A Lactobacillus plantarum and its application in preparing rice bran peptides

Abstract

The present invention provides a Lactobacillus plantarum and its application in the preparation of rice bran peptides, belonging to the technical field of active peptide preparation. When using the Lactobacillus plantarum YY-9 of the present invention to prepare rice bran peptides, rice bran peptides with intestinal barrier protection function can be obtained, and the required time is short, and the quality of the prepared rice bran peptides is high. The rice bran peptides prepared by using the preparation method provided by the present invention have high soluble protein content, protein recovery rate, and ABTS and DPPH free radical scavenging abilities, can significantly reduce the contents of pro-inflammatory factors IL-1β, IL-6 and TNF-α in colon tissues, increase the content of anti-inflammatory factor IL-10, improve the weight loss caused by ulcerative colitis, effectively relieve colon shortening, reduce the disease activity index, reduce the infiltration of inflammatory cells in colon tissues, reduce colon mucosal permeability, and relieve colitis.

Description

Technical Field

[0001] The present invention belongs to the technical field of active peptide preparation, and particularly relates to a Lactobacillus plantarum and its application in the preparation of rice bran peptides. Background Art

[0002] In recent years, various chronic diseases caused by the intestine have shown a trend of multiple and high incidence. The factors causing intestinal diseases are diverse, but fundamentally, it is because the intestinal barrier function has problems. Under normal circumstances, the content of free radicals in the human intestinal mucosa is in a dynamic balance state, and the intestinal mucosa can maintain health. If too many free radicals are generated or the ability to scavenge free radicals decreases, free radicals accumulate in the body and cause oxidative damage. This will lead to disorders in the digestion and absorption function of nutrients, slow growth, decreased disease resistance, and increased susceptibility to pathogenic microorganisms, and thus cause various diseases such as colitis, irritable bowel disease, diarrhea, and constipation.

[0003] Research shows that antioxidant peptides have a certain regulatory effect on intestinal diseases, are characterized by trace and high efficiency, and are a potential intestinal inflammation regulatory substance. In recent years, it has been found that rice bran protein is a high-grade plant protein with good emulsifying property, foaming stability, and solubility. Its amino acid composition is sufficient, with a complete essential amino acid spectrum, and the overall amino acid ratio is close to the formula recommended by the Food and Agriculture Organization / World Health Organization. However, there is currently no research on whether rice bran peptides have the function of protecting the intestinal barrier. Compared with rice bran protein and free amino acids, rice bran peptides have more prominent advantages in the absorption of the body. Currently, there are mainly the following drawbacks in the preparation of rice bran peptides. For example, when producing peptides by enzymatic hydrolysis, the cleavage sites are limited, and bitter peptides are easily generated, and the cost of plant-derived proteases is high, which increases the preparation cost of polypeptides; when producing rice bran peptides by microbial fermentation, the cycle is long, it is easy to cause product deterioration, which is not conducive to the control of product quality, and increases the possibility of sample contamination. Therefore, there is an urgent need in the art to provide a preparation method of rice bran peptides that takes a short time, has high-quality prepared rice bran peptides, and has the function of protecting the intestinal barrier. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a Lactobacillus plantarum that can be used to prepare rice bran peptides with the function of protecting the intestinal barrier and its application.

[0005] Another purpose of the present invention is to provide a rice bran peptide with the function of protecting the intestinal barrier, its preparation method, and its application.

[0006] In order to achieve the above-mentioned invention purposes, the present invention provides the following technical solutions:

[0007] The present invention provides a Lactobacillus plantarum, which is YY-9, taxonomically named Lactobacillus plantarum, deposited in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, with the deposit number of CGMCC No. 24693, and the deposit date of April 18, 2022.

[0008] The present invention also provides an application of the above Lactobacillus plantarum in the preparation of rice bran peptides with intestinal barrier protection function. In the present invention, the intestinal barrier protection function includes preventing and treating ulcerative colitis.

[0009] The present invention provides a preparation method of rice bran peptides with intestinal barrier protection function, including the following steps: enzymatically hydrolyzing rice bran protein with alkaline protease to obtain an enzymatic hydrolysate; fermenting the enzymatic hydrolysate with the above Lactobacillus plantarum, drying the obtained fermentation broth to obtain rice bran peptides.

