Plant lactobacillus XD117, application of plant lactobacillus XD117 in fermentation of astragalus membranaceus, astragalus membranaceus fermentation product and preparation method of astragalus membranaceus fermentation product

Abstract

The invention belongs to the technical field of microbial fermentation, and particularly relates to a plant lactobacillus XD117, application of the plant lactobacillus XD117 in fermentation of astragalus membranaceus, an astragalus membranaceus fermentation product and a preparation method of the astragalus membranaceus fermentation product. The bacterial strain is lactobacillus plantarum XD117 and is preserved in the China Center for Type Culture Collection, and the preservation number of the bacterial strain is CCTCC NO: M 20241730. The preparation method of the astragalus mongholicus fermentation product comprises the following steps: inoculating the lactobacillus plantarum XD117 into astragalus mongholicus enzymatic hydrolysate, and fermenting in a fermentation temperature range suitable for the lactobacillus plantarum XD117 to obtain the astragalus mongholicus fermentation product. The total content of calycosin, formononetin, calycosin glucoside and formononin in the astragalus mongholicus fermentation product is high, and the astragalus mongholicus fermentation product has a very good antioxidant effect.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fermentation, and particularly relates to a plant lactobacillus XD117 and an application thereof in fermenting astragalus, as well as an astragalus fermentation product and a preparation method thereof. Background Art

[0002] Astragalus membranaceus is one of the most representative traditional Chinese medicinal materials in my country. It is widely used in the treatment of enhancing immunity, anti-inflammatory and anti-aging because of its effects of invigorating qi and strengthening the exterior, strengthening the body and eliminating evil. Astragalus has both edible functions and has a history of being used as a food ingredient in Shanxi Province and Gansu Province. The main methods are to make soup, stew meat, cook porridge, steam rice, add to dishes, hot pot, and soak in wine in traditional ways. In 2020, it began to enter the pilot work of medicine and food homology. After safety assessment and pilot production and operation, it was officially included in my country's "Regulations on the Management of the Catalog of Substances that are Traditionally Both Food and Traditional Chinese Medicine" in November 2023. Modern research has found that astragalus contains a variety of active ingredients, such as astragaloside, astragaloside IV and flavonoids (including calycosin glucoside, calycosin, formononetin and formononetin, etc.), which have significant effects in anti-oxidation, immunomodulation and antiviral effects. With the surge in consumer demand for natural and functional foods, especially for products with immune regulation, anti-fatigue and anti-aging effects, they not only carry traditional medicinal value, but also cater to modern people's pursuit of health and nutrition. They have broad market prospects and huge socio-economic value.

[0003] Traditional extraction methods for Astragalus include water extraction, alcohol extraction, water-alcohol combined extraction and other methods. These extraction methods have the disadvantages of complex processes and long operation time, which are not conducive to the extraction of active ingredients of Astragalus. Therefore, the present invention adopts microbial fermentation method, which can not only comprehensively improve the content and bioavailability of active ingredients of Astragalus, but also has the advantages of green environmental protection, low energy consumption and multifunctional development. Based on this, this application not only provides innovative ideas for the deep development and high-value utilization of Astragalus, but also provides important technical support for the research and development of functional foods and herbal medicines, and has broad application prospects and market value. Summary of the invention

[0004] To this end, the present invention provides, on the one hand, a lactobacillus plantarum XD117; on the other hand, the present invention provides the strain and a bacterial agent and an application of the strain in fermenting astragalus; fermenting astragalus with the lactobacillus plantarum XD117 can significantly increase the total content of calycosin, formononetin, calycosin glucoside and formononetin in the fermentation product; on the other hand, the present invention provides an astragalus fermentation product, the total content of calycosin, formononetin, calycosin glucoside and formononetin in the fermentation product is high, and the fermentation product has a very good antioxidant effect.

[0005] To solve the above problems, the technical solution of the present invention is:

[0006] A Lactiplantibacillus plantarum XD117, which is deposited in China Center for Type Culture Collection with a deposit number of CCTCC NO: M 20241730.

