ABSTRACT
In the aerobic conditions, the glycolysis is the prelude of the citric acid cycle. If the conditions are not sufficiently aerobic, the pyruvate ion does not enter into the citric acid cycle. It is transformed into the lactate ion. This is the first step towards the phenomenon of fermentation. It is puzzling that glycolysis, through which energy is recuperated, begins by the destruction of a molecule of ATP which, in fine, permits to stock it. Moreover, it must not be forgotten that the multiple equilibria in the chains of reactions such as that of glycolysis are displaced by other reactions of the chain, whatever the nature of the reaction considered. When dioxygen is present, oxidation continues further until CO2 and H2O are formed. Therefore, the fermentation reactions are common in both the aerobic and anaerobic breakdowns of glucose in facultative organisms, at least until the formation of pyruvate anions is achieved.
