The present study was conducted with the goal of isolation, screening and characterization of most potential nitrogen fixers from the agricultural soil. Five bacterial isolates were isolated and characterized from rhizosphere of ground nut plant. The potential isolate was identified as Bacillus subtilis strain AS-4 based on the morphological, biochemical, cultural and 16s rDNA identification. The organism grew well in SM basal salt medium and nitrogen-free semi-solid LGI medium, tolerated 10-15% salt concentration and the optimum growth was found at 27°C and pH 7.0. The present investigation proves that the soil isolate Bacillus subtilis strain AS-4 is salt tolerant, free living nitrogen fixing bacteria that could be exploited as soil inoculants and can be used for nitrogen fixation in soil with high concentration of salt, which is of long run, eco-friendly and cost ineffective.
