Kinetics of kojic acid fermentation by Aspergillus flavus using different types and concentrations of carbon and nitrogen sources

Kinetics of kojic acid fermentation by Aspergillus flavus Link 44-1 using v arious sources of carbon [glucose, xylose, sucrose, starch, maltose, lactos e or fructose] and nitrogen [NH4Cl, (NH4)(2)S2O8, (NH4)(2)NO3, yeast extrac t or peptone] were analyzed using models based on logistic and Luedeking-Pi ret equations. The highest kojic acid production (39.90 g l(-1)) in submerg ed batch fermentation was obtained when 100 g l(-1) glucose was used as a c arbon source. Organic nitrogen sources such as peptone and yeast extract we re favorable for kojic acid production as compared to inorganic nitrogen so urces. Yeast extract at 5 g l(-1) was optimal. The optimal carbon to nitrog en (C/N) ratio for kojic acid fermentation was 93.3. In a resuspended cell system, the rate of glucose conversion to kojic acid by cell-bound enzymes increased with increasing glucose concentration up to 70 g l(-1), suggestin g that the reaction followed the Michaelis-Menten enzyme kinetic model. The value of K-m and V-max for the reaction was 18.47 g l(-1) glucose and 0.15 4 g l(-1) h(-1), respectively.