Amino acids are the building blocks of proteins, and they are integral to the chemistry of life. Without amino acids, there would be no enzymes, and without enzymes, life as we know it wouldn’t exist. So amino acids are used by every living thing on earth, from the simplest microorganism to the most complex plants and animals.
Plants are “autotrophic”. In other words, they make their own food, including amino acids. Plants take up nitrogen through the roots in the form of ammonium ions or nitrate ions. The plant cells then convert the nitrogen into amino acids, usually in the form of glutamic acid. The glutamic acid is then transported throughout the plant and rebuilt into all of the other amino acids. Then, through the miracle of the genetic code, the amino acids are assembled into specific enzymes to perform the perfect chemical reaction at the perfect time. Life goes on!
L-amino acids are also produced by plant-growth-promoting rhizobacteria through a process called “enzymatic hydrolysis”. As bacteria grow and reproduce, they exude digestive enzymes. Some of the digestive enzymes are called “proteases”. They break down large protein molecules into smaller amino acid molecules. The amino acids are then used as a carbon and nitrogen source for the microorganisms, fueling growth and metabolism. The left over amino acids have a positive effect on plant growth. Although amino acids are not considered fertilizers (no more than 10-15% of the nitrogen in amino acids are ever used by plants), they can have a powerful stimulatory effect on plant growth.
Amino acids come in left-handed and right-handed versions, but only the l-amino acids are biologically active. L-amino acids must be produced in nature’s kitchen. The amino acids produced through enzymatic hydrolysis retain their left-handed chemical structure and they are very biologically active. But synthetic amino acids, produced through acid or alkaline hydrolysis, are right-handed molecules and they are not biologically active. So when purchasing amino acids for plant growth, make sure that they are L-amino acids. Sometimes the l-amino acids are listed individually, but many times they are simply referred to as “protein hydrosylates”.
Some of the amino acids produced by microorganisms can be transported directly into the plant through the plant roots. For example, the amino acid “tryptophan” is absorbed through the roots, transported upward to the leaves, and then changed by the plant into a natural growth hormone called “auxin”. The auxin (IAA) is then pumped to the growing tips to stimulate the new growth of roots and shoots. Other amino acids, such as glutamic acid and glycine, stimulate root cells to open up calcium ion channels. So instead of one calcium ion at a time entering the root, thousands to millions of calcium ions can be taken up by the plant, strengthening the entire vascular system of the plant. The stronger the vascular system, the more efficiently the plant takes up water and nutrients, resulting in thicker stems, stronger cell walls and greater resistance to pests and disease. So even though only a small amount of amino acids are taken up directly by the plant, they have an indirect effect on plant growth and vigor.
Plants also exude amino acids from their roots to feed beneficial microorganisms. For example, plants produce amino acids for their own needs, but they leak some of their excess amino acids into the root zone, including the amino acid tryptophan. Some root-colonizing microorganisms are able to change plant-produced tryptophan directly into the rooting hormone IAA, right on the surface of the roots! The IAA signals the plants to make more roots, microorganisms colonize the increased root mass, and the process of life continues. So plants can produce amino acids for microorganisms, and microorganisms can produce amino acids for plants. And together, plants and microorganisms magnify the positive effects of amino acids far more than the fertilizer value of the nitrogen they contain.
Most importantly of all, L-amino acids are intermediate chelators. The “acid” part of amino acid is carboxolic acid, and it ionizes in water to form a negatively-charged “claw” that can attach to positively-charged minerals that are dissolved in the water. The amino acids hold onto the minerals strongly enough to keep them from “locking up” with other minerals, but loosely enough to be released to the plants on demand. Therefore, amino acids improve the availability of important cations, such as calcium, magnesium, copper, iron, manganese and zinc. These trace elements are co-factors that actually activate or “turn on” many important enzymes in plant cells. The activated enzymes are able to do thousands of chemical reactions per second without being used up in the reaction, and life goes on.
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