Preparation and application of phytobacterium plantarum DPUL-Y42 microcapsule and coated microcapsule

Abstract

The invention discloses preparation and application of a phytobacterium plantarum DPUL-Y42 microcapsule and a coated microcapsule, and belongs to the technical field of microorganisms. The preparation method comprises the following steps: embedding probiotic plant lactobacillus DPUL-Y42 into wall materials of sodium alginate or sodium alginate and chitosan by utilizing a microcapsule technology to prepare a microcapsule, and culturing to prepare a coated microcapsule; the survival rate of the plant lactobacillus DPUL-Y42 in the plant lactobacillus DPUL-Y42 microcapsule and the plant lactobacillus DPUL-Y42 envelope state microcapsule in acid solutions with different pH values, simulated gastric juice, simulated intestinal juice, different temperature conditions and freeze-drying conditions is obviously improved, the resistance of thalli to the digestive tract environment can be effectively enhanced, and the thalli are released at a proper position, so that the survival rate of the plant lactobacillus DPUL-Y42 in the plant lactobacillus DPUL-Y42 microcapsule and the plant lactobacillus DPUL-Y42 envelope state microcapsule is improved. And the probiotic effect is exerted.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbiology, and particularly relates to the preparation of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and film-coated microcapsules and their application in improving the survival rate of Lactiplantibacillus plantarum DPUL-Y42 in different tolerance environments. Background Art

[0002] Probiotics have probiotic functions such as regulating the balance of intestinal flora and promoting the digestion and absorption of nutrients, and are widely used in the fields of food and so on. However, probiotics are very sensitive to external conditions. They are in adverse conditions during processing, transportation, storage, and the targeted delivery to the colon, and it is difficult for a sufficient number of live bacteria to reach the intestine to play their roles. The probiotic encapsulation technology in the existing methods for maintaining the high survival rate of probiotics has attracted considerable attention. Therefore, it has become an urgent need to research and develop new methods for encapsulating probiotics to enhance the survival rate of bacterial cells in adverse environments. Summary of the Invention

[0003] The purpose of the present invention is to provide the preparation of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and film-coated microcapsules and their application in improving the survival rate of Lactiplantibacillus plantarum DPUL-Y42 in different tolerance environments. The present invention uses sodium alginate and chitosan as the microcapsule wall materials to encapsulate Lactiplantibacillus plantarum DPUL-Y42 to prepare microcapsules and film-coated microcapsules, which significantly improves the survival rate of the strain in different tolerance environments.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] In the first aspect, the present invention provides a Lactiplantibacillus plantarum DPUL-Y42, which was deposited at the China Center for Type Culture Collection on September 6, 2023, and the strain deposit number is CCTCC NO: M20231624.

[0006] In the second aspect, the present invention provides a method for preparing Lactiplantibacillus plantarum DPUL-Y42 microcapsules, including the following steps: expanding and culturing the above-mentioned Lactiplantibacillus plantarum DPUL-Y42 and then centrifuging, resuspending the obtained bacterial sludge in a sodium alginate solution, dropping the obtained mixed solution into a sterile soluble calcium salt solution, hardening, and collecting the microcapsules. After washing, the Lactiplantibacillus plantarum DPUL-Y42 microcapsules are obtained;

[0007] Alternatively, after the above-mentioned Lactiplantibacillus plantarum DPUL-Y42 is expanded and cultured and then centrifuged, the obtained bacterial sludge is resuspended in a sodium alginate solution. The obtained mixed solution is dropped into a sterile soluble calcium salt solution, hardened, washed, and then the obtained microcapsules are immersed in a chitosan solution and oscillated and mixed for 5 to 60 min. After washing with water, the Lactiplantibacillus plantarum DPUL-Y42 microcapsules are obtained.

[0008] Based on the above technical solution, further, the centrifugation conditions are centrifugation at 4000 - 7000 g for 10 - 30 min at 1 - 4 °C.

[0009] Based on the above technical solution, further, the concentration of Lactiplantibacillus plantarum DPUL-Y42 in the resuspension solution is 1×10 7 ~1×10 9 CFU / mL, and the concentration of sodium alginate is 0.001 - 0.01 g / mL.

[0010] Based on the above technical solution, further, the mixed solution is dropped into the soluble calcium salt solution through the tip of a 1 mL sterile syringe.