[0007] The application of the above-mentioned Lactobacillus plantarum XD117 in fermenting astragalus or preparing astragalus fermentation products.

[0008] The invention discloses an astragalus fermentation product, which is prepared by enzymatic hydrolysis of the astragalus and inoculation with Lactobacillus plantarum XD117 for fermentation, wherein the Lactobacillus plantarum XD117 is preserved in China Center for Type Culture Collection with a preservation number of CCTCC NO: M 20241730.

[0009] Preferably, the enzyme preparation selected for enzymatic hydrolysis of Astragalus membranaceus includes cellulase and pectinase.

[0010] Preferably, the added amount of the cellulase is 0.05-0.3%, and the added amount of the pectinase is 0.2-0.5%; more preferably, the added amount of the cellulase is 0.1%, and the added amount of the pectinase is 0.25%.

[0011] More preferably, the enzymatic activity of the cellulase is 10000 U / g, and the enzymatic activity of the pectinase is 5000 U / g.

[0012] Preferably, the viable count of Lactobacillus plantarum XD117 is 1.0×10 8 CFU / mL and above.

[0013] Preferably, the activation step of Lactobacillus plantarum XD117 is as follows: inoculating the strain into MRS medium, culturing at 35°C for 24 hours, and continuously subculturing for 3 times to fully activate the strain until the viable count is 1.0×10 8 CFU / mL and above.

[0014] Preferably, the composition and preparation method of the MRS medium are as follows: the medium formula is peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, dipotassium hydrogen phosphate 2.0 g / L, triammonium hydrogen citrate 2 g / L, sodium acetate 5.0 g / L, magnesium sulfate 0.2 g / L, manganese sulfate 0.05 g / L, Tween-80 1 g / L. Take the above MRS medium and add 1L of pure water, sterilize with high pressure steam at 121°C for 15 minutes for standby use.

[0015] Preferably, the inoculation amount of Lactobacillus plantarum XD117 is 1-5%; more preferably, the inoculation amount of Lactobacillus plantarum XD117 is 2%.

[0016] A method for preparing the above-mentioned astragalus fermentation product comprises the following steps: (1) mixing astragalus and water evenly, adding an enzyme preparation for enzymolysis, and sterilizing after the enzymolysis to obtain an astragalus hydrolyzate; (2) inoculating Lactobacillus plantarum XD117 into the astragalus hydrolyzate for fermentation to obtain an astragalus fermentation product.

[0017] Preferably, the weight ratio of the astragalus powder to water is 1:(5-10), more preferably 1:7.

[0018] Preferably, the enzymatic hydrolysis temperature is 40-60°C and the time is 40-80 min.

[0019] Further preferably, the enzymatic hydrolysis is carried out in a shaker at a rotation speed of 150-200 rpm.

[0020] More preferably, the enzymatic hydrolysis further includes a homogenization step, and the homogenization time is 3-10 minutes.

[0021] Preferably, the sterilization temperature is 100-120°C and the time is 10-30 minutes.

[0022] Preferably, the fermentation temperature is 30-40°C, and the fermentation time is 2-4 days; further preferably, the fermentation temperature is 37°C, and the fermentation time is 72 hours.

[0023] The astragalus fermentation product and the use of the astragalus fermentation product prepared by the above method in antioxidant products.

[0024] A product comprises the above-mentioned astragalus fermentation product and pharmaceutical, health food or food acceptable auxiliary materials.

[0025] The technical solution of the present invention has the following advantages:

[0026] 1. The present invention provides a plant lactobacillus XD117, which is used for fermenting astragalus, can significantly increase the total content of calycosin, formononetin, calycosin glucoside and formononetin in the fermentation product of astragalus, and improve the DPPH free radical and hydroxyl free radical elimination ability of the fermentation product.

[0027] 2. The present invention provides an Astragalus fermentation product, which is prepared by fermentation with Lactobacillus plantarum XD117. The fermentation product has a high total content of calycosin, formononetin, calycosin glucoside and formononetin, and the supernatant of the fermentation product has excellent DPPH free radical scavenging ability, hydroxyl free radical scavenging ability and anti-new coronavirus ability, and can be applied to antioxidant products and anti-new coronavirus products.

