Documentation of five potassium- and phosphorus-solubilizing bacteria for their K and P-solubilization ability from various minerals

The ability of a few soil bacteria to transform unavailable forms of phosphorus (P) and potassium (K) to an available form is an important feature in plant growth-promoting bacteria for increasing crop yields of high- P and K-demand crops. In this research, screening and characterization of thirty-five K-solubilizing bacterial (KSB) and P-solubilizing bacteria (PSB) isolate which were evaluated for their ability to solubilize K and P from the waste muscovite (WM), waste biotite (WB), tri-calcium phosphate (TCP) and rock phosphate (RP) by analyzing the soluble P and K content after 7, 14, 21 days after incubation (DAI) at 28±2 °C on MABs (Modified Aleksandrov Broths) and Pikovskaya's medium. The soluble P and K contents in all isolates were significantly (p<0.01) higher than the contents in nonbacteria treatment. K-release from WB varied significantly from 3.5 to 5.0 µg mL−1, 4.4-6.3 µg mL−1 and 5.3-7.2 µg mL−1 at 7, 14 and 21 DAI, respectively. Herein, isolate KSB-105 had caused significantly higher K-release as compared to rest of isolates. Overall K-release from WB was highest by PSB-56 with 7.2 µg mL−1. While, significant higher amount of P-release was observed at 21 DAI (13.7 µg mL−1) followed by at 14 DAI (12 µg mL−1) and lowest was recorded at 7 DAI (5.1 µg mL−1). PSB-56 showed it's significantly superiority in P-release from TCP at 21 DAI (13.7 µg mL−1) as compared rest of isolates. Overall, it can be concluded that the diversity of KSB and PSB as bioinoculants to release K and P provides a win-win situation under in vitro condition. Therefore, it is crucial to adopt efficient KSB and PSB isolates in interventions for the judicious use of chemical and biological resources for maximizing food production while reducing pollution and rejuvenating degraded land for sustainable agriculture.