Fermentation

Fermentation is a biological process occurring in a medium deprived of oxygen.

Function of fermentation

Fermentation produces energy (in the form of ATP) even in the absence of oxygen but with a lower yield. It is used by a very large number of organisms from bacteria to human beings.

Some organisms only use this metabolic pathway whereas others alternate between fermentation and respiration, depending on the conditions (presence of O₂, glucose concentration, etc.).

Fermentation is also used in many industrial processes such as the production of cheese, alcohol,biofuels etc.

Biological fermentation process

In biology, fermentation is anaerobic catabolism (the ability to live in an oxygen-free environment) of organic nutriments which does not use the electron transport chain or oxidative phosphorylation.

There are different types of fermentation:

• alcohol fermentation which produces ethanol ;
• lactic fermentation which produces lactic acid ;
• and malolactic fermentation.

This biochemical process yields less than cell respiration that uses an electron transport chain, whose final acceptor is oxygen. For example, lactic fermentation produces 2 molecules of ATP per molecule of glucose used whereas the cellular respiration process produces 36 to 38 molecules of ATP.