[0028] 3. The present invention provides a method for preparing an astragalus fermentation product. Through the process of enzymolysis followed by fermentation, and after fermentation by Lactobacillus plantarum XD117, the total content of calycosin, formononetin, calycosin glucoside and formononetin in the astragalus fermentation product is improved, and the fermentation product has a good ability to scavenge DPPH free radicals and hydroxyl free radicals, and the process is simple and suitable for industrial production.

[0029] Instructions for strain preservation

[0030] The plant lactobacillus XD087 provided by the present invention was deposited in the China Center for Type Culture Collection on August 2, 2024, with a deposit number of CCTCC NO: M 20241729, and its Latin name is Lactobacillus plantarum. Address: Wuhan University, Wuhan City, Hubei Province, Postal Code: 430072, Telephone: 027-68754052. On August 25, 2022, the updated "List of Bacteria that Can Be Used in Food" renamed Lactobacillus plantarum to Lactiplantibacillus plantarum, and Lactobacillus plantarum XD087 and Lactiplantibacillus plantarum XD087 are the same strain.

[0031] Lactobacillus plantarum XD117 was deposited in the China Center for Type Culture Collection on August 2, 2024, at Wuhan University, Wuhan, China, with the deposit number CCTCC NO: M20241730. Address: Wuhan University, Wuhan, Hubei Province, Postal Code: 430072, Tel: 027-68754052. On August 25, 2022, the National Health Commission officially released the updated "List of Bacteria that Can Be Used in Food", and renamed Lactobacillus plantarum to Lactiplantibacillus plantarum. Lactobacillus plantarum XD117 and Lactiplantibacillus plantarum XD117 are the same strain.

[0032] Lactobacillus plantarum Picp-2 is deposited in China Center for Type Culture Collection, with the deposit number CCTCC NO: M20191045, and its Latin name is Lactiplantibacillus plantarum. Address: Wuhan University, Wuhan, Hubei Province, Postal Code: 430072, Tel: 027-68754052. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the standard chromatogram of verbascosin glucoside, verbascosin, formononetin and formononetin. DETAILED DESCRIPTION

[0034] To make the purpose, technical solution and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail. Based on the embodiments disclosed in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0035] If no specific experimental steps or conditions are specified in the examples, the experiments can be carried out according to the conventional steps or conditions described in the literature in the field. All reagents without manufacturer specified are conventional reagent products that can be obtained through commercial purchase.

[0036] In the following examples, the source information of some products is as follows:

[0037] Cellulase was purchased from Xiasheng Food Grade Cellulase Plant Extract Special Enzyme SPE-017L with an enzyme activity of 10000 U / g; pectinase was Xiasheng Food Grade Pectinase SPE-010 with an enzyme activity of 5000 U / g.

[0038] Kluyveromyces marxianus Hz09 is from China General Microbiological Culture Collection Center, with the collection number CGMCC 2.3940, the Latin name Kluyveromyces marxianus, the original number XZ293, and Hz09 is the number named by the applicant. Address: Chaoyang District, Beijing, Postal Code: 100101, Tel: 0010-64807596.

[0039] Activation and cultivation of bacterial strains in preparation examples

[0040] Activation of lactic acid bacteria (Lactobacillus plantarum XD087, Lactobacillus plantarum XD117 and Lactobacillus plantarum Picp-2): The lactic acid bacteria were inoculated into MRS medium and cultured at 35°C for 24 h. The culture was subcultured three times to fully activate the bacteria until the viable count was 1.0×10 8 CFU / mL and above.

[0041] The composition and preparation method of MRS medium are as follows: peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, dipotassium hydrogen phosphate 2.0 g / L, triammonium hydrogen citrate 2 g / L, sodium acetate 5.0 g / L, magnesium sulfate 0.2 g / L, manganese sulfate 0.05 g / L, Tween-80 1 g / L. Take the above MRS medium and add 1L of pure water, sterilize with high pressure steam at 121°C for 15 min for later use.

