Biotechnology of Lysine
Lysine is one of the 20 natural amino acids with molecules forming proteins. Proteins are present in the structure of any live tissue. Only plants and microorganisms can synthesize lysine. Man and animal organisms are unable to do that. Organism must take up the necessary proteins with food.
If a man consumes enough proteins of animal origin there is no deficit of lysine in the organism, but livestock lack it as their nutrition consists mainly of flora products. The deficit of lysine limits the rational consumption of proteins that have been taken up.
Where to find the necessary lysine for the forage?
Like plants microorganisms can synthesize all amino acids necessary for their proteins, besides this synthesis process is much faster than in plant cells. That is why scientists tried to select bacteria capable to synthesize more lysine that it is necessary for the bacteria themselves. This kind of bacterium consumes the nutrients that have been taken up (sugar, mineral nitrogen etc.) mainly for the synthesis of lysine that is excreted in the outer environment, culture medium together with the waste products of metabolism. Japanese pioneered the selection of such a bacterium. Since 1963 Latvian scientists also began the selection of such bacteria which resulted in the development of original biotechnology of lysine synthesis.
The essence of the invention:
By means of selection several auxotroph mutants of Brevibacterium (Corynebacterium) genus were obtained. They extracellulary synthesize l-lysine in a complex culture medium of carbohydrates and accumulate vitamins of group B in biomass. Due to the fact that sugar-beet molasses is used as carbon source, betaine remains unassimilated in the culture medium capable to replace choline chloride in forage. For the purpose to retain all the valuable forage components in the end product the fermentation solution is chemically stabilized and gradually thermally dehydrated thus obtaining syrup- or powder-like concentrate of lysine. Several methods were used for the optimization of the fermentation process. Several scientists from the Biochemical Institute of the Latvian and USSR Academies of Sciences took part in the development of the technology process.
Selection of patent documents: