Biosynthesis of isocitric acid from ethanol by yeasts

Summary The ability of yeasts of different taxonomic groups to synthesize isocitric (ICA) and citric acids (CA) was studied during their growth on ethanol medium. The most active producer of ICA from ethanol, Candida lipolytica 704, was selected. We have chosen cultivation conditions, i.e. pH of the medium and concentrations of oxygen and substrate, optimal for accumulation of ICA. The yield of ICA exceeded 60% of the weight of substrate used. We have studied the dynamics of acid production under conditions of periodic growth of C. lipolytica 704 on ethanol. On the basis of the analysis of citrate and glyoxylate cycle enzyme activity we have developed a conception for the mechanism of ICA overproduction. Offprint requests to: T. V. Finogenova