Isolation and Characterization Salt Tolerant Strains Of Rhizobium leguminosarum bv. Viciae

Seven strains of Rhizobium leguminosarum bv. vicide were isolated and purified from the root nodules of faba bean (Viciae faba) plants collected from different agroclimatic locations in Baghdad and Diyala provinces of Iraq. Screening of these strains gives four salinity tolernat strains which tolerate 1-5% sodium chloride supplement mannitol to salt yeast extract (M Y) medium. Colony forming units for the four tolerant strains under stress conditions were significantly reduced in comparison with those under normal conditions. Different tests were used to study the surface properties of stress tolerant strains under normal and stress conditions. No differences were found in the production of lipopolysaccharides (LPS), β (1 → 3) glucan and cellulose fibrils under stress and normal conditions. Symbiotic properties of stress tolerant strains were studied by inoculating the respective host plants with these strains. Strain NIMA1 was found to be most efficient in symbiotic nitrogen fixation. No nodulation was observed under stress condition.