agreement of the two methods was obvious when clustering some strains but conflicted in the classification of some other strains. The twenty strains of wild-legume rhizobia were finally classified as follows: 12 strains related to Rhizobium leguminosarum, 5 strains related to Sinorhizobium meliloti and 3 strains to Rhizobium spp.