Isolation and screening of Aspergillus niger strains for citric acid production

Abstract

Isolates of Aspergillus niger obtained from different sources (rotten fruits, irrigated soils, municipal solid wastes, onions and red gram husk) were screened for their citric acid producing capability by employing paper culture technique. Isolates exhibiting acid unitage above 2.0 were further evaluated through submerged fermentation studies for citric acid production. The present study indicates a positive correlation between acid unitage and citric acid production, and reveals that paper culture technique can be efficiently employed to rapidly and economically screen for citric acid producing strains of Aspergillus niger.