BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 19. BIOTECHNOLOGIES FOR L-AMINO ACID PRODUCTION

19.7. BIOTECHNOLOGY FOR L-GLUTAMIC ACID PRODUCTION

Glutamic acid (α-aminoglutaric acid) is a major constituent of PLANT AND ANIMAL Proteins. Although it is classified as a non-essential amino acid, it serves as a precursor for the synthesis of numerous biologically active compounds essential for Human and Animal METABOLISM. It is widely used in the food industry and in medicine for treating Liver and Kidney disorders. In the form of monosodium glutamate (the monosodium salt of glutamic acid), it is employed as a flavor enhancer, particularly in preserved and frozen foods.

Industrially, glutamic acid and its derivative monosodium glutamate are produced through several Methods: multi-step chemical synthesis from acrylonitrile, one-step and two-step microbiological synthesis, extraction from beet molasses, or isolation from protein hydrolyzates. The most prevalent methods are extraction from molasses and one-step microbiological synthesis, with the latter considered the most promising.

The industrial Biosynthesis of L-glutamic acid employs the same microorganisms used in the microbial production of L-Lysine, namely the coryneform Bacteria Corynebacterium glutamicum and Brevibacterium flavum. In addition, certain strains of Micrococcus and Microbacterium serve as industrial producers. Achieving a high yield of glutamic acid requires mutants with a disrupted enzymatic system responsible for converting α-ketoglutaric acid into succinic acid.

Industrial cultivation relies on easily assimilable CARBOHYDRATES (sucrose and glucose) derived from beet molasses and starch hydrolyzates as carbon sources. Nitrogen is supplied by urea, and less frequently by ammonium chloride, ammonium sulfate, or corn steep liquor.

The one-step method for producing L-glutamic acid completely mirrors the technological scheme used for L-lysine production.

Because the manufacture of glutamic acid aims to yield highly purified preparations, the subsequent Processing stages involve producing formulations tailored directly for use as food additives and Pharmaceuticals.

The biosynthetic process is carried out under strictly aseptic conditions in 50 m³ fermenters. The cultivation Temperature is maintained at a constant 28-30 ^oC. By the end of the Fermentation process, the resulting culture broth contains 45 g/L of glutamic acid. This is followed by the Separation of glutamic acid from the culture broth and its subsequent purification. The final product must contain at least 94% of the main substance, no more than 5% sodium chloride, at least 7% total nitrogen, and no more than 1% moisture.