[0042] Activation of yeast: Kluyveromyces marxii Hz09 was inoculated into YPD medium and cultured at 28°C for 24 h. The culture was subcultured three times to fully activate the strain until the viable count was 1.0×10 8 CFU / mL and above.

[0043] The composition and preparation method of the YPD medium are as follows: 10 g / L yeast extract, 10 g / L trypsin, and 20 g / L glucose. 1 L of pure water is added to the above YPD medium, and the medium is sterilized by high-pressure steam at 115°C for 25 min for later use.

[0044] Example Preparation of Astragalus Fermentation Product

[0045] The present embodiment provides a method for preparing an astragalus fermentation product, comprising the following steps: (1) grinding the astragalus and passing it through a 200-mesh sieve to obtain an astragalus powder; (2) mixing the astragalus powder with water in a ratio of 1:7, adding 0.1% cellulase and 0.25% pectinase, homogenizing for 5 minutes, performing enzymolysis at 160 rpm in a shaker at 50°C for 1 hour, and sterilizing at 115°C for 30 minutes after enzymolysis to obtain an astragalus hydrolyzate; (3) inoculating the activated bacterial liquid into the astragalus hydrolyzate and fermenting at 37°C for 3 days to obtain an astragalus fermentation product.

[0046] The inoculated activated bacterial solution, i.e., the fermentation strains, are

[0047] (1) Inoculate 2% Lactobacillus plantarum picp-2

[0048] (2) Inoculate 1% Kluyveromyces marxii HZ09

[0049] (3) Inoculation of 2% Lactobacillus plantarum XD087

[0050] (4) Inoculation of 2% Lactobacillus plantarum XD117

[0051] The viable counts of the above strains are consistent. The inoculation amount and addition amount are based on the volume of the fermentation liquid. For example, if 100 mL of Astragalus fermentation liquid is obtained by fermentation, 0.1% of cellulase is added, i.e. 100 μL, and 0.1 g of solid is added; the inoculation amount is 2%, i.e. 2 mL of bacterial liquid.

[0052] Comparative Example 1 Astragalus enzymatic hydrolysis product

[0053] This comparative example provides an astragalus enzymatic hydrolysis product, and the preparation method thereof is as follows: after astragalus powder and water are mixed in a ratio of 1:7, 0.1% cellulase and 0.25% pectinase are added, homogenized for 5 minutes, and enzymatic hydrolysis is performed at 160 rpm in a 50°C shaker for 1 hour. After enzymatic hydrolysis, the astragalus enzymatic hydrolysis solution is obtained by sterilization at 115°C for 20 minutes, and the astragalus enzymatic hydrolysis product is obtained after being placed at 37°C for 3 days.

[0054] Comparative Example 2 Astragalus water extraction product

[0055] This comparative example provides an astragalus water extract product, and the preparation method thereof is as follows: astragalus powder and water are mixed in a ratio of 1:7, extracted at 95° C. for 30 minutes, sterilized at 115° C. for 20 minutes, and placed at 37° C. for 3 days to obtain the astragalus water extract product.

[0056] Product processing:

[0057] The fermentation product of Astragalus obtained in the example was centrifuged at 8000rpm for 10 minutes, and the supernatant was collected to obtain the corresponding Astragalus fermentation supernatant. The precipitate after centrifugation was freeze-dried, dried and ground, 1g of powder was taken, 70% ethanol was added at a ratio of 1:20, and ultrasonic extraction was performed at 50°C and 500W for 40 minutes to obtain the corresponding Astragalus fermentation precipitate.

[0058] The astragalus enzymatic hydrolysis product was centrifuged at 8000rpm for 10 minutes, and the supernatant was collected to obtain the astragalus enzymatic hydrolysis supernatant; the precipitate after centrifugation was freeze-dried, and then ground after drying. 1g of powder was taken, 70% ethanol was added in a ratio of 1:20, and ultrasonic extraction was performed at 50°C and 500W for 40 minutes to obtain the astragalus enzymatic hydrolysis precipitate.

