Changes in riboflavine over production in the yeast pichia guilliermondii under the effect of branched amino acids
Ukrayins'kyi Biokhimichnyi Zhurnal 49(1): 91-96
The effect of the branched-chain amino acids: L-valine [L-Val], L-isoleucine [L-Ile] and L-leucine [L-Leu] on riboflavin overproduction was studied in the Pichia (Candida) guilliermondii (Cast.) Lang. et G. L-Val, L-Ile and L-leu inhibited riboflavin overproduction only under Fe-deficient growth conditions. Other amino acids used did not show this effect. In crude extracts of P. guilliermondii the specific activity of the .alpha.-acetolactate forming enzyme, pH 8.0 is inhibited by L-Val. The activity of .alpha.-acetolactate synthetase in Fe-deficient riboflavin-overproduction cells was much higher than in the valine-inhibited cells. Under Fe deficiency .alpha.-acetolactate synthetase shows maximal activity after 48 h of growth. Diacetyl (and acetone) were detected in the culture fluid.