Industrial production of amino acids
The significant advances made in our knowledge of amino acid nutrition of animals are undoubtedly due to supply of amino acids at affordable prices. In the case of feed grade lysine and methionine, the economics are largely in favour of their routine use in animal feeds. Four methods are used:-
1. Extraction from hydrolystates of plant or animal protein.
2. Chemical synthesis
3. Fermentation
4. Enzymatic process
 

Amino acid	Raw material	Process	Commercial Products
Methionine	Propylene, methyl mercaptan, methane, ammonia	Chemical synthesis	DL-methionine, DL-methionine sodium salt
Hydrogen analogue of methionine	Acrolein, methyl mercaptan, hydrogen cyanide	Chemical synthesis	DL-2-Hydroxy-4methyl mercaptobutyric acid, liquid
Lysine	Molasses, sugar starch products and their hydrolysates N-source	Fermentation	L-lysine monohydrochloride L-lysine concentrate (liquid) L-lysine monohydrochloride L-lysine sulphate
Threonine	Molases, sugar, starch products and their hydrolysates, N-source	Fermentation	L-threonine
Tryptophan	Molasses, sugar, starch products and their hydrolysates, N-source	Fermentation	L-tryptophan

Among these methods, fermentation technology is now so advanced that many amino acids destined for commercial feed application are currently being produced by this method only.
Methionine may be isolated from naturally occurring sources, produced from genetically engineered organisms, or entirely synthesized by a wild number of processes. While methionine has been produced by fermentation laboratory conditions racemic mixtures of D-and L-methionine (DL-Methionine) are usually produced entirely by chemical methods (Araki and Ozeki, 1991). Methionine can be produced from the reaction of acrolein with methylmercaptan in the presence of a catalyst (Fong et al, 1981). Another method uses propylene, hydrogen sulfide, methane and ammonia to make the intermediates acrolein, methylthiol and hydro cyanic acid (DeGussa). The Strecker synthesis can be used with OC- Methyl thio propionaldehyde as the aldehyde (Fong et al, 1981). A recently patented process reacts 3- methyl mercaptopropionaldhyde, ammonia, hydrogen cyanide, and carbon dioxide in the presence of water in three reaction steps (Geiger et al., 1998).

.