[0010] In the present invention, the addition amount of the alkaline protease is preferably 600-800 U per gram of rice bran protein, more preferably 650-800 U per gram of rice bran protein, and most preferably 650-750 U per gram of rice bran protein, based on the weight of rice bran protein; the temperature of the enzymatic hydrolysis is preferably 55°C-65°C, more preferably 57-63°C, the time of the enzymatic hydrolysis is preferably 2.5 h-3.5 h, more preferably 2.8-3.2 h, and the pH value of the enzymatic hydrolysis is preferably 8.0-9.0, more preferably 8.2-8.8.

[0011] In the present invention, the inoculation amount of the Lactobacillus plantarum YY-9 is preferably 1%-3% L per liter of enzymatic hydrolysate, more preferably 1%-2.5% L per liter of enzymatic hydrolysate, and most preferably 1.5%-2.5% L per liter of enzymatic hydrolysate, based on the volume of the enzymatic hydrolysate. When fermenting with the Lactobacillus plantarum, the temperature of the fermentation is preferably 28°C-34°C, more preferably 29°C-32°C, the time of the fermentation is preferably 32 h-40 h, more preferably 34 h-38 h, and the pH value of the fermentation is preferably 5.0-6.0, more preferably 5.2-5.8.

[0012] In the present invention, before drying, it is preferably further included a step of nanofiltration treatment of the fermentation broth; the pressure of the nanofiltration is preferably 15-25 Bar, further preferably 18-20 Bar; the temperature of the nanofiltration is preferably 15-25°C, further preferably 18-20°C. The present invention has no strict requirement for the time of nanofiltration, and it is sufficient to ensure that the volume of the solution obtained after nanofiltration is 1 / 3-2 / 3 of the volume of the supernatant.

[0013] The present invention also provides a rice bran peptide prepared according to the above preparation method.

[0014] The present invention also provides the use of the above-mentioned Lactobacillus plantarum, the above-mentioned preparation method or the above-mentioned rice bran peptide in the preparation of a product with intestinal barrier protection function. In the present invention, the types of the product preferably include medicines. In the present invention, the intestinal barrier protection function includes preventing and treating ulcerative colitis.

[0015] Advantages of the present invention:

[0016] When preparing rice bran peptide with the Lactobacillus plantarum of the present invention, rice bran peptide with intestinal barrier protection function can be obtained, and the required time is short, and the quality of the prepared rice bran peptide is high. The method for preparing rice bran peptide provided by the present invention realizes the effective utilization of rice bran protein. The rice bran peptide prepared by using the preparation method provided by the present invention has a high soluble protein content, protein recovery rate, and ABTS and DPPH free radical scavenging abilities. The soluble protein content, protein recovery rate, ABTS and DPPH free radical scavenging rates are 54.46±0.8mg / mL, 53.51±0.8%, 90.35±0.1% and 57.42±2.0% respectively, which can significantly reduce the contents of pro-inflammatory factors IL-1β, IL-6 and TNF-α in colon tissues, increase the content of anti-inflammatory factor IL-10, improve the weight loss caused by ulcerative colitis, effectively relieve colon shortening, reduce the disease activity index, reduce the infiltration of inflammatory cells in colon tissues, reduce the colon mucosal permeability, and relieve colitis.

[0017] Preservation description

[0018] The Lactobacillus plantarum YY-9 of the present invention, classified and named as Lactobacillus plantarum, is preserved in the General Microbiological Center of the China Committee for Culture Collection of Microorganisms. The preservation time is April 18, 2022, and the preservation address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The preservation number is CGMCC No. 24693. Description of the drawings

[0019] Figure 1 It shows the effects of different groups on the body weight change of DSS-induced colitis mice;

[0020] Figure 2 It shows the effects of different groups on the disease activity index of DSS-induced colitis mice;

[0021] Figure 3 It shows the effects of different groups on the colon length of DSS-induced colitis mice;

[0022] Figure 4 It shows the effects of different groups on the anti-inflammatory factor IL-10 of DSS-induced colitis mice;

[0023] Figure 5 Effects of different groups on the pro-inflammatory factor TNF-α in DSS-induced colitis mice;

[0024] Figure 6 Effects of different groups on the pro-inflammatory factor IL-6 in DSS-induced colitis mice;

[0025] Figure 7 Effects of different groups on the pro-inflammatory factor IL-1β in DSS-induced colitis mice. Specific implementation manners

[0026] In the following examples, unless otherwise specified, all are conventional methods.

