Corynebacterium mutant microorganism producing L-glutamic acid and method for producing L-glutamic acid using the same

Abstract

The present invention relates to a Corynebacterium mutant microorganism that produces L-glutamic acid and a method for producing L-glutamic acid using the same. More specifically, the present invention relates to a novel mutant of malate:quinone oxidoreductase involved in the biosynthetic pathway of L-glutamic acid, a polynucleotide, a transformant, and a method for producing L-glutamic acid using the same. The malate:quinone oxidoreductase mutant according to the present invention has a change in the activity of the enzyme due to substitution of one or more amino acids in the amino acid sequence constituting the malate:quinone oxidoreductase, and a recombinant microorganism containing the same can efficiently produce L-glutamic acid.

Description

Technical Field

[0001] The present invention relates to a mutant microorganism of the genus Corynebacterium that produces L-glutamic acid and a method for producing L-glutamic acid using the same, and more specifically, to a novel mutant of malate:quinone oxidoreductase involved in the biosynthetic pathway of L-glutamic acid, a polynucleotide, a transformant, and a method for producing L-glutamic acid using the same.

Background Art

[0002] L-Glutamic acid is a typical amino acid produced by microbial fermentation. Monosodium L-glutamate (MSG) enhances the preference for foods such as meat, fish, chicken, vegetables, sauces, soups, and seasonings by balancing and harmonizing the overall taste of food, and can enhance the taste of low-salt foods with up to 30% reduction in salt. It is widely used as a seasoning for household and processed food production.

[0003] Looking briefly at the fermentation pathway of L-glutamic acid, glucose mainly undergoes the glycolytic pathway, but a part of it is metabolized to two molecules of pyruvic acid via the pentose phosphate pathway. One of these molecules fixes CO2 to become oxaloacetic acid, and the other molecule combines with acetyl CoA from pyruvic acid to become citric acid. Furthermore, oxaloacetic acid and citric acid enter the TCA cycle to become α-ketoglutaric acid. Here, the oxidative metabolic pathway from α-ketoglutaric acid to succinic acid is lacking, and since isocitrate dehydrogenase and glutamate dehydrogenase are closely involved, the reductive amination reaction of α-ketoglutaric acid proceeds efficiently to produce L-glutamic acid.

[0004] For the production of L-glutamic acid, wild-type strains obtained in a natural state or mutant strains modified to improve their glutamic acid production ability can be used. Recently, in order to improve the production efficiency of L-glutamic acid, genetic recombination technology has been applied to microorganisms such as Escherichia coli and Corynebacterium, which are widely used for the production of useful substances such as amino acids and nucleic acids, and various recombinant strains or mutant strains with excellent L-glutamic acid production ability and methods for producing L-glutamic acid using them have been developed. In particular, there have been attempts to target genes such as enzymes, transcription factors, and transport proteins involved in the biosynthetic pathway of L-glutamic acid, or to induce mutations in promoters that regulate their expression to increase the production amount of L-glutamic acid. However, since the number of types of proteins such as enzymes, transcription factors, and transport proteins directly or indirectly related to the production of L-glutamic acid reaches more than several tens, there is still a great need for a lot of research on whether the production ability of L-glutamic acid increases due to changes in the activity of such proteins.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a novel malate:quinone oxidoreductase mutant.

[0007] Another object of the present invention is to provide a polynucleotide encoding the mutant.

[0008] Furthermore, an object of the present invention is to provide a transformant containing the mutant or polynucleotide.

[0009] Another object of the present invention is to provide a method for producing L-glutamic acid using the transformant.

Means for Solving the Problems

[0010] One aspect of the present invention provides a malate:quinone oxidoreductase mutant consisting of the amino acid sequence of SEQ ID NO: 2, wherein proline at position 113 in the amino acid sequence of SEQ ID NO: 4 is substituted with serine.

[0011] The “malate:quinone oxidoreductase” used in the present invention is NAD +An enzyme that reversibly catalyzes the reaction of reducing NADH and oxidizing malate to oxaloacetate, and is involved in many metabolic pathways including the citric acid cycle. The malate:quinone oxidoreductase may be a gene encoding malate:quinone oxidoreductase or a sequence having substantial identity thereto. Here, "substantial identity" means that when each gene sequence, i.e., the base sequence or nucleotide sequence, is aligned and analyzed to maximize correspondence with any other nucleotide sequence, the any other nucleotide sequence has a sequence homology of 70% or more, 80% or more, 90% or more, or 98% or more with each nucleotide sequence.

