阅读说明：本技术 新型启动子和利用其生产l-氨基酸的方法 (Novel promoter and method for producing L-amino acid using the same ) 是由 崔先亨 张真淑 金亨俊 尹炳勋 李智软 崔允祯 于 2019-03-08 设计创作，主要内容包括：本公开涉及新型启动子和利用该启动子生产L-氨基酸的方法,并且更具体地涉及具有启动子活性的新型多核苷酸、包含该多核苷酸的载体和棒状杆菌属微生物、利用该微生物生产L-氨基酸的方法和发酵组合物。(The present disclosure relates to a novel promoter and a method for producing an L-amino acid using the same, and more particularly, to a novel polynucleotide having promoter activity, a vector and a microorganism of Corynebacterium genus comprising the same, a method for producing an L-amino acid using the microorganism, and a fermentation composition.)

1. A polynucleotide having promoter activity, wherein SEQ ID NO: 2 by a G substitution at nucleotide 37.

2. The polynucleotide of claim 1, wherein the polynucleotide consists of the sequence of SEQ ID NO: 1.

3. The polynucleotide of claim 1 or 2, wherein the polynucleotide is operably linked to a gene encoding a protein of interest.

4. A vector comprising the polynucleotide of claim 1 or 2; and a gene encoding a protein of interest operably linked to the polynucleotide.

5. The vector according to claim 4, wherein the protein of interest is lactate dehydrogenase.

6. A microorganism of the genus corynebacterium comprising the polynucleotide according to claim 1; and a gene encoding a protein of interest operably linked to the polynucleotide.

7. The microorganism of claim 6, wherein the polynucleotide consists of SEQ ID NO: 1.

8. The microorganism of claim 6, wherein the protein of interest is lactate dehydrogenase.

9. The microorganism according to any one of claims 6 to 8, wherein the microorganism of the genus Corynebacterium is Corynebacterium glutamicum.

10. A method for producing a target substance, comprising:

culturing the microorganism of Corynebacterium genus according to any one of claims 6 to 8 in a medium, and

recovering the target substance from the cultured medium.

11. The method of claim 8, wherein the target substance is an amino acid.

12. A process for preparing a fermentation composition, comprising fermenting by culturing the microorganism of Corynebacterium genus according to any one of claims 6 to 8 in a medium.

13. A fermented composition prepared by the method of claim 12.

Technical Field

The present disclosure relates to a novel promoter and a method for producing an L-amino acid using the same, and more particularly, to a novel polynucleotide having promoter activity, a vector and a microorganism of Corynebacterium (Corynebacterium) comprising the same, a method for producing an L-amino acid using the same, and a fermentation composition.

Background

L-glutamic acid is a representative amino acid produced by fermentation and has a unique, special taste, and thus is an important amino acid widely used in the food field as well as in the medical field and other animal feed fields.

General methods for producing L-glutamic Acid are known to include Fermentation methods using microorganisms of the genus Brevibacterium (Brevibacterium) or Corynebacterium and coryneform bacteria including mutant strains thereof (Amino Acid Fermentation, Gakkai Shuppancenter:195-215,1986) or microorganisms of the genus Escherichia (Escherichia coli) or Bacillus (Bacillus), Streptomyces (Streptomyces), Penicillium (Penicillium), Klebsiella (Klebsiella), Erwinia (Erwinia), Pantoea (Pantoea), and the like (U.S. Pat. Nos. 3,220,929 and 6,682,912). When L-glutamic acid is produced by fermentation of a microorganism, various substances other than L-glutamic acid, including organic acids, are also mixed in the fermentation product.

These organic acids are acidic organic compounds and include lactic acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, and the like. The organic acids in the food show sour taste and umami taste, and have the effect of preventing decay by lowering the pH of the food. Lactic acid is known to occupy the largest portion of the organic acids produced by microbial fermentation.

However, since the lactic acid fraction produced by fermentation is higher, the sourness of the fermentation product increases, and thus palatability may decrease. Therefore, there is a need to regulate the production of lactic acid in fermentation products produced by microbial fermentation.

In this context, the present inventors have made an effort to reduce organic acid productivity in L-glutamic acid-producing microorganisms. Thus, the present inventors developed a novel polynucleotide having the promoter activity of the present disclosure, and found that the polynucleotide can increase L-glutamic acid productivity in a strain and it can decrease lactic acid productivity, thereby completing the present disclosure.

Disclosure of Invention

[ problem ] to

It is an object of the present disclosure to provide a polynucleotide having promoter activity, wherein SEQ ID NO: 2 by a G substitution at nucleotide 37.

It is another object of the present disclosure to provide a vector comprising the polynucleotide; and a gene encoding a protein of interest operably linked to the polynucleotide.

It is still another object of the present disclosure to provide a microorganism of Corynebacterium genus, which comprises the polynucleotide; and a gene encoding a protein of interest operably linked to the polynucleotide.

It is still another object of the present disclosure to provide a method of producing a target substance, comprising: culturing a microorganism of Corynebacterium genus in a medium; and recovering the target substance from the culture medium.

It is still another object of the present disclosure to provide a method of preparing a fermentation composition, comprising fermenting by culturing a microorganism of corynebacterium genus in a medium.

It is a further object of the present disclosure to provide a fermentation composition prepared by the above method.

[ solution ]

Hereinafter, the present disclosure will be described in detail. Meanwhile, each description and embodiment disclosed in the present disclosure may be applied to other descriptions and embodiments. That is, all combinations of the various elements disclosed in this disclosure are within the scope of this disclosure. Furthermore, the specific description disclosed below should not be construed as limiting the scope of the disclosure.

To achieve the above objects, one aspect of the present disclosure provides a polynucleotide having promoter activity, wherein SEQ ID NO: 2 by a G substitution at nucleotide 37.

As used herein, the term "SEQ ID NO: 2 "may refer to a portion of the promoter sequence of a gene encoding Lactate Dehydrogenase (LDH).

Specifically, the term "lactate dehydrogenase" refers to an enzyme that produces lactate (lactate or lactic acid) using pyruvate as a substrate, and is interchangeably referred to as "LDH" in the present disclosure. Specifically, the gene of lactate dehydrogenase may include seq id NO: 3, and the protein thereof may comprise the nucleotide sequence of SEQ ID NO: 4, but these are not limited thereto.

As used herein, the term "promoter" refers to a sequence of untranslated nucleotides upstream of a coding region that includes a polymerase binding domain and that has the target gene to mRNA transcription initiation activity of the promoter, i.e., the DNA domain to which the polymerase binds to initiate transcription of a gene, and may be located 5' to the mRNA transcription initiation region. Specifically, the target gene of the promoter may be lactate dehydrogenase, but is not limited thereto.

The polynucleotides of the present disclosure are polynucleotides that: wherein SEQ ID NO: 2, i.e., the promoter sequence of the lactate dehydrogenase gene, is mutated. Specifically, the mutation may be a substitution of T with G, i.e., nucleotide 37 of the above sequence. Thus, a polynucleotide may consist of SEQ ID NO: 1.

In particular, the term "modification" refers to a genetically or non-genetically stable phenotypic change, and may be interchangeably referred to in this disclosure as a "mutation".

In particular, the polynucleotide may have altered (increased or decreased) promoter activity relative to the activity of a polynucleotide that does not include the polynucleotide modification. Thus, the expression of a target gene operably linked to the polynucleotide and the activity of a protein encoded by the target gene can be regulated (increased or decreased), and further the expression of a gene other than the target gene can be regulated.

For the purposes of this disclosure, the polynucleotide may be a polynucleotide for attenuating lactate dehydrogenase activity.

In addition, the polynucleotide may be a polynucleotide that increases the production of L-glutamic acid and/or decreases the production of lactic acid.

Lactate dehydrogenase is known to be involved in the production of lactic acid, but its relationship with L-glutamic acid production is unknown and was first determined by the present inventors. Specifically, the present inventors have confirmed for the first time the effect of causing a decrease in lactate dehydrogenase activity, and thus increasing L-glutamic acid production and decreasing lactic acid production, by lactate dehydrogenase promoter modification.

Herein, "L-glutamic acid (L-glutamic acid or L-glutamic acid)" refers to an amino acid and is classified as a non-essential amino acid. L-glutamic acid is known to be the most common excitatory neurotransmitter in the central nervous system. In addition, since L-glutamic acid has an umami taste, monosodium glutamate (MSG) has been developed and widely used as a taste enhancer. It is generally produced by fermentation of an L-glutamic acid-producing microorganism.

In addition, the term "lactic acid" is an organic acid having a sour taste. In addition, lactic acid is used as an acidulant for fruit extracts, syrups and soft drinks for eating purposes and for preventing the proliferation of saprophytic bacteria at the early stage of alcoholic fermentation. Lactic acid is typically produced by fermentation in a lactic acid producing microorganism. In addition, if overproduced, the quality of the fermentation product may deteriorate due to excessive sourness, and therefore the concentration of lactic acid needs to be appropriately adjusted during the culture.

Specifically, the polynucleotide may be a polynucleotide consisting of SEQ ID NO: 1 in a polynucleotide sequence.

In addition, the nucleotide sequences of the present disclosure can be modified by known mutagenesis methods, such as directed evolution, site-directed mutagenesis, and the like.

Thus, a polynucleotide may include a polynucleotide that: comprises a nucleotide sequence substantially identical to SEQ ID NO: 1, has a homology of at least 60%, specifically at least 70%, more specifically at least 80%, still more specifically at least 83%, 84%, 88%, 90%, 93%, 95% or 97%. Obviously, polynucleotide sequences having such homology, a portion of which is deleted, modified, substituted or added, are also within the scope of the present disclosure, as long as the resulting polynucleotide sequences have a sequence identity to SEQ ID NO: 1, or a corresponding biological activity.

As used herein, the term "homology" may refer to the degree of match with a given nucleotide sequence and may be expressed in percent (%). In the present disclosure, homologous sequences having the same or similar activity as a given nucleotide sequence are denoted as "% homology". Homology to a nucleotide sequence can be determined, for example, by the algorithm BLAST (see Karlin and dAltshul, Pro.Natl.Acad.Sci.USA,90,5873(1993)) or FASTA (see Pearson, methods Enzymol.,183,63, 1990). Based on this algorithm, a program called BLASTN or BLASTX has been developed (see BLASTN or BLASTX)http://www.ncbi.nlm.nih.gov)。

As used herein, the term "stringent conditions" refers to conditions that allow for specific hybridization between polynucleotides. Such stringent conditions are specifically described in the literature (e.g., j. sambrook et al.). For example, stringent conditions may include conditions such as: genes having high homology (for example, 60% or more, specifically 90% or more, more specifically 95% or more, still more specifically 97% or more, still more specifically 99% or more) can hybridize with each other, while genes having lower homology cannot hybridize with each other; or conditions for conventional DNA hybridization (southern hybridization) (i.e., conditions in which washing is performed once, and specifically twice or three times, at salt concentrations and temperatures corresponding to 60 ℃,1 XSSC, 0.1% SDS, specifically 60 ℃, 0.1 XSSC, 0.1% SDS; more specifically 68 ℃, 0.1 XSSC, 0.1% SDS). Hybridization requires that the two nucleotides have complementary sequences, although mismatches between bases are possible depending on the severity of the hybridization. The term "complementary" is used to describe the relationship between nucleotide bases capable of hybridizing to each other. For example, in the case of DNA, adenosine (adenine) is complementary to thymine, and cytosine is complementary to guanine. Thus, the disclosure may also include substantially similar nucleotide sequences as well as isolated polynucleotide fragments that are complementary to the entire sequence.

Specifically, a polynucleotide having homology can be detected using hybridization conditions including a hybridization step at a Tm value of 55 ℃ and using the above conditions. Further, the Tm value may be 60 ℃,63 ℃ or 65 ℃, but is not limited thereto. The Tm value can be appropriately adjusted by those skilled in the art according to the purpose thereof. The appropriate stringency for hybridizing polynucleotides depends on the length and degree of complementarity of the polynucleotides, and variables are well known in the art (see Sambrook et al, supra,9.50-9.51, 11.7-11.8).

Specifically, the expression "consists of SEQ ID NO: 1 "means that addition, deletion and/or mutation of nucleotides, which may occur during the linkage of a target gene when the corresponding polynucleotide is linked to the target gene and used as a promoter, is not excluded when a restriction enzyme is used.

For example, non-limiting inclusion of a polypeptide consisting of SEQ ID NO: 1, provided that it includes a nucleotide sequence having the promoter activity of the present disclosure and hybridizing with a complementary sequence under stringent conditions, which is a nucleotide sequence identical to SEQ ID NO: 1, or a sequence complementary to all or a portion of the nucleotide sequence of 1.

In addition, the polynucleotides of the present disclosure may be operably linked to a gene encoding a protein of interest.

As used herein, the term "gene expression control sequence" refers to a sequence comprising a polynucleotide of the present disclosure and capable of expressing a target gene operably linked to the polynucleotide.

As used herein, the term "operably linked" refers to a polynucleotide of the present disclosure having promoter activity functionally (functionally) linked to a gene sequence to initiate and mediate transcription of a target gene. The operable linkage to the gene sequence may be achieved using gene recombination techniques known in the art, and site-specific DNA cleavage and linkage may be performed by using restriction enzymes and ligase known in the art, but these are not limited thereto.

In addition, the gene expression control sequence of the present disclosure may further include any manipulation sequence for controlling the transcription of a gene other than a promoter for performing gene transcription, and a sequence encoding an appropriate mRNA ribosome binding site, DNA, etc. to control the termination of transcription and translation.

For example, the regulatory sequences suitable for prokaryotes may further include a ribosome binding site in addition to the promoter, but are not limited thereto. The polynucleotide having promoter activity of the present disclosure may consist of the sequence for regulating gene expression as described above, as required by one of ordinary skill in the art.

In the present disclosure, a target gene refers to a gene encoding a target protein, the expression of which is regulated in a microorganism.

For example, the gene may be a gene involved in production of a product selected from the group consisting of an amino acid (glutamic acid and the like), an organic acid (lactic acid and the like), and a combination thereof, but is not limited thereto. Specifically, the gene may be a gene encoding an enzyme involved in the biosynthesis of an amino acid (glutamic acid and the like) and/or a gene encoding an enzyme involved in the biosynthesis of an organic acid (lactic acid and the like), but is not limited thereto. More specifically, the gene may be a gene encoding Lactate Dehydrogenase (LDH), but is not limited thereto. The sequence of the gene encoding LDH can be easily obtained by a person of ordinary skill in the art through a known database such as GenBank of National Institutes of Health (NIH).

For example, the gene expression control sequences of the present disclosure are operably linked to a gene sequence encoding an LDH, and thus the production of glutamate in a microorganism can be increased and the production of lactate can be decreased.

Yet another aspect of the present disclosure provides a vector comprising the gene; the polynucleotide; and a vector of a gene encoding a protein of interest operably linked to the polynucleotide.

The polynucleotide is as described above.

Specifically, the target protein may be Lactate Dehydrogenase (LDH).

As used herein, the term "vector" refers to an artificial DNA molecule having genetic material capable of expressing a target gene in a suitable host, and refers to a vector comprising the polynucleotide or a suitable gene expression control sequence; and a nucleotide sequence of a gene encoding a protein of interest operably linked to the regulatory sequence.

The vector used in the present disclosure is not particularly limited as long as it can be expressed in a host cell, and any vector known in the art may be used to transform the host cell. Examples of conventional vectors may include natural or recombinant plasmids, cosmids, viruses, and bacteriophages.

For example, as phage vectors or cosmid vectors, pWE15, M13, λ LB3, λ BL4, λ ix II, λ ASHII, λ APII, λ t10, λ t11, Charon4A, Charon21A, and the like; and as the plasmid vector, those based on pBR, pUC, pBluescriptII, pGEM, pTZ, pCL, pET, etc. can be used.

In addition, an endogenous promoter in a chromosome can be replaced with a polynucleotide having promoter activity of the present disclosure by a vector for chromosomal insertion in a host cell. For example, vectors pECCG117, pDZ, pACYC177, pACYC184, pCL, pUC19, pBR322, pMW118, pCC1BAC, pCES208, pXMJ19, etc. may be used, but these are not limited thereto.

In addition, insertion of the polynucleotide into the chromosome can be accomplished by any method known in the art, such as by homologous recombination.

Since the vector of the present disclosure can be inserted into a chromosome by inducing homologous recombination, a selection marker may be additionally included to confirm the success of gene insertion into the chromosome. The selection marker is used to screen cells transformed with the vector, in other words, to determine whether the polynucleotide is inserted. Markers that provide a selectable phenotype, such as drug resistance, auxotrophy, toxic agent resistance, or surface protein expression, can be used. In the environment treated with the selection agent, only cells expressing the selection marker will survive, or the cells will show a different phenotype, and thus successfully transformed cells can be selected by this method.

As used herein, the term "transformation" refers to the introduction of a vector comprising a polynucleotide or gene expression control sequence and a gene encoding a protein of interest into a host cell to allow the gene to be expressed in the host cell. In addition, it does not matter whether the transformed polynucleotide and the gene encoding the target protein are located on or outside the chromosome of the host cell, as long as the target gene can be expressed in the host cell, and both cases are included.

The transformation method may includeAll methods of introducing a gene expression regulatory sequence and a gene encoding a target protein into a cell are included, and can be carried out by selecting an appropriate standard technique known in the art according to the host cell. For example, it can be prepared from electroporation, calcium phosphate (CaPO)₄) Precipitate, calcium chloride (CaCl)₂) An appropriate standard technique is selected from among precipitation, microinjection, polyethylene glycol (PEG) technique, DEAE-dextran technique, cationic liposome technique, and lithium acetate-DMSO technique, but is not limited thereto.

Yet another aspect of the disclosure provides a polynucleotide comprising the polynucleotide; and a gene encoding a target gene operably linked to the polynucleotide.

The polynucleotide and the gene encoding a target gene operably linked to the polynucleotide are as described above.

As used herein, the term "microorganism" includes all wild-type microorganisms and microorganisms that are naturally or artificially genetically modified, and it may be a microorganism having a specific attenuation or enhancement mechanism due to insertion of an exogenous gene or enhancement or attenuation of activity of an endogenous gene.

In the present disclosure, a microorganism may comprise the polynucleotide, in particular the polynucleotide and/or a gene encoding a target gene operably linked to the polynucleotide. Alternatively, the microorganism may include the polynucleotide or gene expression control sequence and a vector including the polynucleotide or gene expression control sequence and a gene encoding a target protein, but is not limited thereto. In addition, the polynucleotide, the gene encoding the target protein, and the vector may be introduced into the microorganism by transformation, but are not limited thereto. Furthermore, it does not matter whether the polynucleotide and the gene encoding the target protein are located on the chromosome or extrachromosomally, as long as the gene can be expressed in the microorganism.

For the purpose of the present disclosure, the microorganism comprising the polynucleotide and the gene encoding the target protein may be a microorganism in which L-glutamic acid production is increased and lactic acid production is decreased.

For example, the microorganism may have a polynucleotide in which lactate dehydrogenase activity is attenuated.

In the present disclosure, the microorganism may be included without limitation so long as it is a microorganism into which a polynucleotide having promoter activity of the present disclosure is introduced so that the polynucleotide operates as a promoter.

Specifically, the microorganism may be a microorganism of Corynebacterium genus; more specifically, it may be Corynebacterium glutamicum (Corynebacterium glutamicum) or Flavobacterium (Corynebacterium flavum); and specifically, it may be Corynebacterium glutamicum, but is not limited thereto.

Yet another aspect of the present disclosure provides a method of producing a target substance, comprising: culturing a microorganism of Corynebacterium genus in a medium; and recovering the target substance from the culture medium.

The polynucleotides and microorganisms are as described above.

In the present disclosure, the target substance may be an amino acid. Specifically, unless otherwise specified, the amino acid may be an L-type amino acid, and may be an amino acid selected from the group consisting of glycine, alanine, valine, leucine, isoleucine, threonine, serine, cysteine, glutamine, methionine, aspartic acid, asparagine, glutamic acid, lysine, arginine, histidine, phenylalanine, tyrosine, tryptophan, proline, and combinations thereof, but is not limited thereto.

More specifically, the amino acid may be glutamic acid, but is not limited thereto.

As used herein, the term "culturing" refers to culturing a microorganism under artificially controlled environmental conditions. In the present disclosure, a method for producing a target substance using a microorganism having the polynucleotide can be performed by a method known in the art. Specifically, the cultivation may be carried out in a batch method or a continuous method, such as a fed-batch method or a repeated fed-batch method, but is not limited thereto. The medium used for the cultivation must meet the requirements of the particular strain used. Suitable media for culturing Corynebacterium strains are known in the art (e.g., Manual of Methods for General Bacteriology, American society for Bacteriology, Washington D.C., USA, 1981).

