This paper is focused on the physiology and metabolism of nonconventional yeasts, especially these belonging to Debaryomyces (syn. Schwanniomyces) occidentalis. In these Crabtree-negative yeast strains, oxygen limitation replica panerai induces alcoholic fermentation as well as activity of the key fermentative enzymes, pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH).