Corynebacterium glutamicum mutant strain with improved L-lysine production ability and method for producing L-lysine using the same

Abstract

The present invention relates to a Corynebacterium glutamicum mutant strain having improved L-lysine production ability and a method for producing L-lysine using the same. The mutant strain can improve the L-lysine production yield compared to the parent strain by increasing or enhancing the expression of a gene encoding diaminopimelate decarboxylase.

Description

[Technical Field]

[0001] The present invention relates to a Corynebacterium glutamicum mutant strain having improved L-lysine-producing ability and a method for producing L-lysine using the same. [Background technology]

[0002] L-lysine is an essential amino acid that cannot be synthesized in the human or animal body and must therefore be supplied from an external source. It is generally produced by fermentation using microorganisms such as bacteria or yeast. Wild-type strains obtained naturally or mutant strains modified to enhance their L-lysine-producing ability are used for L-lysine production. Recently, in order to improve the efficiency of L-lysine production, genetic engineering has been applied to microorganisms such as Escherichia coli and Corynebacterium, which are commonly used to produce L-amino acids and other useful substances, to develop various recombinant or mutant strains with excellent L-lysine-producing ability, as well as L-lysine production methods using them.

[0003] According to Patent Documents 1 and 2, L-lysine production ability can be improved by increasing expression of a gene encoding a protein containing an enzyme involved in L-lysine production by modifying the nucleotide sequence or amino acid sequence of the gene or by deleting an unnecessary gene. Patent Document 3 also discloses a method for modifying the existing promoter of a gene encoding an enzyme involved in L-lysine production with a promoter with stronger activity in order to increase expression of the gene.

[0004] As described above, various methods for improving L-lysine production have been developed. However, since there are several dozen types of proteins, such as enzymes, transcription factors, and transport proteins, that are directly or indirectly involved in L-lysine production, much research is still needed to determine whether L-lysine production can be improved by changing the activity of these proteins. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent No. 10-0838038 [Patent Document 2] Korean Patent Registration No. 10-2139806 [Patent Document 3] Korean Patent Publication No. 10-2020-0026881 [Non-patent literature]

[0006] [Non-Patent Document 1] Manual of Methods for General Bacteriology. American Society for Bacteriology. Washington DC, USA, 1981 [Non-patent document 2] Kim et al., Journal of Microbiological Methods 84 (2011) 128-130 [Non-patent document 3] Tauch et al., FEMS Microbiology letters 123 (1994) 343-347 [Non-patent document 4] Schafer et al., Gene 145 (1994) 69-73 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a Corynebacterium glutamicum mutant strain with improved L-lysine productivity.

[0008] Another object of the present invention is to provide a method for producing L-lysine using the mutant strain. [Means for solving the problem]

[0009] The present inventors conducted extensive research to develop a new mutant strain of Corynebacterium glutamicum with improved L-lysine production ability. As a result, they confirmed that L-lysine production increases when the base sequence at a specific position in the promoter of the lysA gene, which encodes diaminopimelate decarboxylase, which acts in the final step of the L-lysine biosynthetic pathway, is replaced, thereby completing the present invention.

[0010] One aspect of the present invention provides a Corynebacterium glutamicum mutant strain having enhanced L-lysine productivity due to enhanced diaminopimelate decarboxylase activity.

[0011] In the present invention, "diaminopimelate decarboxylase" refers to an enzyme that catalyzes the reaction of cleaving the carbon bond of meso-diaminoheptanedioate (mDAP) to produce carbon dioxide and L-lysine in the final step of the L-lysine biosynthesis pathway.

[0012] According to one embodiment of the present invention, the diaminopimelate decarboxylase may be derived from a strain of the genus Corynebacterium. Specifically, the Corynebacterium strains include Corynebacterium glutamicum, Corynebacterium crudilactis, Corynebacterium deserti, Corynebacterium callunae, Corynebacterium suranareeae, Corynebacterium lubricantis, Corynebacterium doosanense, Corynebacterium efficiens, Corynebacterium utereki, Corynebacterium Corynebacterium uterequi, Corynebacterium stationis, Corynebacterium pacaense, Corynebacterium singulare, Corynebacterium humireducens, Corynebacterium marinum, Corynebacterium halotolerans, Corynebacterium spheniscorum, Corynebacterium freiburgense, Corynebacterium striatum striatum, Corynebacterium canis, Corynebacterium ammoniagenesammoniagenes, Corynebacterium renale, Corynebacterium pollutisoli, Corynebacterium imitans, Corynebacterium caspium, Corynebacterium testudinoris, Corynebacterium pseudopelargi, or Corynebacterium flavescens.

