Advances in Biotech have enabled the production of AMINO ACIDS using biotech processes mostly by fermentation. Amino acid fermenting strains of bacteria have been found or engineered to produce good yields of the target amino acids. In its simplest form a cheap substrate such as glucose can be used to grow selected bacteria on a large scales with resulting production of amino acids. The organism produces the amino acids as a nutrient they need to grow.
The key is to select the organism which produces most of a particular amino acid. There are other factors involved notably enzymes. An enzyme is a protein which acts as a catalyst to enable a reaction to occur more easily. Introduction of the correct enzyme and inhibition of other enzymes can maximise yields.One of the most common reaction is the production of monosodium glutamate where fortunately the organism which produces MSG needs no alteration and produces MSG in large quantities.
AJINOMOTO describes it well here http://www.ajinomoto.com/amino/eng/product_print.html
Not all amino acids can be produced this way cost effectively and still rely on extraction by hydrolysis of natural products. We refer to Leucine and Cysteine which are predominantly from feathers. Cysteine is notably difficult. Taurine, Creatine and Glycine and Methionine are produced from petrochemicals.
Some Amino acids can be produced using enzymes to extract amino acids from suitable precursor. This method can be very selective but depends on raw material being cheap and very few cases are produced this way but useful of D-Amino Acids.
FERMENTATION GRADE LEUCINE
The market wants, natural ,non-animal origin amino acids. In sports nutrition Leucine was obtainable from Japanese producers and now China is able to produce Leucine commercially and in good quality by fermentation.
Suppliers of Fermented Leucine, iso-Leucine, Valine, Glutamine and Arginine
iBCAA 2:1:1 All Fermentation