What Is Lactic Acid Fermentation?

By David Chandler
animals image by Nikolay Kachanov from Fotolia.com

Under aerobic conditions, most cells employ aerobic respiration to generate ATP (adenosine triphosphate). ATP provides the energy needed to fuel other cellular activities. However, when oxygen levels are insufficient for aerobic cellular respiration, some cells employ lactic acid fermentation to produce ATP. The amount of net ATP is greatly reduced in lactic acid fermentation compared to aerobic respiration.

ATP Yield

Lactic acid fermentation yields only two molecules of ATP per molecule of glucose, while aerobic respiration produces 36 molecules of ATP, most of which comes from the electron transport chain.

Product of Lactic Acid Fermentation

Lactic acid fermentation derives its name from the lactic acid (or lactate) produced by the process. The lactic acid is a waste product of the process, which must be removed by the organism. The accumulation of lactic acid in muscle cells can be felt as a aching sensation during exercise. It also produces the sour taste of yogurt and spoiled milk.

Formula for Lactic Acid

The chemical formula of lactic acid is C3H6O3.

Lactic Acid Fermentation Pathway

In lactic acid fermentation, glycolysis (which does not require oxygen) splits glucose into two pyruvate molecules. The lactic acid fermentation pathway then converts the pyruvate into lactate. The NAD+ consumed in glycolysis is replenished by lactic acid fermentation.

Lactic Acid Fermentation Organisms

Some bacteria and fungi undergo lactic acid fermentation as do animal muscle cells.

About the Author

David Chandler has been a freelance writer since 2006 whose work has appeared in various print and online publications. A former reconnaissance Marine, he is an active hiker, diver, kayaker, sailor and angler. He has traveled extensively and holds a bachelor's degree from the University of South Florida where he was educated in international studies and microbiology.