Abstract: | After exhaustion of the N-sources the yeast S.l. excretes citric and isocitric acid with high rates without interferring in the postlogarithmic phase the intracellular production of reserve materials like polysaccharides and especially lipids. The synthesis of citric acids and of reserve materials are therefore autonomically proceeding processes inside of the cells With increasing lipid content the ergosterol content increases The utilization of the ergosterol rich yeasts as valuable byproduct of the citric acid production is discussed. |