The importance of amino-acids as yeast nutrients

Abstract

The effects of 20 individual amino acids, a mixture of the same, and a casein digest on 5 strains of Saccharomyces cerevisiae and one strain of S. ellipsoides were studied. All 6 strains of yst. were markedly stimulated by the addition of individual amino acids and of mixtures when the control medium contained an abundant supply of nutrient factors. These amino acids are not required for growth but growth is enhanced when they are furnished. The 5 most important amino acids were glutamic acid, aspartic acid, asparagine, arginine and leucine. These were strongly stimulating on all of the yeast strains tested. A distinct supplementary effect was shown by a combination of all 20 amino acids. Amino acids may, depending on the test conditions and the yeast strain used, contribute materially to the "bios" effects of tissue extracts.