Lactobacillus plantarum SWUN3927 with probiotic activity and application of lactobacillus plantarum SWUN3927

Abstract

The invention relates to the technical field of probiotic development and utilization, in particular to lactobacillus plantarum SWUN3927 with probiotic activity and application of the lactobacillus plantarum SWUN3927. The lactobacillus plantarum SWUN3927 is obtained by being separated from colostrum of Tibetan yaks, the probiotic effect of the lactobacillus plantarum SWUN3927 is identified through animal experiments, and results show that the lactobacillus plantarum SWUN3927 can resist acid and cholate and has an inhibition effect on pathogenic bacteria; the lactobacillus plantarum SWUN3927 has the advantages that the lactobacillus plantarum SWUN3927 is high in intestinal adhesion, the hydrophobicity is 74.67%, and the self-aggregation property is 58.98%, so that the lactobacillus plantarum SWUN3927 is proved to have good intestinal adhesion and have the potential of probiotics. The lactobacillus plantarum SWUN3927 is verified to be capable of effectively regulating the immunity of animal organisms, improving the antioxidant capacity of the organisms, the content of lysozyme and the activity of alkaline phosphatase, increasing the daily gain and finally improving the growth performance of animals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of probiotic development and utilization, in particular to a plant lactobacillus SWUN3927 with probiotic activity and application thereof. BACKGROUND

[0002] At present, antibiotics are commonly used to relieve or control bacterial diseases such as E. coli and Salmonella in clinic. Therefore, antibiotics are still an important means for treating bacterial infections in the breeding process, but repeated use, overuse or misuse of antibiotics can cause drug side effects. In addition, while antibiotics can kill pathogenic bacteria, they can also have adverse effects on intestinal microorganisms, thereby causing irritable bowel syndrome (IBS) and various immune diseases. More importantly, overuse and misuse of antibiotics can lead to the generation and spread of antibiotic-resistant strains, posing a serious threat to the breeding industry and thus threatening human safety and health. Under this background, probiotic preparations open up a new way for the production of natural, safe, high-quality, green and healthy animal products. As a new type of feed additive, it has advantages in alleviating the shortage of feed resources, improving the nutritional structure, reducing feed costs, protecting the environment, etc., and can be widely used in poultry, pig and ruminant breeding, which is of great significance to the healthy and sustainable development of China's breeding industry.

[0003] Lactic acid bacteria are the most common gram-positive bacteria in probiotics, which produce various beneficial functions to the host, mainly including the following four points: 1. By producing organic acids, bacteriocins and hydrogen peroxide and other bacteriostatic substances, it can competitively bind to the adhesion sites of intestinal mucosal epithelial cells to reduce the content of pathogenic bacteria such as E. coli and Salmonella in the intestinal tract, thereby maintaining the balance of intestinal flora; 2. By stimulating the host's immune system, it can resist pathogen infection and promote the body's humoral and cellular immunity to play an immune regulatory role; 3. By eliminating harmful substances in the body such as free radicals and toxins, it can enhance the animal's antioxidant capacity, intervene in the fatty acid metabolism process, and significantly improve the brightness and tenderness of meat products; 4. By producing various digestive enzymes such as cellulase and protease, it can help the body better digest and promote the host's nutrient absorption, thereby promoting the host's growth. In addition, fermented feed containing a large amount of lactic acid bacteria and lactic acid can inhibit the growth of spoilage bacteria, prolong the storage period of feed, and also rich in organic acids and a variety of flavor substances such as sugars, alcohols and esters, which can improve the palatability of feed and increase the animal's feed intake. At present, the lactic acid bacteria strains used are mostly Lactobacillus plantarum, Lactobacillus acidophilus, Pediococcus acidilactici, Enterococcus faecalis and Enterococcus faecium. As a kind of lactic acid bacteria, Lactobacillus plantarum not only produces bacteriocins, organic acids and other antibacterial substances, but also produces exopolysaccharides, so it has attracted more attention in the medical, food and other industries.

[0004] At present, the research and application of yak colostrum-derived Lactobacillus plantarum in animal probiotic effect are relatively less, but the existing research shows that Lactobacillus plantarum is a probiotic with good probiotic performance, and there is a great research space. Therefore, screening a Lactobacillus plantarum with good tolerance, self-aggregation, antibacterial, growth promotion and immune promotion properties is of great significance for the healthy and green development of the current yak breeding industry. SUMMARY

[0005] In view of the problems in the prior art, the present application provides a Lactobacillus plantarum SWUN3927 with probiotic activity, which has broad-spectrum antibacterial ability, acid and bile salt tolerance, and can improve animal daily gain and has adhesion ability to intestinal epithelium.

