JP2003180348A - Method for producing l-amino acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing L-amino acids, such as L-lysine or L-glutamic acid, through a fermentation process which is more improved than ever, and to provide strains, such as a coryneform bacterium, capable of being used in the method. <P>SOLUTION: This coryneform bacterium is obtained by introducing a gene which codes succinate dehyrogenase into the coryneform bacterium having ability for producing the L-amino acids, such as the L-lysine or the L-glutamic acid, so that succinate dehyrogenase activity of the bacterium is enhanced. Thus, the bacterium is improved in the ability for producing the L-amino acids. The bacterium is utilized in the method for producing the amino acids. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an L-based fermentation method.
The present invention relates to a method for producing an amino acid, particularly L-lysine and L-glutamic acid. L-lysine is widely used as a feed additive and the like, and L-glutamic acid is widely used as a raw material for seasonings and the like.

[0002]

2. Description of the Related Art Conventionally, L-amino acids such as L-lysine and L-glutamic acid have been fermented by a coryneform bacterium belonging to the genus Brevibacterium or Corynebacterium having the ability to produce these L-amino acids. It is manufactured industrially. For these coryneform bacteria, strains isolated from nature or artificial mutants of these strains are used in order to improve productivity.

Further, various techniques have been disclosed for increasing the L-amino acid-producing ability by enhancing the L-amino acid biosynthetic enzyme by recombinant DNA technology. For example, in coryneform bacteria having L-lysine-producing ability, a gene encoding aspartokinase in which feedback inhibition by L-lysine and L-threonine is released (mutant lysC), dihydrodipicolinate reductase gene (dapB), Dihydrodipicolinate synthase gene (dapA), diaminopimelate decarboxylase gene (lysA) gene, and diaminopimelate dehydrogenase gene (ddh) (WO96 / 40934), lysA and ddh
(JP-A-9-322774), lysC, lysA and phosphoenolpyruvate carboxylase gene (ppc) (JP-A-1-322774).
0-165180), mutant lysC, dapB, dapA, lysA and aspartate aminotransferase gene (aspC).
It is known that the introduction of (JP-A-10-215883) improves the L-lysine-producing ability of the bacterium.

In Escherichia bacteria, da
Sequential enhancement of pA, mutant lysC, dapB, diaminopimelate dehydrogenase gene (ddh) (or tetrahydrodipicolinate succinylase gene (dapD) and succinyldiaminopimelate deacylase gene (dapE)) improves L-lysine productivity Is known (WO 95/16042). In WO 95/16042, tetrahydrodipicolinate succinylase is erroneously described as succinyldiaminopimelate transaminase. On the other hand, in a bacterium of the genus Corynebacterium or genus Brevibacterium, the introduction of a gene encoding a citrate synthase derived from Escherichia coli or Corynebacterium glutamicum was effective for enhancing the L-glutamic acid-producing ability. Has been reported (Japanese Patent Publication No. 7-121228). Further, Japanese Patent Application Laid-Open No. 61-268185 discloses a cell having a recombinant DNA containing a glutamate dehydrogenase gene derived from a bacterium belonging to the genus Corynebacterium. Further, Japanese Patent Laid-Open No. 63-214189 discloses a technique for increasing the L-glutamic acid production ability by enhancing the glutamate dehydrogenase gene, the isocitrate dehydrogenase gene, the aconitate hydratase gene, and the citrate synthase gene. Has been done.

However, the structure of the gene encoding succinate dehydrogenase has not been reported in coryneform bacteria, and the use of the gene encoding succinate dehydrogenase in breeding coryneform bacteria has not been known.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method for producing L-amino acids such as L-lysine or L-glutamic acid by a fermentation method which is further improved than before, and a strain used therefor. To do.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors introduced a gene encoding succinate dehydrogenase into a coryneform bacterium to obtain succinate dehydrogenase activity. It was found that the production amount of L-lysine or L-glutamic acid can be increased by amplifying the enzyme, and the present invention was completed. That is, the present invention is as follows.

