Citric acid production by Aspergillus niger using date-based medium fortified with whey and additives

The ability of Aspergillus niger to produce citric acid from dates was evaluated. Two strains of A. niger (ATCC 6275 and 9642) were grown in media containing different concentrations of date extract or molasses fortified with whey, methanol and tricalcium phosphate. The fermentation experiments were conducted at 25° C for 12 days and samples were withdrawn at different time intervals and analyzed for their citric acid content. Results showed that a high level of citric acid (32.4gL-1) was produced by A. niger ATCC 6275 in 20% molasses in whey. When methanol and tricalcium phosphate were added, a significant increase in citric acid production was recorded (P < 0.05). Citric acid concentrations were 38.4 and 42.4 gL-1, in media fortified with methanol and tricalcium phosphate, respectively. Our results showed that molasses could be used as a carbohydrate source for the production of citric acid. Strain type, addition of whey, methanol and tricalcium phosphate had a significant impact on citric acid production by A. niger. Copyright © 2005, Taylor & Francis.