Enhanced Solubilization of Iron and Calcium phosphates by Aspergillus niger by the Addition of Alcohols

The present study deals with the effect of increased concentrations of alcohols (methanol and ethanol) on the solubilization of FePO4 and CaHPO4 by Aspergillus niger. The efficiency of solubilization (ES) of inorganic phosphates, fungal growth, acid production and pH variation were determined. The concentrations of alcohols that most favored the solubilization of phosphates were 4% methanol and 3% ethanol. The ES of phosphates by the fungus in media containing methanol ranged from 11-96% and 0.4-87% for ethanol. The stimulation or inhibition of solubilization was dependent on greater or lesser fungus growth, acid production and decreased pH. These responses were supported by the correlation between the amount of phosphate dissolved and fungal growth (0.630** to 0.831**), the production of acids (0.529* to 0.989**) and a decrease in pH (-0.755** to -0.962**). Thus, the addition of alcohols facilitated insoluble phosphates dissolution during the fungus growth.