Phytobacterium plantarum DPUL-F232 and application of capsular polysaccharide of phytobacterium plantarum DPUL-F232 in food allergy

Abstract

The invention discloses application of plant lactobacillus DPUL-F232 and capsular polysaccharide thereof in food allergy, and belongs to the technical field of microorganisms. The lactobacillus plantarum DPUL-F232 capsular polysaccharide disclosed by the invention can be used for relieving allergic symptoms and weight change of rats; the spleen index and rectum temperature change are reduced; the levels of serum antibodies IgE, IgG1 and IgG2a are reduced; mast cell protease and histamine levels are reduced; regulating the levels of cell factors IFN-gamma, IL-4, IL-10, IL-6 and IL-17A of serum and splenocytes; the heat-inactivated lactobacillus plantarum DPUL-F232 capsular polysaccharide is very high in stability, can be stored for a long time, is suitable for preparing anti-allergic foods or medicines, and has a relatively good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and particularly relates to application of Lactobacillus plantarum DPUL-F232 and capsular polysaccharide thereof in food allergies. Background Art

[0002] Food allergy (FA) has become a major global public health issue, affecting more than 25% of the world's population. To date, due to a lack of a clear understanding of the molecular mechanisms underlying allergic diseases, no cure has been found. Effective strategies for coping with food allergies primarily involve avoiding allergens and taking emergency medications. However, this approach has significant limitations. First, it is impossible to completely control the intake of food allergens. Second, even with medication, it is difficult to guarantee therapeutic efficacy, and chemical drugs can have significant side effects on the human body. Therefore, in order to alleviate the increasing incidence of allergic diseases, it is of great significance to develop a new method for preventing allergies to meet existing medical needs.

[0003] In allergic reactions, IgE-mediated type I hypersensitivity reactions predominate, typically characterized by a Th1 / Th2 balance favoring the Th2 group. Some probiotics have been shown to exhibit promising anti-allergic properties, modulating the Th1 / Th2 balance and alleviating allergic symptoms. Identifying probiotic active ingredients with anti-allergic properties and applying them in anti-allergic applications is an urgent challenge. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide an application of Lactobacillus plantarum DPUL-F232 and its capsular polysaccharide in food allergies.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a Lactobacillus plantarum DPUL-F232, which was deposited in the China Center for Type Culture Collection on April 23, 2023, and the strain deposition number is CCTCC NO: M 2023590.

[0007] In a second aspect, the present invention provides the capsular polysaccharide of the aforementioned Lactobacillus plantarum DPUL-F232.

[0008] Based on the above technical solution, further, the capsular polysaccharide of the Lactobacillus plantarum DPUL-F232 has a weight average molecular weight (Mw) of 95335 Da, a number average molecular weight (Mn) of 63530 Da, and a dispersion coefficient (Mw / Mn) of 1.50.

[0009] Based on the above technical solution, further, the molar percentage of monosaccharides in the capsular polysaccharide of the plant lactobacillus DPUL-F232 is: L-guluronic acid: D-mannuronic acid: D-mannose: D-glucosamine: D-ribose: L-rhamnose: D-glucuronic acid: D-galactosamine: D-glucose: D-galactose: D-xylose: L-arabinose: L-fucose = 0.251: 0.021: 1.828: 6.666: 0.649: 0.195: 0.656: 3.403: 74.937: 8.965: 0.086: 0.336: 2.008.

[0010] Based on the above technical solution, further, the infrared structural data of the capsular polysaccharide of Lactobacillus plantarum DPUL-F232 are as follows: 3418.12 cm -1 There is an OH stretching vibration absorption peak at 2945.25cm -1 There is an absorption peak of CH at 1749.77 cm -1 There is an absorption peak of C=O stretching vibration at 1635.07cm -1 There is an absorption peak of crystal water at 1539.94 cm -1 There is an absorption peak of NH angle vibration at 1460.64cm -1 There is an absorption peak of CH angle vibration at 1384.87cm -1 and 1334.22, the absorption peaks of C=O symmetrical stretching vibration; at 1219.80cm -1 and 1054.62cm -1 There is an absorption peak of OH angle vibration at 837.89cm -1 There is a CH angle vibration absorption peak of the α-end group diastereomer of the pyran ring.