[0006] In order to achieve the above-mentioned purpose, the technical scheme provided is as follows:

[0007] The present application is isolated from yak colostrum in Tibet, named SWUN3927, and analyzed by 16S rRNA gene sequence, the strain SWUN3927 is Lactobacillus plantarum; the strain has been preserved in China Center for Type Culture Collection (CCTCC) on July 22, 2024, address: Wuhan, China, classified and named as Lactobacillus plantarum SWUN3927, and the preservation number is CCTCC NO: M 20241631.

[0008] The Lactobacillus plantarum SWUN3927 is a gram-positive bacterium.

[0009] The present application provides a bacterial agent containing the aforementioned Lactobacillus plantarum SWUN3927.

[0010] The present application also provides an application of Lactobacillus plantarum SWUN3927 in preparing a feed additive or animal feed.

[0011] Preferably, the feed additive or animal feed can have broad-spectrum antibacterial activity.

[0012] Preferably, the feed additive or animal feed is a product for promoting animal growth and regulating animal body immunity.

[0013] Preferably, the feed additive or animal feed is a product for improving antioxidant capacity.

[0014] The present application proves by animal experiments that the aforementioned Lactobacillus plantarum SWUN3927 can improve the growth performance of animals, improve the antioxidant capacity of the body, and effectively regulate the immunity of the animal body.

[0015] In the present application, the antibacterial spectrum of the Lactobacillus plantarum SWUN3927 is selected from gram-positive bacteria or gram-negative bacteria.

[0016] In the present application, the gram-negative bacteria are pathogenic E. coli and enteritidis.

[0017] The present application also provides a medicine containing the aforementioned Lactobacillus plantarum SWUN3927.

[0018] The present application has the following advantages:

[0019] 1. The present application identifies the probiotic effect of Lactobacillus plantarum SWUN3927 through animal experiments using mice as animal models. The results show that Lactobacillus plantarum SWUN3927 can resist acid, acid bile salt, and the gastrointestinal environment; the hydrophobicity is 74.67%, and the self-aggregation is 58.98%, proving that the Lactobacillus plantarum SWUN3927 of the present application has good intestinal adhesion and has the potential of probiotics.

[0020] 2. The present application verifies that Lactobacillus plantarum SWUN3927 can effectively regulate the immunity of the animal body, improve the antioxidant capacity, the content of lysozyme and the activity of alkaline phosphatase, and improve the daily weight gain, ultimately improving the growth performance of the animal. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A is the streaking chart of Lactobacillus plantarum SWUN3927 in the present application in MRS agar medium;

[0022] Figure 1 B is the staining microscopic examination result of Lactobacillus plantarum SWUN3927 in the present application (10x100μm);

[0023] Figure 2 is the hemolysis result in the present application; Figure 2 A is a positive quality control bacteria: Staphylococcus aureus; Figure 2 B is Lactobacillus plantarum SWUN3927;

[0024] Figure 3 is the organ index result in the present application;

[0025] Figure 4 is the daily weight gain result in the present application;

[0026] Figure 5 is the SOD, AKP, and LZM results in the serum of mice in the present application; 5A: SOD result; 5B: AKP result; 5C: LZM result; CG represents the control group; LG represents the low-dose group; HG represents the high-dose group.

[0027] Figure 6 is the IgG content in the blood of mice and the sIgA content in the jejunum in the present application; 6A: IgG content in the blood; 6B: sIgA content in the jejunum. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0029] It should be clear that, unless otherwise specified, the experimental methods used in the following examples are conventional methods, and unless otherwise specified, the materials, reagents, etc. used in the following examples can be obtained from commercial channels.

[0030] Statistical processing: statistical analysis was performed using GraphPad Prism 8.0.2, and the significant level difference was set as P<0.05 or P<0.01.

