Production and Nutritional Evaluation of a High Lysine Baker's Yeast (Saccharomyces cerevisiae) in Rats

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Abstract
A high lysine baker's yeast (HLBY) was prepared by a bioorganic process in which synthetic DL-α-aminoadipic acid was converted to lysine by incubation under appropriate conditions with commercial baker's yeast (BY). HLBY contained about 10% lysine on a dry weight basis or about three times as much lysine as BY. Under the fermentation conditions described employing DL-[6-14C]-α-aminoadipic acid as a substrate, about 94% of the radioactivity was recovered principally in terms of intracellular biosynthesized lysine, or residual extracellular L-α-aminoadipic acid or D-α-aminoadipic acid. At least 90% of the lysine in HLBY was available to support growth of weanling rats fed a 20% wheat gluten diet limiting in lysine, and it was demonstrated that supplementation of wheat flour with 2% HLBY doubled the protein efficiency ratio of the flour. The merits of HLBY as a protein supplement to improve the nutritional quality of cereal grain proteins are briefly discussed.