Hybridization of Homothallic Yeasts by Chen's Technique

Abstract

IN the course of experiments performed in this laboratory it was found that spores of Saccharomyces cerevisiae var. ellipsoideus were unable to germinate unless the medium contained glucose, fructose or mannose¹. Acetate agar (0.5 per cent sodium acetate in 2 per cent agar), or agar without added nutrients, are incapable of promoting germination. On the contrary, vegetative cells are able to form micro-colonies on ‘nutrient-free’ agar or on acetate agar, although the number of buds on this last medium is considerably smaller than on agar without additions. The formation of microcolonies on solid ‘nutrient-free’ media is not at all surprising, and it has been studied in considerable detail in bacteria^2,3. The microcolonies formed under those conditions have larger numbers of cells than those formed on acetate agar, an observation which confirms the inhibitory effect of acetate on yeast growth reported in the literature^4,5.