[0011] In a third aspect, the present invention provides a method for preparing the capsular polysaccharide of the above-mentioned Lactobacillus plantarum DPUL-F232, comprising the following steps: resuspending the inactivated Lactobacillus plantarum DPUL-F232 in an aqueous solution, ultrasonically extracting, adding trichloroacetic acid to the obtained supernatant to precipitate protein, adding anhydrous ethanol to the obtained supernatant to precipitate polysaccharide, dissolving the obtained polysaccharide precipitate in water, dialyzing, and freeze-drying to obtain the polysaccharide.

[0012] Based on the above technical solution, further, the specific process of inactivation is inactivation at 70-100° C. for 10-50 minutes.

[0013] Based on the above technical solution, further, the mass ratio of Lactobacillus plantarum DPUL-F232 to water is 1:1-5, and NaCl is dissolved in the aqueous solution with a concentration of 0.1-2 mol / L.

[0014] Based on the above technical solution, the specific process of ultrasonic extraction is as follows: ultrasonication is performed in an ice water bath under 100-500W ultrasonic action for 10-60 minutes, working for 1-3 seconds and pausing for 3-6 seconds.

[0015] Based on the above technical solution, further, the final concentration of trichloroacetic acid is 1-5%.

[0016] Based on the above technical solution, further, the volume ratio of the supernatant to anhydrous ethanol is 1:1-5.

[0017] In a fourth aspect, the present invention provides a composition comprising the capsular polysaccharide of the aforementioned Lactobacillus plantarum DPUL-F232.

[0018] In a fifth aspect, the present invention provides a food comprising the capsular polysaccharide of the aforementioned Lactobacillus plantarum DPUL-F232.

[0019] In a sixth aspect, the present invention provides a medicine comprising the capsular polysaccharide of the aforementioned Lactobacillus plantarum DPUL-F232.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention discovers for the first time that Lactobacillus plantarum DPUL-F232 capsular polysaccharide can alleviate allergic symptoms and weight changes in rats; reduce spleen index and rectal temperature changes; reduce serum antibody IgE, IgG1, and IgG2a levels; reduce mast cell protease and histamine levels; and regulate the levels of cytokines IFN-γ, IL-4, IL-10, IL-6, and IL-17A in serum and spleen cells. The heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide is very stable and can be stored for a long time, making it suitable for preparing anti-allergic foods or medicines and having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Figure 2 shows the monosaccharide composition analysis, infrared spectrum analysis and molecular weight determination of the capsular polysaccharide of heat-killed Lactobacillus plantarum DPUL-F232. Figure A shows the monosaccharide composition analysis, 1: L-guluronic acid; 2: D-mannuronic acid; 3: D-mannose; 4: D-glucosamine; 5: D-ribose; 6: L-rhamnose; 7: D-glucuronic acid; 8: D-galacturonic acid; 9: D-galactosamine; 10: D-glucose; 11: D-galactose; 12: D-xylose; 13: L-arabinose; 14: L-fucose; Figure B shows the infrared spectrum analysis; and Figure C shows the molecular weight determination.

[0023] Figure 2This figure shows the regulatory effect of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on splenocyte Th1 / Th2, with **p<0.01 indicating a significant difference.

[0024] Figure 3 This figure shows the effect of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on the body weight and allergic symptoms of rats allergic to whey protein, where A is the weight growth rate of rats, B is the allergic reaction score, C is the spleen index, and D is the rectal temperature change; *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001 indicate significant differences, and ns indicates no significant difference.

[0025] Figure 4 This figure shows the effects of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on serum total IgE, serum IgG1 and IgG2a, histamine levels, and mast cell protease in rats with whey protein allergy, where A is the total IgE level, B is the IgG1 level, C is the IgG2a level, D is the histamine level, and E is the mast cell protease level; **p<0.01, ***p<0.001, ****p<0.00001 indicate significant differences, and ns indicates no significant difference.

