Isolement et caractérisation des bactéries nodulant les légumineuses du genre Hedysarum.

Abstract

Bacteria were isolated from the nodules of different leguminous species of the genus Hedysarum: H. pallidum Desf.( endemic north African), H. spinosissimum subsp. Capitatum (species of the Western Mediterranean), H. carnosum Desf. ( endemic north African) and H. naudinianum Coss.( endemic of Algeria). For the species H. naudinianum , it is the first study to highlight the symbiotic association plant-bacterium. The characterization of the strains consist of a morphological study followed by a phenotypical characterization which includes distinctive tests between the genus Rhizobium and Agrobacterium, biochemical and physiological tests as well as the measurement of the resistances and the sensitivities of the strains to heavy metals, antibiotics and with the phages. The aptitude of the isolates to form nodules on the plants hosts is evaluated by nodulation test according to the method of Vincent (1970). The technique of electrophoresis on polyacrylamide gel in denaturing conditions (SDS-PAGE) is carried out to determine the profile of total proteins of the isolates. The phylogenetic characterization is carried out by a molecular study by analyzing the strains by the technique of the ARDRA (Amplified Ribosomal DNA Analysis Restriction) by using the restriction enzyme CfoI, then sequenced their DNAr. Phenotypiquely, the isolates give comparable results with those of the strains of reference Gammaproteobacteria. This is confirmed by the phylogenetic study.