Bacteroides xylanisolvens with high yield of gamma-aminobutyric acid for relieving colitis and application thereof

Abstract

This invention discloses a high-yield γ-aminobutyric acid (GABA)-relieving bacterium for colitis and its application, belonging to the field of microbial technology. The *Bacterium xylanoplastinus* of this invention (… Bacteroides xylanisolvens NSP018 can alleviate weight loss, reduce the disease activity index, increase colon length, and improve colonic tissue damage in mice with ulcerative colitis. The oat arabinoxylan described in this invention has very broad application prospects for preparing pharmaceutical compositions and fermented foods that alleviate ulcerative colitis.

Description

Technical Field

[0001] This invention relates to a xylan-producing Bacteroides that alleviates colitis by producing high levels of γ-aminobutyric acid and its applications, belonging to the field of microbial technology. Background Technology

[0002] Gamma-aminobutyric acid (GABA) is a compound with the chemical formula C4H9NO2. It is an abundant non-protein amino acid found in nature, widely distributed in vertebrates, plants, and microorganisms. In animals, plants, and microorganisms, GABA is an important intermediate, playing a crucial role in the organism's response to environmental stress. In mammals, GABA is an important inhibitory neurotransmitter in the nervous system, playing a vital role in brain development, anxiety reduction, and lowering blood pressure. Furthermore, GABA is an important bioactive food additive. As a low-molecular-weight non-protein amino acid, GABA has been proven safe for consumption and can be used in the production of beverages and other foods. Studies have shown that GABA has various physiological functions, including regulating intestinal barrier function, preventing nervous system diseases, and improving inflammatory bowel disease.

[0003] Bacteroides xylana, as an important component of the normal intestinal microbiota, plays a vital role in maintaining the balance of the intestinal microecology. In recent years, Bacteroides xylana has become a research hotspot due to its health effects and has gained attention in the food and health product industries. The European Commission has approved its strain DSM 23964 for addition to pasteurized dairy products. It is a highly promising next-generation "probiotic".

[0004] Patent publication number CN119709549A discloses a strain of *Lactobacillus plantarum* YYY01 and its application in anti-inflammation and the production of γ-aminobutyric acid (GABA); patent publication number CN108289917A discloses the application of a xylooligosaccharide compound bacterial agent containing *Bacteroides xylana* as an endogenous folic acid supplement; patent publication number CN114933993A discloses the application of a strain of *Bacteroides xylana* and its compound preparation in alleviating ulcerative colitis; patent publication number CN114933994A discloses the application of a compound bacterial agent containing *Bacteroides xylana* that effectively reduces intestinal permeability and intestinal inflammation levels in alleviating ulcerative colitis; patent publication number CN114806962A discloses a strain of *Bacteroides xylana* AY11. 1. Its application in the preparation of drugs and health foods for treating inflammatory bowel disease; Patent publication number CN114606166A describes a strain of *Bacteroides xylana* and its application in the preparation of products for the treatment or prevention of alcoholic liver disease; Patent publication number CN104403980A describes a method for producing cellulase using a compound bacterial agent containing *Bacteroides xylana*; *Bacteroides xylana* has various probiotic effects. Although studies have shown that *Bacteroides xylana* can alleviate symptoms of ulcerative colitis, the bioactive metabolites produced by *Bacteroides xylana* are important functional substances for alleviating ulcerative colitis, and γ-aminobutyric acid (GABA) is the main metabolite produced by *Bacteroides xylana*. Currently, there are no reports indicating that *Bacteroides xylana* with high GABA production has an ameliorative effect on ulcerative colitis.

[0005] Therefore, developing a xylan-producing Bacteroides species that can produce high levels of γ-aminobutyric acid (GABA) and has anti-inflammatory effects is of great significance in the fields of medicine, food, and health products, and provides some reference and guidance for the development of products rich in GABA. Summary of the Invention

[0006] To alleviate the symptoms of ulcerative colitis, this invention screened a strain of *Bacteroides xylana* that produces high levels of γ-aminobutyric acid (GABA) from normal human feces and demonstrated its comprehensive efficacy against ulcerative colitis. This invention provides important theoretical support and guidance for the adjunctive treatment of ulcerative colitis.

