Difference Between Fermentation and Respiration

Fermentation takes place in an anaerobic environment. As a result, glucose is largely converted to fizzy fatty acids during metabolism. When oxygen is available, the process of respiration creates energy from glucose. Then, from one glucose molecule, fermentation and respiration create additional ATP. Moreover, respiration results in a full breakdown of the substrate, whereas fermentation results in a partial breakdown.

Fermentation vs Respiration

The main difference between fermentation and respiration is that NADH is not utilized in oxidative phosphorylation to create ATP during fermentation, whereas NADH is used in oxidative phosphorylation to generate three ATPs per NADH during respiration. Fermentation takes place in the absence of oxygen, whereas respiration necessitates the presence of oxygen.

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Fermentation is the process of breaking down sugar molecules into simpler chemicals that can be utilized to generate chemical energy. Chemical energy, usually in the form of ATP, is crucial because it powers a variety of biological functions. Fermentation is anaerobic because it does not consume oxygen. The end products created from pyruvate or its derivatives differentiate many different forms of fermentation.

In aerobic species, respiration is a biological process of energy generation. It takes glucose as a substrate and generates 36 ATP molecules from a single glucose molecule. The production of energy through respiration necessitates the use of oxygen. Glycolysis, Krebs cycle, and electron transport chain are the three primary steps.

Comparison Table Between Fermentation and Respiration

Parameters of ComparisonFermentationRespiration
OxygenDoes not require oxygen.Oxygen is essential.
Yet of ATPTwo ATPs.36 ATPs.
TypesEthanol fermentation and lactic acid fermentation.Aerobic and anaerobic respiration.  
End ProductEthanol and CO2 are produced in ethanol fermentation and lactic acid is the end product of lactic acid fermentation.Carbon dioxide and water.  
Contribution in creating energyContributes the least.Contributes the most.

What is Fermentation?

When it comes to fermentation, oxygen isn’t used. It consumes glucose and generates ATP as well as another molecule as a byproduct. There is less energy generated during fermentation than during respiration. It receives its energy from glucose as well. Lactate bacteria are introduced to milk for it to ferment into yogurt.

It will subsequently be fermented by lactate bacteria. As a result, the end product is sour yogurt. The technique may be modified in other goods, such as beer, by sealing the alcoholic beverage. As a result, it will generate beer as its ultimate product at the end of fermentation. The same may be said about root beer. Ethanol and lactic acid fermentation are two forms of fermentation.

In the absence of oxygen, ethanol fermentation occurs in yeast. They’re known as facultative anaerobes because of this. Bacteria produce lactic acid. Animals create lactic acid mostly in their muscles when they are deprived of oxygen. Lactic acid is a tissue irritant. For both fermentations, glycolysis is the same.

During glycolysis, glucose is broken down into two pyruvate molecules, resulting in the production of two ATP molecules. Obtaining electrons from glyceraldehyde-3-phosphate results in the formation of two molecules of NADH. Pyruvate is decarboxylated into acetaldehyde when carbon dioxide is removed during ethanol production. The hydrogen atoms of the NADH are used to convert acetaldehyde to ethanol. The effervescence is caused by the cells in the medium producing carbon dioxide gas.

What is Respiration?

Respiration is a natural process that every form of life goes through to make energy by breaking down molecules inside the cell and using oxygen to do so. ATP, or adenosine triphosphate, is the fundamental type of energy in cells, as we all know. The stored energy inside these cells is released and broken down as they break down and undergo respiration.

To do so, oxygen is required to liberate the energy that has been stored. Muscle contractions and impulse production are two more roles of cellular respiration. The three phases of respiration are glycolysis, citric acid cycle, and electron transport chain. Glycolysis takes place in the cytoplasm of the cell, much as it does during fermentation.

The mitochondrial matrix receives the two pyruvate molecules generated during glycolysis. During oxidative decarboxylation, they release two carbon dioxide molecules, one from each, and form acetyl-CoA. The citric acid cycle, often known as the Krebs cycle, takes this acetyl-CoA.

A single glucose molecule is entirely oxidized into six carbon dioxide molecules throughout the citric acid cycle, yielding 2 GTPs, 6 NADH, and 2 FADH2. During oxidative phosphorylation, which takes place in the inner mitochondrial membrane, this NADH and FADH2 are coupled with oxygen to produce ATP.

An electron transport chain, which is a series of electron carriers, moves electrons in NADH and FADH2 during oxidative phosphorylation.

Main Differences Between Fermentation and Respiration

  1. Fermentation does not need to use oxygen to carry out the process, whereas respiration does.
  2. The breakdown of a single glucose molecule creates just two ATPs in fermentation, but the breakdown of a single glucose molecule yields 36 ATPs in respiration.
  3. The two forms of fermentation found in organisms are ethanol fermentation and lactic acid fermentation, while the two types of respiration found in organisms are aerobic and anaerobic respiration.
  4. Both ethanol and CO2 are produced during ethanol production. Lactic acid fermentation results in the production of lactic acid, whereas respiration results in the production of inorganic end products such as carbon dioxide and water.
  5. On Earth, fermentation contributes the least to the creation of energy for cellular operations, whereas respiration contributes the most to the production of energy for cellular processes.


Organisms require energy to carry out their cellular functions. As a result, they produce ATP, which is an energy molecule. They break down into various forms on various substrates, and the released energy is converted into energy molecules that the cells may utilize. Many creatures use glucose as their major energy source.

Fermentation and respiration are two biological processes that break down glucose in a series of stages to create energy. Respiration, on the other hand, is more efficient and creates more ATP molecules than fermentation. The potential energy held in organic molecules is transformed into kinetic chemical energy in the form of ATP during fermentation and respiration. Both begin with glycolysis, which produces two pyruvate molecules.


  1. https://journals.asm.org/doi/full/10.1128/JB.183.15.4509-4516.2001
  2. https://www.nature.com/articles/2151038a0
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