초록
<P><B>Abstract</B></P> <P>Comparative study of 43 natural yeast strains belonging to 20 species for their capability for overproduction of citric acid (CA) from glucose under nitrogen limitation of cell growth was carried out. As a result, natural strain <I>Yarrowia lipolytica</I> VKM Y-2373 was selected. The effect of growth limitation by biogenic macroelements (nitrogen, phosphorus, or sulfur) on the CA production by the selected strain was studied. It was shown that yeasts <I>Y. lipolytica</I> grown under deficiency of nitrogen, phosphorus, or sulfur were able to excrete CA in industrially sufficient amounts (80–85g/L with the product yield (Y<SUB>CA</SUB>) of 0.70–0.75g/g and the process selectivity of 92.5–95.3%). Based on the obtained data on activities of enzymes involved in the initial stages of glucose oxidation, the cycle of tricarboxylic acids, and the glyoxylate cycle, the conception of the mechanism responsible for the CA overproduction from glucose in <I>Y. lipolytica</I> was formulated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Yarrowia lipolytica</I> VKM Y-2373 was selected for citric acid production from glucose. </LI> <LI> Growth limitation by nitrogen, phosphorus, or sulfur stimulates acid production. </LI> <LI> The concentration of citric acid reached 80–85g/L. </LI> <LI> The product yield and the process selectivity achieved 0.70–0.75g/g and 92.5–95.3%. </LI> </UL> </P>