[0012] The malate:quinone oxidoreductase in the present invention is encoded by the ncgl1926 gene and contains the amino acid sequence of SEQ ID NO: 4.

[0013] According to one specific example of the present invention, the amino acid sequence of SEQ ID NO: 4 may be derived from a microorganism of the genus Corynebacterium of the wild type.

[0014] More specifically, the microorganism of the genus Corynebacterium may be Corynebacterium glutamicum.

[0015] The "variant" used in the present invention means a polypeptide in which one or more amino acids are conservatively substituted, deleted, modified or added at the N-terminus, C-terminus and / or internally in the amino acid sequence of a specific gene, which is different from the amino acid sequence before the mutation of the variant, but the functions or properties are maintained. Here, "conservative substitution" means substituting one amino acid with another amino acid having similar structural and / or chemical properties, which has little or no effect on the activity of the protein or polypeptide. The amino acids are selected from alanine (Ala), isoleucine (Ile), valine (Val), leucine (Leu), methionine (Met), asparagine (Asn), cysteine (Cys), glutamine (Gln), serine (Ser), threonine (Thr), phenylalanine (Phe), tryptophan (Trp), tyrosine (Tyr), aspartic acid (Asp), glutamic acid (Glu), arginine (Arg), histidine (His), lysine (Lys), glycine (Gly) and proline (Pro).

[0016] In addition, the variant includes those in which one or more parts such as an N-terminal leader sequence or a transmembrane domain are removed, or a part is removed from the N- and / or C-terminus of the mature protein.

[0017] Such variants may have increased (enhanced), unchanged, or decreased (attenuated) abilities compared to the protein or polypeptide before the mutation. Here, "increase or enhancement" includes cases where the activity of the protein itself increases compared to the protein before the mutation, cases where the overall protein activity level in the cell is higher than that in the wild-type strain or the strain expressing the protein before the mutation due to increased gene expression or increased translation of the gene encoding the protein, and combinations thereof. Also, "decrease or attenuation" includes cases where the activity of the protein itself decreases compared to the protein before the mutation, cases where the overall protein activity level in the cell is lower than that in the wild-type strain or the strain expressing the protein before the mutation due to inhibition of gene expression or inhibition of translation of the gene encoding the protein, and combinations thereof. In the present invention, the variant can be used interchangeably with mutant, variant, mutant polypeptide, mutated protein, mutation, etc.

[0018] The variant in the present invention is a malate:quinone oxidoreductase in which proline, which is the amino acid located at position 113 in the amino acid sequence of SEQ ID NO: 4, is substituted with serine, and may consist of the amino acid sequence of SEQ ID NO: 2.

[0019] Another aspect of the present invention provides a polynucleotide encoding the malate:quinone oxidoreductase variant.

[0020] The "polynucleotide" used in the present invention is a polymer of nucleotides in which nucleotide monomers are covalently linked in a long chain, and is a DNA or RNA strand having a certain length or more. More specifically, it means a polynucleotide fragment encoding the variant.

[0021] The polynucleotide may include a base sequence encoding the amino acid sequence of SEQ ID NO: 2.

[0022] According to one specific example of the present invention, the polynucleotide may contain the nucleotide sequence represented by SEQ ID NO: 1.

[0023] Another aspect of the present invention provides a vector comprising a polynucleotide encoding the malate:quinone oxidoreductase variant.

[0024] Also, another aspect of the present invention provides a transformant comprising the malate:quinone oxidoreductase variant or polynucleotide.

[0025] As used in the present invention, the term "vector" means all types of nucleic acid sequence carrier structures used as a means for transferring and expressing a target gene in a host cell. Unless otherwise specified, the vector can mean one in which the carried nucleic acid sequence is inserted into the host cell genome and expressed and / or expressed independently. Such a vector contains essential regulatory elements operably linked so that the gene insert is expressed. "Operably linked" means that the target gene and its regulatory sequences are linked in a manner that enables genetic expression by being functionally bound to each other. "Regulatory elements" include a promoter for transcription, any operator sequence for regulating transcription, a sequence encoding a suitable mRNA ribosome binding site, and a sequence for regulating the termination of transcription and translation.

