The Synthesis of “bios” by Yeast Grown in a Solution of Purified Nutrients

It has been shown in feeding tests with young rats that yeast grown in a distilled water solution of sucrose and the necessary mineral salts may furnish the vitamin B essential for growth (1, 2). It has also been found in tests made in this laboratory that pigeons which had developed polyneuritis on a diet of polished rice, were (‘cured” by the administration of this yeast. Heller has recently reported similar results with “synthetic” yeast (3). These findings establish beyond a doubt the ability of yeast to synthesize vitamin B when growing in vitamin-free media. The results obtained in the feeding tests and the conclusions drawn from them are at variance with those of Eijkman and his coworkers (4), who, after much experience in yeast experimentation, expressed the conviction that the yeast cell gains its antineuritic factor as such from the culture medium and cannot, strictly speaking, synthesize it. The subject of yeast growth and stimulation was given a new interest in 1919 by the publication of methods for the detection and estimation of water-soluble B, using yeast as a test organism (5, 6). These methods were based on the supposition that Wildiers’ “bias” and vitamin B are identical. Attempts to apply these methods failed of their original intent, but brought to light a number of interesting facts. In their use of Williams’ method Souza and McCollum (7) found that alkalinized material, inactive for rats, gave excellent results in stimulating yeast. Later Fleming (8) reported that an extract of unmilled rice produced as great an increase in the growth of yeast after treatment with alkali to destroy vitamin B as before