[0013] In the present invention, "enhancing activity" means increasing the expression level compared to a wild-type strain or a strain before modification by newly introducing or increasing the expression of a gene encoding a protein such as a target enzyme, transcription factor, or transport protein. Such activity enhancement includes improving the activity of a protein itself compared to the activity of the protein originally possessed by the microorganism through substitution, insertion, deletion, or a combination thereof of nucleotides encoding the gene, as well as increasing the overall level of enzymatic activity within the cell compared to a wild-type strain or a strain before modification through increased expression or translation of the gene encoding it, and combinations thereof.

[0014] According to one embodiment of the present invention, the activity of diaminopimelate decarboxylase may be enhanced by site-specific mutagenesis of the promoter of the gene encoding diaminopimelate decarboxylase.

[0015] According to one embodiment of the present invention, the promoter of the gene encoding diaminopimelate decarboxylase may be represented by the nucleotide sequence of SEQ ID NO:1.

[0016] In the present invention, the term "promoter" refers to a specific DNA site that initiates mRNA transcription of a target gene, contains a binding site for RNA polymerase, and regulates gene transcription, and is generally located upstream of the transcription start site. A prokaryotic promoter is defined as a site near the transcription start site to which RNA polymerase binds, and generally consists of two short base sequences spaced apart by base pairs in the -10 and -35 regions upstream of the transcription start site. The promoter mutations in the present invention are used to improve promoter activity compared to wild-type promoters, and by inducing mutations in the promoter region located upstream of the transcription start site, the expression of downstream genes can be increased.

[0017] According to one embodiment of the present invention, the activity of diaminopimelate decarboxylase may be enhanced by substituting at least one base in the -25 to -10 region upstream of the transcription start point in the promoter sequence of the gene encoding diaminopimelate decarboxylase.

[0018] More specifically, the promoter mutation in the present invention may be a continuous or discontinuous substitution of at least one base in the -25 to -10 region, preferably one, two, three, four, or five bases in the -20 to -15 region, the -19 to -16 region, or the -18 and -17 regions.

[0019] According to one embodiment of the present invention, the lysA gene encoding diaminopimelate decarboxylase forms an operon with the argS gene encoding arginyl-tRNA synthetase, and the argS-lysA operon is regulated by a single promoter. Therefore, a Corynebacterium glutamicum mutant strain having a new promoter sequence for the lysA gene was obtained by substituting CG for CT in the base sequences at -17 and -18 in the promoter sequence of the argS-lysA operon of a Corynebacterium glutamicum strain. Such a Corynebacterium glutamicum mutant strain may contain a mutated promoter sequence for the lysA gene represented by the base sequence of SEQ ID NO: 2.

[0020] According to one embodiment of the present invention, a Corynebacterium glutamicum mutant having a new promoter sequence for the lysA gene was obtained by substituting CG for GA in the nucleotide sequences at -17 and -18 regions of the promoter sequence of the argS-lysA operon of a Corynebacterium glutamicum strain. Such a Corynebacterium glutamicum mutant may contain a mutated promoter sequence for the lysA gene represented by the nucleotide sequence of SEQ ID NO: 3.

[0021] According to one embodiment of the present invention, a Corynebacterium glutamicum mutant strain having a new promoter sequence of the lysA gene was obtained by substituting CG for GT in the nucleotide sequences of the -17 and -18 regions of the promoter sequence of the argS-lysA operon of a Corynebacterium glutamicum strain. Such a Corynebacterium glutamicum mutant strain may contain a mutated promoter sequence of the lysA gene represented by the nucleotide sequence of SEQ ID NO: 4.

[0022] In the present invention, "improved productivity" refers to a strain that has improved L-lysine productivity compared to a parent strain. The parent strain refers to a wild-type or mutant strain that is the target of mutation, and includes strains that are the target of direct mutation and those that are the target of transformation using a recombinant vector, etc. In the present invention, the parent strain may be a wild-type Corynebacterium glutamicum strain or a strain mutated from the wild type.

[0023] According to one embodiment of the present invention, the parent strain may be a mutant strain in which mutations have been induced in the sequences of genes involved in lysine production (e.g., lysC, zwf, and hom genes), and may be a Corynebacterium glutamicum strain deposited at the Korean Culture Center of Microorganisms on April 2, 2021 under accession number KCCM12969P (hereinafter referred to as the "C. glutamicum DS1 strain").