[0026] The vector used in the present invention is not particularly limited as long as it can replicate in a host cell, and any vector known in the art can be used. Examples of the vector include plasmids, cosmids, viruses, and bacteriophages in their natural or recombinant states. For example, phage vectors or cosmid vectors include pWE15, M13, λMBL3, λMBL4, λIXII, λASHII, λAPII, λt10, λt11, Charon4A, Charon21A, etc., and plasmid vectors include pBR series, pUC series, pBluescriptII series, pGEM series, pTZ series, pCL series, and pET series, etc., but are not limited thereto.

[0027] The vector can typically be constructed as a vector for cloning or a vector for expression. Vectors for expression can use those commonly used in the art for expressing foreign genes or proteins in plants, animals, or microorganisms, and can be constructed by various methods known in the art.

[0028] The "recombinant vector" used in the present invention can be replicated regardless of the host cell genome or integrated into the genome itself after being transformed into a suitable host cell. At this time, the "suitable host cell" can be one in which the vector can replicate and can contain an origin of replication which is a specific base sequence at which replication is initiated. For example, when the vector used is an expression vector and a prokaryotic cell is used as the host, it generally contains a strong promoter capable of promoting transcription (for example, pLλ promoter, CMV promoter, trp promoter, lac promoter, tac promoter, T7 promoter), a ribosome binding site for the start of translation, and a transcription / translation termination sequence. When a eukaryotic cell is used as the host, the origin of replication that functions in eukaryotic cells contained in the vector includes, but is not limited to, f1 origin of replication, SV40 origin of replication, pMB1 origin of replication, adenovirus origin of replication, AAV origin of replication, and BBV origin of replication. In addition, a promoter derived from the genome of a mammalian cell (for example, metallothionein promoter) or a promoter derived from a mammalian virus (for example, adenovirus late promoter, vaccinia virus 7.5K promoter, SV40 promoter, cytomegalovirus promoter, HSV tk promoter) may be used, and it generally has a polyadenylation sequence as a transcription termination sequence.

[0029] The recombinant vector can contain a selection marker, and the selection marker is for screening transformants (host cells) transformed with the vector. Since only cells expressing the selection marker can survive in a medium treated with the selection marker, it is possible to screen the transformed cells. Representative examples of the selection marker include, but are not limited to, kanamycin, streptomycin, chloramphenicol, etc.

[0030] Transformants can be created by inserting a recombinant vector into a host cell, and the transformant may be obtained by introducing the recombinant vector into an appropriate host cell. The host cell is a cell capable of stably and continuously cloning or expressing the expression vector, and any host cell known in the art can be used.

[0031] When transforming a prokaryotic cell to produce a recombinant microorganism, host cells such as Escherichia coli strains such as E. coli JM109, E. coli BL21, E. coli RR1, E. coli LE392, E. coli B, E. coli X 1776, E. coli W3110, E. coli XL1-Blue, Bacillus subtilis, Bacillus thuringiensis strains such as Bacillus strains, Corynebacterium strains, Salmonella typhimurium, Serratia marcescens and various enterobacteria and strains such as Pseudomonas species may be used, but are not limited thereto.

[0032] When transforming a eukaryotic cell to produce a recombinant microorganism, host cells such as yeast (e.g., Saccharomyces cerevisiae), insect cells, plant cells and animal cells, e.g., Sp2 / 0, CHO K1, CHO DG44, PER.C6, W138, BHK, COS7, 293, HepG2, Huh7, 3T3, RIN, MDCK cell lines, etc. may be used, but are not limited thereto.

[0033] "Transformation" as used in the present invention means a phenomenon of artificially causing a genetic change by introducing foreign DNA into a host cell, and "transformant" means a host cell into which foreign DNA has been introduced and which stably maintains the expression of the target gene.

[0034] For the above-mentioned transformation, a suitable vector introduction technique is selected by the host cell, and the target gene or the recombinant vector containing the same can be expressed in the host cell. For example, the introduction of the vector may be carried out by electroporation, heat-shock, calcium phosphate (CaPO4) precipitation, calcium chloride (CaCl2) precipitation, microinjection, polyethylene glycol (PEG) method, DEAE-dextran method, cationic liposome method, lithium acetate-DMSO method, or a combination thereof, but is not limited thereto. As long as the transformed gene can be expressed in the host cell, it is inclusively and unrestrictedly included whether it is inserted into the chromosome of the host cell or located extrachromosomally.

[0035] The above-mentioned transformant includes cells that are transfected, transformed, or infected with the recombinant vector according to the present invention in vivo or in vitro, and can be used as the same term as a recombinant host cell, recombinant cell, or recombinant microorganism.

[0036] According to one specific example of the present invention, the above-mentioned transformant may be a microorganism belonging to the genus Corynebacterium.