(1) A coryneform bacterium having an enhanced succinate dehydrogenase activity in cells and an L-amino acid-producing ability. (2) The coryneform bacterium of (1), wherein the L-amino acid is selected from L-lysine, L-glutamic acid, L-threonine, L-isoleucine, and L-serine. (3) The coryneform bacterium of (1) above, wherein the enhancement of the succinate dehydrogenase activity is due to an increase in the copy number of the gene encoding the succinate dehydrogenase in the bacterial cell. (4) The coryneform bacterium according to (3), wherein the gene encoding the succinate dehydrogenase is derived from a bacterium belonging to the genus Escherichia. (5) The method of culturing the coryneform bacterium according to any one of (1) to (4) above in a medium to produce and accumulate L-amino acid in the culture, and collecting the L-amino acid from the culture. And a method for producing an L-amino acid. (6) The method according to (5), wherein the L-amino acid is selected from L-lysine, L-glutamic acid, L-threonine, L-isoleucine and L-serine.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

<1> Coryneform bacterium of the present invention The coryneform bacterium of the present invention has L-amino acid-producing ability,
It is a coryneform bacterium with enhanced succinate dehydrogenase activity in cells. Examples of L-amino acids include L-lysine, L-glutamic acid, L-threonine, L-isoleucine and L-serine. Among these,
L-lysine and L-glutamic acid are preferred. Hereinafter, the embodiment of the present invention will be mainly described with reference to L-lysine-producing ability
-A coryneform bacterium capable of producing glutamic acid will be described, but the present invention can be similarly applied to a target L-amino acid-specific biosynthesis system located downstream of succinate dehydrogenase.

The coryneform bacteria referred to in the present invention include Bergey's Manual of Determinative Baciology.
teriology) 8th edition pp. 599 (1974), a group of microorganisms that are aerobic, gram-positive, non-acidic, non-sporulating rods, and are conventionally classified as Brevibacterium. However, it contains bacteria that have been integrated as Corynebacterium (Int. J. Syst. Bacterio
l., 41, 255 (1981)), and also Brevibacterium and Microbacterium which are closely related to the genus Corynebacterium. Examples of coryneform bacterial strains that are preferably used for the production of L-lysine or L-glutamic acid include:
For example, the following may be mentioned.

[0011]   Corynebacterium acetoside film ATCC13870   Corynebacterium acetoglutamicum ATCC15806   Corynebacterium carnae ATCC15991   Corynebacterium glutamicum ATCC13032   (Brevibacterium divaricatum) ATCC14020   (Brevibacterium lactofermentum) ATCC13869    (Corynebacterium Lilium) ATCC15990   (Brevibacterium flavum) ATCC14067   Corynebacterium meracecola ATCC17965   Brevibacterium saccharolyticum ATCC14066   Brevibacterium Inmario Film ATCC14068   Brevibacterium roseum ATCC13825   Brevibacterium thiogenitalis ATCC19240   Microbacterium Ammonia Philum ATCC15354   Corynebacterium thermoaminogenes AJ12340 (FERM BP-1539)

To obtain these, for example, American Type Culture Collection (American Type
Culture Collection, Address 12301 Parklawn Drive, Roc
kville, Maryland 20852, United States of America)
You can get more sales. That is, a registration number corresponding to each microorganism is given, and the registration number can be quoted to receive the sale. The registration number corresponding to each microorganism is listed in the American Type Culture Collection catalog. Also, AJ12340
The shares have been deposited under the Budapest Treaty at the Institute of Biotechnology, Industrial Technology Institute, Ministry of International Trade and Industry (Postal Code 305-8566, 1-3-1 Higashi, Tsukuba, Ibaraki, Japan).

In addition to the above strains, L-lysine or L-glutamic acid-derived L-derived from these strains
Mutant strains having amino acid-producing ability can also be used in the present invention. Such artificial mutant strains include the following.
S- (2-aminoethyl) -cysteine (hereinafter referred to as "AE
Abbreviated as "C") resistant mutant strain (for example, Brevibacterium lactofermentum AJ11082 (NRRL B-1147
0), Japanese Patent Sho 56-1914, Japanese Patent Sho 56-1915, Japanese Patent Sho 57-14
No. 157, Japanese Examined Japanese Patent No.
8-10075, Japanese Examined Sho 59-4993, Japanese Examined Sho 61-35840, Examined Sho 62-24074, Examined Sho 62-36673, Examined Hei 5-11958,
Japanese Patent Publication Nos. 7-112437 and 7-112438), mutants that require amino acids such as L-homoserine for their growth (Japanese Patent Publication Nos. 48-28078 and 56-6499), resistant to AEC , L-leucine, L-homoserine, L-proline, L-serine, L-arginine, L-alanine, L-
Variants requiring amino acids such as valine (US Patent No. 3708
395 and No. 3825472), DL-α-amino-ε-caprolactam, α-amino-lauryllactam, aspartic acid-analog, sulfa drugs, quinoids, L-lysine-producing mutant strains resistant to N-lauroylleucine, L-lysine-producing mutants showing resistance to oxaloacetate decarboxylase (decarboxylase) or respiratory enzyme inhibitors (JP-A-50-53588, JP-A-50-31093, JP-A-52-102498)
JP-A-53-9394, JP-A-53-86089, JP-A-55-97
83, JP-A-55-9759, JP-A-56-32995, JP-A-56-
39778, JP-B-53-43591, JP-B-53-1833), L-lysine-producing mutant strains requiring inositol or acetic acid (JP-A-55-9784, JP-A-56-8692), fluoropyrubin L- showing sensitivity to acids or temperatures above 34 ° C
Lysine-producing mutants (JP-A-55-9783, JP-A-53-86090)
No.), a production mutant strain of the genus Brevibacterium or Corynebacterium, which is resistant to ethylene glycol and produces L-lysine (US Pat. No. 4411997).

As a coryneform bacterium having L-threonine-producing ability, corynebacterium acetoacidophilum AJ12318 (FERM BP-1172) (US Pat. No. 5,188,94)
Brevibacterium flavum AJ121 is a coryneform bacterium capable of producing L-isoleucine.
49 (FERM BP-759) (see US Pat. No. 4,656,135) and the like.

<2> Amplification of succinate dehydrogenase activity In order to amplify succinate dehydrogenase activity in coryneform bacterial cells, a gene fragment encoding succinate dehydrogenase is introduced into a vector that functions in the bacterium, preferably a vector. Recombinant DNA may be prepared by ligating with a multi-copy type vector, and the recombinant DNA may be introduced into a coryneform bacterium capable of producing L-lysine or L-glutamic acid for transformation. As a result of the increase in the copy number of the gene encoding succinate dehydrogenase in the cells of the transformant,
The succinate dehydrogenase activity is amplified. Succinate dehydrogenase is found in Escherichia coli
It is encoded by the sdh gene.

The succinate dehydrogenase gene is
Either a coryneform bacterium gene or a gene derived from another organism such as Escherichia bacterium can be used. The nucleotide sequence of the sdh gene of Escherichia coli has already been revealed (Genbank / EMBL / DDBJ acceti
on No. J01619 K00542 M11121), a primer prepared based on the nucleotide sequence, for example, SEQ ID NO: 1 in the sequence listing
And PCR using the Escherichia coli chromosomal DNA as a template (PCR: polymer
se chain reaction; White, TJ et al; Trends Gene
t. 5,185 (1989)), the sdh gene can be obtained. Genes encoding succinate dehydrogenase of other microorganisms such as coryneform bacteria can be obtained in the same manner.

Chromosomal DNA can be obtained from bacteria that are DNA donors, for example, by the method of Saito and Miura (H. Saito and K. Mi).
ura Biochem. Biophys. Acta, 72, 619 (1963), Biotechnology Experiment Manual, Japan Society for Biotechnology, pages 97-98, Baifukan,
1992) and the like.

The gene encoding succinate dehydrogenase amplified by the PCR method is Escherichia coli.
When recombinant DNA is prepared by ligating to a vector DNA capable of autonomous replication in E. coli and / or coryneform bacterium cells and introducing this into Escherichia coli cells,
The later operation becomes easier. The vector capable of autonomous replication in Escherichia coli cells is preferably a plasmid vector, preferably a vector capable of autonomous replication in host cells, for example pUC19, pUC18, pBR322, pHSG299,
Examples include pHSG399, pHSG398, RSF1010 and the like.

Examples of the vector capable of autonomously replicating in the cells of coryneform bacteria include pAM330 (see JP-A-58-67699) and pHM1519 (see JP-A-58-77895). When a DNA fragment capable of autonomously replicating a plasmid in a coryneform bacterium is extracted from these vectors and inserted into the Escherichia coli vector, autonomous replication is possible in both Escherichia coli and a coryneform bacterium. Can be used as a so-called shuttle vector. Examples of such shuttle vectors include the following. The microorganisms carrying the respective vectors and the deposit numbers of the international depository institutions are shown in parentheses. pAJ655 Escherichia coli AJ11882 (FERM BP-136) Corynebacterium glutamicum SR8201 (ATCC39135) pAJ1844 Escherichia coli AJ11883 (FERM BP-137) Corynebacterium glutamicum SR8202 (ATCC39136) pAJ1884 ) pAJ3148 Corynebacterium glutamicum SR8203 (ATCC39137) pAJ440 Bacillus subtilis AJ11901 (FERM BP-140) pHC4 Escherichia coli AJ12617 (FERM BP-3532)

In order to prepare a recombinant DNA by ligating a gene encoding succinate dehydrogenase with a vector functioning in coryneform bacteria, the vector should be constructed with a restriction enzyme that matches the ends of the gene encoding succinate dehydrogenase. Disconnect. Ligation is usually performed using a ligase such as T4 DNA ligase.

The recombinant DNA prepared as described above can be introduced into a coryneform bacterium by any of the transformation methods previously reported. For example, a method of treating recipient cells with calcium chloride to increase DNA permeability, as reported for Escherichia coli K-12 (Mandel, M. and Higa, A., J. Mol. Biol. , 53,159
(1970)), and a method of preparing competent cells from cells in the growth stage and introducing DNA as described for Bacillus subtilis (Duncan, CH, Wil.
son, GAand Young, FE, Gene, 1, 153 (1977)). Alternatively, cells of DNA-accepting bacteria, such as those known for Bacillus subtilis, actinomycetes and yeast, are brought into a protoplast or spheroplast in which the recombinant DNA is easily taken up, and the recombinant DNA is DNA.
Method of introducing into recipient bacteria (Chang, S. And Choen, SN, Mole
c. Gen. Genet., 168, 111 (1979); Bibb, MJ, Ward, J.
M. and Hopwood, OA, Nature, 274, 398 (1978); Hinnen,
A., Hicks, JBand Fink, GR, Proc. Natl. Acad. Sci.
USA, 75 1929 (1978)) can also be applied. The transformation method used in the examples of the present invention was the electric pulse method (Japanese Patent Laid-Open No.
207791).

Amplification of the activity encoding succinate dehydrogenase can also be achieved by allowing multiple copies of the gene encoding succinate dehydrogenase to be present on the chromosomal DNA of the above host. In order to introduce multiple copies of a gene encoding succinate dehydrogenase into the chromosomal DNA of a microorganism belonging to coryneform bacterium,
This is carried out by homologous recombination by utilizing a sequence present in multiple copies on the chromosomal DNA as a target. Repetitive DNA and inverted repeats present at the ends of transposable elements can be used as the sequences present in multiple copies on the chromosomal DNA. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 2-109985, it is also possible to mount a gene encoding succinate dehydrogenase on a transposon and allow it to be transferred to introduce multiple copies onto chromosomal DNA. Either method increases the copy number of the gene encoding succinate dehydrogenase in the transformant, resulting in amplification of succinate dehydrogenase activity.

Amplification of succinate dehydrogenase activity is not limited to the above-described gene amplification, but substitution of a strong expression control sequence such as a promoter of a gene encoding succinate dehydrogenase on chromosomal DNA or a plasmid on a plasmid. Can also be achieved by (Japanese Patent Laid-Open No. 1-
215280). For example, lac promoter, trp promoter, trc promoter, ta
c promoter, P _R promoter of lambda phage,
The P _L promoter and the like are known as strong promoters. Substitution with these promoters enhances expression of the gene encoding succinate dehydrogenase, thereby amplifying succinate dehydrogenase activity.

In addition to the succinate dehydrogenase activity of the coryneform bacterium of the present invention, the enzyme activity of other amino acid biosynthetic pathways or glycolytic pathways is enhanced to enhance those enzyme activities. Good. For example, L
-Examples of genes that can be used to produce lysine include L-
Gene encoding for aspartokinase α subunit protein or β subunit protein (WO94 / 25605 International Publication Pamphlet) in which synergistic feedback inhibition by lysine and L-threonine is substantially canceled, wild-type phospho from coryneform bacteria An enolpyruvate carboxylase gene (JP-A-60-87788), a gene encoding a wild-type dihydrodipicolinate synthase derived from coryneform bacteria (JP-B6-55149), and the like are known.

Examples of genes that can be used for the production of L-glutamic acid include glutamate dehydrogenase (GDH, JP-A-61-268185), glutamine synthetase, glutamate synthase, and isocitrate dehydrogenase (JP-A-62-166890). No. JP-A-63-214189), aconitate hydratase (JP-A-62-294086), citrate synthase, pyruvate carboxylase (JP-A-60-877).
88, JP-A-62-55089), phosphoenolpyruvate carboxylase, phosphoenolpyruvate synthase, enolase, phosphoglyceromutase,
Phosphoglycerate kinase, glyceraldehyde-3
-Phosphate dehydrogenase, triose phosphate isomerase, fructose bisphosphate aldolase, phosphofructokinase (JP-A-63-102692), glucose phosphate isomerase and the like.

Furthermore, the activity of an enzyme that catalyzes a reaction that branches from the L-amino acid biosynthetic pathway of interest to produce a compound other than the L-amino acid may be decreased or lacking. For example, as an enzyme that catalyzes a reaction that branches from the L-lysine biosynthetic pathway to produce a compound other than L-lysine, there is homoserine dehydrogenase (WO 95 /
23864). In addition, as an enzyme that catalyzes a reaction that branches from the L-glutamic acid biosynthetic pathway to produce a compound other than L-glutamic acid, α-ketoglutarate dehydrogenase, isocitrate lyase, phosphate acetyltransferase, acetate kinase, acetohydroxy acid Synthase, acetolactate synthase, formate acetyltransferase, lactate dehydrogenase, glutamate decarboxylase, 1-pyrophosphate dehydrogenase, and the like.

Furthermore, by imparting a temperature-sensitive mutation to a coryneform bacterium capable of producing L-glutamic acid, a temperature-sensitive mutation for a biotin-inhibiting substance such as a surfactant, the biotin-inhibiting effect in a medium containing an excess amount of biotin. L-glutamic acid can be produced in the absence of a substance (see WO96 / 06180). Examples of such coryneform bacteria include Brevibacterium lactofermentum AJ13029 described in WO96 / 06180. AJ130
Twenty-nine shares were deposited at the Institute of Biotechnology, Institute of Biotechnology, Institute of Industrial Science with the deposit number FERM P-14501 on September 2, 1994,
It was transferred to an international deposit under the Budapest Treaty on August 1, 1995 and is given the deposit number FERM BP-5189.

In addition, a coryneform bacterium capable of producing L-lysine and L-glutamic acid is provided with a temperature-sensitive mutation to a biotin action-suppressing substance, whereby a biotin action-suppressing substance is contained in a medium containing an excess amount of biotin. L-lysine and L-glutamic acid can be co-produced in the absence of (see WO96 / 06180). Examples of such strains include Brevibacterium lactofermentum AJ12993 strain described in WO96 / 06180. The strain was deposited at the Institute of Biotechnology, Institute of Biotechnology, Institute of Industrial Science with the deposit number FERM P-14348 as of June 3, 1994, and was transferred to the international deposit under the Budapest Treaty on August 1, 1995 and deposited. It is numbered FERM BP-5188.

<3> Production of L-amino acid The succinate dehydrogenase activity is amplified, and
When a coryneform bacterium having an L-amino acid-producing ability is cultured in a suitable medium, the L-amino acid accumulates in the medium. For example, when a coryneform bacterium having an amplified succinate dehydrogenase activity and L-lysine acid-producing ability is cultured in a suitable medium, L-lysine is accumulated in the medium. Also,
Succinate dehydrogenase activity is amplified and L
When L-glutamic acid is accumulated in the medium, the coryneform bacterium capable of producing glutamic acid is cultured in a suitable medium.

Furthermore, when a coryneform bacterium having an amplified succinate dehydrogenase activity and an ability to produce L-lysine and L-glutamic acid is cultured in a medium, L-lysine and L-glutamic acid are accumulated in the medium. When simultaneously producing L-lysine and L-glutamic acid by fermentation,
The L-lysine-producing bacterium may be cultured under L-glutamic acid-producing conditions, or a coryneform bacterium having L-lysine-producing ability and a coryneform bacterium having L-glutamic acid-producing ability may be mixed and cultured. (JP-A-5-3793).