[0007] This invention provides a strain of xylanbacterium ( Bacteroides xylanisolvens NSP018 was deposited on November 11, 2025, at the Institute of Microbiology, Guangdong Academy of Sciences, at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No: 67272.

[0008] In one embodiment of the present invention, the xylanobacterium ( Bacteroides xylanisolvens NSP018 was isolated from the fermentation broth of human fecal samples from normal individuals in Jiangxi Province. Sequencing analysis revealed its 16S rDNA sequence to be shown in SEQ ID NO.1. The sequence was then compared with the nucleic acid sequence of *Bacteroides xylana* using NCBI, showing a 99% similarity. Therefore, this strain is identified as *Bacteroides xylana*. Bacteroides xylanisolvens ), named: Bacteroides xylanopsinogen ( Bacteroides xylanisolvens ) NSP018.

[0009] In one embodiment of the present invention, the xylanobacterium ( Bacteroides xylanisolvensNSP018 has the following properties: Cell characteristics: Gram-negative rod-shaped bacteria, non-spore-forming, non-flagellated, approximately 0.9-1.2 μm wide and 3-8 μm long. Colony characteristics: Forms distinct colonies on culture media, with a diameter between 0.3-2 mm. The colonies are round with a raised center, neat edges, slightly whitish, opaque, and moist. Growth characteristics: This strain is a strict anaerobe, sensitive to oxygen. It grows optimally at 35-38 ℃, with an optimal pH of 6.6-7.0. It grows well in glucose-containing media, entering the late logarithmic growth phase or early stationary phase within 16-24 hours.

[0010] The present invention also provides a microbial agent containing the above-mentioned Bacteroides xylanopsinogen (Bacteroides spp.) Bacteroides xylanisolvens ) NSP018.

[0011] In one embodiment of the present invention, the microbial agent contains *Bacteroides xylanopsinus* (…). Bacteroides xylanisolvens The viable count of NSP018 is not less than 1×10⁻⁶. 9 CFU / mL or 1×10 9 CFU / g.

[0012] The present invention also provides a product containing the above-mentioned xylan-degrading Bacteroides ( Bacteroides xylanisolvens ) NSP018.

[0013] In one embodiment of the present invention, the product contains *Bacteroides xylanopsinogen* (…). Bacteroides xylanisolvens The viable count of NSP018 is not less than 1×10⁻⁶. 9 CFU / mL or 1×10 9 CFU / g.

[0014] In one embodiment of the present invention, the product is a microbial agent, food, medicine, health product, or feed additive.

[0015] In one embodiment of the present invention, the food includes beverages, dairy products, or other products containing the aforementioned Bacteroides xylanae (Bacteroides spp.). Bacteroides xylanisolvens Food products of NSP018.

[0016] In one embodiment of the invention, the drug comprises Bacteroides xylanopsinogen (Bacteroides xylanopsinogenogene) Bacteroides xylanisolvens NSP018, drug carriers and / or pharmaceutical excipients.

[0017] In one embodiment of the present invention, the dosage form of the medicine or health product includes granules, capsules, tablets, pills or oral liquids.

[0018] In one embodiment of the present invention, the pharmaceutical excipient is a pharmaceutically acceptable excipient.

[0019] In one embodiment of the present invention, the acceptable excipients include one or more commonly used thickeners, antioxidants, pH adjusters, emulsifiers, preservatives, fillers, binders, wetting agents, disintegrants, lubricants, and flavoring agents.

[0020] In one embodiment of the present invention, the filler is starch, sucrose, lactose, calcium sulfate and / or microcrystalline cellulose.

[0021] In one embodiment of the present invention, the adhesive is a cellulose derivative, alginate, gelatin, and / or polyvinylpyrrolidone.

[0022] In one embodiment of the present invention, the wetting agent is water, ethanol, starch and / or syrup.

