Solubilization of hardly soluble iron phosphate in culture medium

Abstract

The objective of this work was to evaluate the efficiency of solubilization of FePO₄ by Aspergillus niger, in culture medium with different carbon (C) and nitrogen (N) sources, and enhancing concentrations of phosphate. The amount of soluble phosphate, acidity and final pH were determined after the fungus growth in a stationary culture at 30°C. Efficiency of solubilization increased according to fungus growth, reaching the maximum at the 11^th day (68%) and later decreased. In relation to C and N sources, the largest efficiencies of solubilization were found with mannitol (21%) and glutamic acid (17%). Increasing phosphate concentration (0 to 1,330 µg mL^-1), maximal efficiency of solubilization (70%) was found with 330 µg mL^-1 PO₄^3-, and decreased up to 47% with 1,330 µg mL^-1 PO₄^3-. The amount of acids produced was the factor that more influenced FePO₄ solubilization, based in the positive and significant correlation between phosphate and acidity production.