Fermentative adaptations to the lack of oxygen

Abstract

Survival of organisms in the absence of oxygen depends on their ability to ferment substrates. The fermentative pathways start with substrates, such as carbohydrates, that are rich in hydroxyl groups and that can undergo oxidation or reduction reactions. The limit of the oxidations is the production of a carboxyl group, and the limit of the reductions is the formation of saturated carbon chains. When these limiting factors are combined, the furthest that the reactions can be taken is the production of fatty acids. The excess energy produced by the oxidations over that used by the reductions is used for the production of adenosine triphosphate for other metabolic demands. Invertebrates have exploited several combinations of these reactions, and this is reflected in the many different end products that they produce.