Increased Growth of a Population of Yeast Obtained with Inosite

Following Eastcott's 1 identification of Bios I as inactive inosite it seemed desirable to determine whether or not the medium used in the investigation of the growth of a population of yeast 2 might be improved by the addition of this substance. This was done with William's medium 3 and slightly increased growth (106-116% of that of the control) was obtained with the addition of 0.1-0.4 mg./cc. of inosite, but decreased growth (down to 75% of the control) was found on the addition of 1.0-1.6 mg./cc. of the culture medium.

This increased growth is definite and contrasts with the experiments of Williams, Warner and Roehm 4 and Narayanan, 5 who find that the addition of inosite did not increase their yield of yeast. It is difficult to understand this result as Williams et al used the same medium and the same culture of yeast as was used in my experiments. The only difference was that my strain of yeast comes from a single cell of yeast No. 2335 (Am. Type Culture Coll.) 6 and that we are probably not using the same brands of chemicals in the medium. Later Williams and Bradway 7 obtained a transfer of the yeast used in Miller's laboratory by Miss Eastcott and found that this transfer gave increased growth when 1 mg. of inosite was added to 12 cc. of their medium.

The findings of Williams and myself emphasize the difference, between one strain of a species of yeast and a pedigreed strain obtained from an isolated single cell of the same species. The following experiments point out a resolution of this dilemma.