Fermentation

∞ generated and posted on 2015.12.29 ∞

Anaerobic means by which cells can regenerate NAD+ that does not involve an electron transport chain.

The concept of Fermentation has a number of meaning, all of which revolve around the metabolism of microorganisms particularly under conditions lacking in oxygen and particularly which produces organic fermentative products such as ethanol or lactic acid.

More completely stated: Fermentation employs neither molecular oxygen nor an electron transport chain but otherwise is associated with biochemical pathways such as glycolysis in which ATP is generated and organic compounds, such as pyruvate, serve as final electron acceptors.

A typical fermentation product, that is, a waste product of fermentative catabolism, is acidic. The result is a reduction in the pH of media in which organisms are fermenting, with greater reductions in pH occurring depending on the fermentative products generated along with the amounts they are produced in.

Anaerobic means that it occurs in the absence of oxygen (O2). Fermentation in particular involves the passing of electrons, from NADH, to water-soluble organic molecules – such as pyruvate, the end product of glycolysis – rather than to electron transport chains.

A number of very interesting fermentative products exist including lactic acid (lactic acid fermentation) as generated by our skeletal muscles or by bacteria producing yogurt. Ethanol as generated by the yeast, Saccharomyces cerevisiae, along the gas the makes bread dough rise, are together generated by what is known as alcohol fermentation.

For discussion of fermented foods, click here.


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