Abstract
The adaptation of Saccharomyces carlsbergensis 4228 to thiamine-and vitamin B_6 free medium containing serine as the single nitrogen source (serine medium) was tried, and the growth of this serine-adapted strain in the presence of thiamine or vitamin B_6 was investigated. It was found that thiamine inhibited the growth of the adapted strain in the serine medium to the later growth phase as well as the growth of the original strain, and the antagonistic recovery by vitamin B_6 of the inhibited growth was demonstrated. In the experiment using this adapted organism heavily inoculated in the serine medium, it was proved that the vitamin B_6 content of the cells at the initial growth phase was greatly depressed by addition of thiamine. Using U-^<14>C-L-serine, it was demonstrated that the incorporation rate of serine into the cells of adapted organism was not inhibited by thiamine.