[0024] According to one embodiment of the present invention, the Corynebacterium glutamicum mutant strain with improved L-lysine production ability exhibits improved L-lysine production ability compared to the parent strain due to the inclusion of a promoter mutation in the lysA gene encoding diaminopimelate decarboxylase. In particular, the L-lysine production amount is increased by at least 2%, specifically 2 to 40%, more specifically 3 to 30%, compared to the parent strain, and thus can produce 60 to 80 g, preferably 65 to 75 g, of L-lysine per liter of strain culture medium.

[0025] According to one embodiment of the present invention, a Corynebacterium glutamicum mutant strain is produced by a recombinant vector containing a mutant in which the promoter sequence of the gene encoding diaminopimelate decarboxylase is partially substituted in the parent strain.

[0026] In the present invention, "part" means not the entire base sequence or polynucleotide sequence, and refers to 1 to 300, preferably 1 to 100, and more preferably 1 to 50, but is not limited to these.

[0027] In the present invention, the term "mutant" refers to a promoter mutant in which at least one base in the -25 to -10 region of the promoter sequence of the diaminopimelate decarboxylase gene involved in the biosynthesis of L-lysine is substituted.

[0028] According to one embodiment of the present invention, a mutant in which the base sequence of the -17 and -18 regions in the promoter sequence of the diaminopimelate decarboxylase gene has been replaced with CT may have the base sequence of SEQ ID NO: 2, a mutant in which the base sequence has been replaced with GA may have the base sequence of SEQ ID NO: 3, and a mutant in which the base sequence has been replaced with GT may have the base sequence of SEQ ID NO: 4.

[0029] As used herein, the term "vector" refers to an expression vector that expresses a target protein in a suitable host cell, and is a genetic construct containing essential regulatory elements operably linked to allow expression of a gene insert. Here, "operably linked" refers to a gene whose expression is required and its regulatory sequence being functionally linked to each other in a manner that enables gene expression. "Regulatory elements" include a promoter for transcription, an optional operator sequence for regulating transcription, a sequence encoding a suitable mRNA ribosomal binding site, and a sequence for regulating the termination of transcription and translation. Examples of such vectors include, but are not limited to, plasmid vectors, cosmid vectors, bacteriophage vectors, and viral vectors.

[0030] When a "recombinant vector" of the present invention is transformed into a suitable host cell, it replicates independently of the genome of the host cell or is integrated into the genome itself. Here, the "suitable host cell" may be one in which the vector can replicate and which contains an origin of replication, which is a specific base sequence from which replication is initiated.

[0031] The transformation can be performed by selecting an appropriate vector introduction technique depending on the host cell, thereby allowing the gene of interest to be expressed in the host cell. For example, vector introduction can be performed by electroporation, heat shock, calcium phosphate (CaPO) precipitation, calcium chloride (CaCl) precipitation, microinjection, polyethylene glycol (PEG) method, DEAE-dextran method, cationic liposome method, lithium acetate-DMSO method, or a combination thereof. The transformed gene may be any gene that is expressed in the host cell, regardless of whether it is inserted into the host cell's chromosome or located extrachromosomally.

[0032] The host cell includes cells transfected, transformed, or infected in vivo or in vitro with a recombinant vector or polynucleotide of the invention. A host cell containing a recombinant vector of the invention may be a recombinant host cell, recombinant cell, or recombinant microorganism.

[0033] Furthermore, the recombinant vector of the present invention may contain a selection marker. The selection marker is used to select transformants (host cells) transformed with the vector. In a medium treated with the selection marker, only cells expressing the selection marker will survive, allowing the selection of transformed cells. Representative examples of the selection marker include, but are not limited to, kanamycin, streptomycin, and chloramphenicol.

[0034] The gene inserted into the recombinant vector for transformation of the present invention is replaced in a host cell such as a microorganism of the genus Corynebacterium by homologous crossover.

[0035] According to one embodiment of the present invention, the host cell may be a strain of the genus Corynebacterium, for example, the Corynebacterium glutamicum DS1 strain.

[0036] Another aspect of the present invention provides a method for producing L-lysine, comprising: a) culturing the Corynebacterium glutamicum mutant strain in a medium; and b) recovering L-lysine from the mutant strain or the medium in which the mutant strain has been cultured.

[0037] The culture can be carried out in a suitable medium and under suitable conditions known in the art, and a skilled artisan can easily adjust the medium and conditions. Specifically, the medium is a liquid medium, but is not limited thereto. The culture method can be, for example, but is not limited to, batch culture, continuous culture, fed-batch culture, or a combination thereof.

[0038] According to one embodiment of the present invention, the medium should be adapted to meet the requirements of the particular strain in a suitable manner and can be appropriately modified by a person skilled in the art. Culture media for Corynebacterium strains are disclosed in a known literature (Non-Patent Document 1), but are not limited thereto.

[0039] According to one embodiment of the present invention, the medium may contain various carbon sources, nitrogen sources, and trace element components. Usable carbon sources include sugars and carbohydrates such as glucose, sucrose, lactose, fructose, maltose, starch, and cellulose; fats and oils such as soybean oil, sunflower oil, castor oil, and coconut oil; fatty acids such as palmitic acid, stearic acid, and linoleic acid; alcohols such as glycerin and ethanol; and organic acids such as acetic acid. These substances can be used alone or in mixtures, but are not limited to these. Usable nitrogen sources include peptone, yeast extract, meat juice, malt extract, corn steep liquor, soybean flour, and urea, or inorganic compounds such as ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium carbonate, and ammonium nitrate. Nitrogen sources can also be used alone or in mixtures, but are not limited to these. Usable phosphorus sources include, but are not limited to, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, or their corresponding sodium-containing salts. The culture medium may also contain, but is not limited to, metal salts necessary for growth, such as magnesium sulfate and iron sulfate. Other essential growth substances, such as amino acids and vitamins, may also be used. Precursors suitable for the culture medium may also be used. The medium or individual components may be added to the culture solution in a suitable manner, such as batchwise or continuously, during the culture process, but are not limited to these.

[0040] According to one embodiment of the present invention, the pH of the culture medium may be adjusted by adding compounds such as ammonium hydroxide, potassium hydroxide, ammonia, phosphoric acid, or sulfuric acid to the microbial culture medium during cultivation using a suitable method. Furthermore, foam formation may be suppressed during cultivation using an antifoaming agent such as a fatty acid polyglycol ester. Furthermore, oxygen or an oxygen-containing gas (e.g., air) may be injected into the culture medium to maintain an aerobic state in the culture medium. The temperature of the culture medium is typically 20°C to 45°C, for example, 25°C to 40°C. The cultivation period may be continued until the desired production amount of the useful substance is obtained, and may be, for example, 10 to 160 hours.

[0041] According to one embodiment of the present invention, the step of recovering L-lysine from the mutant strain cultured as described above and from the culture medium in which the mutant strain was cultured may involve collecting or recovering the produced L-lysine from the medium using any suitable method known in the art, depending on the culture method, such as, but not limited to, centrifugation, filtration, extraction, spraying, drying, evaporation, precipitation, crystallization, electrophoresis, differential dissolution (e.g., ammonium sulfate precipitation), and chromatography (e.g., ion exchange, affinity, hydrophobic, and size exclusion).

[0042] According to one embodiment of the present invention, the step of recovering lysine may involve centrifuging the culture medium at low speed to remove the biomass, and separating the resulting supernatant by ion exchange chromatography.

[0043] According to one embodiment of the present invention, the step of recovering L-lysine may comprise a step of purifying L-lysine. [Effects of the Invention]

[0044] The Corynebacterium glutamicum mutant strain according to the present invention can improve the L-lysine production yield compared to the parent strain by increasing or enhancing the expression of the gene encoding diaminopimelate decarboxylase. [Brief explanation of the drawings]

[0045] [Figure 1] FIG. 1 shows the structure of the pCGI(Pm1-argS+lysA) vector containing the promoter of the argS-lysA operon in which the −17 and −18 regions of the promoter have been replaced from CG to CT according to one embodiment of the present invention. [Figure 2] FIG. 1 shows the structure of the pCGI(Pm2-argS+lysA) vector containing the promoter of the argS-lysA operon in which the −17 and −18 regions of the promoter have been replaced from CG to GA according to one embodiment of the present invention. [Figure 3]FIG. 1 shows the structure of the pCGI(Pm3-argS+lysA) vector containing the promoter of the argS-lysA operon in which the −17 and −18 regions of the promoter have been replaced from CG to GT according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention will be described in more detail below. However, these descriptions are merely examples to help understand the present invention, and the present invention is not limited to these. [Example]

[0047] 1. Preparation of Corynebacterium glutamicum Mutants To generate a Corynebacterium glutamicum mutant with enhanced diaminopimelate decarboxylase activity, Corynebacterium glutamicum DS1 and E. coli DH5a (HIT Competent Cells) were cultured. TM , Cat No. RH618) was used.

