Endustrideki genel uretim sekli l-glutamine sentezleyen bir bakterinden fermente etmek. Bakteriler yeteri kadar sentezledikten sonra l-glutamine'e ikinci asamaya geciliyor. Bu asamada once urun centrifuje edilip sonra filtreleniyor olu bakteri ve artik maddelerden ayirmak icin.
Daha sonra kalan maddeye dikkat! Piyasadaki urunler bu noktada birbirinden ayriliyor. Urunu saflastirmak icin ne kadar uzun ve zahmetli bir prosedur uygulanirsa urunun safligi o kadar yuksek oluyor. Bu noktada urun ya direkt kristalize ediliyor (cozucuyu ucuruyorsun solusyondan, geriye toz kaliyor) ya da once chromotographic tekniklerle diger yan urunlerden iyice ayirip ( bu teknikler cesit cesit, hemen basit bir ornek vereyim. Urunu bir ozel bir cozucu ile karistirip gaz haline getiriyorsunuz. Agirligina gore gazlar ayni surede degisik mesafeler katediyorlar. Buna dayanarak istediginiz amino asiti diger urunlerden ayirmak mumkun cunku o amino asitin ucus suresi biliniyor) daha sonra yine kristalize ediyorsunuz.
Butun makaleyi cevirmiyorum cok vakit alacagi icin. Baska sorulariniz olursa, ya da orjinal makalelere ulasmak isterseniz yardimci olurum.
Not: Baska uretim teknikleri de oldugu soyleniyor makalede ama en yaygini buymus ucuz oldugu icin. Hayvan ya da bitkiden cikarmak amino asiti cok daha zahmetli ve pahali.
Makaleyi ekliyorum.
Glutamine Metabolism: Nutritional and Clinical Significance
Industrial Production of
L-Glutamine1
Isao Kusumoto
2
Ajinomoto Co., Inc., Kawasaki, Japan
ABSTRACT The industrial production of
L-glutamine (L-Gln) started with its fermentation in the late 1960s.
Currently, it is manufactured for use as pharmaceuticals and health foods at the worldwide annual production of
;
2000 metric tons. To manufacture high quality L-Gln at a low cost, it is of prime importance to obtain a strain of
microorganism with good production efficiency and minimum by-products. Furthermore, to obtain the final
crystalline powder product, the efficient removal of impurities contained in the fermentation broth becomes
paramount. Therefore, the industrial process is designed to take into account characteristics of the fermentation
broth as well as chemical, physical and biological properties of L-Gln. Points that should be considered in the
process design and typical industrial production of L-Gln are described in this report. J. Nutr. 131: 2552S–2555S,
2001.
KEY WORDS: c glutamine c amino acid c ion exchange resin c resin chromatography c crystallization
c
polymorphism
The industrial production of amino acids is briefly reviewed
before discussing the production technology of
Lglutamine
(L-Gln).3 Historically, the industrial production
of amino acids started with the availability of monosodium
glutamate (MSG) in 1909. MSG was discovered in 1908 by
Dr. Kikunae Ikeda as a basic taste substance of kelp that is
a traditional seasoning in Japan. Currently, MSG is used
worldwide as a flavor enhancer. Originally, MSG was manufactured
by extraction from acid hydrolysate of plant protein.
Small-scale production of various amino acids followed
but they were produced by the same extraction
method used in MSG production. In the late 1950s, fermentation
technology was established and used for the
commercial production of MSG. This was the beginning of
modern amino acid production. Since then, fermentation
technologies for various amino acids have been established.
Production of L-Gln by fermentation started in the late
1960s.
Current total annual worldwide consumption of amino
acids is estimated to be over 2 million tons (Ajinomoto,
estimate). The annual demand for amino acids as MSGbased
flavor enhancers, and as feed additives comprised
mainly of L-lysine hydrochloride, DL-methionine and Lthreonine,
is estimated to be 1 million tons for each amino
acid (Ajinomoto, estimate). The annual demand for amino
acids used in pharmaceutical products mainly for intravenous
and enteral nutrition is ;15,000 tons. The annual
demand for L-Gln as a pharmaceutical ingredient, such as
for the treatment of gastric ulcer, and as a health food
ingredient is estimated to be ;2000 tons.
General manufacturing process for amino acids
The manufacturing methods of amino acids are categorized
as:
1) extraction from hydrolysates of animal or plant
protein, 2) chemical synthesis, 3) fermentation, and 4)
enzymic. Although DL-methionine for feed additives use
and glycine, without an asymmetric carbon, are manufactured
in a large scale by chemical synthesis, most amino
1
Presented at the International Symposium on Glutamine, October 2–3,
2000, Sonesta Beach, Bermuda. The symposium was sponsored by Ajinomoto
USA, Inc. The proceedings are published as a supplement to The Journal of
Nutrition. Editors for the symposium publication were Douglas W. Wilmore, the
Department of Surgery, Brigham and Women’s Hospital, Harvard Medical School
and John L. Rombeau, the Department of Surgery, the University of Pennsylvania
School of Medicine.
2
3
Abbreviations used: L-Gln, L-glutamine; MSG, monosodium glutamate. FIGURE 1 Schematic of the fermentation process.
0022-3166/01 $3.00 © 2001 American Society for Nutritional Sciences.
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acids are manufactured by fermentation and enzymic methods.
Several amino acids including
L-leucine, hydroxy Lproline,
L
-tyrosine and L-cystine are still being manufactured
by extraction in addition to fermentation and
chemical synthesis. L-Gln is manufactured by several manufacturers
throughout the world, all using fermentation.