[0026] Figure 5 This figure shows the effect of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on serum cytokines in rats with whey protein allergy, where A is the level of IFN-γ, B is the level of IL-4, C is the ratio of IFN-γ / IL-4, D is the level of IL-10, E is the level of IL-6, and F is the level of IL-17A; **p<0.01, ***p<0.001, and ****p<0.00001 indicate significant differences. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0028] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0029] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0030] Example 1 Strain culture

[0031] The plant lactobacillus DPUL-F232 of the present invention is isolated and obtained from Xinjiang fermented milk. The plant lactobacillus DPUL-F232 of the present invention is cultured and activated in MRS culture medium. The specific steps are as follows:

[0032] a. Strain culture method

[0033] (1) Preparation of MRS culture medium

[0034] According to 20 g / L glucose, 10 g / L peptone, 5 g / L yeast extract, 10 g / L beef extract, 1 mL Tween-80, 2 g / L dipotassium hydrogen phosphate, 2 g / L diammonium citrate, 5 g / L sodium acetate, 0.58 g / L magnesium sulfate heptahydrate, and 0.25 g / L manganese sulfate tetrahydrate, these raw materials were weighed and mixed uniformly, and the resulting mixture was dissolved in deionized water. The resulting solution was sterilized at a temperature of 121° C. for 20 min to obtain the MRS medium.

[0035] Lactobacillus plantarum DPUL-F232 was streaked onto MRS medium containing 2% agar and cultured anaerobically at 37°C for 48-72 hours. Single colonies were picked and Gram-stained. Morphological observation was performed under a microscope and a catalase test was performed. All operations involving the transfer of microbial strains should be performed under strict aseptic conditions.

[0036] b. Strain staining

[0037] Gram staining is used to stain the strains. Microscopic examination is performed first at low magnification, then at high magnification, and finally under an oil immersion lens. The Gram stain reactivity of the bacteria is determined. Bacteria that stain blue-purple are Gram-positive bacteria, while those that stain red are Gram-negative bacteria.

[0038] c. Catalase test of bacterial strains

[0039] The above Gram-positive strains were picked up with an inoculation loop and placed on a glass slide containing a drop of 3% hydrogen peroxide solution. If a large number of bubbles were produced, it was positive; otherwise, it was negative.

[0040] The Gram staining of Lactobacillus plantarum DPUL-F232 was positive and the catalase test was negative. The strain was inoculated into MRS liquid culture medium and cultured at 37°C for 24-48 hours. Shanghai Sangon Biotechnology Co., Ltd. was commissioned to perform 16SrDNA sequencing and identification, and the identification result was Lactobacillus plantarum.

[0041] d. Strain preservation

[0042] The plant lactobacillus DPUL-F232 is deposited in the China Center for Type Culture Collection (CCTCC for short, address: Luojia Mountain, Wuchang, Wuhan City, China Center for Type Culture Collection, Postal Code 430072), the strain deposit number is CCTCC NO: M2023590, the preservation date is April 23, 2023, the classification name is plant lactobacillus (Lactiplantibacillus plantarum), and the strain name is DPUL-F232.

[0043] Example 2 Extraction of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide

[0044] The plant lactobacillus DPUL-F232 of Example 1 was inactivated at 80°C for 20 min to obtain heat-killed plant lactobacillus cells, weighed, and resuspended in a 1 mol / L NaCl aqueous solution 1.2 times the cell mass to achieve cell wall separation; the cells were then ultrasonicated in an ice-water bath at 400W for 20 min, with a working period of 2.0 s and a pause of 5.0 s. After the ultrasonic treatment, the supernatant was collected, a trichloroacetic acid solution with a final concentration of 4% was added, and the cells were shaken at room temperature for 60 min and then centrifuged at 10,000 × g at 4°C for 20 min to remove the cell surface protein. The supernatant obtained by centrifugation was mixed with 2.5 volumes of anhydrous ethanol at 4°C and allowed to stand overnight. The cells were then centrifuged at 10,000 × g at 4°C for 10 min to collect the polysaccharide precipitate, which was dissolved with a small amount of deionized water, dialyzed at 4°C for 48 h, and then freeze-dried. The capsular polysaccharide concentration was determined using the phenol-sulfuric acid method before the experiment.

[0045] Example 3 Monosaccharide composition, infrared spectroscopy analysis and molecular weight analysis of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide

[0046] Weigh 10-20 mg of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide into a 10 mL hydrolysis tube, add 5 mL of 2 mol / L TFA, fill the tube with N2 and seal it (10 L / min, 1 min), and hydrolyze it in a 110 ° C oven for 2 h; after cooling, take 1 mL of the hydrolyzate and add 1 mL of methanol, blow dry with N2 in a 70 ° C water bath, and repeat the blow-drying twice to completely remove TFA; add 1 mL of 0.3 mol / L NaOH solution to fully dissolve the residue to obtain polysaccharide hydrolyzate, which is appropriately diluted for derivatization determination.