[0027] In the following examples, the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0028] Example 1

[0029] Screening lactic acid bacteria on the surface of wild fruits using calcium carbonate plates. During the growth of lactic acid bacteria, lactic acid is produced, and lactic acid will dissolve calcium carbonate in the plate to produce a calcium dissolution circle. Therefore, 30 strains of lactic acid bacteria were isolated from the surface of wild blueberry fruits in the West Second Campus of Qiqihar University according to the produced calcium dissolution circle. Further screening yielded 5 strains of lactic acid bacteria with high protease production. DNA was extracted from the 5 strains of lactic acid bacteria cells, and then PCR amplification was performed to detect whether the amplification products met the requirements. The qualified amplification products were sent to Shanghai Sangon Biotech Co., Ltd. for sequencing. The obtained sequencing sequences were compared with the NCBI Blast database to further confirm that the 5 strains were lactic acid bacteria. Lactobacillus plantarum YY-9 of the present invention is one of them.

[0030] Cultivation of Lactobacillus plantarum YY-9: It was cultured in MRS medium. The medium formula was: peptone 10 g, yeast extract 5 g, beef extract 10 g, glucose 10 g, dipotassium hydrogen phosphate 2 g, diammonium citrate 2 g, sodium acetate anhydrous 5 g, Tween 80 1 ml, magnesium sulfate 0.58 g, manganese sulfate 0.25 g. It was dissolved in distilled water and made up to 1000 ml, and sterilized at 121 °C and 0.1 Mpa for 30 min for standby. Lactobacillus plantarum YY-9 was inoculated in MRS medium. After culturing for 24 h, the OD 600nm value was about 0.6 or so for standby.

[0031] Example 2

[0032] The rice bran protein powder (with a protein content of about 85%, purchased from Shaanxi Parnil Biotechnology Co., Ltd.) was prepared into a suspension with a substrate concentration of 13% (m / v). Alkaline protease (Novozymes Alcalase 2.4L, purchased from Novozymes A / S, Denmark) was added according to the amount of 700 U of alkaline protease per gram of rice bran protein. The pH value of the solution was adjusted to 8.5, and enzymatic hydrolysis was carried out at 60 °C for 3 h to obtain an enzymatic hydrolysate.

[0033] The pH value of the enzymatic hydrolysate was adjusted to 5.5, and it was sterilized by high-pressure steam at 101 °C and 0.1 Mpa for 30 min. Lactobacillus plantarum YY-9, Lactobacillus paracasei, and Lactobacillus bulgaricus were respectively inoculated at 3% v / v according to the volume of the enzymatic hydrolysate, and fermentation was carried out at 37 °C for 24 h to obtain a fermentation broth. The fermentation broth was centrifuged at 4000 r / min for 15 min, and the supernatant was taken and freeze-dried to obtain rice bran peptides. The DPPH and ABTS radical scavenging rates were measured, and the measurement methods were as follows:

[0034] The rice bran peptides were prepared to 1 mg / mL, and the DPPH radical scavenging rate was measured by the micro-method. Take 100 μL of the above sample in a 96-well plate, and then add 100 μL of a 0.1 mmol / L DPPH anhydrous ethanol solution, mix well, and react in the dark for 30 min. Then, measure its absorbance at a wavelength of 517 nm and record it as Ai; take another 100 μL of the sample to be measured, add 100 μL of anhydrous ethanol, and measure the absorbance and record it as Aj; use the reaction of 100 μL of 0.1 mmol / L DPPH anhydrous ethanol solution and 100 μL of anhydrous ethanol as a reference, and its absorbance is recorded as A0. All measurements need to be carried out in parallel 3 times.

[0035] DPPH radical scavenging rate = 1 - (Ai - Aj) / A0 × 100%

[0036] The rice bran peptides were prepared to 0.5 mg / mL for the measurement of the ABTS radical scavenging rate. The prepared ABTS radical stock solution was diluted with PBS to an absorbance value of 0.7 ± 0.02 at a wavelength of 734 nm as the ABTS radical working solution. Add 100 μL of each sample solution to each well of a 96-well plate, and then add 100 μL of the ABTS radical working solution. Use PBS instead of the sample as a control A0. Each sample was set with 3 replicates, shaken well, and left to stand at room temperature for 10 min, and then the absorbance was measured at a wavelength of 734 nm.

