Comparative studies on submerged, liquid surface and solid state fermentation for citric acid production by Aspergillus niger RCNM 17

A comparative study on three different fermentation techniques was carried out for citric acid production by a new soil isolate Aspergillus niger RCNM 17 using Shu and Johnson's (1948a) medium. A. niger RCNM 17 produced highest titer of citric acid in Solid State Fermentation (61.08 g citric acid at 72 h with 43.61% and 53.19% conversions based on the total initial sugar and the sugar consumed during fermentation respectively) compared to Submerged Fermentation (10.23 g citric acid/l at 168 h with 7.32 and 9.65% conversions based on the total initial sugar and the sugar consumed during fermentation respectively) and Liquid Surface Fermentation (24.37 g citric acid/l at 144 h with 17.40% and 24.72% conversions based on the total initial sugar and the sugar consumed during fermentation respectively).