A strain with high production of gamma-aminobutyric acid and application thereof

Abstract

The application belongs to the technical field of microorganisms, and provides a strain for high-yield gamma-aminobutyric acid and application thereof. Levilactobacillus brevis The strain C8 is preserved in the China General Microbiological Culture Collection Center, located at No.1, Xibaheyi, Chaoyang District, Beijing, on June 8, 2026, and has a preservation number of CGMCC No.39278. The application obtains the strain C8, which has efficient gamma-aminobutyric acid synthesis and production capacity, fast growth rate, easy artificial cultivation, outstanding acid tolerance, strong metabolic specificity, stable genetic traits and high biological safety, thereby providing an excellent strain basis and technical support for efficient industrial production of gamma-aminobutyric acid and industrial application development of related functional products.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, and in particular relates to a strain that produces high levels of γ-aminobutyric acid and its applications. Background Technology

[0002] Gamma-aminobutyric acid (GABA) is a naturally occurring non-protein amino acid widely found in the metabolic systems of animals, plants, fungi, and microorganisms. Its hydrophilic amino and carboxyl groups and short carbon chain skeleton endow it with excellent water solubility and biocompatibility, allowing it to penetrate biological membranes and participate in core physiological regulation. This compound possesses multiple core physiological functions: as an endogenous agonist of specific receptors in the central nervous system, it can activate the GABA receptor pathway, inhibit abnormal nerve discharges, relieve anxiety, and improve sleep quality; at the metabolic regulation level, it can promote insulin secretion, regulate blood glucose homeostasis, lower blood pressure, and improve lipid metabolism; in the food and health fields, GABA, with its calming and sleep-aiding, blood pressure and lipid-lowering, anti-fatigue, and gut microbiota-regulating effects, has become a core functional ingredient in functional foods, dietary supplements, and health food ingredients, with extremely wide applications.

[0003] As an indispensable active metabolic molecule in living organisms, γ-aminobutyric acid (GABA) has irreplaceable application value in functional foods, biomedicine, health products, and feed additives. However, its industrial-scale production is still constrained by multiple technical bottlenecks, making it difficult to meet the industry's demand for low cost, high purity, and high yield in the high-end market.

[0004] Currently reported mainstream methods for preparing γ-aminobutyric acid (GABA) fall into three main categories: chemical synthesis, biocatalysis, and microbial fermentation. Among these, chemical synthesis, with readily available raw materials, mature processes, and high initial recovery rates, was the primary method for early industrial production. However, it suffers from significant technical drawbacks: the synthesis reaction process is cumbersome, multi-step cascade reactions result in numerous byproducts, product purification processes are complex, and the overall total yield is low; the production process requires the input of highly corrosive and polluting raw materials such as strong acids, strong alkalis, and organic solvents, resulting in large emissions of waste and a heavy burden on the ecological environment; some synthesis processes rely on precious metal catalysts and high-temperature, high-pressure reaction equipment, significantly increasing energy consumption, material costs, and operational safety risks, which is inconsistent with the concept of green industrial development.

[0005] Glutamate decarboxylase (GAD) is the key rate-limiting enzyme catalyzing the irreversible decarboxylation of L-glutamate to produce γ-aminobutyric acid (GABA) and CO2, and is also the core functional enzyme in the biosynthesis of GABA. Existing research shows that GAD catalytic systems from high-quality modified strains can achieve high-concentration substrate conversion, significantly improving the efficiency of GABA synthesis. Enzymatic conversion methods have advantages such as high product specificity, few byproducts, and mild reaction conditions, enabling one-step bioconversion to synthesize GABA. Compared to chemical synthesis methods, they offer significant advantages in green production. However, currently, both natural and modified glutamate decarboxylases generally suffer from core shortcomings: limited substrate tolerance concentrations, significant feedback inhibition at high substrate / product concentrations, and poor enzyme-catalyzed reaction stability, resulting in low overall catalytic productivity. The comprehensive cost of large-scale industrial production is far higher than that of traditional chemical synthesis methods, making industrial-scale substitution difficult.