[0037] More specifically, examples of the Corynebacterium genus microorganisms include Corynebacterium glutamicum, Corynebacterium crudilactis, Corynebacterium deserti, Corynebacterium callunae, Corynebacterium suranareeae, Corynebacterium lubricantis, Corynebacterium doosanense, Corynebacterium efficiens, Corynebacterium uterequi, Corynebacterium stationis, Corynebacterium pacaense, Corynebacterium singulare, Corynebacterium humireducens, Corynebacterium marinum, Corynebacterium halotolerans, Corynebacterium spheniscorum, Corynebacterium freiburgense, Corynebacterium striatum, Corynebacterium canis, Corynebacterium ammoniagenes, Corynebacterium renale, Corynebacterium portisoli, Corynebacteriumpollutisoli), Corynebacterium imitans, Corynebacterium caspium, Corynebacterium testudinoris, Corynebacterium pseudopelargi or Corynebacterium flavescens, etc., but not limited thereto. The transformant in the present invention may be a strain containing the aforementioned malate:quinone oxidoreductase variant or a polynucleotide encoding the same, or a vector containing the same, a strain expressing the malate:quinone oxidoreductase variant or polynucleotide, or a strain having activity against the malate:quinone oxidoreductase variant, but is not limited thereto.

[0038] According to a specific example of the present invention, the transformant may have the ability to produce L-glutamic acid.

[0039] The transformant may naturally have the ability to produce L-glutamic acid or may be artificially endowed with the ability to produce L-glutamic acid.

[0040] According to a specific example of the present invention, the transformant may have a change in the activity of malate:quinone oxidoreductase and an improved ability to produce L-glutamic acid.

[0041] "Improved productivity" used in the present invention means that the productivity of L-glutamic acid has increased compared to the parent strain. The parent strain means a wild type or mutant strain to be mutated, including those directly targeted for mutation or those transformed with a recombinant vector, etc. In the present invention, the parent strain may be a wild type Corynebacterium genus microorganism or a Corynebacterium genus microorganism mutated from the wild type.

[0042] The transformant according to the present invention has a malate:quinone oxidoreductase variant introduced therein, resulting in a change in the activity of malate:quinone oxidoreductase and exhibiting an increased L-glutamic acid-producing ability as compared to the parent strain. More specifically, the transformant may have a production amount of L-glutamic acid that is at least 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% increased, or 1.1-fold, 1.5-fold, 2-fold, 2.5-fold, 3-fold, 3.5-fold, 4-fold, 4.5-fold, 5-fold, 5.5-fold, 6-fold, 6.5-fold, 7-fold, 7.5-fold, 8-fold, 8.5-fold, 9-fold, 9.5-fold, or 10-fold increased as compared to the parent strain, but is not limited thereto. As an example, the transformant containing the malate:quinone oxidoreductase variant may have a production amount of L-glutamic acid that is increased by 5% or more, specifically 5 to 50% (preferably 7 to 30%) as compared to the parent strain.

[0043] Another aspect of the present invention provides a method for producing L-glutamic acid, comprising the steps of culturing the transformant in a medium and recovering L-glutamic acid from the transformant or the medium in which the transformant has been cultured.

[0044] The culturing may be performed using an appropriate medium and culturing conditions known in the art, and an ordinary technician can easily adjust and use the medium and culturing conditions. Specifically, the medium may be a liquid medium, but is not limited thereto. The culturing method may include, for example, batch culture, continuous culture, fed-batch culture, or a combined culture thereof, but is not limited thereto.

[0045] According to a specific example of the present invention, the medium must meet the requirements of a specific strain in an appropriate manner and can be appropriately modified by an ordinary technician. Culture media for microorganisms of the genus Corynebacterium can refer to known literature (Manual of Methods for General Bacteriology. American Society for Bacteriology. Washington D.C., USA, 1981), but are not limited thereto.

[0046] According to a specific example of the present invention, the medium can 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, cellulose, oils and fats such as soybean oil, sunflower oil, castor oil, coconut oil, fatty acids such as palmitic acid, stearic acid, linoleic acid, alcohols such as glycerol, ethanol, and organic acids such as acetic acid. These substances can be used individually or as a mixture, but are not limited thereto. Usable nitrogen sources include peptone, yeast extract, gravy, malt extract, corn steep liquor, soybean meal, and urea, or inorganic compounds such as ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium carbonate, and ammonium nitrate. The nitrogen source can also be used individually or as a mixture, but is not limited thereto. Usable sources of phosphorus may include potassium dihydrogen phosphate or dipotassium hydrogen phosphate or the corresponding sodium-containing salts, but are not limited thereto. In addition, the culture medium can contain metal salts such as magnesium sulfate or iron sulfate necessary for growth, but is not limited thereto. Other essential growth substances such as amino acids and vitamins may also be included. Furthermore, appropriate precursors can be used in the culture medium. The medium or individual components may be added batchwise or continuously to the culture broth in an appropriate manner during the culture process, but are not limited thereto.