[0031] Example 1 Isolation and identification of Lactobacillus plantarum SWUN3927 from yak colostrum

[0032] 1. Isolation of Lactobacillus plantarum: The sample from yak colostrum in a certain area of Tibet was gradiently diluted with PBS, and then coated on GYP solid culture medium and placed in an anaerobic incubator at 37°C for 24 h. Single colonies with calcium-dissolving rings were picked and cultured on MRS agar medium until the colony morphology was unchanged. Lactobacillus plantarum colonies on MRS agar medium were round, small and wet, white or milky white. The colony surface was smooth, the edge was neat and regular, and the colony was surrounded by a clear zone. Figure 1 A.

[0033] A drop of sterile normal saline was dropped on a clean glass slide, and a small amount of bacteria was picked up with an inoculation loop and coated on the glass slide. After drying, Gram staining was performed, and the colony morphology was observed under a microscope. The strain with rod-shaped bacteria and positive Gram staining was numbered uniformly. After screening for resistance to artificial gastrointestinal fluid and other tests, it was found that the biological characteristics of strain SWUN3927 were the best. Strain SWUN3927 was a Gram-positive bacterium, which was usually rod-shaped, single, paired or arranged in chains under a microscope, as shown in Figure 1 B.

[0034] 2. PCR identification

[0035] DNA extraction: The DNA of the strain with antibacterial activity was extracted by phenol-chloroform method, and the DNA concentration and purity were detected by ultramicro nucleic acid protein detector.

[0036] Using strain DNA as template, 16S rRNA universal primers

[0037] 27F (5'-AGAGTTTGATCCTGGCTCAG-3'), 1492R (5'-GGTTACCTTGTTACGACT T-3'), the primers were synthesized by Shenguo Bioengineering (Shanghai) Co., Ltd., and the synthesized primers were subjected to PCR amplification.

[0038] The PCR amplification system was as follows: 2 µL of DNA template, 10 µL of 2×T5 Super PCR Mix, 1 µL of 27F, 1 µL of 1492R, and 20 µL of double-distilled water (dd H2O) were added to make up 20 µL, and the PCR amplification conditions were as follows: 95 ℃ pre-denaturation for 30 min; 94 ℃ denaturation for 30 s; 50.8 ℃ annealing for 30 s; 72 ℃ extension for 90 s, 35 cycles; and 72 ℃ re-extension for 5 min.

[0039] Agarose gel electrophoresis: 2% agarose gel was used for electrophoretic detection of PCR amplification products, and 1×TAE buffer was used as the electrophoretic medium. The electrophoretic conditions were as follows: voltage 120 V, current 200 mA, and time 26 min. The PCR product sequencing was completed by Shenguo Bioengineering Co., Ltd., the sequencing results were subjected to sequence splicing, the sequencing results were submitted to the GenBank data in the national center for biotechnology information (NCBI) database for basic local alignment search tool (BLAST) alignment, and the species were determined.

[0040] Strain preservation information:

[0041] Lactobacillus plantarum SWUN3927 was sent to the China Center for Type Culture Collection (CCTCC) for preservation, the preservation address was Wuhan, Hubei Province, China, the preservation number was CCTCC NO: M 20241631, the classification and naming was Lactobacillus plantarum SWUN3927, and the preservation date was July 22, 2024.

[0042] Example 2 Determination of the bacteriostatic ability of the supernatant of Lactobacillus plantarum SWUN3927 from yak colostrum

[0043] The bacterial liquid was inoculated into the MRS liquid medium at a certain proportion, and after 37 ℃ constant temperature culture for 24 h, the seed liquid was prepared, and the fermentation supernatant was obtained by high-speed refrigerated centrifuge at 10,000 rpm and 4 ℃ for 15 min. After removing the bacteria and other impurities in the supernatant with a 0.22 µm disposable sterile filter, the supernatant was stored at -20 ℃ for standby.

[0044] The inhibition ability of fermentation supernatant was measured by Oxford cup method, and the control strains were E. coli ATCC25922 and Salmonella ATCC14028. The detection plate was LB nutrient agar medium, and the OD 600 nm of the indicator bacteria was adjusted to 0.5 as the turbidity of the indicator bacteria suspension, 0.2 mL of the bacteria liquid was taken and evenly coated on the surface of the medium with a disposable coating rod, and the Oxford cup was placed in the middle of the plate. About 0.2 mL of fermentation supernatant was slowly added into the Oxford cup, and a control was set. Then, it was placed in a 4℃ refrigerator for 8 h, and then placed in a 37℃ constant temperature incubator for 12 h after the supernatant was diffused. The inhibition zone was observed and recorded, (see Table 1)

[0045] Table 1 Inhibition effect ; Note: "-" indicates that the inhibition zone is <8 mm and has no inhibition activity; +: the diameter of the inhibition zone is 8-11 mm, ++: the diameter of the inhibition zone is 12-17 mm, +++: the diameter of the inhibition zone is 18-23 mm.