Carbon sources that can be used for the medium may be sugars and carbohydrates, such as glucose, sucrose, lactose, fructose, maltose, starch and cellulose; oils and lipids, such as soybean oil, sunflower oil, peanut oil, and coconut oil; fatty acids such as palmitic acid, stearic acid (stearic acid), linoleic acid; alcohols such as glycerol and ethanol; and organic acids such as acetic acid. These materials may be used alone or in combination, but are not limited thereto.

Examples of the nitrogen source which can be used include peptone, yeast extract, broth, 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. These nitrogen sources may also be used alone or in combination, but are not limited thereto.

Phosphorus sources that may be used in the medium may include dipotassium hydrogen phosphate, potassium dihydrogen phosphate or the corresponding sodium-containing salts. In addition, the medium may contain metal salts necessary for the growth of cells, and may be supplemented with substances necessary for growth, such as amino acids and vitamins, in addition to the above materials. In addition, precursors suitable for the culture medium may be used. The above-mentioned raw materials may be sufficiently added to the culture in a batch or continuous manner.

During the cultivation of the microorganism, the pH of the culture can be adjusted by means of suitable basic compounds such as sodium hydroxide, potassium hydroxide or ammonia; or an acidic compound such as phosphoric acid or sulfuric acid. Foaming can be regulated by defoamers such as fatty acid polyglycol esters. Aerobic conditions of the culture can be maintained by introducing oxygen or oxygen-containing gas mixtures (e.g., air).

The temperature of the culture (medium) may be generally 20 ℃ to 45 ℃, specifically 25 ℃ to 40 ℃. The culturing may be continued until a desired yield of the target substance is obtained, specifically 10 hours to 160 hours.

The recovery of the target substance from the culture (culture medium) can be carried out by a conventional separation method known in the art. For the separation method, methods such as centrifugation, filtration, chromatography, crystallization, and the like can be used. For example, the supernatant obtained by removing biomass by low-speed centrifugation of the medium may be separated by ion exchange chromatography, but is not limited thereto. In an alternative method, the target substance can be recovered without an additional purification process by performing a method of separating bacterial cells from the culture product (culture medium) and filtering. In another alternative method, the target substance may be recovered, and the recovering step may further comprise a purification process.

Yet another aspect of the present disclosure provides a method of preparing a fermentation composition, comprising fermenting by culturing a microorganism of corynebacterium genus in a medium.

Yet another aspect of the present disclosure provides a fermented composition prepared by the above method.

The polynucleotide and the microorganism are as described above, and the step of culturing the microorganism in the medium is also as described above.

As used herein, the term "fermentation composition" refers to a composition obtained by culturing a microorganism of the present disclosure in a culture medium. Furthermore, the fermentation composition may comprise a composition in liquid or powder form obtained after culturing the microorganism and then appropriate post-treatment. Specifically, suitable post-treatment processes may include, for example, a process of culturing microorganisms, a process of removing bacterial cells, a concentration process, a filtration process, and a process of mixing carriers, and may further include a drying process. In some cases, the post-treatment process may not include a purification process. The fermentation composition obtained by culturing the microorganism of the present disclosure is characterized in that the production of glutamic acid is increased while the production of lactic acid is decreased, thereby making it possible to provide the best taste.

In addition, "fermented composition" does not exclude flavored products (e.g., powdered soup products, snack flavored products, etc.) containing the composition in liquid or powder form. In addition, "fermented composition" does not exclude the case of further including a substance obtained by a non-fermentation method or other substances obtained by a non-natural method, as long as a composition obtained by culturing the microorganism of the present disclosure is contained therein.

[ advantageous effects ]

The novel promoter of the present disclosure can be introduced into amino acid-producing microorganisms, thereby increasing the production of amino acids and decreasing the production of organic acids in the microorganisms. Specifically, when L-glutamic acid is produced using the novel promoter of the present disclosure, the amounts of L-glutamic acid and organic acid in the fermentation product are adjusted to improve the taste and palatability of the fermentation product.

Detailed Description

Hereinafter, the present disclosure will be described in detail in connection with the attached exemplary embodiments. However, the exemplary embodiments disclosed herein are for illustrative purposes only and should not be construed to limit the scope of the present disclosure.