[0011] Based on the above technical solution, further, the soluble calcium salt includes CaCl2, CaBr2, Ca(NO3)2, CaHPO4, and the mass percentage concentration of the soluble calcium salt solution is 0.01 - 0.20%; the hardening time is 10 - 60 min.

[0012] Based on the above technical solution, further, the solution used for washing is a peptone aqueous solution with a mass percentage of 0.01 - 0.2%.

[0013] Based on the above technical solution, further, the concentration of the chitosan solution is 0.001 - 0.010 g / mL; the oscillation speed is 50 - 300 rpm.

[0014] In the third aspect, the present invention provides the Lactiplantibacillus plantarum DPUL-Y42 microcapsules prepared by the above preparation method.

[0015] In the fourth aspect, the present invention provides a preparation method for the Lactiplantibacillus plantarum DPUL-Y42 coated microcapsules. The above-mentioned Lactiplantibacillus plantarum DPUL-Y42 microcapsules are put into a sterile MRS culture medium and cultured at 35 - 39 °C for 12 - 48 h to obtain the Lactiplantibacillus plantarum DPUL-Y42 coated microcapsules.

[0016] In the fifth aspect, the present invention provides the Lactiplantibacillus plantarum DPUL-Y42 coated microcapsules prepared by the above preparation method.

[0017] Sixth aspect, the present invention provides the application of the above-mentioned Lactiplantibacillus plantarum DPUL-Y42 microcapsules and the film-coated Lactiplantibacillus plantarum DPUL-Y42 microcapsules in improving the survival rate of Lactiplantibacillus plantarum DPUL-Y42.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses microcapsule technology to embed the probiotic Lactiplantibacillus plantarum DPUL-Y42 in the wall materials of sodium alginate and sodium alginate or chitosan to prepare microcapsules, and after cultivation, film-coated microcapsules are prepared, which significantly improves the survival rate of Lactiplantibacillus plantarum DPUL-Y42 in the Lactiplantibacillus plantarum DPUL-Y42 microcapsules and the film-coated Lactiplantibacillus plantarum DPUL-Y42 microcapsules under different pH acid solutions, simulated gastric juice, simulated intestinal juice, different temperature conditions, and freeze-drying conditions. It can effectively enhance the resistance of the bacterial cells to the digestive tract environment and release them at an appropriate position to exert their probiotic effects. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the preparation process of the sodium alginate film-coated microcapsules and sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0021] Figure 2 It is a schematic diagram of the preparation process of the sodium alginate-chitosan film-coated microcapsules and sodium alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0022] Figure 3 It is a picture of the sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42 and the sodium alginate film-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0023] Figure 4 It is a graph of the pH change results of the fermentation culture of Lactiplantibacillus plantarum DPUL-Y42 microcapsules for 24 h. Among them, Biofilm is the film-coated Lactiplantibacillus plantarum DPUL-Y42, SA-MC is the sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42, and AC-MC is the sodium alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0024] Figure 5Survival rates of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and encapsulated microcapsules in acid solution. Here, Biofilm refers to Lactiplantibacillus plantarum DPUL-Y42 in the biofilm state, SA-BMC refers to alginate-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, SA-MC refers to alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42, AC-BMC refers to alginate-chitosan-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, and AC-MC refers to alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0025] Figure 6 Survival rates of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and encapsulated microcapsules in simulated gastric fluid. Here, Biofilm refers to Lactiplantibacillus plantarum DPUL-Y42 in the biofilm state, SA-BMC refers to alginate-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, SA-MC refers to alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42, AC-BMC refers to alginate-chitosan-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, and AC-MC refers to alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0026] Figure 7 Survival rates of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and encapsulated microcapsules in simulated intestinal fluid. Here, Biofilm refers to Lactiplantibacillus plantarum DPUL-Y42 in the biofilm state, SA-BMC refers to alginate-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, SA-MC refers to alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42, AC-BMC refers to alginate-chitosan-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, and AC-MC refers to alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0027] Figure 8 Survival rates of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and encapsulated microcapsules under high-temperature conditions. Here, Biofilm refers to Lactiplantibacillus plantarum DPUL-Y42 in the biofilm state, SA-BMC refers to alginate-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, SA-MC refers to alginate microcapsules of Lactiplantibacillus plantarum DPUL-Y42, AC-BMC refers to alginate-chitosan-coated microcapsules of Lactiplantibacillus plantarum DPUL-Y42, and AC-MC refers to alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0028] Figure 9Survival rates of Lactiplantibacillus plantarum DPUL - Y42 microcapsules and modal microcapsules under freeze - drying conditions. Among them, Biofilm is the biofilm - state Lactiplantibacillus plantarum DPUL - Y42, SA - BMC is the alginate - coated microcapsule of Lactiplantibacillus plantarum DPUL - Y42, SA - MC is the alginate microcapsule of Lactiplantibacillus plantarum DPUL - Y42, AC - BMC is the alginate - chitosan - coated microcapsule of Lactiplantibacillus plantarum DPUL - Y42, and AC - MC is the alginate - chitosan microcapsule of Lactiplantibacillus plantarum DPUL - Y42. Detailed implementation manners

