Mineral Nutrition of Aspergillus niger for citric acid production.

The mineral requirements of a strain of Aspergillus niger for the production of citric acid in a synthetic medium were studied. It was observed that K2HPO4 and MgSO4. 7 H2O were required at concentrations of 0.1% and 0.02% respectively. The optimum level of each of the trace elements Fe, Mn and Zn was 1.0 mug/ml. NaC1 and CaC12 at lower concentrations had no effect on citric acid production. Trace elements, Cu, Co and Mo, had an adverse effect on the production of citric acid while Ni and V were without effect.