Dissolution of Indian rock phosphates by phosphate solubilising microorganisms obtained from stress environment

The phosphorus solubilisation efficacy of three bacterial and three fungal isolates from abiotic stress environment were tested with various sources of insoluble inorganic phosphates at different pH values (acidic to alkaline pH 5–9), NaCl concentrations (0 to 10% w/v NaCl) and at various temperature regimes (9° to 40° C). All these isolates caused highest dissolution of tricalcium phosphate (TCP), followed by Mussoorie rock phosphate (MRP) and Udaipur rock phosphate (URP). The P solubilisation increased towards neutral to alkaline pH w.r.t. bacterial isolates and decreased in case of fungal isolates. Bacterial isolate SBC5 (Bacillus sp.) solubilised maximum URP at pH 9 and minimum at pH 5. Amongst fungal isolates, FC28 (Penicillium sp.) solubilised maximum URP at pH 5 while recorded minimum P solubilisation at pH 9. The P dissolution abilities of PSB were higher in the presence of 2.5% w/v NaCl than control. The bacterial isolate SBC5 (Bacillus sp.) solubilised highest amount of URP at 2.5% w/v NaCl. The fungal isolate FC28 (Penicillium sp.) represented highest potential to solubilise Pin control than all other salt concentrations. These isolates showed no solubilisation of rock phosphate at 10% w/v NaCl. The isolates SBC5 (Bacillus sp.) and FC28 (Penicillium sp.) solubilised maximum URP at 24° C temperature. However at various temperature regimes the fungi represented highest P dissolution than that of bacteria.