[0029] The following non - restrictive examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way.

[0030] Lactiplantibacillus plantarum DPUL - Y42 used in the examples, taxonomically named Lactiplantibacillus plantarum DPUL - Y42, was deposited at the China Center for Type Culture Collection on September 6, 2023, and the strain deposit number is CCTCC NO: M 20231624.

[0031] Example 1 Preparation of alginate - coated microcapsules and alginate microcapsules of Lactiplantibacillus plantarum DPUL - Y42

[0032] Centrifuge 10 mL of the MRS culture solution of Lactiplantibacillus plantarum DPUL - Y42 (5770 g, 4 °C, 20 min) to obtain bacterial sludge. Resuspend the obtained bacterial sludge in 10 ml of sterile sodium alginate aqueous solution. The concentration of Lactiplantibacillus plantarum DPUL - Y42 is 1×10 8 CFU / mL, and the concentration of sodium alginate is 0.005 g / mL. Drop 1 mL of the Lactiplantibacillus plantarum DPUL - Y42 - sodium alginate bacterial suspension into 9 mL of sterile 0.05% (mass percentage) CaCl2 aqueous solution through the tip of a 1 mL sterile syringe needle. The prepared sodium alginate microcapsules (SA - MCs) are hardened in the CaCl2 solution for 15 minutes, and then collected by gravity sedimentation. Wash with sterile 0.1% (mass percentage) peptone aqueous solution to remove excess Ca 2+ and non - encapsulated bacteria, thus obtaining the sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL - Y42.

[0033] Put the prepared sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL - Y42 into 10 mL of sterile MRS culture solution and culture at 37 °C for 24 h to obtain the biofilm - state sodium alginate microcapsules of Lactiplantibacillus plantarum DPUL - Y42.

[0034] Example 2 Preparation of Alginate-Chitosan Coated Microcapsules and Alginate-Chitosan Microcapsules of Lactiplantibacillus plantarum DPUL-Y42

[0035] Centrifuge 10 mL of the MRS culture solution of Lactiplantibacillus plantarum DPUL-Y42 (5770 g, 4 °C, 20 min) to obtain bacterial sludge. Resuspend the obtained bacterial sludge in 10 ml of a sterile sodium alginate aqueous solution. The concentration of Lactiplantibacillus plantarum DPUL-Y42 is 1×10 8 CFU / mL, and the concentration of sodium alginate is 0.005 g / mL. Drop 1 mL of the Lactiplantibacillus plantarum DPUL-Y42-sodium alginate bacterial suspension into 9 mL of a sterile 0.05% (w / v) CaCl2 aqueous solution through the tip of a 1 mL sterile syringe. The synthesized sodium alginate microcapsules (SA-MCs) are hardened in the CaCl2 solution for 15 minutes and then collected by gravity sedimentation. Wash with a sterile 0.1% (w / v) peptone aqueous solution to remove excess Ca 2+ and non-encapsulated bacteria. Then, immerse 1 g of fresh alginate beads in 8 mL of a chitosan solution (chitosan concentration 0.004 g / mL) and mix at 200 rpm for 20 min. Then wash the microcapsules twice with deionized water to obtain the alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0036] Put the prepared alginate-chitosan microcapsules into 10 mL of sterile MRS culture solution and culture at 37 °C for 24 h to obtain the coated alginate-chitosan microcapsules of Lactiplantibacillus plantarum DPUL-Y42.

