Abstract
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.
Highlights
Phosphorus (P), the second most essential element after nitrogen, is required by the plants for their growth and development
These findings suggest that phosphate solubilization was affected by various carbon and nitrogen sources
The fungus was identified as Penicillium purpurogenum Stoll (NFCCI 3788) by National Fungal Culture Collection (NFCCI), Pune, Maharashtra, India
Summary
Phosphorus (P), the second most essential element after nitrogen, is required by the plants for their growth and development. Apart from its abundance in soil in both organic and inorganic forms, the availability of soluble P in the soil is limited, explaining the need for the application of chemical phosphatic fertilizers for adequate plant growth. The involvement of soil microorganisms in dissolution of fixed forms of P and solubilization of RP is well documented by many researchers (Goldstein, 1986; Kucey et al, 1989; Khan et al, 2007; Xiao et al, 2008). These microorganisms are known as phosphate solubilizing microorganisms (PSM) and include bacteria, fungi and actinomycetes. The main objective of this work was to examine the effect of carbon and nitrogen sources, RP concentration and salinity on fungal growth and solubilization of RP by Penicillium purpurogenum Stoll
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