Isolation and Identification of Culturable Soil Phosphorus and Potassium Solubilizing Bacteria and Their Impact on Nutrient Release and Biological Activities in Soil

This study aimed to isolate, purify, and identify the most effective phosphorus (P) and potassium (K) solubilizing bacteria from soil samples and investigate their impact on nutrient release and biological activities in the soil. Following isolation and screening of 13 isolates in culture media, three superior isolates were chosen for further analysis based on the solubility of P and K, and the reduction in the pH of the culture medium. These isolates were added both alone and as a consortium, in sterile and nonsterile conditions, with and without the minerals, to a soil sample. Results showed that the soils inoculated with isolates 2 and 3 either individually or as a consortium, had the highest amounts of available K, with values of 471, 466, and 463.30 mg kg-1, respectively under sterile conditions and with muscovite. Similar to the available K, these isolates also had the highest available soil P values of 60.61, 60.29, and 60.07 mg kg-1, respectively, under sterile conditions and with rock phosphate. The maximum values of biological activities were observed under sterile conditions and with minerals in the presence of superior isolates. Isolate identification revealed that isolates 2 and 3 belonged to Pseudomonas (Pseudomonas frederiksbergensis strain C40).