Influence of milk whey, nitrogen and phosphorus concentration on oxalic acid production by Aspergillus niger

Abstract

A factorial design at two levels was used to determine the effect of milk whey concentration and the addition of nitrogen (as NH₄NO₃) and phosphorus (as KH₂PO₄) on the oxalic acid production by Aspergillus niger. The results of the experiments indicated that milk whey contains enough nutrients for fungus growth, therefore medium supplementing with N and P is not necessary. The optimum milk whey concentration was 100 kg/m³ reaching a final oxalic acid concentration of 37 kg/m³ and a maximum production rate of 3.4 kg/m³ · d. The yield of oxalic acid was 0.4, a very high value compared to previous works.