Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing alpha or beta amino acid or substituted amino acid...
Reexamination Certificate
1999-03-18
2001-12-18
Ware, Deborah K. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing alpha or beta amino acid or substituted amino acid...
C435S106000, C435S170000, C435S252100, C435S822000, C435S880000
Reexamination Certificate
active
06331419
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel L-glutamic acid-producing bacterium and a method for producing L-glutamic acid by fermentation using the same. L-Glutamic acid is an important amino acid as food, drugs and the like.
L-Glutamic acid has conventionally been produced by fermentation methods utilizing the so-called coryneform L-glutamic acid-producing bacteria which principally belong to the genera Brevibacterium, Corynebacterium, and Microbacterium or variants thereof (“Amino Acid Fermentation”, Gakkai Shuppan Center, pp.195-215, 1986). As methods for producing L-glutamic acid by fermentation utilizing other bacterial strains, there have been known the methods utilizing microorganisms of the genera Bacillus, Streptomyces, Penicillium and the like (U.S. Pat. No. 3,220,929), the methods utilizing microorganisms of the genera Pseudomonas, Arthrobacter, Serratia, Candida and the like (U.S. Pat. No. 3,563,857), the methods utilizing microorganisms of the genera Bacillus, Pseudomonas, Serratia and the like or Aerobacter aerogenes (currently referred to as Enterobacter aerogenes) (Japanese Patent Publication (KOKOKU) No. 32-9393(1957)), the method utilizing variant strains of
Escherichia coli
(Japanese Patent Application Laid-Open (KOKAI) No. 5-244970(1993)) and the like.
Though the productivity of L-glutamic acid has considerably been improved by breeding of such microorganisms as mentioned above or improvements of production methods, it is still desired to develop a more inexpensive and more efficient method for producing L-glutamic acid in order to meet the expected markedly increasing future demand of the amino acid.
SUMMARY OF THE INVENTION
The object of the present invention is to find a novel L-glutamic acid-producing bacterium having a high ability to produce L-glutamic acid, thereby developing a more inexpensive and more efficient method for producing L-glutamic acid.
To achieve the aforementioned object, the present inventors intensively searched for and studied microorganisms having the ability to produce L-glutamic acid that are different from the previously reported microorganisms. As a result, they found that certain strains derived from microorganisms belonging to the genus Enterobacter or Serratia had a high ability to produce L-glutamic acid, and have completed the present invention.
Thus, the present invention provide:
(1) a microorganism belonging to the genus Enterobacter or Serratia and having an ability to produce L-glutamic acid and at least one of the following properties:
(a) the microorganism increases in an activity of an enzyme catalyzing a reaction for L-glutamic acid biosynthesis; and
(b) the microorganism decreases in or is deficient in an activity of an enzyme catalyzing a reaction branching from a pathway for L-glutamic acid biosynthesis and producing a compound other than L-glutamic acid;
(2) a microorganism of the above (1) wherein the enzyme catalyzing the reaction for the L-glutamic acid biosynthesis is at least one selected from the group consisting of citrate synthase (abbreviated as “CS” hereinafter), phosphoenolpyruvate carboxylase (abbreviated as “PEPC” hereinafter), and glutamate dehydrogenase (abbreviated as “GDH” hereinafter);
(3) a microorganism of the above (2) wherein the enzyme catalyzing the reaction for the L-glutamic acid biosynthesis includes all of CS, PEPC and GDH;
(4) a microorganism of any one of the above (1) to (3) wherein the enzyme catalyzing the reaction branching from the pathway for L-glutamic acid biosynthesis and producing the compound other than L-glutamic acid is &agr;-ketoglutarate dehydrogenase (abbreviated as “&agr;KGDH” hereinafter);
(5) a microorganism of any one of the above (1) to (4) which is
Enterobacter agglomerans
or
Serratia liquefacience;
and
(6) a method for producing L-glutamic acid which comprises culturing the microorganism as defined in any one of the above (1) to (5) in a liquid culture medium to produce and accumulate L-glutamic acid in the culture medium, and collecting the L-glutamic acid from the culture medium.
Because the microorganism of the present invention have a high ability to produce L-glutamic acid, it is considered to be possible to impart a further higher production ability to the microorganism by using the breeding techniques previously known for the coryneform L-glutamic acid-producing bacteria and the like, and it is expected to contribute to development of a more inexpensive and more efficient method for producing L-glutamic acid by appropriately selecting culture conditions and the like.
REFERENCES:
patent: 3563857 (1971-02-01), Oki et al.
patent: 5643769 (1997-07-01), Katsumata et al.
patent: 0 670 370 (1995-09-01), None
patent: 7-203980 (6-825) (1995-08-01), None
Hara Yoshihiko
Ito Hisao
Izui Hiroshi
Matsui Kazuhiko
Moriya Mika
Ajinomoto Co. Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ware Deborah K.
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