How Amino Acids are Made

Amino acids refers to compounds whose molecules contain an amine group (-NH2) and carboxyl group (-COOH).

Amino acids are made from plant-derived ingredients. Fermented products such as miso and soy sauce are made by fermenting soy or wheat with a koji culture. The fermentation process breaks down the protein and turns it into amino acids. Miso and soy sauce are examples of how amino acids have long been part of the Japanese diet and how Japanese people tried to create delicious food. The amino acids used in amino acid products are mainly made by fermenting plant-derived ingredients in the same way that miso and soy sauce are made.

In amino acid fermentation, amino acids are made by fermenting ingredients with microorganisms (like probiotic bacteria). These microorganisms turn the ingredients into food and other substances that are needed by the microorganisms. In fermentation ingredients such as molasses are added to a medium that cultivates microorganisms. This helps the microorganisms multiply and make amino acids. Microorganisms contain enzymes that accelerate reactions to break down and synthesize new substances The fermentation process is a series of reactions involving around 10 to 30 types of enzymes.

To make amino acids using microorganisms, we first have to find microorganisms that have a strong potential for making amino acids. One gram of natural soil contains about 100 million microorganisms. From this, we have to then find which microorganisms are most effective.
When the right microorganism is found, better strains of it must be developed to get microorganisms with the best potential. The amount of amino acids made depends on the quantity and quality of enzymes. More amino acids can be made if the enzymes for making the right amino acids are kept at ideal conditions. However, less can be made if these conditions are not present. Let’s say that a microorganism has a metabolic pathway of A→(a)→B→(b)→C→(c)→D, where (a), (b), and (c) are enzymes. In order to make large quantities of amino acid C, enzymes (a) and (b) need to be more active and enzyme (c) must not be active. This can be done by developing improved strains through various techniques.
To make amino acids, fermentation tanks are filled with molasses and sugar ingredients such as sugar cane, corn and cassava. Ideal conditions are achieved for stirring, oxygen supply, temperature and pH levels. The desired amino acids are then purified from this fermented broth.

In addition to fermentation, there are other ways to make amino acids, such as by enzymatic reaction, extraction and synthesis.

In the enzymatic reaction process, one or two types of enzymes are used to turn an amino acid precursor into the right amino acid. In this method there is no need to multiply microorganisms by converting the specific amino acid, and there is no long process starting from glucose. The enzymatic reaction process is ideal if the precursor substance has a low cost.
Amino acids can be produced by breaking down proteins, known as the extraction method. However, the amount of amino acids in the source protein limits the amount of amino acids made. Extraction is not good for making mass quantities of specific amino acids.

Synthesis uses chemical reactions to make amino acids, and was widely used in the early development of ways to make amino acids. The problem with synthesis is that chemical reactions make equal amounts of L- and D-amino acids. As a result, the D-amino acids that are made must then be made into L-amino acids. This more costly method therefore requires extra processing steps and equipment and so it was gradually phased out of production. However, it is still used to make glycine, which does not occur in D- and L- forms, and for amino acids where there is no difference if they are D- or L- forms when used.

The advantage of fermentation is that it lets us make mass quantities of amino acids at a low cost with relatively small facilities. Using fermentation to make amino acids has helped grow the amino acid market. In the 1960s, manufacturing of glutamate shifted from extraction to fermentation and the manufacturing of other amino acids followed in succession.