[0023] In one embodiment of the present invention, the disintegrant is sodium carboxymethyl starch, carboxypropyl cellulose, croscarmellose, agar, calcium carbonate and / or sodium bicarbonate.

[0024] In one embodiment of the present invention, the lubricant is talc, calcium stearate, magnesium stearate, micronized silica gel, and / or polyethylene glycol.

[0025] In one embodiment of the present invention, the flavoring agent is a simple syrup, sucrose, lecithin, orange peel syrup, cherry syrup, lemon, fennel, peppermint oil, sodium alginate, gum arabic, gelatin, methylcellulose, sodium carboxymethyl cellulose, citric acid, tartaric acid and / or sodium bicarbonate.

[0026] The present invention also provides the above-mentioned xylan-degrading Bacteroides ( Bacteroides xylanisolvens NSP018, or the above-mentioned microbial agents, in the preparation of medicines for the prevention and / or treatment of colitis.

[0027] In one embodiment of the present invention, the pharmaceutical product contains *Bacteroides xylanopsinus* (…). Bacteroides xylanisolvens The viable count of NSP018 is not less than 1×10⁻⁶. 9 CFU / mL or 1×10 9 CFU / g.

[0028] In one embodiment of the invention, the drug comprises Bacteroides xylanopsinogen (Bacteroides xylanopsinogenogene) Bacteroides xylanisolvens NSP018, drug carriers and / or pharmaceutical excipients.

[0029] In one embodiment of the present invention, the dosage form of the medicine includes granules, capsules, tablets, pills, or oral liquids.

[0030] In one embodiment of the present invention, the pharmaceutical excipient is a pharmaceutically acceptable excipient.

[0031] In one embodiment of the present invention, the acceptable excipients include one or more commonly used thickeners, antioxidants, pH adjusters, emulsifiers, preservatives, fillers, binders, wetting agents, disintegrants, lubricants, and flavoring agents.

[0032] In one embodiment of the present invention, the filler is starch, sucrose, lactose, calcium sulfate and / or microcrystalline cellulose.

[0033] In one embodiment of the present invention, the adhesive is a cellulose derivative, alginate, gelatin, and / or polyvinylpyrrolidone.

[0034] In one embodiment of the present invention, the wetting agent is water, ethanol, starch and / or syrup. In one embodiment of the present invention, the disintegrant is sodium carboxymethyl starch, carboxypropyl cellulose, croscarmellose, agar, calcium carbonate and / or sodium bicarbonate.

[0035] In one embodiment of the present invention, the lubricant is talc, calcium stearate, magnesium stearate, micronized silica gel, and / or polyethylene glycol.

[0036] In one embodiment of the present invention, the flavoring agent is a simple syrup, sucrose, lecithin, orange peel syrup, cherry syrup, lemon, fennel, peppermint oil, sodium alginate, gum arabic, gelatin, methylcellulose, sodium carboxymethyl cellulose, citric acid, tartaric acid and / or sodium bicarbonate.

[0037] The present invention also provides the above-mentioned xylan-degrading Bacteroides ( Bacteroides xylanisolvens The use of NSP018, or the above-mentioned microbial agents, in the preparation of health products for maintaining intestinal health.

[0038] Beneficial effects 1. This invention screened out a strain of xylan-producing Bacteroides that produces high levels of γ-aminobutyric acid (GABA). Bacteroides xylanisolvens The *Bacteroides xylana* strain NSP018 can produce 3.49 mM of γ-aminobutyric acid (GABA) in an in vitro culture medium environment. The yield is 2.5 times that of the model strain *Bacteroides xylana* DSM 18836 (1.38 mM). Compared with other *Bacteroides xylana* strains screened at the same time (0.38~1.67 mM), the GABA yield is increased by 2.1~9.2 times, which is a significant improvement.

[0039] 2. The *Bacteroides xylanoplasminella* strain screened in this invention has the effect of alleviating ulcerative colitis, specifically manifested in: 1) It can alleviate weight loss and disease activity index in mice with ulcerative colitis and improve colon length; 2) It can improve colonic tissue damage in mice with ulcerative colitis; 3) It can increase the expression of the colonic inflammatory factor IL-10 in mice with ulcerative colitis and decrease the expression of the colonic inflammatory factors IL-6, IL-1β and TNF-α in mice with ulcerative colitis.

[0040] 3. Bacteroides xylanoplastinus ( Bacteroides xylanisolvens *Bacteroides xylanatus* is a potentially valuable probiotic, and its various probiotic effects have been extensively reported. Through numerous creative experimental studies, the inventors of this invention have discovered that *Bacteroides xylanatus* NSP018 can effectively alleviate the symptoms of ulcerative colitis and can be used in drugs, foods, or health products for the prevention and treatment of ulcerative colitis.

[0041] Preservation of biological materials A strain of xylanbacterium ( Bacteroides xylanisolvens NSP018 was deposited at the Institute of Microbiology, Guangdong Academy of Sciences on November 11, 2025, and its taxonomic name is: Bacteroides xylanisolvens The accession number is GDMCC No: 67272, and the accession address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences Institute of Microbiology. Attached Figure Description

[0042] Figure 1 The length of the colon in mice with ulcerative colitis was determined by intervention with Bacteroides xylana NSP018.

[0043] Figure 2 H&E staining of the posterior colon of mice with ulcerative colitis treated with Bacteroides xylana NSP018, scale bar 100 μm. Detailed Implementation

[0044] The mice used in the following examples were purchased from Jiangsu Jicui Yaokang Biotechnology Co., Ltd., and were housed at 25±2℃, constant humidity 50±5%, with 12 hours of light (8:00-20:00), soundproofed, and with free access to food and water. Experiments began after one week of acclimatization. The TNF-α inflammatory factor kit (catalog number: FMS-ELM028), IL-1β inflammatory factor kit (catalog number: FMS-ELM002), IL-10 inflammatory factor kit (catalog number: FMS-ELM009), and IL-6 inflammatory factor kit (catalog number: FMS-ELM006) used in the following examples were purchased from Nanjing Fomax Biotechnology Co., Ltd.; the normal diet used in the following examples was purchased from Jiangsu Xietong Pharmaceutical Biotechnology Co., Ltd. (growing and breeding feed for rats and mice).

[0045] The following examples involve culture media: Preparation of activation medium (g / L): The components include carbon sources: pectin 0.047, xylan 0.047, arabinogalactan, amylopectin 0.04, soluble starch 0.392; nitrogen sources: bacterial peptone 24, tryptone 24; inorganic salts: magnesium sulfate heptahydrate 0.5, potassium dihydrogen phosphate 2.5, sodium chloride 4.5, calcium chloride dihydrate 0.45, ferric sulfate heptahydrate 0.005; bile salts 0.4, cysteine ​​hydrochloride 0.2, and acid-base buffer (MES) 19.52. First, the above components were prepared, and the pH was adjusted to 6 before deoxygenation and sterilization (121℃, 15 min). After sterilization, the culture medium was transferred to an anaerobic glove box. 1 μg of heat-sensitive heme, 1 μg of vitamin K3 (VK3), and 0.1 mL of a vitamin mixture (Wolfe's Vitamin Solution) were added to 1 L of the culture medium and filtered through a 0.22 μm filter membrane. The medium was then deoxygenated overnight in the anaerobic glove box to obtain the activated liquid culture medium.

