Effect of vitamins on microbial production of citric acid by Aspergillus niger.

The effect of different concentrations of ascorbic acid, biotin, p-aminobenzoic acid (PABA), riboflavin and thiamine on the growth and activity of Aspergillus niger strain AL 29 was studied at different incubation periods. It was observed that ascorbic acid and PABA inhibited the growth and activity of the mould, while the presence of thiamine and riboflavin stimulated the citric acid formation to the extent of 59.09% and 50.36%, respectively. However, biotin was found to be most suitable for increasing the mycelial growth and also enhancing the production of citric acid (66.4%).