Citric acid is one of the most important organic acids in the foods and pharmaceutical industries, citric acid had extracted from natural resources specially citrus fruits, then citric acid was begin to produced with using Aspergillus niger. This study aim to use Aspergillus niger to produce citric acid by screening some strains which can produce citric acid and screening some media which used for citric acid production, then to reach the maximum citric acid production were studied some factors affected on citric acid production. We study the effect of immobilized the spores with calsium algenate, and use this immobiliezd spores as an inoculum to produce citric acid. The possibility of citric acid production was 51.1 g/L in fermentor by the selected stain No, 2, meduim which containing (g/L): sugar cane molasses 272, ammonium phosphate 2, phosophoric acid 0.3 ml, magnesium sulfate 0.2, pH 5.5, at 30ËšC, after eight days of fermentation.
