Determination of Optimal Conditions for Kojic Acid Production from Aspergillus oryzae by Surface Liquid Cultures Fermentation Method

Abstract

Kojic acid (KA) one of the natural compounds existing in fermented foods produced by some species of fungi. Recently, there is more interest in KA as a natural compound and its benefits in different fields. This study aimed to determine the optimal conditions for KA production from the mold A. oryzae by the use of surface liquid cultures fermentation techniques. It appeared that the elongation of the incubation period more than 8 days decreased the amounts of the produced KA, and the production was also decreased if the pH were higher or lower than pH 6. The use of polysaccharides as a carbon source didn’t give high production of KA in contrast with the use of glucose and also the use of peptone as a nitrogen source didn’t give a high production of KA in contrast with the use of yeast extract. Adding of sodium citrate or sodium acetate to the production media inhibited KA production. The use of part time shaking at 150 round / mint speed for four hours a day gave high production of KA in contrast to the full time shaking mode at the same speed. From this study we conclude that the optimal conditions for highly KA production were, 8 days of fermentation period, pH 6 at 30 ˚C and at 100 g/L glucose as a carbon source, 5 g/L yeast extract as a nitrogen source, 1 g/L disodium phosphate or potassium dihydrogen phosphate and with occasional shaking for four hours a day at 150 round/min, the production of KA was 57.65±0.49 g/L at this conditions.