Evaluation of stress tolerance of Azotobacter isolates

  • Navin Kumar Nag
  • Biplab Dash
  • Shyam Bihari Gupta
  • Dharmendra Khokher
  • Ravindra Soni
Keywords: stress, Azotobacter, tolerance, bio-fertilizers


Evaluation of 50 Azotobacter isolates was done for tolerance to pH, high temperature, and salinity, and four isolates (Azo-48, Azo-137, Azo-144, and Azo-160) passed all three tests. Tolerance to pH (5.0) was shown by a large quota of 20 isolates, while most of them (75%) also showed temperature-tolerance ability. Analysis of colony characteristics, biochemical properties, nitrogen fixing capacity, and phytohormone production of 14 selected isolates was carried out. Finally, after an extensive evaluation and critical analysis, we were able to sort out the above-mentioned four isolates and one of them (Azo-144) exhibited tolerance to a reasonably high degree of salinity stress.