[0048] The Corynebacterium glutamicum DS1 strain was cultured at 30°C in CM-broth medium (pH 6.8) containing 5 g of glucose, 2.5 g of NaCl, 5.0 g of yeast extract, 1.0 g of urea, 10.0 g of polypeptone, and 5.0 g of beef extract in 1 L of distilled water.

[0049] The E. coli DH5a was cultured at 37°C in LB medium containing 10.0 g of tryptone, 10.0 g of NaCl, and 5.0 g of yeast extract in 1 L of distilled water.

[0050] The antibiotics kanamycin and streptomycin were manufactured by Sigma Co., Ltd. tDNA sequencing analysis was performed by Macrogen Co., Ltd.

[0051] 1-1. Construction of recombinant vectors To improve the lysine productivity of this strain, we introduced an enhanced expression of diaminopimelate decarboxylase, which acts in the final step of the lysine biosynthetic pathway. The method used in this example involved specific mutations in the promoter of the argS-lysA operon to increase expression of the lysA gene, which encodes diaminopimelate decarboxylase. The base sequences at -17 and -18 of the argS-lysA operon promoter were substituted from CG to CT. A 510-bp region on the left arm and a 480-bp region on the right arm were amplified by PCR, centered on the center of the argS-lysA operon in the Corynebacterium glutamicum genome. These were then linked by overlap PCR and subsequently cloned into the recombinant vector pCGI (see Non-Patent Document 2). The resulting plasmid was designated pCGI(Pm1-argS+lysA) (see Figure 1). To construct this plasmid, the primers listed in Table 1 were used to amplify each gene fragment.

[0052] [Table 1]

[0053] PCR was performed using these primers under the following conditions: 100 μM of each deoxynucleoside triphosphate (dATP, dCTP, dGTP, dTTP) was added to the reaction mixture, and 1 pM of oligonucleotides and 10 ng of Corynebacterium glutamicum DS1 chromosomal DNA were used as the template. PCR was performed for 25–30 cycles in the presence of 1 unit of pfu-X DNA polymerase mixture (Solgent) in a thermocycler (TP600, Takara Bio Inc., Japan). The PCR conditions were: (i) denaturation step: 94°C for 30 seconds; (ii) annealing step: 58°C for 30 seconds; and (iii) extension step: 72°C for 1–2 minutes (allowing 2 minutes of polymerization time per 1 kb).

[0054] The gene fragment thus constructed was cloned into the pCGI vector by self-assembly cloning. The vector was transformed into E. coli DH5a, spread onto an LB agar plate containing 50 μg / ml kanamycin, and cultured at 37°C for 24 hours. The resulting colonies were isolated to confirm whether the insert was correctly present in the vector. The vector was then isolated and used to recombine Corynebacterium glutamicum strains.

[0055] The gene amplification, a common step in all of the above methods, was performed by PCR amplification from the genomic DNA of the Corynebacterium glutamicum strain DS1. Depending on the strategy, the gene was inserted into the pCGI vector by self-assembled cloning and selected in E. coli DH5a. Chromosomal base substitutions were performed by amplifying each gene fragment individually and then generating the desired DNA fragment by overlap PCR. For gene manipulation, Ex Taq polymerase (Takara) and Pfu polymerase (Solgent) were used as PCR amplification enzymes, and various restriction enzymes and DNA modifying enzymes were from NEB products, using the supplied buffers and protocols.