[0037] ABTS radical scavenging rate = (A0 - A 测定 ) / A0 × 100%

[0038] The results showed that the DPPH radical scavenging rates were 46.92% (Lactobacillus plantarum YY-9), 43.06% (Lactobacillus paracasei), and 31.65% (Lactobacillus bulgaricus), respectively, and the ABTS radical scavenging rates were 81.65% (Lactobacillus plantarum YY-9), 77.13% (Lactobacillus paracasei), and 68.66% (Lactobacillus bulgaricus), respectively.

[0039] Example 3

[0040] The preparation of rice bran peptide consists of the following steps:

[0041] Configure rice bran protein powder (purchased from Shaanxi Parneboio Biotechnology Co., Ltd., with a protein content of about 85%) into a suspension with a substrate concentration of 13% (m / v). Add alkaline protease (Novozymes Alcalase 2.4L, purchased from Novozymes A / S, Denmark) according to the amount of 700U alkaline protease per gram of rice bran protein. Adjust the pH value of the solution to 8.5 and enzymatically hydrolyze at 60°C for 3h to obtain an enzymatic hydrolysate.

[0042] Adjust the pH value of the enzymatic hydrolysate to 5.5, sterilize it by high-pressure steam at 101°C and 0.1 Mpa for 30 min, and inoculate 2% v / v of Lactobacillus plantarum YY-9 obtained in Example 1 according to the volume of the enzymatic hydrolysate, and ferment at 31°C for 36h to obtain a fermentation broth.

[0043] Centrifuge the fermentation broth at 4000 r / min for 15 min and take the supernatant; desalt the supernatant with a nanofiltration membrane with a molecular weight cut-off of 300 Da. The parameters of nanofiltration are: solution volume 3L, operating pressure 20 Bar, temperature 20°C. After nanofiltration, concentrate the volume to 1 / 2 and freeze-dry to obtain 90g of rice bran peptide (the present invention has no special limitation on the specific drying method, and any conventional drying method in the art can be used).

[0044] Comparative Example 1

[0045] The difference from Example 3 is that it does not include the step of fermenting with Lactobacillus plantarum YY-9, and the rest are the same as in Example 3.

[0046] Comparative Example 2

[0047] The difference from Example 3 is that it does not include the step of enzymatic hydrolysis with alkaline protease, and the rest are the same as in Example 3.

[0048] Comparative Example 3

[0049] The difference from Example 3 is that the step of fermenting with Lactobacillus plantarum YY-9 is carried out first, and then the step of enzymatic hydrolysis with alkaline protease is carried out, and the rest are the same as in Example 3.

[0050] Example 4

[0051] The soluble protein content, protein recovery rate, DPPH and ABTS free radical scavenging rates of the rice bran peptides obtained in Example 3 and Comparative Examples 1-3 were measured separately. Specifically: The rice bran peptides obtained in Example 3 and Comparative Examples 1-3 were divided into four test samples. For the first sample, the Folin-phenol method was used to measure the soluble protein content of the rice bran peptides. For the second sample, the Dumas combustion method was used to measure the total protein of the rice bran peptides to calculate the protein recovery rate.

[0052] For the third sample, the concentration of the rice bran peptide was diluted to 1 mg / mL, and the DPPH free radical scavenging rate was measured by the micro-method. The specific method was the same as that in Example 2.

[0053] For the last sample, the concentration of the rice bran peptide was diluted to 0.5 mg / mL for the measurement of the ABTS free radical scavenging rate. The specific method was the same as that in Example 2.

[0054] The results are shown in Table 1. It can be seen from Table 1 that the soluble protein content, protein recovery rate, DPPH and ABTS free radical scavenging rates of the rice bran peptides obtained in Comparative Examples 1-3 are all lower than those in Example 3, indicating that the soluble protein content, protein recovery rate, DPPH and ABTS free radical scavenging rates obtained by the method of first hydrolyzing and then fermenting rice bran protein with alkaline protease and Lactobacillus plantarum YY-9 of the present invention are high.