[0059] The Astragalus water extract product was centrifuged at 8000rpm for 10 minutes, and the supernatant was collected to obtain the Astragalus water extract supernatant; the precipitate after centrifugation was freeze-dried, and then ground, 1g of powder was taken, 70% ethanol was added in a ratio of 1:20, and ultrasonic extraction was performed at 50°C and 500W for 40 minutes to obtain the Astragalus water extract precipitate.

[0060] Experimental Example 1 Determination of the Contents of Calycosin Glucoside, Calycosin, Formononetin and Formononetin

[0061] Samples to be tested: The above-mentioned Astragalus fermentation supernatant, Astragalus fermentation precipitate, Astragalus enzymatic hydrolysis supernatant, Astragalus enzymatic hydrolysis precipitate, Astragalus water extraction supernatant, Astragalus water extraction precipitate were filtered through a 0.45 μm filter membrane for index detection.

[0062] (1) Liquid chromatography conditions

[0063] Chromatographic column: Elite C 18 Reverse phase chromatography column (4.6 mm × 250 mm, 5 μm); column temperature: 30 °C; injection volume: 10 μL; detection wavelength: 260 nm; mobile phase: phase A acetonitrile, phase B, 0.2% phosphoric acid water. Elution conditions: gradient elution, 0-5 min, 20% A, 5-20 min, 20%-40% A, 20-30 min, 40% A, 30-40 min, 40%-20% A, 40-45 min, 20% A.

[0064] (2) Setting the concentration of standard samples

[0065] Take 2.7 mg of calycosin glucoside, 1.3 mg of calycosin, 1.8 mg of formononetin, and 0.9 mg of formononetin, add 20 mL of ethanol to prepare a mixed standard, the concentrations of which are 135, 65, 90, and 45 μg / mL respectively. Then take 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, and 1 mL of the standard respectively, and make up to 1 mL with ethanol to prepare the standard test solution. The concentrations of calycosin glucoside were 6.75, 13.5, 27, 54, 81, 108, and 135 μg / mL, respectively; the concentrations of calycosin were 3.25, 6.5, 13, 26, 39, 52, and 65 μg / mL, respectively; the concentrations of formononetin were 4.5, 9, 18, 36, 54, 72, and 90 μg / mL, respectively; and the concentrations of formononetin were 2.25, 4.5, 9, 18, 27, 36, and 45 μg / mL, respectively.

[0066] (3) Preparation of standard curve

[0067] Under the above-mentioned liquid chromatography conditions, the standard samples were injected and tested respectively, and the standard curve was calculated according to the sample concentration and the detection peak area.

[0068] The standard curves are:

[0069] Isoflavone glucoside y = 35852x - 8099.9 (R 2 =0.9992), peak time is around 8.298; y = 53979x - 5982.4 (R 2 =0.9992), peak time around 20.913; formononetin y = 41461x- 5455.4 (R 2 =0.9992), peak time around 17.976; formononetin y = 58131x - 4834.4 (R 2 =0.9992), peak time around 28.582; standard chromatogram see Figure 1 , from left to right are verbacoside, formononetin, verbacoside, and formononetin.

[0070] (4) Testing of samples to be tested

[0071] The samples to be tested were injected and tested under the above-mentioned liquid chromatography conditions, and the peak areas measured by the samples were brought into the standard curve to obtain the sample concentrations. The contents of the samples to be tested obtained in the examples and comparative examples are shown in Table 1.

[0072] Table 1 Contents of calycosin glucoside, calycosin, formononetin and formononetin in the supernatant and precipitate obtained in the examples and comparative examples

[0073]

[0074] The total amount in Table 1 is the total amount of calycosin glucoside, calycosin, formononetin and formononetin in Astragalus, and the content is the content of the substance in each gram of Astragalus, where the supernatant is extracted at a ratio of 1:7, that is, the supernatant content = supernatant concentration × 7, the precipitate extract is extracted at a ratio of 1:20, and the precipitate content = precipitate concentration 20, the supernatant content and the precipitate content are the sum of the substance contents in 1g of Astragalus. As shown in Table 1, the total amount of calycosin glucoside, calycosin, formononetin and formononetin in the Astragalus fermentation product obtained by Lactobacillus plantarum XD117 fermentation is the highest.

