[Kinetics of citric acid production in Candida lipolytica]

The kinetics of citrate and isocitrate accumulation by Candida lipolytica has been studied, with special emphasis of the carbon sources glucose and n-alkanes and the shifts from one carbon source to the other. The accumulation of the citric acids starts with the beginning of ideophase. Trophophase and ideophase behaviour is in parts different. Ideophase behaviour may be influenced by exogenic factors during growth. From the course of the curves for the citric acids two phases can be distinguished: The specific production rate of the first phase is higher than in the second phase (pi1 approximately 0.19 h-1; pi2 approximately 0.14 h-1). The influence of the carbon source on the course of the curves and the numeric value for the specific production rate is negligible. Alcane grown cells accumulate citric acids from added glucose and left-over n-alcanes simultaneously. When both substrates are added from the beginning only glucose is taken up for growth, for citric acid production both substances are utilized simultaneously. Glucose grown cells do not utilize alcanes for production of citric acids. Citric acids are accumulated only as long as glucose is available. Alcane uptake starts after addition of a nitrogen source.