[0037] Example 3 Viable Cell Count and Encapsulation Efficiency of Microcapsules and Coated Microcapsules of Lactiplantibacillus plantarum DPUL-Y42

[0038] Add 1 mL of the microcapsules and coated microcapsules prepared in the above example to 9 mL of a sodium citrate solution (pH 8), shake in a shaker at 37 °C and 230 r / min for 30 min, take samples, and perform viable cell counting.

[0039] The encapsulation efficiency (EY) can be calculated by the formula: EY = m2 / m0 × 100;

[0040] where, m0: the initial number of viable cells added, CFU / mL;

[0041] m2: the number of viable cells encapsulated in the microcapsules, CFU / mL;

[0042] The results are shown in Table 1. The colony concentration in the alginate-chitosan film microcapsules was significantly higher than that in the alginate-chitosan microcapsules, indicating that Lactobacillus plantarum DPUL-Y42 grew and reproduced in the alginate-chitosan microcapsules. The embedding rate of the alginate microcapsules was 82.17%, and that of the alginate-chitosan microcapsules was 91.3%.

[0043] Table 1 Statistical results of viable counts of microcapsules, film microcapsules, and Lactobacillus plantarum DPUL-Y42

[0044]

[0045] Example 4 Fermentation experiments of Lactobacillus plantarum DPUL-Y42 microcapsules and film microcapsules

[0046] The embedded alginate-chitosan microcapsules were placed in MRS liquid medium and cultured in a constant temperature incubator at 37 °C for 24 h, and the change in the pH value of the medium was recorded.

[0047] The results were as Figure 4 shown. There was no significant difference in the pH value of the microcapsules at each time period in the MRS medium compared with that of the film Lactobacillus plantarum DPUL-Y42 medium.

[0048] Example 5 Acid tolerance experiments of Lactobacillus plantarum DPUL-Y42 microcapsules and film microcapsules

[0049] 1 mL of microcapsules, film microcapsules, and film DPUL-Y42 were cultured in MRS medium at pH 1.5, 2.0, 3.0, and 4.0 for 3 hours, and the strain survival rate was recorded. After releasing the Lactobacillus plantarum DPUL-Y42 in 1 mL of microcapsules and dissolving it in 10 mL of PBS solution for gradient dilution, 1 mL of the microcapsule dilution was added to the plate, 25 mL of MRS solid medium was poured, and it was cultured in an incubator at 37 °C for 48 h for counting.

[0050] Survival rate calculation formula: m1 / m2 × 100%;

[0051] m1: Number of strains after the experiment;

[0052] m2: Number of strains before the experiment;

[0053] The results were as Figure 5 shown. Under acid stress (pH 1.5) for 3 h, the survival rate of the film microcapsules was significantly higher than that of the microcapsules and Lactobacillus plantarum DPUL-Y42. As the pH value increased, the survival rates of each group increased to varying degrees. The above results indicate that the acid tolerance of the film microcapsules is the highest.

[0054] Example 6: Simulated gastric juice experiment of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and film-coated microcapsules

[0055] Mix 1 mL of microcapsules, film-coated microcapsules, and film-coated Lactiplantibacillus plantarum DPUL-Y42 with 9 mL of simulated gastric juice (1.64 mL of dilute hydrochloric acid, 1 g of pepsin dissolved in a small amount of deionized water, mix the two evenly and make up to 100 mL, adjust the pH to 2) respectively. Shake at 100 rpm at 37 °C for 3 hours, centrifuge to collect the microcapsules. After releasing the Lactiplantibacillus plantarum DPUL-Y42 in 1 mL of microcapsules, dissolve it in 10 mL of PBS solution and then dilute it step by step. Add 1 mL of the microcapsule dilution to the plate, pour in 25 mL of MRS solid medium, and place it in an incubator at 37 °C for 48 h for counting.

[0056] Survival rate calculation formula: m1 / m2×100%;

[0057] m1: Number of strains after the experiment;

[0058] m2: Number of strains before the experiment;

[0059] The results are as Figure 6 shown. Lactiplantibacillus plantarum DPUL-Y42 is the most sensitive to simulated gastric juice, and the survival rate of the strain is greatly reduced. In contrast, the survival rate of the strain in the microcapsule Lactiplantibacillus plantarum DPUL-Y42 is significantly higher than that of the free Lactiplantibacillus plantarum DPUL-Y42, indicating that the microcapsules can protect the strain and reduce the digestion of the strain by gastric juice. The survival rate of the strain in the film-coated microcapsule Lactiplantibacillus plantarum DPUL-Y42 is the highest, and it has the strongest resistance to gastric juice.