The manufacturing process of an amino acid by fermentation
comprises fermentation, crude isolation and purification
processes. In the fermentation process, the desired
amino acid is specifically produced by the fermentation
microorganism. In the crude isolation process, most impurities
contained in the fermentation broth are removed by
combining various technologies. Final purification is performed
to ensure the required quality for the intended use.
The final product is obtained as a crystalline powder. The
product is released only after quality tests have verified that
the product meets specific requirements, and the normal
functioning of each process step has been verified. All
manufacturing processes for the production of amino acids
for medical use must comply with current good manufacturing
practice requirements.
As stated, most impurities are removed by the crude isolation
process. The purification process is relatively simple and
performed frequently. Careful performance of the fermentation
and isolation processes, as well as the combination of
these two processes, is critical to manufacture a high quality
product with high productivity.
Manufacturing method of
L-Gln
The following describes production of
L-Gln by the fermentation
process. It is essential to the outcome of the fermentation
process to maintain a clean and sterile fermentation tank.
Compared with wild-type strains, L-Gln-producing strains are
weak and are compromised in a contaminated environment.
Furthermore, it is important to maintain the tank under positive
pressure by aeration during fermentation to prevent contamination
by other microorganisms and external materials.
The fermentation medium consists of glucose as a carbon
source, ammonia as a nitrogen source, a small amount of
minerals and vitamins as growth factors. Control factors during
fermentation are pH, temperature and dissolved oxygen
(Fig. 1).
An L-Gln-producing bacterium is shown in Figure 2.
This strain is derived from an improved strain of L-glutamic
FIGURE 2
L-Gln-producing bacterium.
FIGURE 3
Time course of L-Gln fermentation.
FIGURE 4
Flow diagram of the isolation process.
FIGURE 5
Stability of L-Gln in aqueous solution.
L
-GLUTAMINE INDUSTRIAL PRODUCTION 2553S
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acid producing bacteria capable of high quality and high
productivity
L-Gln, while minimizing the formation of byproducts.
Figure 3
illustrates the fermentation profile of L-Gln.
The amount of fed glucose is decreased with proliferation
of the fermentation bacteria. L-Gln begins to accumulate
when the growth of the bacteria reaches a certain level.
When the initial glucose concentration decreases, more
glucose is added to the batch to improve productivity and to
increase the accumulation of L-Gln. Each step of fermentation
is controlled by optimizing pH, temperature and dissolved
oxygen.
Crude isolation process
Figure 4
illustrates a typical process for the isolation of
crude L-Gln. The purpose of the isolation process is to
obtain crude L-Gln with adequate purity from the fermentation
broth. The broth is centrifuged or filtered through a
membrane filter to separate cells and debris. It is desirable
that crude crystals are harvested through the direct crystallization
of the supernatant or filtrate. If it is difficult to
harvest crude crystals with adequate purity, then preparatory
steps are required usually involving repeated ion exchange
resin treatment, chromatographic treatment and
crystallization.
The main points to be considered in designing processes for
amino acid production are characteristics of the desired amino
acid and impurity levels in the fermentation broth. The chemical,
physical and biological properties of the amino acid are all
important.
L
-Gln is stable around the isoelectric point (pH 5.65), but
if the pH shifts from the isoelectric point to either acid or
alkaline conditions, L-Gln is easily hydrolyzed to L-glutamic
acid and ammonia. Figure 5 shows stability of L-Gln in aqueous
solution.
The solubility of several amino acids, including L-Gln, is
shown in Figure 6. The solubility of L-glutamic acid and
L
-histidine HCl increases with increasing temperature.
In contrast, the solubility of L-Gln is barely affected by
temperature as shown by the flat solubility curve. Consequently,
cooling crystallization is not applicable for harvesting
L
-Gln.
Purification of amino acids by crystallization is an effective
means to produce polymorphism. For example, as shown in
Figure 7
, two crystal forms can be used. After crystallization of
L
-glutamic acid in the a-form, the crystals are dissolved, and
FIGURE 6
Solubility of several amino acids, including L-Gln.
FIGURE 7
Amino acids crystal forms.
FIGURE 8
Decomposition of L-Gln in aqueous solution at 35°C.
FIGURE 9
Simplified production flow chart of the L-Gln manufacturing
process.
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then recrystallized in the
b-form. In this manner, it is possible
to remove impurities based on their different affinities for the
two crystal forms.
Unfortunately, L-Gln occurs only as one crystal form.
Therefore, to use crystallization for purification, there is no
way other than the inefficient simple repetitive crystallization
of the one crystal form of L-Gln.
Figure 8
shows the biodegradability of L-Gln in aqueous
solution at 35°C. Because L-Gln is easily degraded by microorganisms,
proper control of the process as well as aspects of
process design is imperative.
The intrinsic properties of L-Gln need to be considered when
designing its isolation and purification processes. Compared with
other amino acids, L-Gln is an amino acid that is difficult to
design. Therefore, the purity of the fermentation broth is of vital
importance to obtain high purity L-Gln with high productivity.
The flow diagram depicted in Figure 9 briefly illustrates the
entire process of L-Gln production.
CONCLUSION
The industrial production of
L-glutamine has been reviewed
with a historical background of the industrial production of
amino acids. From the standpoint of the manufacturing industry
of glutamine, it is hoped that basic and clinical research on
glutamine will continue and further contribute to the improvement
of human health.
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-GLUTAMINE INDUSTRIAL PRODUCTION 2555S
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