[0046] Preparation of enrichment medium: Each liter of enrichment medium is composed of 350 mL of solution A, 150 mL of solution B, 500 mL of solution C, 1 mL of solution D, and 0.08 mL of Wolfe's Vitamin Solution. The formula (g / L) includes: Solution A: bacterial peptone 68.57, tryptone 68.57, bile salts 1.14, anaerobic agent cysteine ​​hydrochloride 1.43, magnesium sulfate 1.14, potassium monohydrogen phosphate 5.48, sodium chloride 12.86, calcium chloride 0.97, ferric sulfate heptahydrate 0.014; Solution B: acid-base buffer (MES) 130; Solution C: Dendrobium officinale polysaccharide 10; Solution D: heme 10 mg, vitamin K3 (VK3) 8 mg. First, the autoclaved components (A and B solutions) are prepared, the pH is adjusted to 6, and deoxygenation is performed, followed by sterilization (121℃, 15 min). After sterilization, the culture medium was transferred to an anaerobic glove box and left overnight. Finally, solution D and Wolfe's Vitamin Solution were filtered through a 0.22 μm membrane and added to the culture medium in the specified proportion to obtain the enrichment medium.

[0047] BHI liquid medium (g / L): 10.0g peptone, 17.5g ox heart extract, 5.0g sodium chloride, 2.0g glucose, and 2.5g disodium hydrogen phosphate are dissolved in 1L of distilled water. 0.5g cysteine ​​hydrochloride is added and mixed thoroughly. The pH is then adjusted to 7.2-7.6. The mixture is sterilized at 115-121℃ for 15-20 min to obtain the BHI liquid medium.

[0048] Preparation of BHI solid medium: Add 1.5-2% agar to BHI liquid medium. Mix well, then adjust the pH to 7.2-7.6, and sterilize at 115-121℃ for 15-20 min to obtain the BHI solid medium.

[0049] BHI selective medium (g / L): BHI solid medium is prepared by adding 5 mg / L of heme (sterilized by membrane filtration), 10 mg / L of vitamin K1, 7.5 mg / L of vancomycin, and 100 mg / L of kanamycin.

[0050] The detection methods involved in the following embodiments are as follows: Mouse body weight, disease activity index (DAI), and colon length determination: During the modeling period, mouse body weight, fecal morphology, and degree of rectal bleeding were measured and recorded daily. Changes in body weight, fecal morphology, and degree of rectal bleeding were scored according to a scoring rule, as shown in Table 1. The DAI was calculated using the following formula: DAI = (Weight change score + Stool morphology score + Stool bleeding severity score) / 3.

[0051] Table 1 Disease Activity Index (DAI)

[0052] After the mice were euthanized, the entire colon was harvested, and the distance from the ascending colon to the end of the rectum was measured as the length of the mouse colon.

[0053] Hematoxylin-eosin staining (H&E) and histopathological scoring of mouse colon: A 1 cm distal colon sample was immersed in 4% paraformaldehyde solution for 24 h to obtain fixed colon tissue. The sample underwent dehydration, embedding, sectioning, dewaxing, and rehydration. Hematoxylin and eosin were then used for staining to obtain H&E-stained sections of the colon tissue. The sections were then observed and images were acquired using a pathological section scanner. The histopathological scoring criteria are shown in Table 2, calculated using the following formula: Pathological histological score = epithelial damage + degree of inflammation + lesion depth score.

[0054] Table 2 Histological Damage Scoring Criteria

[0055] For the determination of TNF-α, IL-1β, IL-10 and IL-6: refer to the instructions of the corresponding kit.

[0056] Example 1: Isolation and screening of *Bacteroides xylanalyticum* NSP018, a high-yield producer of γ-aminobutyric acid (GABA). 1. Sample collection Fecal samples were collected from normal individuals in Jiangxi Province. The samples were placed in preservation tubes and 5 times their weight of protective solution were added (preparation of protective solution: weigh 1 g / L cysteine ​​hydrochloride and 200-300 g / L glycerol, dissolve them evenly in PBS (1×), and sterilize at 115-121℃ for 15-20 min). The samples were then stored in an insulated box containing dry ice and brought back to the laboratory. The samples were then quickly placed in a -80°C freezer for separation and screening.

[0057] 2. Accumulation of fecal bacteria The above fecal microbiota solution was removed from the -80℃ freezer, thawed, and centrifuged at low speed (500 g, 5 min, 4℃) to obtain the supernatant. The supernatant was then filtered through a 100 μm filter to remove impurities. The supernatant fecal microbiota solution was inoculated into activation medium (fecal microbiota solution: activation medium = 1:9, (v / v)) and incubated at 37℃ and 140 rpm for 16 h. Then, it was inoculated into enrichment medium at an inoculation ratio of 10% (v / v) and incubated at 37℃ and 140 rpm for 24 h. The resulting fecal microbiota solution was enriched with arabinoxylan. All operations were performed in a sterile anaerobic environment.