[0060] Example 7: Simulated intestinal juice experiment of Lactiplantibacillus plantarum DPUL-Y42 microcapsules and film-coated microcapsules

[0061] Mix 1 mL of microcapsules, film-coated microcapsules, and film-coated Lactiplantibacillus plantarum DPUL-Y42 with 9 mL of simulated intestinal juice (dissolve 0.68 g of potassium dihydrogen phosphate in 25 mL of deionized water, adjust the pH value to 7 with NaOH solution, weigh 10 g of trypsin and dissolve it in a small amount of deionized water, and finally mix the two evenly and make up to 100 mL) respectively; incubate and shake at 100 r / min at 37 °C for 3 h, centrifuge to collect the microcapsules. After releasing the Lactiplantibacillus plantarum DPUL-Y42 in 1 mL of microcapsules, dissolve it in 10 mL of PBS solution and then dilute it step by step. Add 1 mL of the microcapsule dilution to the plate, pour in 25 mL of MRS solid medium, and place it in an incubator at 37 °C for 48 h for counting.

[0062] Survival rate calculation formula: m1 / m2×100%

[0063] m1: Number of bacterial strains after the experiment;

[0064] m2: Number of bacterial strains before the experiment;

[0065] The results are as Figure 7 shown. Lactiplantibacillus plantarum DPUL-Y42 is the most sensitive to simulated intestinal fluid, and the survival rate of the bacterial strains decreases significantly. In contrast, the survival rate of the bacterial strains in microencapsulated Lactiplantibacillus plantarum DPUL-Y42 is significantly higher than that of planktonic Lactiplantibacillus plantarum DPUL-Y42, indicating that microcapsules can protect the bacterial strains and reduce the digestion of the intestinal fluid on the bacterial strains. The survival rate of the bacterial strains in the film-coated microencapsulated Lactiplantibacillus plantarum DPUL-Y42 is the highest and the resistance to intestinal fluid is the strongest.

[0066] Example 8 Heat resistance experiment of microencapsulated Lactiplantibacillus plantarum DPUL-Y42 and film-coated microcapsules

[0067] Heat 1 mL of microcapsules, film-coated microcapsules, and film-coated Lactiplantibacillus plantarum DPUL-Y42 in a water bath at 55 °C and 65 °C for 15 min respectively, and record the survival rate of the bacterial strains. After releasing the Lactiplantibacillus plantarum DPUL-Y42 in 1 mL of microcapsules and dissolving it in 10 mL of PBS solution for gradient dilution, add 1 mL of the microcapsule dilution to the plate, pour 25 ml of MRS solid medium, and place it in an incubator at 37 °C for 48 h for counting.

[0068] Survival rate calculation formula: m1 / m2 × 100%;

[0069] m1: Number of bacterial strains after the experiment;

[0070] m2: Number of bacterial strains before the experiment;

[0071] The results are as Figure 8 shown. After heating in a water bath at 55 °C and 65 °C for 15 min, there are still surviving bacterial strains in the film-coated microcapsules, and there are also some surviving in the film-coated Lactiplantibacillus plantarum DPUL-Y42, but the survival rate of the bacterial strains decreases significantly. The survival rate of the bacterial strains in the film-coated microcapsules is significantly higher than that of the film-coated Lactiplantibacillus plantarum DPUL-Y42 after heating in a water bath for 15 min, indicating that the microcapsules have a good protective effect on Lactiplantibacillus plantarum DPUL-Y42.

[0072] Example 9 Lyophilization resistance experiment of microencapsulated Lactiplantibacillus plantarum DPUL-Y42 and film-coated microcapsules

[0073] The wet microcapsules, the wet film-coated microcapsules, and the film-coated Lactobacillus plantarum DPUL-Y42 were separately placed in a -80°C freezer and pre-frozen for 12 hours, then placed in a vacuum freeze dryer and freeze-dried for 48 hours to obtain dry powder. After releasing the Lactobacillus plantarum DPUL-Y42 in 1 mL of the microcapsules and dissolving it in 10 mL of PBS solution, it was then serially diluted. 1 mL of the microcapsule dilution was added to the plate, 25 mL of MRS solid medium was poured in, and it was placed in a 37°C incubator for 48 hours for counting.