[0055] Table 1 Results of soluble protein content, protein recovery rate, DPPH and ABTS free radical scavenging rates in rice bran peptides of different groups

[0056] Group Soluble protein content (mg / mL) Protein recovery rate ABTS radical scavenging rate DPPH radical scavenging rate Example 3 54.46 53.51％ 90.35％ 57.42％ Comparative Example 1 50.2 52.23％ 76.27％ 36.12％ Comparative Example 2 2.16 1.35％ 89.41％ 47.38％ Comparative Example 3 41.99 31.63％ 79.15％ 28.51％

[0057] Example 5

[0058] The alleviating effect of the rice bran peptide obtained in Example 3 on the symptoms of mice with intestinal barrier injury induced by dextran sulfate sodium (DSS).

[0059] 1. Sixty 6- to 8-week-old healthy male Kunming mice (purchased from Changchun Yisi Experimental Animal Technology Co., Ltd.) were randomly divided into 6 groups, with 10 mice in each group, namely: blank control group, DSS model group, negative control group (medium dose of rice bran peptide), low (125 mg / kg·d), medium (250 mg / kg·d) and high (500 mg / kg·d) dose groups of rice bran peptide.

[0060] 2. Model establishment: Mice were gavaged for 14 days. In the negative control group and the low, medium, and high-dose groups of rice bran peptides, the rice bran peptides of Example 3 were administered. In the blank control group and the DSS model group, an equal amount of normal saline was gavaged. All 6 groups had normal food and water intake. The experiment started on the 8th day. Specifically: The DSS model group and the rice bran peptide group freely drank a 3% dextran sulfate sodium aqueous solution (purchased from Yeasen Biotech Co., Ltd.). The blank control group and the negative control group had normal food and water intake. The specific grouping and dosing methods are shown in Table 2.

[0061] Table 2 Grouping and dosing methods for animal experiments

[0062] Experimental group Days 1 - 7 Days 8 - 14 Blank control group Gavage with 100 μL of normal saline + normal drinking water Gavage with 100 μL of normal saline + normal drinking water DSS model group Gavage with 100 μL of normal saline + normal drinking water Gavage with 100 μL of normal saline + drinking 3% DSS aqueous solution Negative control group Gavage with 250 mg / kg·bw + normal drinking water Gavage with 250 mg / kg·bw + normal drinking water Low-dose rice bran peptide group Gavage with 125 mg / kg·bw + normal drinking water Gavage with 125 mg / kg·bw + drinking 3% DSS aqueous solution Medium-dose rice bran peptide group Gavage with 250 mg / kg·bw + normal drinking water Gavage with 250 mg / kg·bw + drinking 3% DSS aqueous solution High-dose rice bran peptide group Gavage with 500 mg / kg·bw + normal drinking water Gavage with 500 mg / kg·bw + drinking 3% DSS aqueous solution

[0063] 3. During the model establishment period, the body weight changes of mice in each group and the changes in the disease activity index (DAI) of mice in each group were monitored. The DAI scoring rules are shown in Table 3 below.

[0064] Table 3 DAI scoring rules

[0065]

[0066]

[0067] The results of the body weight changes of mice in each group are shown in Table 4 and Figure 1 as shown, and the changes in the disease activity index (DAI) of mice in each group are shown in Table 5 and Figure 2 as shown, where Figure 2 the score shown on the vertical axis is the sum of the scores for weight loss, fecal viscosity, and fecal occult blood. For example, Figure 2 a score of 7 in [example] can indicate that a 10% weight loss gets 2 points, a fecal viscosity of mucous-like feces gets 3 points, and fecal occult blood with blood around the anus gets 2 points, with a cumulative score of 7 points.

[0068] Table 4 Body weight change rates of mice in each group during model establishment

[0069]

[0070] Table 5 Disease activity index (DAI) of mice in each group during model establishment

[0071]

[0072] It can be seen from Tables 4 - 5 and Figures 1 - 2 that compared with the DSS model group, different doses of rice bran peptides can significantly improve the weight loss of mice and reduce the disease activity index.

[0073] The mice in each group were gavaged in the manner shown in Table 2 for 14 days. After 12 h of the last feeding, the mice were sacrificed, and the colon length of each group of mice was measured. Colon tissues were taken to detect cellular inflammatory factors such as TNF-α, IL-1β, IL-6, and IL-10 (the kits used for detection were purchased from Shanghai Jianglai Biotech Co., Ltd.). The detection results are shown in Table 6 and Figures 3 - 7 as described.

