ABSORPTION OF AMINO ACIDS BY YEASTS FROM A SEMI‐DEFINED MEDIUM SIMULATING WORT

Abstract

The biosynthetic pathways involved when α‐amino acids are absorbed by yeasts from a semi‐defined medium simulating wort have been measured using 15N and 14C isotopes. When grown in this medium under brewery conditions, a complex transaminase equilibrium system operates within the cell, showing that the theory of intact assimilation of amino acids into yeast protein is invalid. A relatively high level of specificity was found in respect of the transfer of carbon skeletons of amino acids in the medium to carbon skeletons of yeast protein amino acids and the contributions in respect of each amino acid have been measured throughout growth. Simple sugars have been shown to contribute significantly to the carbon skeletons of most amino acids found in yeast and the extent of these syntheses has been quantitatively assessed. 1969 The Institute of Brewing & Distilling