[0006] Numerous studies have confirmed that γ-aminobutyric acid (GABA) in organisms is mainly synthesized via the glutamate decarboxylation metabolic pathway. The background levels of GABA in plant and animal tissues, as well as in common fungal cells, are extremely low, resulting in low metabolic synthesis efficiency. Therefore, it is impossible to obtain high-purity, large-scale GABA products through direct separation and extraction. Microbial cells, however, possess characteristics such as high glutamate decarboxylase activity, clear metabolic pathways, rapid proliferation, and strong environmental adaptability, making them the optimal carrier for the green fermentation production of GABA. Compared to chemical synthesis and in vitro enzymatic catalysis, microbial fermentation offers core advantages such as mild reaction conditions, ambient temperature and pressure throughout the process, simple operation, single byproduct, high product purity, and green, pollution-free operation. It is currently the mainstream development direction for industrial production. However, traditional wild fermentation strains still face many challenges in industrialization: long fermentation cycles, high raw material costs for composite culture media, low cell biomass and product synthesis yields, and limited conversion efficiency, hindering large-scale industrial development. It is noteworthy that acid-base stress is a core environmental pressure in the microbial liquid fermentation process, exerting a dual regulatory effect on the growth, proliferation, and metabolic synthesis of γ-aminobutyric acid (GABA)-producing strains. On the one hand, a suitable acidic fermentation environment can inhibit contamination by other microorganisms, reduce the risk of contamination in the fermentation system, and improve the stability of the fermentation system. On the other hand, low pH stress can specifically activate the stress-induced metabolic regulation mechanism of GABA-producing strains, significantly inducing efficient expression of glutamate decarboxylase and promoting the large-scale synthesis of GABA. GABA is a basic amino acid, and microorganisms can balance the intracellular acid-base environment and maintain intracellular pH homeostasis by synthesizing and accumulating GABA, which is a core survival strategy for strains to adapt to acid stress. At the same time, the glutamate decarboxylation metabolism can drive cell membrane proton transport, regulate the intracellular and extracellular proton dynamics balance, provide energy support for the basic metabolism of the cells under stress, and ensure the normal growth and metabolism of the strains under harsh fermentation conditions. Numerous experiments have confirmed that moderately lowering the pH value of the fermentation system can significantly activate the activity of glutamate decarboxylase. The optimal catalytic pH for most lactic acid bacteria-derived GAD is 4.5-5.5. Enzyme activity and catalytic efficiency reach their peak under acidic conditions. In addition, most Gram-positive probiotics can significantly enhance the synthesis capacity of glutamate decarboxylase through acid stress induction, accelerating the directional conversion of L-glutamate to γ-aminobutyric acid. Summary of the Invention

[0007] The purpose of this invention is to provide a strain that produces high levels of γ-aminobutyric acid and its applications, thereby addressing the problems mentioned in the background section.

[0008] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides a strain that produces high levels of γ-aminobutyric acid (GABA), wherein the strain is a short-fermenting agent Lactobacillus (… Levilactobacillus brevisC8 was deposited on June 8, 2026 at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 39278.

[0009] On the other hand, the present invention provides an application of a strain that produces high levels of γ-aminobutyric acid in the fermentation synthesis of γ-aminobutyric acid.

[0010] Compared with the prior art, the specific beneficial effects of the present invention are as follows: This invention obtains a short-fermenting agent, Lactobacillus, through natural matrix screening, purification, and domestication. Levilactobacillus brevis C8 has a high efficiency in synthesizing and producing γ-aminobutyric acid (GABA). The strain has a fast growth rate, is easy to cultivate artificially, has outstanding acid tolerance, strong metabolic specificity, stable genetic traits, and high biosafety. It provides an excellent strain foundation and technical support for the efficient industrial production of GABA and the industrial application development of related functional products. This strain can provide core bacterial material for developing functional probiotic resources with effects such as nerve soothing, metabolic regulation, health maintenance and skin repair. Attached Figure Description