[0058] 3. Isolation and purification of Bacteroides (1) Gradual dilution of fecal microbial solution: In a sterile anaerobic environment, take the above-enriched fecal microbial solution and add it to 9 mL of physiological saline to obtain the first gradient dilution. Take 1 mL of the first gradient dilution and add it to 9 mL of physiological saline to obtain the second gradient dilution. And so on, to prepare a total of 5 gradient dilutions. (2) Spreading culture: Take 100 μL of each of the above gradient dilutions and place them on BHI fixative medium. After spreading, incubate under anaerobic conditions at 37°C for 48 h to obtain diluted spread plates. (3) Purification culture: Select pure single colonies with neat edges, slightly white, opaque, moist and smooth surfaces, and uniform morphology from the solid culture medium and inoculate them into 5 mL of liquid BHI selective medium. Incubate under anaerobic conditions at 37°C for 24 h to obtain a purified culture solution with a viable count of approximately 1 × 10⁻⁶ cells / mL. 9 CFU / mL.

[0059] 4. Preservation and Identification of Microbial Strains The purified culture medium with the best growth obtained in step 3 was centrifuged at 8000 rpm for 10 min, and the supernatant was discarded to obtain bacterial cells. PCR was performed using bacterial 16S rDNA PCR-specific primers (see Table 2). After the PCR products were confirmed by nucleic acid electrophoresis analysis, the amplified products were sent to the company for sequencing. The sequencing results were compared with the sequences in the NCBI database; the results showed that the similarity with the nucleic acid sequence of gene expression was as high as 99%, and a total of 33 strains of Bacteroides xylana were screened.

[0060] Table 3 Primer Names

[0061] 5. Targeted metabolic assay of the ability of 33 strains of Bacteroides xylana to produce γ-aminobutyric acid. The purified culture medium obtained in step 3 with good growth was centrifuged at 12000 rpm for 10 min, and the supernatant was collected to remove the bacterial cells. 100 μL of the supernatant was added to 400 μL of pure methanol, vortexed, centrifuged at 12000 rpm for 15 min, and filtered through a membrane. γ-aminobutyric acid (GABA) was detected using QTRAP 4500 HPLC-MS / MS. The experimental results are shown in Table 4. The range of GABA production by the 33 strains of *Bacteroides xylana* was 0.38–3.49 mM. The highest GABA production was 3.49 mM in *Bacteroides xylana*, significantly higher than that of the *Bacteroides xylana* model strain (…). Bacteroides xylanisolven DSM 18836, whose 16S rDNA sequence is shown in SEQ ID NO.1, is named *Bacteroides xylanopsinus* (DSM 18836). Bacteroides xylanisolvens ) NSP018.

[0062] Table 4. Production capacity of γ-aminobutyric acid by 33 strains of *Bacteroides xylana*

[0063] Example 2: Effects of Bacteroides xylanoplastinus NSP018 on body weight changes, DAI, and colon length in mice with ulcerative colitis The specific steps are as follows: 1. Preparation of Bacteroides xylanoplastin NSP018 cryopreservation medium: (1) Cultivation method: In a sterile anaerobic environment, Bacteroides xylana NSP018 strain was streaked on BHI solid medium and cultured under anaerobic conditions for 48 h. After single colonies were formed, single colonies were picked and inoculated into BHI liquid medium. The culture was carried out anaerobically at 37℃ for 16-24 h to reach the stationary phase. The OD value at this time was 0.8~1.0, and the seed liquid was prepared.

[0064] (2) Preparation of protective agent: Weigh 1 g / L cysteine ​​hydrochloride and 200-300 g / L glycerol, dissolve them evenly in distilled water, and sterilize at 115-121℃ for 15-20 min.

