Alcoholic beverage fermentations

TLDR: It is now recognized that these two species are completely interfertile and should be considered as one, namely S. cerevisiae, rather than distinct species.

Abstract: Most alcoholic beverage fermentations are carried out using strains of the yeast Saccharomyces cerevisiae. Although traditionally brewers distinguished between ale yeast S. cerevisiae and lager yeast S. carlsbergensis, or S. uvarum as it was later called, it is now recognized that these two species are completely interfertile and should be considered as one, namely S. cerevisiae ([Gilliland, 1981]). However, this is not to say that lager yeasts do not have some distinctive features, since the ability of the classical lager yeast to produce α-galactosidase and metabolize melibiose is well established. Similarly, strains defined as S. diastaticus have a well-established ability to metabolize low-molecular-weight dextrins, since they possess a glucoamylase gene. However, these strains are now considered to be strains of S. cerevisiae rather than distinct species.