[0047] Weigh 14 monosaccharide standards (D-glucose, L-fucose, L-rhamnose, L-arabinose, D-galactosamine, D-glucosamine, D-galactose, D-xylose, D-mannose, D-ribose, D-galacturonic acid, D-glucuronic acid, L-guluronic acid, and D-mannuronic acid) to prepare a standard solution at approximately 0.4 mg / mL. Pipette 400 μL of the mixed monosaccharide standard solution or monosaccharide standard solution into a 5 mL stoppered test tube. Add 400 μL of the PMP methanol solution and vortex to mix thoroughly. Incubate in a 70°C water bath for 2 h. Remove and cool to room temperature. Neutralize with 400 μL of 0.3 mol / L HCl (pH 6-7). Add 1200 μL of water and an equal volume of chloroform. Vortex to mix thoroughly. Allow to stand. Discard the chloroform phase. Repeat this extraction process twice. The aqueous phase was filtered through a 0.45 μm microporous membrane and then injected into the HPLC for analysis. Instrument model: Agilent 1100, equipped with DAD detector. Chromatographic conditions: C18 column, 250 mm x 4.6 mm, 5 μm particle size; mobile phase A: 100 mM sodium phosphate buffer (pH 6.7); mobile phase B: acetonitrile; detection wavelength: 250 nm; column temperature: 30°C; flow rate: 1 mL / min; injection volume: 5 μL. Elution gradient: 0 min: phase A / phase B (86:14, V / V), 9 min: phase A / phase B (83:17, V / V), 28 min: phase A / phase B (78:22, V / V), 29 min: phase A / phase B (50:50, V / V), 31 min: phase A / phase B (50:50, V / V), 32 min: phase A / phase B (86:14, V / V), 36 min: phase A / phase B (86:14, V / V). According to the single-label method, the concentrations of different monosaccharides were determined, and the monosaccharide molar ratio of the heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide was calculated based on the molar mass of the monosaccharides.

[0048] Infrared spectroscopy analysis: 2 mg of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide and 200 mg of potassium bromide were accurately weighed and pressed into tablets. A blank control was prepared by pressing potassium bromide powder into tablets. The tablets were placed on a Fourier transform infrared spectrometer FT-IR 650 for scanning and recording.

[0049] Molecular weight analysis: The molecular weight of the capsular polysaccharide of heat-killed Lactobacillus plantarum DPUL-F232 was determined using a Waters 1525, a differential refractive index detector 2414, a PLaquqgel-OH MIXED 8 μm column, a mobile phase of 0.2 M NaNO₃, 0.01 M NaH₂PO₄, pH 7, a flow rate of 1 ml / min, and a temperature of 30°C. Polyethylene glycol was used as a standard.

[0050] The monosaccharide composition, infrared spectroscopy analysis and molecular weight of the capsular polysaccharide of heat-killed Lactobacillus plantarum DPUL-F232 are shown in Figure 2. Figure 1 As shown in the figure, the molar percentages of the capsular polysaccharide of heat-killed Lactobacillus plantarum DPUL-F232 are: L-guluronic acid: D-mannuronic acid: D-mannose: D-glucosamine: D-ribose: L-rhamnose: D-glucuronic acid: D-galacturonic acid: D-galactosamine: D-glucose: D-galactose: D-xylose: L-arabinose: L-fucose = 0.251: 0.021: 1.828: 6.666: 0.649: 0.195: 0.656: 0.000: 3.403: 74.937: 8.965: 0.086: 0.336: 2.008. The weight average molecular weight (Mw) is 95,335 Da, the number average molecular weight (Mn) is 63,530 Da, and the dispersion coefficient (Mw / Mn) is 1.50.