[0074] Survival rate calculation formula: m1 / m2 × 100%

[0075] m1: Number of strains after the experiment;

[0076] m2: Number of strains before the experiment;

[0077] The results are as Figure 9 shown. The survival rate after freeze-drying of the sodium alginate film-coated microcapsule (SA-BMC) group was 3.54 times that of the film-coated group and 2.41 times higher than that of the sodium alginate microcapsule (SA-MC) group. The survival rate after freeze-drying of the sodium alginate-chitosan film-coated microcapsule (AC-BMC) group was 5.21 times that of the film-coated group and 2.17 times higher than that of the sodium alginate-chitosan microcapsule (AC-MC) group. Although the biofilm has a certain protective effect on Lactobacillus plantarum DPUL-Y42, the protective effect of the microcapsule on Lactobacillus plantarum DPUL-Y42 is significantly better than that of the biofilm, and the double-layer embedding effect with sodium alginate-chitosan as the embedding material is significantly better than that of a single layer of sodium alginate.

Claims

1. A Lactiplantibacillus plantarum DPUL-Y42, characterized in that, The Lactiplantibacillus plantarum DPUL-Y42 was deposited at the China Center for Type Culture Collection on September 6, 2023, with the strain deposit number CCTCC NO: M 20231624.

2. A method for preparing microcapsules of Lactiplantibacillus plantarum DPUL-Y42, characterized in that, It includes the following steps: After the Lactiplantibacillus plantarum DPUL-Y42 described in claim 1 is expanded and cultured and then centrifuged, the obtained bacterial sludge is resuspended in a sodium alginate solution, and the resulting mixed solution is dropped into a sterile soluble calcium salt solution, hardened, and the microcapsules are collected. After washing, the Lactiplantibacillus plantarum DPUL-Y42 microcapsules are obtained. Alternatively, after the Lactiplantibacillus plantarum DPUL-Y42 described in claim 1 is expanded and cultured and then centrifuged, the obtained bacterial sludge is resuspended in a sodium alginate solution, and the resulting mixed solution is dropped into a sterile soluble calcium salt solution, hardened, and after washing, the obtained microcapsules are immersed in a chitosan solution and oscillated and mixed for 5 - 60 min. After washing with water, the Lactiplantibacillus plantarum DPUL-Y42 microcapsules are obtained.

3. The preparation method according to claim 2, characterized in that, The centrifugation conditions are centrifugation at 4000 - 7000g for 10 - 30 min at 1 - 4°C; the concentration of Lactiplantibacillus plantarum DPUL - Y42 in the resuspension solution is 1×10 7 - 1×10 9 CFU / mL, and the concentration of sodium alginate is 0.001 - 0.01 g / mL.

4. The preparation method according to claim 2, characterized in that, The said mixed solution is dropped into the soluble calcium salt solution through the tip of a 1 mL sterile syringe; the said soluble calcium salts include CaCl2, CaBr2, Ca(NO3)2, CaHPO4, and the mass percentage concentration of the soluble calcium salt solution is 0.01 - 0.20%; the hardening time is 10 - 60 min.

5. The preparation method according to claim 2, characterized in that, The solution used for washing is a peptone aqueous solution with a mass percentage of 0.01 - 0.2%.

6. The preparation method according to claim 2, characterized in that, The concentration of the chitosan solution is 0.001 - 0.010 g / mL; the rotation speed of oscillation is 50 - 300 rpm.

7. The Lactiplantibacillus plantarum DPUL-Y42 microcapsules prepared by the preparation method according to any one of claims 2 - 6.

8. A preparation method of Lactiplantibacillus plantarum DPUL-Y42 biofilm microcapsules, characterized in that, The Lactiplantibacillus plantarum DPUL-Y42 microcapsules described in claim 7 are placed in a sterile MRS culture medium and cultured at 35 - 39 °C for 12 - 48 h to obtain the Lactiplantibacillus plantarum DPUL-Y42 encapsulated microcapsules.

9. The Lactiplantibacillus plantarum DPUL-Y42 encapsulated microcapsules prepared by the preparation method described in claim 8.

10. The application of the Lactiplantibacillus plantarum DPUL-Y42 microcapsules described in claim 7 and the Lactiplantibacillus plantarum DPUL-Y42 encapsulated microcapsules described in claim 9 in improving the survival rate of Lactiplantibacillus plantarum DPUL-Y42.

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