[0074] Table 6 Colon length and contents of inflammatory factors in mice after 14 days of gavage

[0075]

[0076]

[0077] As can be seen from Table 6 and Figures 3 - 7 it can be seen that compared with the DSS model group, rice bran peptides at different doses can relieve colon shortening. After DSS treatment, the contents of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α in the colon tissue increased, reaching 81.91 pg / g of colon tissue, 48.59 pg / g of colon tissue, and 339.36 pg / g of colon tissue respectively, and the content of the anti-inflammatory cytokine IL-10 decreased, reaching 14.98 pg / g of colon tissue. Compared with the DSS model group, after treatment with rice bran peptides at different doses, the contents of pro-inflammatory factors IL-1β, IL-6, and TNF-α in the colon can be significantly reduced, and the content of the anti-inflammatory cytokine IL-10 can be increased. Especially in the high-dose rice bran peptide group, the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α decreased by 38.32%, 29.88%, and 30.04% respectively, and the anti-inflammatory cytokine IL-10 increased by 51.68%, which was comparable to the levels of the normal group and the negative control group, indicating that a certain dose of rice bran peptide can effectively relieve DSS-induced intestinal barrier damage and has a certain protective effect on the intestinal barrier, restoring it to the normal level.

[0078] As can be seen from the above examples, the rice bran peptide obtained by the preparation method of the present invention has strong free radical scavenging ability, can effectively improve the weight loss of mice, reduce the disease activity index, relieve colon shortening, reduce the contents of pro-inflammatory factors IL-1β, IL-6, and TNF-α in the colon, increase the content of the anti-inflammatory cytokine IL-10, effectively relieve DSS-induced intestinal barrier damage, and has a certain protective effect on the intestinal barrier.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A Lactobacillus plantarum, characterized in that, The Lactobacillus plantarum is YY-9, classified and named as Lactobacillus plantarum, deposited in the General Microbiological Center of the China Committee for Culture Collection of Microorganisms, with the deposit number of CGMCC No. 24693, and the deposit date of April 18, 2022.

2. Use of the Lactobacillus plantarum according to claim 1 in the preparation of rice bran peptide with intestinal barrier protection function, characterized in that, It includes the following steps: using alkaline protease to enzymatically hydrolyze rice bran protein to obtain an enzymatic hydrolysate; using the Lactobacillus plantarum described in claim 1 to ferment the enzymatic hydrolysate, and drying the obtained fermentation broth to obtain rice bran peptides.

3. A preparation method of rice bran peptide with intestinal barrier protection function, characterized in that, It includes the following steps: using alkaline protease to enzymatically hydrolyze rice bran protein to obtain an enzymatic hydrolysate; using the Lactobacillus plantarum described in claim 1 to ferment the enzymatic hydrolysate, and drying the obtained fermentation broth to obtain rice bran peptides.

4. The preparation method according to claim 3, wherein The addition amount of the alkaline protease is 600 - 800 U per gram of rice bran protein based on the weight of the rice bran protein.

5. The preparation method according to claim 3, characterized in that, The temperature of the enzymatic hydrolysis is 55°C - 65°C, the time of the enzymatic hydrolysis is 2.5 h - 3.5 h, and the pH value of the enzymatic hydrolysis is 8.0 - 9.

0.

6. The preparation method according to claim 3, wherein, The inoculation amount of the Lactobacillus plantarum YY-9 is 1% - 3% per liter of the enzymatic hydrolysate based on the volume of the enzymatic hydrolysate.

7. The preparation method according to claim 3, wherein The temperature of the fermentation is 28°C - 34°C, the time of the fermentation is 32 h - 40 h, and the pH value of the fermentation is 5.0 - 6.

0.

8. The preparation method according to claim 3, characterized in that, Before drying, it further includes nanofiltration treatment of the fermentation broth; the pressure of the nanofiltration is 15 - 25 Bar, and the temperature is 15 - 25°C.

9. Use of the Lactobacillus plantarum described in claim 1 or the preparation method described in any one of claims 3 - 8 in the preparation of drugs for treating ulcerative colitis.

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