[0051] The infrared structure is as follows: 3418.12cm -1 There is an OH stretching vibration absorption peak at 2945.25cm -1 There is an absorption peak of CH at 1749.77 cm -1 There is an absorption peak of C=O stretching vibration at 1635.07cm -1 There is an absorption peak of crystal water at 1539.94 cm -1 There is an absorption peak of NH angle vibration at 1460.64cm -1 There is an absorption peak of CH angle vibration at 1384.87cm -1 and 1334.22, the absorption peaks of C=O symmetrical stretching vibration; at 1219.80cm -1 and 1054.62cm -1 There is an absorption peak of OH angle vibration at 837.89cm -1 There is a CH angle vibration absorption peak of the α-end group diastereomer of the pyran ring.

[0052] Example 4 Effect of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on rat spleen cytokine levels

[0053] The experimental design included two groups: an allergy group (SD rat splenocytes, 200 μg / mL whey protein, complete 1640 medium) and a heat-inactivated Lactobacillus plantarum DPUL-F232 capsular polysaccharide group (CPS) (SD rat splenocytes, 200 μg / mL whey protein, 50 μg / mL capsular polysaccharide). Cultures were incubated at 37°C and 5% carbon dioxide for 72 hours. The supernatants were centrifuged (8000 × g, 5 minutes) and the levels of IFN-γ (Cat. No. BPE30654) and IL-4 (Cat. No. BPE30647) in the supernatants were directly measured using ELISA kits (Shanghai Langdun Biotechnology Co., Ltd.).

[0054] The results are as follows Figure 2 As shown in the results, the IFN-γ / IL-4 ratio of the heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide group was significantly higher than that of the allergy group, indicating that the heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide can efficiently regulate the Th1 / Th2 balance of spleen cells and has the potential to alleviate allergies in vitro.

[0055] Example 5 Effects of heat-killed Lactobacillus plantarum capsular polysaccharide on allergic symptoms, serum antibody and allergic mediator levels in rats

[0056] After one week of adaptive feeding, five-week-old female SD rats were randomly divided into a control group (Control), an allergy group (Allergy), a high-dose group of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide (12 mg / kg, H-CPS), and a low-dose group of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide (6 mg / kg, L-CPS), with 8 rats in each group. On day 0, the control group (PBS + Freund's complete adjuvant), the allergic group (0.2 mg whey protein + Freund's complete adjuvant), the heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide high-dose group (0.2 mg whey protein + Freund's complete adjuvant) and the heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide low-dose group (0.2 mg whey protein + Freund's complete adjuvant) were intraperitoneally sensitized in a total volume of 1 mL, with the antigen and adjuvant mixed in a ratio of 1:1. On days 14 and 21, the control group (PBS + Freund's incomplete adjuvant) was given an IVF dose of 10 mg / kg. The allergy group, the high-dose heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide group, and the low-dose heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide group (0.1 mg whey protein + incomplete Freund's adjuvant) were given a booster sensitization in a total volume of 1 mL. On day 28, the control group (PBS), the allergy group, the high-dose heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide group, and the low-dose heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide group (0.1 mg whey protein) were given a booster sensitization in a total volume of 0.5 mL. The high-dose group (H-CPS) was gavaged daily with 1 mL of the corresponding concentration of Lactobacillus plantarum DPUL-F232 capsular polysaccharide according to body weight, while the low-dose group (L-CPS) was gavaged daily with 1 mL of the corresponding concentration of Lactobacillus plantarum DPUL-F232 capsular polysaccharide according to body weight. Allergy and control groups were gavaged with an equal volume of 1 mL of 0.01 mol / L PBS for 5 weeks, with body weights recorded on days 0, 7, 14, 21, 28, and 35. On day 35, rats were challenged orally with 240 mg of whey protein in the allergy, high-dose, and low-dose heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide groups, while rats in the control group were orally administered with an equal volume of 0.01 mol / L PBS. Allergy symptoms were recorded over 30 minutes, and rectal temperature was measured using a veterinary thermometer 30 minutes before and after gavage. Following the experimental results, rats were sacrificed under anesthesia, and serum samples, spleen, and peritoneal mast cells were collected for analysis.

[0057] After anesthesia, rats were bled from the eyeballs into standard EP tubes and EP tubes containing anticoagulant. Whole blood was placed at 4°C overnight and centrifuged at 4000 rpm for 20 minutes. Serum was carefully aspirated and aliquoted for cryopreservation. Plasma was immediately mixed by inversion 8-10 times and centrifuged at 4000 rpm for 10 minutes at 4°C. The upper plasma layer was transferred to EP tubes and cryopreserved. Serum and plasma were directly assayed for serum total IgE (Cat. No. BPE30441), total IgG1 (Cat. No. BPE30811), total IgG2a (Cat. No. BPE30824), mast cell protease (Cat. No. BPE30701), and plasma histamine (Cat. No. BPE30476) using ELISA kits (Shanghai Langdun Biotechnology Co., Ltd.).

