Phenotypic and symbiotic characterization of rhizobia isolated from Medicago ciliaris L. growing in Zerizer from Algeria

Phenotypic characteristics of 37 rhizobia strains isolated from root nodules of Medicago ciliaris L. growing in soils collected from Zerizer (North Eastern Algeria) were studied. Tolerance to salinity, high temperatures, acid and alkaline pHs, drought and to antibiotics as well as symbiotic and cultural characteristics allowed the description of a wide physiological diversity among tested isolates. Thirteen (13) isolates from the total could grow at 45°C. Only six isolates grew at 4% NaCl. Furthermore, the isolates which showed tolerance to salinity stress also showed tolerance to water stress, indicating direct relationships between these two physiological pathways. High salt and water stress tolerant strains were isolated and tested for their ability to biological nitrogen fixation. However, seven isolates were categorized into Agrobacterium.