Pathways for acetaldehyde metabolism in Saccharomyces cerevisiae. The main isoforms active during glucose fermentation are indicated. Pdc1 and Pdc5, pyruvate decarboxylase; Adh1, alcohol dehydrogenase; Ald6, Ald5, acetaldehyde dehydrogenase; Acs1, acetyl coenzyme A (CoA) synthase; Bdh1, butanediol dehydrogenase; TPP, thiamine pyrophosphate.