[0047] According to one specific example of the present invention, during cultivation, compounds such as ammonium hydroxide, potassium hydroxide, ammonia, phosphoric acid, and sulfuric acid can be added to the microbial culture solution in an appropriate manner to adjust the pH of the culture solution. Also, during cultivation, the generation of bubbles can be suppressed by using an antifoaming agent such as a fatty acid polyglycol ester. Additionally, in order to maintain the aerobic state of the culture solution, oxygen or an oxygen-containing gas (e.g., air) can be injected into the culture solution. The temperature of the culture solution is usually 20 to 45 °C, for example, it may be 25 to 40 °C. The cultivation period can be continued until the useful substance is obtained in the desired production amount, and for example, it may be 10 to 160 hours.

[0048] According to one specific example of the present invention, the step of recovering L-glutamic acid from the cultured transformant or the medium in which the transformant was cultured can collect or recover the L-glutamic acid produced from the medium using a suitable method known in the art according to the cultivation method. For example, methods such as centrifugation, filtration, extraction, spraying, drying, evaporation, precipitation, crystallization, electrophoresis, fractional dissolution (e.g., ammonium sulfate precipitation), chromatography (e.g., ion exchange, affinity, hydrophobicity, and size exclusion) can be used, but it is not limited thereto.

[0049] According to one specific example of the present invention, the step of recovering the L-glutamic acid can centrifuge the culture medium at a low speed to remove the biomass, and the obtained supernatant can be separated by ion exchange chromatography.

[0050] According to one specific example of the present invention, the step of recovering the L-glutamic acid can include a step of purifying the L-glutamic acid.

Advantages of the Invention

[0051] The malate:quinone oxidoreductase variant according to the present invention has one or more amino acids in the amino acid sequence constituting the malate:quinone oxidoreductase substituted, resulting in a change in the enzyme activity, and a recombinant microorganism containing this can efficiently produce L-glutamic acid.

Brief Description of Drawings

[0052]

Figure 1

Modes for Carrying Out the Invention

[0053] Hereinafter, the present invention will be described in more detail. However, such a description is only presented as an example for understanding the present invention, and the scope of the present invention is not limited by such an exemplary description.

[0054] Example 1. Preparation of a Vector for Expression of Malate: Quinone Oxidoreductase Mutant A vector was prepared that expresses a mutant in which proline (P) located at position 113 in the amino acid sequence of malate: quinone oxidoreductase (SEQ ID NO: 4) was substituted with serine (S).

[0055] Using the gDNA of wild-type Corynebacterium glutamicum ATCC13869 as a template, PCR was performed using the primer pairs of primer 1 and primer 2 and the primer pairs of primer 3 and primer 4, respectively. Thereafter, using the mixture obtained by mixing the two PCR products as a template, overlapping PCR was performed again using primer 1 and primer 4 to obtain a fragment. Here, Takara PrimeSTAR Max DNA polymerase was used as the polymerase, and the PCR amplification conditions were denaturation at 95°C for 5 minutes, followed by 30 cycles of 30 seconds at 95°C, 30 seconds at 58°C, and 1 minute 30 seconds at 72°C, and reaction at 72°C for 5 minutes. The pK19msb vector was treated with smaI and ligated with the obtained PCR product (fragment), and the plasmid obtained here was named pK-mqo(P113S).

[0056] The primer sequences used for the preparation of the vector are as shown in Table 1 below.

[0057]

Table 1

[0058] Example 2. Preparation of a mutant strain into which a malate:quinone oxidoreductase variant has been introduced Corynebacterium glutamicum U3 (KCCM13218P) was used as the parent strain for introducing the malate:quinone oxidoreductase variant, and the method for producing electrocompetent cells modified based on the method of van der Rest et al. was used as the method for transforming the U3 strain.

