Phosphate solubilization potential of salinity tolerant azotobacter species

Phosphate solubilizing bacteria plays a central role in maintaining soil nutrient status and in plant growth promotion. The performance of these organisms is affected severely in presence of high salt concentrations and nitrogen limitation. Use of salinity tolerant nitrogen fixing bacteria belonging to genus Azotobacter as bioinoculant can help to overcome this situation. In the present study, sixty three salinity tolerant Azotobacter species were isolated from agricultural soils and were screened for their phosphate solubilization potential in presence of varying salt concentration (0.5 to 5%). Twenty seven isolates showing effective phosphate solubilization ability were screened further by quantitative studies. Three potential isolate were identified at species level by conventional methods. Three isolates AZP-13, AZP-21 and AZP-39 were potent phosphate solubilizers under high salt concentration. The isolates AZP-13 and AZP-21 were identified as Azotobacter chroococcum and AZP-39 was found as Azotobacter vinelandii. The phosphate solubilization ability of these isolates under saline conditions highlighted their significance to exploit them as biofertilizer for saline soils.