Mediated and Residual Methionine Transport by Brewer's Yeast

The characteristics of methionine uptake by brewer's yeast (S. carlsbergentis “Schwehat No. 2”) and the regulation of the process have been studied. The methionine uptake by brewer's yeast grown on wort is a complex process Composed of a mediated transport process saturating at low concentration and permeation that is in linear dependence on the concentration. The mediated transport process is under regulated control and can be repressed by (a) certain amino acids added to wort media or applied to phosphate buffer in shorter pre-treatment, (b) ammonium ions added to a synthetic nutrient solution or, in shorter pre-treatment, by ammonium ions applied to a synthetic nutrient solution containing glutamic acid.