Investigation on Phosphate Solubilization Potential of Agricultural Soil Bacteria as Affected by Different Phosphorus Sources,Temperature, Salt,and pH

Ten phosphate-solubilizing bacterial strains belonging to genera Pseudomonas, Burkholderia, Enterobacter, Serratia, Klebsiella, and Aeromonas were tested for mineral phosphate solubilization activity in Pikovskaya's broth using different phosphate sources at four temperatures (15, 25, 35, and 45 ^οC). Dicalcium and tricalcium phosphate were solubilized more effectively (≥1000 mg L^?1) than ferric and rock phosphate (≥100 mg L^?1) and 35 °C was found to be the optimum temperature. Although Klebsiella and Aeromonas spp. are well known for their dinitrogen (N₂)–fixing ability, to the best of our knowledge, this is the first report of inorganic phosphate solubilization by Klebsiella terrigena and Aeromonas vaga. Interestingly, A. vaga BAM-77 is the most efficient strain at solubilizing inorganic phosphorus (P) even in the presence of 8% sodium chloride (NaCl) at pH 10. These findings indicate that all four strains are efficient P solubilizers under variable conditions of temperature, pH, and P source and thus can be recommended for P fertilization in different soils.