Essential problem in biosynthesis of citric acid (CA) is the purity of process. Even low contamination by izocitric acid (ICA) perturbs crystallization. In the case of CA producers, selected from Yarrowia lipolytica A-101 yeasts strain, the amount of accumulated ICA from glucose, fructose or glycerol did not exceeded some %. The parent strain, on the same substrates, secretes over a dozen % of ICA and over 30% on hexadecane or fatty acids as substrates. The aim of the study was to evaluate kinetics of biosynthesis of CA and ICA by Y. lipolytica A-101 on hexadecane with three agitation rates (600, 300 and 150 rpm). The highest amount of acids (79,3 gL^-1) was obtained with the highest agitation rate (600 rpm). Accumulation of acids was significantly lower (8,5 gL^-1) with the lowest agitation rate (150 rpm). With two higher agitation rates, the amount of accumulated ICA was nearly 60% of the total acids amount. With low agitation rate mainly CA was secreted (70%). On glucose, tested strain secreted 31,7gL^-1 CA and the amount of ICA did not exceeded 10% of total acids .

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