Biosynthesis of citric acid by Yarrowia lipolytica repeat-batch culture onethanol

After analysis of batch culture and identification of the ways for prolonga tion of citric acid active synthesis by yeast, repeat-batch (RB) cultivatio n was suggested. Yarrowia lipolytica strain RB cultivation was studied and optimal conditions for cultivation selected. It was shown that when applyin g RB cultivation, better results were obtained than for batch cultivation. The activity of the culture remained stable after cultivation for more than 700 h. Comparative analysis of enzyme activities confirmed the regularity of the effect described, as the activity of practically of all the enzymes participating in ethanol oxidation and citric acid biosynthesis remained st able over time during RE cultivation. Advantages of RB cultivation for the production of citric acid by yeast are discussed.