Using the microorganism of the present invention, L-lysine or L
The medium used for producing L-amino acids such as glutamic acid is a normal medium containing a carbon source, a nitrogen source, inorganic ions and, if necessary, other organic micronutrients. As the carbon source, glucose, lactose, galactose, fructose, sucrose, molasses, carbohydrates such as starch hydrolysate, alcohols such as ethanol and inositol, organic acids such as acetic acid, fumaric acid, citric acid, and succinic acid. Can be used.

As the nitrogen source, ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, inorganic ammonium salts such as ammonium acetate, ammonia, peptone, meat extract, yeast extract, yeast extract,
Organic nitrogen such as corn steep liquor and soybean hydrolyzate, ammonia gas, and ammonia water can be used.

As the inorganic ions, potassium phosphate, magnesium sulfate, iron ions, manganese ions and the like are added in small amounts. As the organic micronutrients, it is desirable to contain required substances such as vitamin B ₁ or yeast extract in an appropriate amount as necessary.

The culture is preferably carried out for 16 to 72 hours under aerobic conditions such as shaking culture and aeration and stirring culture. The culture temperature is controlled at 30 ° C to 45 ° C and the pH during culture is controlled at 5-9. To do. Inorganic or organic acidic or alkaline substances, ammonia gas, etc. can be used for pH adjustment.

Collection of L-amino acids from the fermentation broth can be carried out in the same manner as in ordinary L-amino acid production methods. For example, L-lysine can be usually collected by combining an ion exchange resin method, a precipitation method and other known methods. Further, the method for collecting L-glutamic acid may be carried out by a conventional method, for example, an ion exchange resin method,
A crystallization method or the like can be used. Specifically, L-glutamic acid is adsorbed and separated by an anion exchange resin, or
Alternatively, neutralization crystallization may be performed. When producing both L-lysine and L-glutamic acid, it is not necessary to separate these amino acids from one another if they are used as a mixture.

[0036]

EXAMPLES The present invention will be described in more detail below with reference to examples.

<1> Cloning of sdh gene of Escherichia coli JM109 strain The nucleotide sequence of the sdh gene of Escherichia coli has already been clarified (Genbank / EMBL / DDBJ accetion No.J016.
19 K00542 M11121). The primers shown in SEQ ID NOS: 1 and 2 of the Sequence Listing were synthesized based on the reported nucleotide sequence,
The pyruvate dehydrogenase gene was amplified by PCR using the chromosomal DNA of Escherichia coli JM109 strain as a template.

Among the synthesized primers, SEQ ID NO: 1 is
Genbank / EMBL / DDBJ accetion No. J01619 K00542 M1112
1 corresponds to the sequence extending from the 1992th base to the 2015th base in the base sequence of the sdh gene, and SEQ ID NO: 2 corresponds to the sequence extending from the 6309th base to the 6286th base.

Chromosomal DN of Escherichia coli JM109 strain
Preparation of A was carried out by a conventional method (Biotechnology Experiment Book, edited by Japan Society for Biotechnology, pp. 97-98, Baifukan, 1992). Also,
For the PCR reaction, the standard reaction conditions described on page 185 of the PCR method front line (Takeo Sekiya et al., Edited by Kyoritsu Shuppan, 1989) were used.

After purifying the generated PCR product by a conventional method,
After ligation with SmaI-cut plasmid pHC4 using a ligation kit (Takara Shuzo), transformation was performed using Escherichia coli JM109 competent cells (Takara Shuzo), and chloramphenicol 30 μg / ml
L medium containing 10 g / L of bactotryptone, 5 g / L of bacto yeast extract, 5 g / L of NaCl, 15 g / L of agar, pH 7.
After applying to 2) and culturing overnight, the white colonies that appeared were picked up and single colonies were separated to obtain a transformant. Extract the plasmid from the obtained transformant and use it as a vector.
A plasmid pHC4pps to which the sdh gene was bound was obtained.

Escherichia coli which retains pHC4 is named as a private number AJ12617, 199.
On April 24, 1991, the Ministry of International Trade and Industry, Institute of Industrial Science and Technology, Institute of Biotechnology, Industrial Technology (Postal code 305-8566, 1-3-1 Higashi, Tsukuba, Ibaraki, Japan), with the contract number FERM P-12215
And was transferred to an international deposit under the Budapest Treaty on August 26, 1991, with the deposit number FERM B.
P-3532 is added.