[0065] (3) Preparation of cryoprotectant: After centrifuging the Bacteroides xylanoplastin NSP018 seed culture from step (1) to the stable phase (8000 rpm, 10 min, 4℃), wash it 1-2 times with sterile phosphate buffer (pH 7.2), and then resuspend the bacterial culture with the protectant prepared in step (2) to obtain Bacteroides xylanoplastin NSP018 cryoprotectant, and store it at -80℃ for later use.

[0066] 2. Preparation of Bacteroides xylanoplastin NSP018 bacterial agent: (1) Activation of strains: The xylan-degrading Bacteroides NSP018 cryopreservative prepared in step 1 was streaked on BHI solid medium and cultured under anaerobic conditions for 48 h. After single colonies were formed, they were inoculated into BHI liquid medium and cultured anaerobically at 37℃ for 16-24 h to reach the stationary phase (OD value: 0.8~1.0).

[0067] (2) Preparation of bacterial agent: Take 100 μL of the culture medium obtained in step (1) at different dilution ratios and spread it on BHI solid medium. Count the number of colonies on the BHI solid plate and calculate the number of viable bacteria in the liquid medium of step (1). After washing 1-2 times with sterile phosphate buffer (pH 7.2), prepare the bacterial solution to a concentration of 1×10⁻⁶. 9 For formulations with a concentration of CFU / mL, the gavage volume is 0.1 mL.

[0068] (3) Preparation of heat-inactivating agent: Ferment Bacteroides xylanolyticus NSP018 to obtain a culture medium according to the method in step (1). Centrifuge the culture medium and wash the bacterial cells 2-3 times with sterile PBS. Resuspend the bacterial cells in PBS and adjust to the target concentration. Inactivate the bacterial suspension in an autoclave at 121 °C for 15 min. After cooling, spread the solution on agar plates to verify sterile growth and confirm that the inactivation is complete.

[0069] 3. Experimental methods: Intervention and treatment experiment process: This invention uses dextran sodium sulfate (DSS) to induce an ulcerative colitis model in mice. Twenty-four 6-week-old healthy male C57BL / 6J mice were randomly divided into three groups (n=8 per group): a normal group (NC for convenience), an ulcerative colitis group (model group, DSS), a live xylanobacterium NSP018 group (Bx for convenience), and a heat-inactivated xylanobacterium NSP018 group (KBx for convenience). The experimental procedure is shown in Table 5. After a one-week acclimatization period, the xylanobacterium NSP018 group (Bx) was administered 0.1 mL of xylanobacterium NSP018 (bacterial concentration 1×10⁻⁶) by gavage once daily during the intervention period. 9 CFU / mL); Heat-inactivated xylan-degrading Bacteroides NSP018 group (KBx): 0.1 mL of heat-inactivated xylan-degrading Bacteroides NSP018 bacterial suspension (bacterial concentration of 1×10⁻⁶) was administered by gavage once daily during the intervention period. 9 Mice in the NC and DSS groups were administered 0.1 mL of sterile phosphate-buffered saline (PBS) via gavage once daily for 14 days. Starting on day 8, mice in the normal control group continued to freely drink autoclaved distilled water, while the model group, Bx, and KBx groups drank 3% DSS distilled water for 7 consecutive days to establish a mouse model of colitis. On day 15, mice were euthanized by enucleation, and tissue samples were collected and stored at -80 °C for future studies.

[0070] Table 5 Experimental Procedure

[0071] 4. Effects of Bacteroides xylanoplastinus NSP018 on body weight changes, DAI, and colon length in mice with ulcerative colitis. The specific experimental procedure is the same as step 3. During the modeling period, the mouse weight, fecal morphology, and degree of rectal bleeding were measured and recorded daily. The changes in mouse weight, fecal morphology, and degree of rectal bleeding were scored according to a scoring rule. After the experiment, the entire colon was harvested, and the distance from the ascending colon to the end of the rectum was measured as the mouse colon length. The experimental results are shown in Tables 6, 7, and 8. Figure 1As shown, Bx intervention significantly alleviated weight loss and DAI in mice with ulcerative colitis and significantly increased colon length.

