The sherry flor yeast, Saccharomyces beticus, which causes accumulation of acetaldehyde when growing as a film on the surface of alcohol-containing media, also causes an accumulation of acetaldehyde when shaken with ethyl alcohol in air. The ability to accumulate aldehyde under these conditions is not confined to this species, however, but was also found in S. cerevisiae, S. carlsbergensis, and S. ellipsoideus.