Next, in order to confirm that the cloned DNA fragment encodes a protein having a succinate dehydrogenase activity, the succinate dehydrogenase activity of JM109 strain and JM109 strain carrying pHC4sdh was confirmed by Ackerll, BAC et a
L., Meth. Enzymol. 53, 466-483 (1978). As a result, the JM109 strain that retains pHC4sdh was identified as JM10 that does not retain pHC4sdh.
Since the succinate dehydrogenase activity was about 19 times that of the 9 strains, it was confirmed that the sdh gene was expressed.

<2> Introduction of pHC4sdh into L-glutamic acid-producing strain of coryneform bacterium and plasmid pHC4sdh of L-glutamic acid-producing Brevibacterium lactofermentum AJ13029 by the electric pulse method (see JP-A-2-207791). The resulting transformant was obtained. Using the obtained transformant AJ13029 / pHC4sdh, L-
The culture for producing glutamic acid was performed as follows.
The cells of AJ13029 / pHC4sdh strain obtained by culturing in CM2B plate medium containing 5 μg / ml of chloramphenicol were
An L-glutamic acid-producing medium having the following composition containing μg / ml of chloramphenicol was inoculated, shake-cultured at 31.5 ° C., and shake-cultured until the sugar in the medium was consumed.
The resulting culture was inoculated into a medium of the same composition in an amount of 5%,
Shaking culture was carried out at ℃ until the sugar in the medium was consumed. As a control, the strain AJ13029 of the genus Corynebacterium was transformed by the electric pulse method with the plasmid pHC4 capable of autonomous replication in the bacterium of the genus Corynebacterium, which was obtained in the same manner as above.

[L-glutamic acid-producing medium] The following components (in 1 L) were dissolved, adjusted to pH 8.0 with KOH, and then at 115 ° C for 15
Sterilize for minutes. Glucose _{150g KH 2 PO 4 2g MgSO 4} · 7H 2 O 1.5g FeSO 4 · 7H 2 O 15mg MnSO 4 · 4H 2 O 15mg soy protein hydrolyzate 50ml biotin 2mg thiamine hydrochloride 3mg

After completion of the culturing, the accumulated amount of L-glutamic acid in the culture broth was measured by Asahi Kasei Kogyo Biotech Analyzer AS.
It was measured by -210. The results at this time are shown in Table 1.

[0046]

[Table 1]

<3> Introduction of pHC4sdh into an L-lysine-producing strain of coryneform bacterium and L-lysine-producing Brevibacterium lactofermentum AJ11082 by the electric pulse method (see Japanese Patent Laid-Open No. 2-207791) for plasmid pHC4sdh. The resulting transformant was obtained. Using the obtained transformant AJ11082 / pHC4sdh, L-
Culture for lysine production was performed as follows. 5 μg / m
5 μg / ml of cells of AJ11082 / pHC4sdh strain obtained by culturing in CM2B plate medium containing 1 chloramphenicol
Was inoculated into the L-lysine production medium having the following composition containing chloramphenicol and cultured at 31.5 ° C. with shaking until the sugar in the medium was consumed. As a control, the strain AJ11082 of the genus Corynebacterium was transformed by the electric pulse method with the plasmid pHC4 capable of autonomous replication in the bacterium of the genus Corynebacterium already obtained, and cultured in the same manner as above.

Brevibacterium lactofermentum AJ11082 was prepared on the 18th of June, 1979.
Research Service Culture Collection (Agri
cultural research service culture collection) and has been deposited with the deposit number NRRL B-11470.

[L-lysine production medium] The following components (in 1 L) other than calcium carbonate were dissolved, adjusted to pH 8.0 with KOH, sterilized at 115 ° C for 15 minutes, and then dry heat-sterilized calcium carbonate was added. Add 50 g. Glucose 100 g (NH ₄ ) ₂ SO ₄ 55 g KH ₂ PO ₄ 1 g MgSO ₄ / 7H ₂ O 1 g biotin 500 μg thiamine 2000 μg FeSO ₄ / 7H ₂ O 0.01 g MnSO ₄ / 7H ₂ O 0.01 g nicotinamide 5 mg protein hydrolyzate (bean concentrate) 30 ml calcium carbonate 50 g

After completion of the culturing, the amount of L-lysine accumulated in the culture broth was measured as Biotech Analyzer AS-21 manufactured by Asahi Kasei Corporation.
It was measured by 0. The results at this time are shown in Table 2.

