Metabolic characteristics of the Yarrowia lipolytica strain producing alpha-ketoglutaric and citric acids from ethanol and the effect of [NH4+] and [O2] on yeast respiration and biosynthesis

The comparative studies performed in this work showed that overproduction of alpha-ketoglutaric acid (KGA) from ethanol by the mutant Yarrowia lipolytica strain I requires both a deficiency of thiamine and a relatively high concentration of ammonium ions in the medium, whereas CA overproduction requires an almost zero concentration of ammonium ions. The threshold value of the dissolved oxygen concentration in the medium, pO2, for CA overproduction is considerably higher than for KGA overproduction. The respiration rate of CA-overproducing cells was 2-3.5 times higher than that of KGA-overproducing cells. The main terminal electron carrier functioning in the KGA-overproducing cells was cytochrome oxidase. In the CA-overproducing cells, the main terminal oxidase was presumably o-type cytochrome.