[0011] Figure 1 Liquid phase diagram of γ-aminobutyric acid provided in an embodiment of the present invention; Figure 2 The standard curve of γ-aminobutyric acid provided in the embodiments of the present invention; Figure 3 The content of γ-aminobutyric acid produced by the strains provided in the embodiments of the present invention is expressed as mean ± standard deviation (n=3); different lowercase letters (a, b, c, d, e, f) on the column indicate significant differences (P<0.05), and the same letter indicates no significant difference (P>0.05); Figure 4 The images show the morphology of the strains provided in the embodiments of the present invention. A shows the colony morphology on the plate, and B shows the Gram staining morphology. Figure 5 The acid resistance results of the strains provided in the embodiments of the present invention are expressed as mean ± standard deviation (n=3); different capital letters (A, B) on the column indicate significant differences (P<0.05), and the same letter indicates no significant differences (P>0.05); Figure 6 The bile salt tolerance results of the strains provided in the embodiments of the present invention are expressed as mean ± standard deviation (n=3); different lowercase letters (a, b, c, d, e, f) on the column indicate significant differences (P<0.05), and the same letter indicates no significant differences (P>0.05); Figure 7 The hydrophobicity results of strain C8 provided in the embodiments of the present invention are expressed as mean ± standard deviation (n=3); different capital letters (A, B, C) on the column indicate significant differences (P<0.05), and the same letter indicates no significant differences (P>0.05); Figure 8 The results of the self-aggregation ability determination of strain C8 provided in the embodiments of the present invention are expressed as mean ± standard deviation (n=3); different capital letters (A, B, C, D, E) on the column indicate significant differences (P<0.05), and the same letter indicates no significant differences (P>0.05); Figure 9 The growth status of strain C8 provided in this embodiment of the invention on blood agar plates; Figure 10 The growth curve of strain C8 provided in the embodiments of the present invention; Figure 11 The phylogenetic tree of strain C8 provided in the embodiments of the present invention; Figure 12 The effect of different pH values ​​on GABA production of strain C8 provided in the embodiments of the present invention is shown in the mean ± standard deviation (n=3); different uppercase letters (A, B, C) and lowercase letters (a, b, c, d, e) on the column indicate significant differences (P<0.05), and the same letter indicates no significant difference (P>0.05). Figure 13 The effects of different L-glutamic acid concentrations on GABA production in strain C8, as provided in the embodiments of the present invention, are expressed as mean ± standard deviation (n=3); different uppercase letters (A, B, C, D) and lowercase letters (a, b, c, d, e) on the column indicate significant differences (P<0.05), while the same letter indicates no significant difference (P>0.05). Figure 14 The effects of different fermentation temperatures on GABA production of strain C8 provided in this embodiment of the invention are presented as mean ± standard deviation (n=3); different uppercase letters (A, B, C) and lowercase letters (a, b, c, d, e) on the column indicate significant differences (P<0.05), while the same letter indicates no significant difference (P>0.05). Figure 15 The effect of different inoculum amounts on GABA yield provided in embodiments of the present invention Data are expressed as mean ± standard deviation (n=3); different uppercase letters (A, B, C) and lowercase letters (a, b, c, d, e) on the column indicate significant differences (P<0.05), while the same letter indicates no significant difference (P>0.05). Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0013] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0014] Example 1: Short-acting starter Lactobacillus ( Levilactobacillus brevis Isolation and identification of C8: 1. Sample source: Fermented kimchi sample.

[0015] 2. Culture medium: MRS liquid culture medium: peptone 10.0 g, beef extract 8.0 g, yeast extract 4.0 g, glucose 20.0 g, dipotassium hydrogen phosphate 2.0 g, diammonium hydrogen citrate 2.0 g, sodium acetate 5.0 g, magnesium sulfate 0.2 g, manganese sulfate 0.04 g, Tween 80 1.0 mL, distilled water 1000 mL, pH 5.5-5.9; MRS solid medium: The preparation method is the same as that of MRS liquid medium, but 15 g of agar powder is added to the MRS liquid medium. Screening medium: The preparation method is the same as that of MRS liquid medium, but 7.5 g of calcium carbonate is added to the MRS liquid medium.

[0016] 3. Isolation and purification of strains: After thoroughly shaking the collected fermentation broth, pipette 0.1 mL of the broth into a test tube containing 0.9 mL of sterile physiological saline and allow it to ferment for 10 minutes. -1 -10 -6 Serial dilution, take 0.1 mL of 10 mL of each solution. -4 10 -5 10 -6 Diluted solutions of varying dilution levels were spread on screening medium and incubated at 37°C for 2 days. If a clear zone appeared, the strain could be preliminarily identified as a γ-aminobutyric acid (GABA)-producing strain. Single colonies with different morphologies and sizes and large clear zone diameters were then selected and purified three times using the streak plate method. The purified strains were activated three times in MRS liquid medium fortified with 0.1% L-glutamate to enhance glutamate decarboxylase activity. The activated strains were then cryopreserved in glycerol tubes at -80°C for later use.

