Abstract:

The effect of low grade phosphate tailings (LGPT) concentration, different nitrogen source and pH in the media on phosphate solubilizing activity of Aspergillus niger was studied under liquid pure culture medium, and the mechanism of phosphate solubilization was explored. The result showed that oxatic acid which plays an more important role in the dissolution of LGPT is the main organic acid produced by A. niger in the culture peroid. When 5 g LGPT was added into one liter of the medium, the maximum phosphate solubilization capacity and phosphate solubilization efficiency are 56.02 mg/L and 20.87%, respectively. When more than 5 g LGPT was added into one liter of the medium, the phosphate solubilization efficiency decreased from 20.87% (5 g/L LGPT) to 0.65% (40 g/L LGPT). Moreover, when (NH4)2SO4 was supplied as nitrogen source, the maximum phosphate solubilization efficiency are 2.17 times higher than that of NaNO3. Besides, there is the highest phosphate solubilization efficiency when pH value is from 5 to 6.