[0075] Experimental Example 2 Antioxidant Index Detection

[0076] (1) Determination of DPPH free radical scavenging rate

[0077] Sample to be tested: Take 10 mL of the fermentation supernatant obtained from the product treatment, add 90 mL of water, dilute 10 times, then take 10 mL of the diluted supernatant and add 90 mL to obtain a sample to be tested that is diluted 100 times.

[0078] The experimental group was added with 1mL of the sample solution + 1mL of 0.2mmoL / L DPPH. The control group was added with 1mL of anhydrous ethanol + 1mL of the sample solution. The blank group was added with 1mL of anhydrous ethanol + 1mL of 0.2mmol / L DPPH, mixed and allowed to stand at room temperature (25°C) for 30min. 300 μL was drawn and the absorbance of the experimental group was measured at a wavelength of 517nm, recorded as Ai. The absorbance of the control group was measured, recorded as Aj. The blank group was recorded as A0. Each sample was measured 3 times in parallel. The specific results are shown in Table 2.

[0079] DPPH removal rate (%) = [1-(Ai-Aj) / A0] × 100%

[0080] (2) Determination of hydroxyl free radical scavenging rate

[0081] Sample to be tested: Take 10 mL of the fermentation supernatant obtained from the product treatment, add 90 mL of water, and dilute 10 times to obtain a sample to be tested diluted 10 times.

[0082] Pipette 6 mmol / L FeSO4 into a 10 mL EP tube, add 1 mL of the sample to be tested (diluted to an appropriate concentration), then add 1 mL of 6 mmol / L H2O2, and let it react for 10 min. Replace the extract with an equal amount of pure water for the blank group; then add 1 mL of 6 mmol / L salicylic acid solution, shake and mix, and let it react for 30 min. Take 1-2 mL of the reaction solution and centrifuge it in a 2 mL EP tube. After the centrifugation, pipette 200 µL of the reaction solution into an ELISA plate, put it into an ELISA reader, and measure the OD at a wavelength of 510 nm. 510 nm Value. Vitamin C was used as a positive control. Each sample was tested 3 times in parallel. The specific results are shown in Table 3. The clearance rate was calculated according to the following formula:

[0083] Clearance = [1-A X / A0]×100% Where: A X : absorbance value of the experimental group; A0, absorbance value of the control group.

[0084] Table 2 DPPH free radical scavenging rate (diluted 100 times)

[0085]

[0086] Note: Different letters in the same column represent significant differences, p < 0.05.

[0087] Table 3 Hydroxyl radical scavenging rate (diluted 10 times)

[0088]

[0089] Note: Different letters in the same column represent significant differences, p < 0.05.

[0090] Result analysis: It can be seen from Table 2 and Table 3 that the DPPH radical scavenging rate and hydroxyl radical scavenging rate of the astragalus fermentation supernatant after fermentation by Lactobacillus plantarum XD117 were significantly different from those of the astragalus fermentation supernatant after fermentation by Lactobacillus plantarum XD087 and the astragalus enzymatic hydrolysis supernatant, indicating that Lactobacillus plantarum XD117 is more suitable for fermenting astragalus and improving the antioxidant activity of the astragalus fermentation supernatant.

[0091] Experimental Example 3 Antiviral Ability Detection

[0092] Antiviral ability testing method:

[0093] (1) Resuscitate cells; co-transfect SARS-CoV-2 S protein expression plasmid, pHIV-luciferase and pSPAX2 plasmid into HEK293T-hACE2 cells. Collect cell culture supernatant 48 hours after transfection, filter with a 0.45μm filter, and centrifuge at 4°C, 3000g for 10 minutes. Transfer the supernatant to a new tube and aliquot it, and store it in a -80°C refrigerator for later use. Dilute it to an equal volume with pH 7.4 PBS buffer before use.

