The production of citric acid by using immobilized Aspergillus niger A-9 and investigation of its various effects

The production of citric acid was achieved by using Aspergillus niger conidiaspores, entrapped in Ca-alginate beads, and the factors that affect this production were investigated. The effects of starting sucrose concentration (100-180 g/l), nitrogen concentration (0-0.3 g/l), methanol concentration (0-6 ml) and finally ethanol concentration (0-5 ml) in 100 ml feeding medium on citric acid production were studied and optimum experimental conditions were determined. The starting nitrogen concentration (0.05 g/l) and the starting sucrose concentration (140 g/l) were optimized and maximum citric acid production observed under these given conditions. Maximum citric acid production was observed upon addition of 4.0 ml methanol and 3.0 ml ethanol.