Microbial Fermentation

Eniola Elizabeth Fase

Expertise: Microbial Fermentation | Alltech
Microbial Fermentation
Cr: Alltech

Microbial fermentation is defined as a metabolic process where microbes’ activity produces a fascinating change in food and beverages. This is even though it’s either preserving foodstuffs, providing health benefits, increasing flavor, or more.

Microbial Fermentation can also be referred to as the decomposition of enzymatic and usage of foodstuffs, specifically carbohydrates, by microorganisms. Fermentation happens all through the gastrointestinal tract of animals, none in exception. However, the power of fermentation depends on the number of microorganisms, which are normally elevated in the large bowel. Hence, the large intestine occurs to be the most crucial location of fermentation, except for ruminants species.

Moreover, there are fundamental variations in the contribution of fermentation to the energy production of various species. In cats, dogs, and humans, fermentation produces a small number of calories, but in some other herbivores, fermentation produces more calories.

Through the action of enzymes, fermentation produces chemical changes in organic substrates. In biochemistry, it is known as the extraction of energy from carbohydrates where there is no oxygen. In microbes, fermentation is the major means of generating adenosine triphosphate (ATP) by the deterioration of organic nutrients anaerobically. There are various products from fermentation, however, the most common are carbon dioxide, ethanol, lactic acid, and hydrogen gas (H2). These products are utilized in pharmaceuticals, foods, vitamins, or as industrial chemicals.

Types of Microbial Fermentation

 These are three different types of fermentation that people utilize to convert certain substances into a variety of foodstuffs and beverages. These major types of microbial fermentation are;

  • Lactic Acid Fermentation
  • Ethanol Fermentation/Alcohol Fermentation
  • Acetic Acid Fermentation

Lactic Acid Fermentation

This illustration shows that during glycolysis, glucose is broken down into two pyruvate molecules and, in the process, two NADH are formed from NAD^{+}. During lactic acid fermentation, the two pyruvate molecules are converted into lactate, and NADH is recycled back into NAD^{+}.
 Lactic acid fermentation is common in muscle cells that have run out of oxygen
Cr: Lumen learning

With Lactic Acid fermentation, bacteria and yeast strains convert starches or sugars into lactic acid, without any heat in preparation. These anaerobic chemical reactions utilize hydrogen (NADH) and nicotinamide adenine dinucleotide to form NAD+ and lactic acid. This type of fermentation also exists in human muscle cells. When humans engage themselves in strenuous activity, muscles can consume adenosine triphosphate (ATP) quicker than oxygen can be supplied to muscle cells. This results in sore muscles and lactic acid buildup. The accumulation of lactic acid must be removed in the muscles by the lactate brought to the liver and blood circulation for metabolism

 Lactic acid bacteria are important in preserving and producing wholesome foods, which is particularly important in feeding underprivileged populations. This method makes pickles, kimchi, yogurt, sauerkraut, and sourdough bread.

Ethanol fermentation/alcohol fermentation: Withethanol fermentation, yeasts break pyruvate molecules in starches or sugars down into carbon dioxide molecules alcohol. Ethanolfermentation is what is used to produce wine and beer.

In alcohol fermentation. One glucose molecule breaks down into two pyruvates via glycolysis (1). The energy from these exothermic reactions is used to bind inorganic phosphates to ADP and convert NAD+ to NADH. The two pyruvates are then broken down into two Acetaldehyde and give off two CO2 as a waste product (2). The two Acetaldehydes are then reduced to two ethanol, and NADH is oxidized back into NAD+ (3).
Diagram of alcohol fermentation Cr: Lumen Learning

Acetic acid fermentation: With Acetic acid fermentation, sugars and starches from fruit and grains ferment into sour tasting vinegar and seasonings. Examples include wine vinegar, apple cider vinegar, and kombucha.

Fermentation of Vinegar | Biotechnology | The Biology Notes
Fermentation of Vinegar
Image Source: doi: 10.20944/preprints201612.0007.v1

 What is Fermentation Process?