[0058] The results are as follows Figure 3 and Figure 4 As shown in the results, heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide can significantly alleviate the allergic symptoms of rats and reduce the changes in spleen index and rectal temperature; significantly alleviate the levels of total IgE, IgG1 and IgG2a in rat serum, and significantly reduce the levels of serum mast cell protease and plasma histamine in rats.

[0059] Example 6 Effect of heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide on serum cytokine levels in rats

[0060] Serum was obtained as described in Example 5, and the levels of IFN-γ (Cat. No.: BPE30654), IL-4 (Cat. No.: BPE30647), IL-10 (Cat. No.: BPE30561), IL-6 (Cat. No.: BPE30646), and IL-17A (Cat. No.: BPE30950) in the serum were directly measured using ELISA kits (Shanghai Langdon Biotechnology Co., Ltd.).

[0061] The results are as follows Figure 5 As shown in the results, heat-killed Lactobacillus plantarum DPUL-F232 capsular polysaccharide can significantly reduce the level of Th2 cytokine IL-4 in rat serum, alleviate the Th1 / Th2 imbalance caused by allergies, significantly increase the IFN-γ / IL-4 ratio, and significantly reduce the levels of IL-6 and IL-17A.

Claims

1. A Lactobacillus plantarum DPUL-F232, characterized in that The plant lactobacillus DPUL-F232 was deposited in the China Center for Type Culture Collection on April 23, 2023, and the strain preservation number is CCTCC NO: M 2023590.

2. The capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to claim 1.

3. The capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to claim 2, characterized in that The capsular polysaccharide of Lactobacillus plantarum DPUL-F232 has a weight average molecular weight (Mw) of 95335 Da, a number average molecular weight (Mn) of 63530 Da, and a dispersion coefficient (Mw / Mn) of 1.

50.

4. The capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to claim 2, characterized in that The monosaccharide molar percentages of the capsular polysaccharide of the plant lactobacillus DPUL-F232 are: L-guluronic acid: D-mannuronic acid: D-mannose: D-glucosamine: D-ribose: L-rhamnose: D-glucuronic acid: D-galactosamine: D-glucose: D-galactose: D-xylose: L-arabinose: L-fucose=0.251:0.021:1.828:6.666:0.649:0.195:0.656:3.403:74.937:8.965:0.086:0.336:2.

008.

5. The method for preparing the capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to any one of claims 2 to 4, characterized in that: The method comprises the following steps: resuspending inactivated Lactobacillus plantarum DPUL-F232 in an aqueous solution, performing ultrasonic extraction, adding trichloroacetic acid to the obtained supernatant to precipitate protein, adding anhydrous ethanol to the obtained supernatant to precipitate polysaccharide, adding water to dissolve the obtained polysaccharide precipitate, dialyzing, and freeze-drying to obtain the product.

6. The preparation method according to claim 5, characterized in that The specific process of inactivation is inactivation at 70-100° C. for 10-50 minutes; the mass ratio of plant lactobacillus DPUL-F232 to water is 1:1-5, and NaCl is dissolved in the aqueous solution with a concentration of 0.1-2 mol / L.

7. The preparation method according to claim 5, characterized in that The specific process of ultrasonic extraction is as follows: ultrasonication is performed in an ice water bath at 100-500W for 10-60 minutes, with a working time of 1-3 seconds and a pause time of 3-6 seconds; the final concentration of trichloroacetic acid is 1-5%; and the volume ratio of the supernatant to anhydrous ethanol is 1:1-5.

8. A composition, characterized in that The invention relates to a polysaccharide comprising the capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to any one of claims 2 to 4.

9. A food, characterized in that The invention relates to a capsular polysaccharide comprising the capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to any one of claims 2 to 4.

10. A drug, characterized in that The invention relates to a polysaccharide comprising the capsular polysaccharide of Lactobacillus plantarum DPUL-F232 according to any one of claims 2 to 4.

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