[0017] 4. Accurate determination of GABA using HPLC (High Performance Liquid Chromatography): GABA standard curves were prepared using HPLC: GABA standard samples of 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, and 1.5 g / L were prepared. 200 μL of the sample, 200 μL of acetonitrile, 200 μL of NaHCO3 (pH=9.8), 200 μL of water, and 100 μL of dansyl chloride (40 g / L) were mixed thoroughly and reacted in the dark at 60 ℃ for 1 h. Then, 100 μL of acetic acid (20 μL / mL) was added to stop derivatization. The chromatographic column was a Shimadzu C-18 column; mobile phase A was 25 mmol / L sodium acetate, adjusted to pH=6.2 with 4% acetic acid; mobile phase B was pure acetonitrile; flow rate was 1 mL / min; column temperature was 40 ℃; injection volume was 20 μL; UV detection wavelength was 386 nm; and the elution program was shown in Table 1. Table 1

[0018] Determination of GABA production in fermentation broth: The fermented sample was centrifuged at 8000 rpm for 15 min. The supernatant was diluted 30 times and the GABA production of different strains was determined according to the standard curve prepared by HPLC. The liquid phase diagram of γ-aminobutyric acid is as follows: Figure 1 As shown, the chromatographic peak shape of γ-aminobutyric acid (GABA) was good, with no overlapping peaks, and the elution time was 16.001 min; the standard curve of GABA is shown below. Figure 2 As shown, within the range of 0.1-1.0 g / L, the regression equation is y=1682.7x-0.2988, and the correlation coefficient r is... 2 =0.9999, indicating a good linear relationship (r 2 >0.999), indicating that the method for determining the content has good reliability; the results of γ-aminobutyric acid content produced by different strains are as follows: Figure 3 As shown, among the 10 tested strains, C8 had the highest GABA production (2.9 g / L), followed by J4 (2.4 g / L) and N3 (2.3 g / L), with some significant differences among the three (P<0.05); S2 (1.9 g / L) and H7 (2.1 g / L) were at a moderate level; while D9 had the lowest production (0.4 g / L), significantly lower than all other strains (P<0.05).

[0019] 5. Morphological observation: 5.1 Gram staining test: The isolated and purified C8 strain was stained according to the Gram staining procedure of primary staining, mordanting, destaining and counterstaining, and the cell morphology was observed under an oil immersion lens of 4×100.

[0020] The results are as follows Figure 4As shown, the colony morphology on the plate is as follows: Figure 4 As shown in Figure A, the strain forms round colonies with regular edges on the culture medium, appearing pale yellow with a raised center. Gram staining results are as follows. Figure 4 As shown in Figure B, the bacteria are purple in color and have slender, rod-shaped cells arranged in an alternating pattern, indicating that the strain is a Gram-positive bacterium.

[0021] 5.2 Acid tolerance test: The pH of MRS liquid culture medium was adjusted to 3.0 and sterilized at 121℃ for 15 min. Four strains, including C8, were inoculated into the culture medium at an inoculation rate of 10%. The medium was then incubated at 37℃. Viable bacteria were counted at 0 h and 3 h using the dilution plating method. The survival rate of the strains in acidic physiological saline at different pH values ​​was calculated, and the acid tolerance of the strains was determined. The results are as follows Figure 5 As shown, all four strains had good survival rates at pH 3, with C8 exhibiting the best acid resistance and a survival rate of 68.64%.

[0022] 5.3 Bile salt tolerance test: 0.1%, 0.2%, 0.3%, and 0.4% ox bile salts were added to MRS liquid medium, respectively, and the pH was adjusted to 6.8. The medium was sterilized at 121 °C for 15 min. The bacterial suspensions of four strains, including C8, which had been cultured for 30 h, were inoculated into the medium at a 10% inoculation rate. The medium was then incubated at 37 °C. Viable bacteria were counted at 0 h and 3 h using the dilution plating method to calculate the survival rate of lactic acid bacteria in the bile salt-containing medium. The results are as follows Figure 6 As shown, the four strains all showed a decreasing trend in bile salt concentrations of 0.1%, 0.2%, 0.3%, and 0.4%. Among them, the survival rate of strain C8 was significantly higher than that of the other three strains in a bile salt concentration of 0.3%. Therefore, C8 was selected as the target strain.

