Studies on some nutritional factors influencing the production of gluconic acid.

Investigations were carried out to formulate an economical medium that can give maximum yield of gluconic acid by the submerged culture technique, using Aspergillus niger NRRL3. It was found that the highest yield of acid could be secured when a medium of the following ingredients was used: 13.0% glucose syrup, 0.1% NaNO3, 0.025% calcium superphosphate, 0.007% KCl, 0.025% MgSO4-7H20, and 0.5% CaCO3. It was also found that glucose syrup, which represents an available and cheap carbohydrate source for gluconic acid production by fermentation, can replace glucose powder which is more expensive.