Abstract:

The objective of this study was determination of the taxonomic position of these isolates and the evaluation of the level of approximation or divergence between these strains and the reference strains belonging to different genus of rhizobia. Amplification of the ribosomal 16S rDNA gene (PCR / RFLP of 16S rDNA) was digested with four different restriction enzymes: Msp I, Hinf I, Hha I and Taq I. The results of different electrophoretic profiles of fragments obtained shown the selection of the most discriminating enzymes Msp I and Hinf I. The length polymorphism of the restriction fragments (RFLP) analysis of PCR amplified 16S rDNA was compared with those of reference strains. Numerical analysis of molecular characteristics showed that 20 strains studied were divided into three distinct groups; we noted that three isolates only Lablab purpureus have a high level of similarity with the reference strain "Bradyrhizobium", while 17 isolates did not exhibit precise taxonomic status and therefore their exact phylogenetic classification is to be determined. The nearly complete sequence of the 16S rRNA gene from a representative strain of each REP-PCR pattern showed that the strains were closely related to the members of the family Bradyrhizobium.

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