[0023] 5.4 Hydrophobicity determination: After incubating C8 strain at 37 ℃ for 36 h, 5 mL of bacterial culture was added to a 10 mL centrifuge tube and centrifuged at 4 ℃, 6000 rpm for 10 min. The supernatant was discarded, the precipitate was collected, and the bacterial cells were washed twice with sterile PBS buffer, then resuspended and the OD was adjusted. 600 To investigate the hydrophobic properties of different hydrophobic agents, 4 mL of the adjusted bacterial culture was taken, and 0.8 mL of xylene, chloroform, and dodecane were added respectively. The mixture was vortexed for 2 min, allowed to stand at room temperature for 20 min, and the aqueous phase was collected. The absorbance (Ab) of the aqueous phase was measured at 600 nm. The hydrophobicity of the cell surface was calculated according to the following formula: Surface hydrophobicity / % = (1-Ab / Aa) × 100%; The results are as follows Figure 7 As shown, the hydrophobicity of strain C8 in different hydrophobic agents ranges from 63.83% to 75.30%. Generally, a hydrophobicity greater than 60% is considered a highly hydrophobic strain, therefore strain C8 is determined to be highly hydrophobic.

[0024] 5.5 Self-aggregation ability determination: Freshly cultured strain C8 was centrifuged at 4 ℃, 6000 rpm for 10 min, the supernatant was discarded, the bacterial cells were collected, washed twice with sterile PBS buffer, and resuspended in sterile PBS buffer to adjust the OD of the strain. 600 To obtain a concentration of 0.5 ± 0.02 (Ac), take 4 mL of bacterial suspension in a test tube and let it stand at room temperature for 24 h. During this period, take samples at 2, 4, 6, 12, and 24 h and measure the absorbance (Ad) of the supernatant of the bacterial suspension at 600 nm. The self-aggregation ability is calculated according to the following formula: Self-aggregation ability / % = (1 - Ad / Ac) × 100%; The results are as follows Figure 8 As shown, the self-aggregation capacity of strain C8 increased over time, reaching 64.36% after 24 h.

[0025] 5.6 Hemolytic assay: A single C8 strain was streaked on a sheep blood agar plate and incubated at 37 ℃ for 24-48 h. The hemolytic phenomenon around the colony was observed. The results are as follows Figure 9 As shown, strain C8 exhibits γ-hemolysis on the plate, with neither a grass-green ring nor a clear zone, indicating no hemolysis, which is consistent with the results of many hemolytic experiments on Lactobacillus brevis.

[0026] 5.7 Growth curve: After the C8 strain was activated, it was cultured in MRS liquid medium for 48 h. After a single colony grew in the plate, a single colony of lactic acid bacteria was picked and inoculated into MRS liquid medium. The culture was incubated at 37℃. The fermentation broth was shaken and sampled every 2 h. The OD600 value of the fermentation broth was measured and the growth curve was plotted. like Figure 10 As shown, strain C8 grows most vigorously within 4 to 24 hours after inoculation, reaching its maximum biomass (OD) at around 28 hours. 600 (≈2.25), then entered a stable period and began to slowly decay after 32 hours, with the entire monitoring period being 48 hours.

[0027] 5.8. Molecular biological assays of the strain: The isolated and purified C8 strain was molecularly identified using 16S rDNA analysis. Hangzhou Kaitai Biotechnology Co., Ltd. sequenced the strain, and the sequenced samples were submitted to NCBI. Similarity analysis was performed using the BLAST program with known bacterial 16S rDNA gene sequences. Primer information is shown in Table 2. Table 2 27F AGAGTTTGATCMTGGCTCAG 1492R TACGGYTACCTTGTTACGACTT The assembled result is shown in SEQ ID NO:1. The sequencing results were input into NCBI, and the BLAST function was used to compare the homology of the measured gene sequence with the 16S rRNA sequence in the NCBI database to draw a phylogenetic tree. Figure 11 It can be seen that strain C8 is related to Lactobacillus brevis ( Levilactobacillus brevis Based on the closest genetic distance, strain C8 can be preliminarily identified as belonging to the genus *Lactobacillus*. Levilactobacillus ).

[0028] The C8 strain was deposited at the China General Microbiological Culture Collection Center on June 8, 2026, and classified as *Lactobacillus short fermentation agent*. Levilactobacillus brevis C8, with accession number CGMCC No.39278.