[0051]

[Table 2]

<4> L-lysine and L- of coryneform bacterium
Introduction of pHC4sdh into a glutamic acid-producing strain and Brevibacterium lactofermentum AJ12993 co-producing L-lysine and L-glutamic acid were transformed with the plasmid pHC4sdh by the electric pulse method (see Japanese Patent Laid-Open No. 2-207791). A transformed strain was obtained. Using the obtained transformant AJ12993 / pHC4sdh, L-
Culturing for lysine and L-glutamic acid production was performed as follows. AJ12993 / pHC4sd obtained by culturing in CM2B plate medium containing 5 μg / ml chloramphenicol
The cells of the h strain were inoculated into the L-lysine production medium containing 5 μg / ml of chloramphenicol and cultured at 31.5 ° C.
The culture temperature was shifted to 34 ° C. 12 hours after the culture was started, and the culture was performed with shaking until the sugar in the medium was consumed.
Corynebacterium bacterium AJ12993 as a control
A strain obtained by transforming the already obtained plasmid pHC4 capable of autonomous replication in a bacterium belonging to the genus Corynebacterium by the electric pulse method was cultured in the same manner as above.

After completion of the culture, L-lysine and L in the culture solution
-The amount of accumulated glutamic acid was measured by Biotech Analyzer AS-210 manufactured by Asahi Kasei. The results at this time are shown in Table 3.

[0054]

[Table 3]                                 Table 3 ───────────────────────────────────     Strain L-lysine production (g / L) L-glutamic acid production (g / L) ───────────────────────────────────   AJ12993 / pHC4 10.1 20.0   AJ12993 / pHC4sdh 11.8 22.3 ───────────────────────────────────

[0055]

Industrial Applicability According to the present invention, the ability of coryneform bacteria to produce L-amino acids such as L-lysine or L-glutamic acid can be improved.

[0056]

[Sequence list]                             Sequence Listing

[0057] <110> Ajinomoto Co., Inc. <120> Method for producing L-amino acid <130> P-6641 <141> 1999-07-02 <160> 2 <170> PatentIn Ver. 2.0

[0058] <210> 1 <211> 24 <212> DNA <213> Artificial Sequence <220> <223> Description of Artificial Sequence: primer for       amplifying Esherichia coli sdh gene <400> 1 tcgcgacgga aagcatggaa caga 24

[0059] <210> 2 <211> 24 <212> DNA <213> Artificial Sequence <220> <223> Description of Artificial Sequence: primer for       amplifying Esherichia coli sdh gene <400> 2 ttacgcatta cgttgcaaca acat 24

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C12P 13/08 C12P 13/14 A 13/14 C12R 1:15 // (C12P 13/06 C12P 13/14 C12R 1:15) C12N 15/00 A (C12P 13/08 C12R 1:15) (C12P 13/14 C12R 1:15) (72) Inventor Osamu Kurahashi 1-1 Ajinomoto, Suzuki Town, Kawasaki-ku, Kanagawa Prefecture F-term in Fermentation Research Institute of the company (reference) 4B024 AA03 BA71 BA72 BA73 BA74 CA03 DA10 EA04 FA13 GA11 4B064 AE07 AE08 AE10 AE19 AE25 CA02 CA19 CC24 DA10 4B065 AA22X AA24X AA26Y AA32X AB01 AC14 BA02 CA17 CA41

Claims (6)

[Claims] 1. A coryneform bacterium having enhanced succinate dehydrogenase activity in cells and L-amino acid-producing ability. 2. The L-amino acid is L-lysine or L-
Glutamic acid, L-threonine, L-isoleucine, L
-The coryneform bacterium of claim 1, selected from serine. 3. The coryneform bacterium according to claim 1, wherein the succinate dehydrogenase activity is enhanced by increasing the copy number of a gene encoding succinate dehydrogenase in the bacterial cell. 4. The coryneform bacterium according to claim 3, wherein the gene encoding the succinate dehydrogenase is derived from a bacterium belonging to the genus Escherichia. 5. The coryneform bacterium according to any one of claims 1 to 4 is cultured in a medium, L-amino acids are produced and accumulated in the culture, and the L-amino acids are collected from the culture. A method for producing an L-amino acid, which comprises: 6. The L-amino acid is L-lysine or L-
Glutamic acid, L-threonine, L-isoleucine, L
-The method of claim 5 selected from serine.