[0059] First, 10 ml of 2YT medium (containing 16 g / l of tryptone, 10 g / l of yeast extract, and 5 g / l of sodium chloride) supplemented with 2% glucose was used to primary culture the U3 strain to prepare a seed culture solution. Subsequently, 1 mg / ml of isonicotinic acid hydrazine and 2.5% glycine were added to 100 ml of 2YT medium without glucose, and the seed culture solution was inoculated so that the OD610 value reached 0.3. Then, the culture was incubated at 18°C and 180 rpm for 12 - 16 hours to make the OD610 value reach 1.2 - 1.4. After the culture solution was left on ice for 30 minutes, it was centrifuged at 4°C and 4000 rpm for 15 minutes. Then, the supernatant was discarded, and the precipitated U3 strain was washed 4 times with a 10% glycerol solution and finally resuspended in 0.5 ml of 10% glycerol solution to prepare competent cells. Electroporation was performed using an electroporator from Bio - Rad. After adding the prepared competent cells and the pK_mqo(P113S) vector to an electroporation cuvette (0.2 mm), an electrical shock was applied under the conditions of 2.5 kV, 200 Ω, and 12.5 μF. Immediately after the electrical shock, 1 ml of regeneration medium (containing 18.5 g / l of Brain Heart infusion and 0.5 M of sorbitol) was added and heat - treated at 46°C for 6 minutes. Then, after cooling to room temperature, it was transferred to a 15 - ml capped tube and cultured at 30°C for 2 hours, and then spread on a selection medium (containing 5 g / l of tryptone, 5 g / l of NaCl, 2.5 g / l of yeast extract, 18.5 g / l of Brain Heart infusion powder, 15 g / l of agar, 91 g / l of sorbitol, and 20 μg / l of kanamycin). The colonies generated after culturing at 30°C for 72 hours were cultured in BHI medium until the stationary phase to induce secondary recombination, and -5 ~10 -7 diluted to 10 and spread on a 2YT plate medium without antibiotics (containing 10% sucrose) to select strains that were not kanamycin - resistant and were growth - viable on the medium containing 10% sucrose, and this was named MD1.

[0060] Experimental Example 1. Evaluation of L-Glutamic Acid Production Ability of Mutant Strains into which Malate:Quinone Oxidoreductase Mutants have been Introduced The L-glutamic acid production abilities of the parent strain U3 and the mutant strain MD1 into which a malate:quinone oxidoreductase mutant had been introduced were compared.

[0061] Each strain (parent strain or mutant strain) was inoculated at 1% by volume into a 100 mL flask containing 10 mL of the glutamic acid production medium shown in Table 2 below, and cultured with shaking at 30 °C and 200 rpm for 48 hours. After the culture was completed, the concentration of L-glutamic acid in the medium was measured using HPLC (Agilent), and the results are shown in Table 3 below respectively.

[0062]

Table 2

[0063]

Table 3

[0064] As shown in Table 3 above, it was confirmed that in the mutant strain into which the malate:quinone oxidoreductase mutant had been introduced, the production amount of L-glutamic acid was improved by about 11.3% compared to the parent strain. Such results suggest that the L-glutamic acid production ability increases due to an increase in the flow of the carbon source in the glutamic acid production pathway by the malate:quinone oxidoreductase mutation.

[0065] As described above, the present invention has been described mainly with reference to its preferred embodiments. Those having ordinary knowledge in the technical field to which the present invention pertains will understand that the present invention can be realized in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting perspective. The scope of the present invention is shown not in the above description but in the claims, and all differences within the equivalent scope thereof should be construed as being included in the present invention.

[0066] [Deposit Number] Depositing Institution: Korea Culture Center of Microorganisms (KCCM) Deposit Number: KCCM13218P Date of Deposit: 20220629

Claims

**Claim 1** A malate:quinone oxidoreductase variant consisting of the amino acid sequence of SEQ ID NO: 2, wherein the 113th proline in the amino acid sequence of SEQ ID NO: 4 is substituted with serine. **Claim 2** A polynucleotide encoding the variant according to Claim 1. **Claim 3** A transformant comprising the variant according to Claim 1 or the polynucleotide according to Claim 2. **Claim 4** The transformant according to Claim 3, wherein the transformant is a microorganism belonging to the genus Corynebacterium. **Claim 5** The transformant according to Claim 3, wherein the transformant has the ability to produce L-glutamic acid. **Claim 6** A method for producing L-glutamic acid, comprising culturing the transformant according to Claim 3 in a medium, and recovering L-glutamic acid from the transformant or the medium in which the transformant has been cultured. ​

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