【Objective】The present experiment was aimed to study the effects of different ingredients and cultural conditions on phosphate solubilization capacity of Aspergillus niger strain PSFM (isolated from soil) for obtaining best fermentation conditions. 【Method】The treatments included different media (inorganic and organic P, SP, NBRIY, NBRIP and NBRIYP), C (xylose, glucose, lactose, sugar, maltose, galactose, sorbose, mannose, fructose, soluble starch, rhamnose, glycerin) and N (NaNO3, urea, yeast extract, NH4Cl, Mg(NO3)2, (NH4)2SO4, tryptophan, ammonium acetate, beef extract, pancreas-petone, glycine, tyrosine, alanine and arginine) sources, micro- and macronutrients (NaCl, KCl, MgSO4·7H2O, FeSO4·7H2O and MnSO4·7H2O), fermentation time (0-10 days), temperature (20-40℃), initial pH (3.0-11.0), inoculation quantity (1-11%), and rotation speed of incubator shaker (120-300 rpm). The orthogonal tests were performed to optimize the fermentation conditions of phosphate-solubilizing fungi. The absorbance of fermentation liquid was determined to calculate the solubilized phosphate content. 【Result】The solubilized phosphate content in inorganic liquid medium was highest (526.42 mg/L) at 6 days after culturing in different media compared to the other mediums. Out of 12 carbon sources, the best growth of PSFM strain was recorded in xylose followed by glucose, while it was least in medium containing rhamnose and glycerin. Out of all the N sources, (NH4)2SO4 showed significantly higher solubilized phosphate content (990.31 mg/L) compared to the other N sources. With the increase of NaCl, KCl, MgSO4·7H2O, FeSO4·7H2O and MnSO4·7H2O concentration in inorganic phosphorus medium, the phosphate solubilization capacity of PSFM strain increased initially, followed by a decrease, and it reached the highest at their 0.03, 0.01, 0.03, 0.001 and 0.001% concentration, respectively. The phosphate solubilization content of PSFM strain was recorded highest as 599.24, 528.23, 603.69, 530.57 and 731.48 mg/L in 6 days of fermentation, 28℃ temperature, 6.0 of initial pH, 5% inoculation quantity and 300 rpm rotation speed, respectively. 【Conclusion】The results revealed that inorganic phosphorus medium containing 1.0% xylose (carbon source), 0.10% (NH4)2SO4 (nitrogen source), 0.1, 0.7, 0.7, 0.01, and 0.01 g/L concentrations of inorganic salts, viz., NaCl, KCl, MgSO4·7H2O, FeSO4·7H2O and MnSO4·7H2O, respectively, was the best when 5% Aspergillus niger strain PSFM was cultured for 6 days at 28℃ temperature, initial pH 6.0 and 300 rpm rotation speed.
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