[0072] Table 6. Effects of Bacteroides xylanica on body weight change (%) in mice with ulcerative colitis

[0073] Table 7. Effects of *Bacteroides xylana* on DAI in mice with ulcerative colitis.

[0074] Table 8. Effects of Bacteroides xylaniae on colon length in mice with ulcerative colitis

[0075] Example 3: Effects of Bacteroides xylanoplasty NSP018 on colonic tissue scores and colonic inflammatory factors in mice with ulcerative colitis The specific steps are as follows: The specific experimental method was the same as in Example 2, except that mouse colons were collected after the experiment, and H&E staining was performed on the mouse colons to determine the levels of free TNF-α, IL-1β, IL-10, and IL-6. The results are shown in Tables 9 and 10. Figure 2 As shown.

[0076] The results showed that the colonic tissue structure of mice in the NC group was clear, with intact mucosa, neatly arranged epithelial cells, and intact crypts, and no obvious inflammatory cell infiltration was found. In contrast, the colonic tissue structure of mice in the DSS group was severely damaged, with almost complete mucosal destruction, disappearance of crypts, and obvious inflammatory cell infiltration. After administration of *Bacteroides xylana*, the colonic tissue was significantly improved, showing basically normal colonic tissue morphology with only a small amount of inflammatory infiltration and abundant crypts. The colonic tissue score of the Bx group was significantly lower than that of the DSS group. In addition, the colonic inflammatory factors in the Bx group were also significantly lower than those in the DSS group. Compared with the DSS group, the expression of inflammatory factors TNF-α, IL-1β, and IL-6 was significantly decreased, while the expression of IL-10 was significantly increased. This indicates that *Bacteroides xylana* NSP018 of the present invention can improve colonic tissue damage and colonic inflammatory factor levels in colitis mice.

[0077] Table 9: Effects of Bacteroides xylaniae on colon tissue scores in mice with ulcerative colitis

[0078] Table 10 Effects of Bacteroides xylaniae on colonic inflammatory factors in mice with ulcerative colitis

[0079] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A strain of Bacteroides xylanoplastinus ( Bacteroides xylanisolvens NSP018 was deposited on November 11, 2025, at the Institute of Microbiology, Guangdong Academy of Sciences, at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No: 67272.

2. A microbial inoculant, characterized in that, Contains Bacteroides xylanase NSP018 as described in claim 1.

3. The microbial agent as described in claim 2, characterized in that, In the microbial agent, the bacterial count of Bacteroides xylana-NSP018 is not less than 1×10⁻⁶. 9 CFU / mL or 1×10 9 CFU / g.

4. A product containing *Bacteroides xylanoplastinus* NSP018 as described in claim 1, characterized in that, The products include microbial agents, food, pharmaceuticals, health products, or feed additives.

5. The product as described in claim 4, characterized in that, In the product, the viable count of Bacteroides xylanaminifera NSP018 is not less than 1×10⁻⁶. 9 CFU / mL or 1×10 9 CFU / g.

6. The product as described in claim 4, characterized in that, The food products mentioned include beverages and dairy products.

7. The product as described in claim 4, characterized in that, The drug comprises Bacteroides xylanase NSP018 as described in claim 1, and also contains a drug carrier and / or pharmaceutical excipients; the dosage form of the drug includes granules, capsules, tablets, pills or oral liquids.

8. A method for preparing GABA, characterized in that, The xylan-degrading Bacteroides NSP018 of claim 1 was inoculated into a culture medium for fermentation.

9. The use of Bacteroides xylanaminifera NSP018 as described in claim 1, or the microbial agent as described in claim 2 or 3, in the preparation of a medicament for the prevention and / or treatment of colitis.

10. The use of Bacteroides xylanase NSP018 as described in claim 1, or the microbial agent as described in claim 2 or 3, in the preparation of health products for maintaining intestinal health.

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