Melibiose Broth for Classifying Yeasts

In her monograph on ascosporogenous yeasts, Stelling-Dekker (1931) used fermentation of various sugars as the principal criterion for separating species of the important genus Saccharomyces. Most of the species of industrial im-portance fall into two species with several varieties in each species. Saccharo-myces carlsbergensis ferments all the sugar in raffinose broth and Saccharomyces cerevisiae, including the important variety ellipsoideus, ferments only one-third of this sugar. The separation of these species is of some economic importance since most wine, distillery, and baking yeasts, as well as those used in the brewing of ale, are top yeasts, and those used for the manufacture of beer are bottom yeasts. Most top yeasts are S. cerevisiae and most bottom yeasts are S. carls-bergensis. This commercial distinction of ale from beer is a convenient one, but it does not seem to be general. Thus ale and beer in British nations, Bier in Ger-many and in Czechoslovakia where German was understood, 61 in Scandinavian countries, and cerveza ini Mexico are words used in these beer-drinking countries more or less commonly for both types of brews. S. cerevisiae and S. carlsber