Induced Autotrophism in Yeast

Abstract

8 strains of Saccharomyces cerevisiae were induced to grow well without an exogenous supply of one or more vitamins. The technic consisted of increasing the initial quantity of the inoculum, of prolonging the incubation period, and of successively subculturing the yeasts on media from which one of the essential vitamins was missing. Eventually the amt. of inoculum and the length of the incubation period were reduced to normal, but the yeast continued to grow as readily in the absence of the vitamin as it did in its presence. Yeasts developed in the absence of one vitamin often developed the ability to grow without one or more additional ones. Partial or total reversions occurred in most cases after the variants were grown continuously for 6 months on a medium containing all the vitamins.