[0094] (2) Test samples: Astragalus fermentation supernatant obtained in Example and Astragalus enzymatic hydrolysis supernatant obtained in Comparative Example.

[0095] (3) Testing process

[0096] Day 1: HEK293t-hACE2 cells were plated in 96-well plates.

[0097] The next day: ① Incubate the fermentation liquid and supernatant with the virus: Take 100 μL of the diluted virus liquid + 2 μL of the test sample as a mixture and incubate it in a 37°C cell culture incubator for 20 minutes. ② Infect cells: Discard the culture supernatant of the pre-plated 96-well 293t-hACE2 cells, transfer 100 μL of the mixture in ① to 293t-hACE2 cells for infection, and continue to culture in a 37°C cell culture incubator for about 24 hours.

[0098] Day 3: ① Take out the 96-well plate, discard the supernatant, add 100 μL PBS and gently rinse; ② Prepare lysis buffer (5x passive lysis buffer) in advance, add 50 μL lysis buffer to each well, shake and lyse at room temperature for 30 min; ③ Transfer 20 μL of lysis buffer to an opaque white 96-well plate; ④ Prepare luciferase substrate solution in advance, add 100 μL substrate solution to each well, and use a multifunctional microplate reader to detect luciferase activity in real time. The specific results are shown in Table 4.

[0099] Table 4 Antiviral ability

[0100]

[0101] Note: Different letters in the same column represent significant differences, p < 0.05.

[0102] Result analysis:

[0103] The lower the luminescence, the better the antiviral effect. As shown in Table 4, the luminescence of the fermentation supernatant of Lactobacillus plantarum XD117 is lower than that of the supernatant of Astragalus membranaceus enzymatic hydrolysis, indicating that the fermentation supernatant of Lactobacillus plantarum XD117 has a certain antiviral ability.

[0104] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A Lactobacillus plantarum XD117, characterized in that The deposit number of the Lactobacillus plantarum XD117 is CCTCC NO: M 20241730.

2. Application of Lactobacillus plantarum XD117 in fermenting astragalus or preparing astragalus fermentation products, characterized in that: The deposit number of the Lactobacillus plantarum XD117 is CCTCC NO: M 20241730.

3. A fermented product of Astragalus, characterized in that: The astragalus is prepared by enzymatic hydrolysis and inoculation with Lactobacillus plantarum XD117 with a preservation number of CCTCC NO: M20241730.

4. The astragalus fermentation product according to claim 3, characterized in that The enzymatic hydrolyzing agents selected for the enzymatic hydrolysis of Astragalus include cellulase and pectinase.

5. The astragalus fermentation product according to claim 4, characterized in that The added amount of the cellulase is 0.05-0.3%, and the added amount of the pectinase is 0.2-0.5%.

6. The astragalus fermentation product according to claim 3, characterized in that: The inoculation amount of Lactobacillus plantarum XD117 is 1-5%, and the number of viable bacteria is 1.0×10 8 CFU / mL and above.

7. The method for preparing the astragalus fermentation product according to any one of claims 3 to 6, characterized in that: The method comprises the following steps: (1) mixing astragalus powder and water evenly, performing enzymolysis, and sterilizing after the enzymolysis to obtain an astragalus enzymolysis solution; and (2) inoculating Lactobacillus plantarum XD117 into the astragalus enzymolysis solution for fermentation to obtain an astragalus fermentation product.

8. The method for producing an astragalus fermentation product according to claim 7, wherein: The temperature of the enzymolysis is 40-60°C, and the time is 40-80 minutes; the temperature of the sterilization is 100-120°C, and the time is 10-30 minutes; the temperature of the fermentation is 30-40°C, and the fermentation time is 2-4 days.

9. Use of the astragalus fermentation product according to any one of claims 3 to 6 or the astragalus fermentation product obtained by the preparation method according to any one of claims 7 to 9 in the preparation of antioxidant products.

10. A product, characterized in that The invention comprises the astragalus fermentation product as claimed in claim 3 and auxiliary materials acceptable to food, medicine and health care products.

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