[0056] 1-2. Creation of mutant strains The pCGI(Pm1-argS+lysA) vector was used to generate the mutant strain DS3. The vector was adjusted to a final concentration of 1 μg / μl or higher, and primary recombination was induced in the Corynebacterium glutamicum DS1 strain by electroporation (see Non-Patent Document 3). The electroporated strain was then plated on a CM agar plate containing 20 μg / μl kanamycin to isolate colonies. The successful insertion of the vector into the genomic DNA at the target site was then confirmed by PCR and sequence analysis. To induce secondary recombination in the isolated strain, the strain was inoculated into a CM agar liquid medium containing streptomycin and cultured overnight or longer. The colonies were then plated onto agar plates containing the same concentration of streptomycin to isolate colonies. Finally, the isolated colonies were examined for kanamycin resistance, and the presence or absence of a mutation in the lysA gene in strains not resistant to antibiotics was confirmed by sequence analysis (see Non-Patent Document 4). Finally, a Corynebacterium glutamicum mutant strain (DS3) carrying the mutant lysA gene was obtained. [Example]

[0057] 1. Preparation of Corynebacterium glutamicum Mutants A Corynebacterium glutamicum mutant was prepared in the same manner as in Example 1, except that the base sequence in the −17 and −18 regions of the promoter of the argS-lysA operon was replaced from CG to GA.

[0058] To prepare the plasmid, the primers listed in Table 2 were used to amplify each gene fragment, and the resulting plasmid, pCGI(Pm2-argS+lysA) vector (see Figure 2), was used to generate the mutant strain DS3-1. Finally, a Corynebacterium glutamicum mutant (DS3-1) carrying the mutant lysA gene was obtained.

[0059] [Table 2] [Example]

[0060] 1. Preparation of Corynebacterium glutamicum Mutants A Corynebacterium glutamicum mutant was prepared in the same manner as in Example 1, except that the base sequence in the −17 and −18 regions of the promoter of the argS-lysA operon was replaced from CG to GT.

[0061] To prepare the plasmid, the primers listed in Table 3 were used to amplify each gene fragment, and the resulting plasmid, pCGI(Pm3-argS+lysA), was used to generate the mutant strain DS3-2. Finally, a Corynebacterium glutamicum mutant (DS3-2) carrying the mutant lysA gene was obtained.

[0062] [Table 3]

[0063] Experimental Example 1: Comparison of L-lysine productivity among mutant strains The parent strain Corynebacterium glutamicum DS1 and the lysine-producing mutant strain DS prepared in Examples 1 to 3 were used. 3 strain, DS 3 -1 strain and DS 3 The L-lysine productivity of the two strains was compared.

[0064] Each strain was inoculated into a 100 ml flask containing 10 ml of lysine medium with the composition shown in Table 4, and cultured at 30°C and 180 rpm for 48 hours with shaking. After the culture was completed, the amount of L-lysine produced was measured by HPLC (Shimazu, Japan) to analyze lysine. The results are shown in Table 5.

[0065] [Table 4]

[0066] [Table 5]

[0067] As shown in Table 5, the Corynebacterium glutamicum mutants DS3, DS3-1, and DS3-2 were modified with the optimal base sequence (CT, GA, or GT) at specific positions (-17 and -18 regions) of the promoter sequence of the argS-lysA operon to enhance the lysine biosynthetic pathway. This resulted in L-lysine productivity improvements of approximately 4.7%, 6.3%, and 12.5%, respectively, compared to the parent strain, Corynebacterium glutamicum DS1. These results demonstrate that enhanced expression of the lysA gene promotes the cleavage of the carbon bond in the lysine precursor, thereby improving the strain's L-lysine production ability.

[0068] The present invention has been described above with reference to preferred embodiments. Those skilled in the art will understand that the present invention can be modified without departing from its essential characteristics. Therefore, the disclosed embodiments are illustrative of the present invention, and are not intended to limit the present invention. The scope of the present invention is defined by the claims, not by these descriptions, and all differences within the scope of the claims should be construed as being within the scope of the present invention.

Claims

1. A promoter for expressing diaminopimelate decarboxylase in Corynebacterium glutamicum, in which the nucleotide sequence at positions 183 and 184 of the promoter sequence of the gene encoding diaminopimelate decarboxylase, represented by SEQ ID NO: 1, is substituted from CG to GT.

2. A Corynebacterium glutamicum mutant having improved L-lysine-producing ability and containing a promoter for expression of diaminopimelate decarboxylase, wherein the nucleotide sequence at positions 183 and 184 of the promoter sequence of the gene encoding diaminopimelate decarboxylase, as shown in SEQ ID NO: 1, has been substituted from CG to GT.

3. The Corynebacterium glutamicum mutant strain according to claim 2 , wherein the mutant strain comprises the nucleotide sequence represented by SEQ ID NO:

4.

4. a) culturing the mutant strain of claim 2 in a medium; and b) recovering L-lysine from the mutant strain or the culture medium in which the mutant strain was cultured; Method for producing L-lysine.

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