Although many researchers studied the ethanol fermentation with S. cerevisiae, in some cases a lack of recognition of its metabolic pathway led to approaches that are unlikely to yield significant improvements.
The main metabolic pathway involved in the ethanol fermentation is glycolysis (Embden–Meyerhof–Parnas or EMP pathway), through which one molecule of glucose is metabolized, and two molecules of pyruvate are produced (Madigan et al., 2000), as illustrated in Fig. 2.
Under anaerobic conditions, the pyruvate is further reduced to ethanol with the release of CO2.