[0029] Example 2: Optimization of conditions for the fermentation synthesis of γ-aminobutyric acid by strain C8: 1. Optimization of initial pH value of culture medium: The effect of different initial pH values ​​on GABA production by strain C8 was studied. The initial pH value of the MRS liquid medium was adjusted by using 0.2 mol / L HCl. 3% of the strain seed culture was inoculated into the medium (with a substrate L-glutamic acid concentration of 35 g / L) at initial pH values ​​of 3.5, 4.0, 4.5, 5.0, and 6.0 and cultured for 48 h at a temperature of 33℃. The effect of different pH values ​​on GABA production was analyzed to determine the optimal initial pH value. The experiment was conducted in triplicate. The results are as follows Figure 12 As shown, the GABA yield first increases and then decreases with increasing pH value. The highest GABA yield is 5.98 g / L when the initial pH value is 4.5. Therefore, the optimal initial pH value of the culture medium is 4.5.

[0030] 2. Optimization of substrate L-glutamate concentration: Based on the optimal carbon source type and concentration, the concentration of the substrate L-glutamic acid in the culture medium was changed. MRS liquid culture medium (initial pH 4.5) with L-glutamic acid concentrations of 5 g / L, 10 g / L, 15 g / L, 25 g / L and 35 g / L was prepared. Strain C8 was inoculated at a 3% inoculum and fermented at 33 ℃ for 48 h. The GABA production was measured to determine the optimal L-glutamic acid concentration. Three replicate experiments were set up for each group of samples. The results are as follows Figure 13 As shown, GABA production increases with increasing substrate concentration. The highest GABA production is 5.87 g / L when the L-glutamic acid concentration is 35 g / L. Therefore, the optimal substrate concentration of L-glutamic acid is 35 g / L.

[0031] 3. Optimization of fermentation temperature: The optimal temperature for GABA production is usually between 30 and 40°C. To investigate the effect of fermentation temperature on GABA production by strain C8, fermentation temperatures of 22°C, 26°C, 33°C, 37°C, and 42°C were set. 3% seed culture was inoculated into MRS liquid medium (initial pH 4.5, substrate L-glutamic acid concentration 35 g / L) and fermented for 48 h. GABA yield was then measured to determine the optimal fermentation temperature. Three replicate experiments were set up for each sample group. The results are as follows Figure 14 As shown, as the temperature increases, the ability of strain C8 to produce GABA first increases and then decreases, reaching a peak at 33℃ with a yield of 4.8 g / L, indicating that the strain exhibits the best ability to produce GABA at this temperature.

[0032] 4. Optimization of inoculation volume: The seed culture of strain C8 was inoculated into MRS liquid medium (initial pH 4.5, substrate L-glutamic acid concentration 35 g / L) at inoculation rates of 1%, 2%, 3%, 4%, and 5%, respectively. After incubation at 33℃ for 48 h, the GABA yield was measured at 4℃ to determine the optimal inoculation rate. Three replicate experiments were set up for each sample group. The results are as follows Figure 15 As shown, the GABA yield first increases and then decreases with the increase of the inoculum amount. When the inoculum amount is 3%, the GABA yield is the highest, which is 5.82 g / L. Therefore, the optimal initial inoculum amount of the culture medium is 3%.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A strain that produces high levels of γ-aminobutyric acid, characterized in that, The strain is *Lactobacillus short fermentation agent* (… Levilactobacillus brevis C8 was deposited on June 8, 2026 at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 39278.

2. The application of a strain that produces high levels of γ-aminobutyric acid as described in claim 1 in the fermentation synthesis of γ-aminobutyric acid.

3. The application according to claim 2, characterized in that, Includes the following steps: The seed culture of the strain producing high levels of γ-aminobutyric acid as described in claim 1 was inoculated into MRS liquid medium at an inoculation rate of 3%. The initial pH of the MRS liquid medium was 4-4.5, and the concentration of the substrate L-glutamic acid in the MRS liquid medium was 25-35 g / L. The medium was then cultured at a constant temperature of 33-37°C.

4. The application according to claim 3, characterized in that, The initial pH value was 4.5, the concentration of L-glutamic acid was 35 g / L, and the isothermal incubation temperature was 33 °C.

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