Effect of nutritional parameters and NaCl concentration on phosphate solubilization potential of Penicillium purpurogenum Stoll isolated from paddy field

Phosphorus (P) is the major essential macronutrient of plants. But its availability in Indian soil is relatively low due to high rate of P fixation. The use of phosphate solubilizing microorganism (PSM) to solubilize the fixed form of P is economically reasonable and ecologically safe as compared to chemical phosphatic fertilizers. Fungi have been reported to possess greater ability to solubilize insoluble phosphate than bacteria. However, phosphate solubilizing efficiency of PSM is found to be affected by different environmental factors. The main objective of this work was to optimize different process parameters for the solubilization of rock phosphate (RP) by the phosphate solubilizing fungus, Penicillium purpurogenum Stoll (NFCCI 3788) isolated from paddy field. The concentration of soluble P release by the isolate was tested in Pikovskaya’s broth supplemented with RP. Glucose (169 µg/ml) and sucrose (153 µg/ml) significantly promoted P solubilization as compared to other carbon sources. Ammonium sulphate was found to be optimum for maximum RP solubilization. Change in medium pH and mycelial dry weight were also recorded in all the tested groups. The fungus showed different levels of phosphate solubilization under different NaCl concentration tolerating maximum upto 6% sodium chloride concentration. Key words: Penicillium purpurogenum Stoll, carbon source, nitrogen source, optimization, rock phosphate, Chhattisgarh.