The relationship of some metal ions with citric acid production by Aspergillus niger using tamarind seed powder as raw material

Tamarind seed powder (TSP) was used as raw material for microbial production of citric acid. The maximum citric acid production was observed when the TSP-basal medium (TSP with inorganic nitrogen and phosphorus source) was supplemented with Mg2+, Fe2+, Cu2+ and Zn2+. The use of methanol and ferrocyanide as a modulator for citric acid production was studied. On methanol supplementation to the medium, ammonium nitrate was found to be better than ammonium carbonate as a source of inorganic nitrogen. Addition of ferrocyanide after sterilization to the medium containing methanol gave the maximum citrate production of 363 μg/ml.