Current Microbiology

, Volume 50, Issue 1, pp 11–16 | Cite as

High Salt and High pH Tolerance of New Isolated Rhizobium etli Strains from Egyptian Soils

  • Abdelaal Shamseldin
  • Dietrich Werner


Saline and alkaline soils are major problems contributing to the low productivity of common bean (Phaseolus vulgaris) in arid and semi-arid regions such as Egypt. Therefore our study was directed toward selecting strains more tolerant to these environmental stresses. Among seven Rhizobium etli strains isolated from Egyptian soils, we found a high degree of diversity. Strains EBRI 21 and EBRI 26 are highly tolerant to a salt concentration up to 4% NaCl. A positive correlation was found between the salt tolerance and the adaptation to alkaline pH (9). Strains EBRI 2 and EBRI 26 were adapted to elevated temperatures (42°C). The minimum level of low pH for the majority of Rhizobium etli strains from Egypt was pH 4.7 while the Colombian strain Rhizobium tropici CIAT 899 survived well at pH 4. At 0.4% NaCl, the symbiotic efficiency of the salt-tolerant strain EBRI 26 was superior in cultivar Giza 6 compared with the salt-sensitive strain EBRI 2 (18.2 compared with 13.9 nM C2H4 h−1 mg−1 nodule fresh weight). In the bean cultivar Saxa, nitrogen fixation was much more affected by high salt concentration (0.4% NaCl) than in the cultivar Giza 6 with both strains (3.9 and 3.8 nM C2H4 h−1 mg−1 nodule fresh weight, respectively). In general, stress of alkalinity had a less detrimental effect on nodulation and N2 fixation than stress of salinity.


Salt Stress Nitrogen Fixation Rhizobium Common Bean Faba Bean 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank the EU for support by INCO-DEV-ICA4-CT-2001-10057.

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Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  1. 1.Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technological ApplicationsDekheelaAlexandriaEgypt
  2. 2.Fachbereich BiologieFachgebiet Zellbiologie und Angewandte Botanik, Philipps-Universität MarburgGermany

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