Isolation and Identification of non-symbiotic nitrogen fixing and phosphate-solubilizing salt tolerant bacteria

Azotobacter a non-symbiotic nitrogen-fixing bacterial genus, along with some species of Bacillus genus as phosphate-solubilizing bacteria (PSB), are recognized for their significant contributions to sustainable agriculture. These microorganisms enhance soil fertility and plant productivity by facilitating key nutrient cycles most notably through the biological fixation of atmospheric nitrogen and the solubilization of insoluble phosphate compounds. However, soil salinity hinders the work of these bacteria and makes them unable to supply plants with nitrogen or phosphorus.  In this work an efficient strains of non-symbiotic nitrogen fixing bacteria and phosphate dissolving bacteria were isolated from saline soil. These isolates were used for microorganisms  identification based on cultural, morphological and biochemical characteristics as mentioned in Bergey’s Manual of Systematic Bacteriology. These isolates were used for microorganisms  identification based on cultural, morphological and biochemical characteristics as mentioned in Bergey’s Manual of Systematic Bacteriology. The ability of these isolates to fix nitrogen or dissolve precipitated phosphorous were tested. Probabilistic and then confirmatory identification tests confirmed that the best strain isolated from saline soil that fixes nitrogen non-symbiotically is Azotobacter chroococcum while the best one for phosphorus solubilization is Bacillus megatherium.