Journal of Pure and Applied MicrobiologyVol. 8 No. May 2014 Special Edition

Submerged Fermentation of Whey for Citric Acid Production by Aspergillus niger NRRL 567: Optimization of Medium Composition by Statistical Experimental Design

Jin-Woo Kim

Department of Biosystems Engineering, Faculty of Agricultural and Environmental Sciences, McGill University, 21,111 Lakeshore Road, Ste Anne de Bellevue, H9X 3V9, Canada.

Received on 12 April 2014 and accepted on 09 May 2014



Citric acid production by Aspergillus niger NRRL 567 from whey-based medium with different concentrations of supplementing nutrients was studied. The effect of nutrients including glucose, (NH4)2SO4 and KH2PO4 on citric acid production was evaluated using statistically-based optimization method and found that glucose and KH2PO4 supplementation significantly influenced citric acid production, while (NH4)2SO4 had insignificant effects. The statistical analysis showed that the optimum medium containing 60 g/L of glucose, 1.5 g/L of (NH4)2SO4 and 8.1 g/L of KH2PO4 predicted the maximum citric acid production of 12.0 g/L at 240 hr. The predicted citric acid production matched well that measured citric acid production (12.4 g/L) of the validation experiment. The results showed the effectiveness of the statistically-based optimization method and the optimized level of nutrients increased citric acid production by 2 folds, compare with the basal whey medium with 60 g/L glucose.

Keywords : Citric acid, Optimization, Fermentation condition, Submerged fermentation.