Alleged Transformation of Yeast

Abstract

CRUDE preparations of deoxyribonucleic acid from one yeast strain, called the donor, sometimes appear to confer fermentation properties of the cell on a second strain, the acceptor, when added to the growth medium^1–3. For example, when a yeast which did not ferment sucrose was grown in wort containing a preparation of deoxyribonucleic acid derived from a sucrose-fermenting strain, the transfer of part of the culture to a bijou bottle containing sucrose dissolved in yeast water (3 per cent ‘Difco’ yeast extract in water) resulted in fermentation. Single-cell isolates obtained from the treated yeast, which had been serially sub-cultured through the same medium, also fermented sucrose, and on crossing with the original acceptor strain gave Mendelian segregation of sucrose-fermenting power. These observations were explained^1–3 by assuming that nuclear transformations akin to that already observed in various bacterial species^4–9 had been induced in the acceptor yeast by the deoxyribonucleic acid from the donor. In view of the potential importance of such transformation from both the technological and scientific points of view an attempt has been made to investigate this phenomenon further.