ISOLATION AND SCREENING FOR CITRIC ACID PRODUCTION BY ASPERGILLUS NIGER USING SUCROSE AS A CARBON SOURCE

Abstract

The numerous applications of citric acid have increased its demand. It is of great importance toproduce citric acid using adequate monosaccharides and dissacharides as they have proven to beeasily catabolyzed and decomposed by Fungi when compared to polysaccharides. The superiorityof sucrose to other sugars is a result of strong extracellular mycelium-bound invertase of A. nigerwhich rapidly hydrolyses sucrose at low pH. This project was undertaken to isolate, screen andproduce citric acid in a submerged fermentation by four different strains of Aspergillus niger usingsucrose. Aspergillus niger was isolated and characterized from garden soil. Citric acid productionfrom Aspergillus niger in a submerged basal medium was quantitatively determined usingtitrimetric method. Aspergillus niger strain HUS1 (ASHUS1), Aspergillus niger strain HUS7(ASHUS7), Aspergillus niger strain HG49 (ASHG49) and Aspergillus niger strain AN8 (ASAN8)showed significant accumulation of citric acid from the submerged basal medium, of whichASHUS 1 significantly (?<0.05) recorded the most yield from the production after 9 days ofincubation.