Fermentation happens where there are beneficial microorganisms such as molds, yeasts, and bacteria and there is no oxygen such as anaerobic conditions that collect their energy through fermentation. If there is the availability of enough sugar, some yeast cells prefer fermentation to aerobic respiration even when there is sufficient oxygen.

The fermentation process occurs when beneficial microorganisms break down starches and sugars into alcohols Ind acids, causing food to be more nutritional and preserving it for consumers to store it for a longer time without it spoiling.

Fermentation products produce enzymes essential for digestion. This is significant because human beings have a limited number of enzymes. Fermented foods include the enzymes needed to break them down.

Applications and Uses of Microbial Fermentation

There are various uses and applications of microbial fermentation in the food industry. Microbial enzymes are majorly used in various food industries because of the substantial availability of sources. The production of microbial enzymes by application of fermentation methods comprises microbial propagation like mold, bacteria, and yeast to produce the desired product. Microbial fermentation can also be used in various applications in different industries such as cheese making, dairy, brewing, winemaking, milling, beverages, baking, and cereals industry.

Food Production

Microbial fermentation processes are largely used in the production of different foods and other commercial products, including pharmaceuticals. Microbial fermentation is also used to identify microbes for diagnostic purposes. During the production of cheese and yogurt, the highly acidic environment that lactic acid fermentation generated denatures proteins contained in milk, causing it to thicken. Lactic acid fermentation is fermentation by some bacteria, like those in soured food products and yogurt, including the fermentation by animals in muscles during oxygen shortage.

Alcohol Beverage Production

Microbial fermentation is used to produce alcoholic beverages based primarily on two factors. These two factors are the enzymes used for fermentation and the fermented plant. Various peoples in the food industry use wheat, honey, potatoes, cactus juice, cassava roots, barley, grapes, berries, corn, rice, hops, and other plant materials for fermentation. The products of these above-listed food products are different forms of wine, beer, or distilled liquors, which are named based on the source from which they come.

Laboratory Chemicals Production

Acetone-butanol-ethanol fermentation is used to produced chemical solutions such as butanol and acetone. Perplexing organic pharmaceutical compounds utilized in vaccines, antibiotics like penicillin, and vitamins are generated through mixed acid fermentation. Fermentation products are used in the laboratory for differentiating several bacteria for diagnostic purposes.

For instance, enteric bacteria perform mixed acid fermentation, decreasing the pH, which can be detected with a pH indicator.

Baked Food Preservation

Microbial fermentation can also be used to preserve and improve the quality of baked food. The carbon dioxide produced during fermentation is a very significant component of many baked goods. For instance, When we mix the batter with a small amount of sugar and yeast. When the batter is rising, sugar is fermented by enzymes in the yeast. This is done with the formation of carbon dioxide gas. The carbon dioxide allows the batter to be bulky and gives it a good quality which it might be lacking without the fermentation process.

Increase Food Vitamin

Fermentation can be used to promote or increase the minerals and vitamins in food. Fermentation also makes them more accessible for absorption. Fermentation increases and promotes vitamin B and C in food products. It also improves niacin, thiamin, folic acid, riboflavin, and biotin. The probiotics, lactic acid, and enzymes in fermented foods promote the absorption of these minerals and vitamins into the body. Additionally, improving the useful bacteria in your stomach helps in promoting the ability to produce vitamin B and synthesize vitamin K.


Fermentation also helps digest food easily. This is because the starches and sugar in food have been broken down through the process of fermentation. For instance, fermentation helps in breaking down the lactose in milk to simpler sugars and can be used to produce end products such as yogurt and cheese which is very easier to digest.  Also, Fermented foods are very rich in probiotics, beneficial microbes that help sustain a healthy stomach so that they can take out nutrients from food.

Anti-nutrients Neutralization

Fermentation is used during food production to neutralize anti-nutrients such as phytic acid, which exists in seeds, grains, nuts, and legumes and can lead to mineral shortcomings. Phytates also produces proteins, starches, and fats, so neutralizing them is incredibly a great idea.


  • https://en.m.wikipedia.org/wiki/Fermentation
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464223/
  • https://science.jrank.org/pages/2677/Fermentation-Uses.html


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