Cytosolic Adaptations to an Anaerobic Energy Metabolism

Some eukaryotes can survive hypoxia by using simple fermentations in which the electrons from glycolysis are transferred to pyruvate or a derivative of it. Many variations of this type of fermentation exist, resulting in end products such as lactate or ethanol (Fig. 5.1). The formation of lactate produces 2 mol of ATP per glucose degraded, is found in all phyla, and it is the sole anaerobic pathway of evolutionarily more advanced species like arthropoda and vertebrates (Livingstone 1991). 

Conversion of pyruvate into ethanol is a variant of cytosolic fermentation, which occurs, for instance, in yeast and hypoxia-tolerant fish, such as crucian carp and goldfish (van Waarde et al. 1993 Lutz and Nilsson 1997). Ethanol 

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