[0046] The results in Table 1 show that Lactobacillus plantarum SWUN3927 has good inhibition effect on S. aureus 4509, Salmonella enteritidis reference strain, E. coli 4566, E. coli 6794, S. enteritidis 3807 and E. coli 4135.

[0047] Example 3 Biological characteristics of Lactobacillus plantarum SWUN3927 from yak colostrum

[0048] 1. Growth curve of Lactobacillus plantarum SWUN3927

[0049] Lactobacillus plantarum SWUN3927 was inoculated into 50 mL MRS broth at a ratio of 2%, and incubated at 37℃. From 0 h, every 2 h, 3 mL of bacteria liquid was taken to measure the OD 600 nm value of the strain, and the data was recorded. Three parallel controls were repeated, and the blank MRS medium was used as a control. The results showed that Lactobacillus plantarum SWUN3927 met the rules of lag phase, logarithmic phase, stationary phase and decline phase. The strain was in the lag phase for the first 2 h, in the logarithmic growth phase for 2-10 h, and entered the stationary phase after 10 h. After entering the stationary phase and decline phase, the viable bacteria were inhibited by their own metabolites. It can be determined that the best harvesting time of the bacteria is 10 h.

[0050] 2. Experiment on the ability of Lactobacillus plantarum SWUN3927 from yak colostrum to resist gastric and intestinal juice

[0051] Gastrointestinal fluid preparation: 0.35 g pepsin was added to 100 mL of 0.2% sterile normal saline to prepare gastric juice. The pH of the solution was adjusted to 2.5 with 1 mol / L HCl, and the solution was stored for later use by passing through a 0.22 μm filter. 0.1 g of trypsin and 1.8 g of sodium taurocholate were added to 100 mL of distilled water containing 1.1 g of NaHCO3 and 0.2 g of NaCl to prepare intestinal juice. The pH of the solution was adjusted to 8.0 with 1 mol / L NaOH, and the solution was filtered through a 0.22 μm filter and stored for later use. The bacterial solution (10 8 ~10 9 CFU / mL) was inoculated into simulated gastric juice at 10% of the inoculum, and plate counts were performed at 0 h and 3 h (intestinal juice 4 h), respectively, to determine the number of viable bacteria, and the survival rate of the strain (%) was calculated according to the following formula: Survival rate (%) = C1 / C2 x 100%;

[0052] In the formula, C1 is the number of viable bacteria (CFU / mL) measured after treatment with gastrointestinal juice; C2 is the number of viable bacteria (CFU / mL) measured at 0 h in gastrointestinal juice.

[0053] The results showed that the survival rate of Lactobacillus plantarum SWUN3927 in gastric juice at 3 h was 84.48%, and the survival rate of the bacterial solution in intestinal juice at 4 h was 71.87%. Lactobacillus plantarum SWUN3927 has good acid and bile salt resistance, and has the potential to become a probiotic.

[0054] 3. Determination of self-aggregation and hydrophobicity of yak colostrum-derived Lactobacillus plantarum SWUN3927

[0055] (1) Self-aggregation: The seed solution was inoculated at 2% into sterilized liquid MRS medium and incubated at 37 ℃ for 24 h. The culture was centrifuged at 4 ℃ and 10 000 r / min for 10 min, and the supernatant was discarded. The bacteria were washed twice with pH 7.2 phosphate buffer and resuspended in PBS. The concentration of the bacterial suspension was adjusted to 10 7 ~10 8 CFU / mL, and 3 mL of the bacterial suspension was taken to measure the absorbance at 600 nm, which was recorded as A0. After the bacterial suspension was incubated at 37 ℃ for 5 h, 3 mL of the upper clear solution was taken into another test tube, and the absorbance was measured at 600 nm, which was recorded as At. Three independent experiments were repeated, and the average value was taken.

[0056] ;

[0057] At represents the value of OD 600 at t = 5 h; A0 is the value of OD 600 at t = 0 h.

[0058] (2) Hydrophobicity: Prepare a bacterial suspension according to (1), then add an equal volume of xylene, vortex mix the two-phase system for 3 min, take the supernatant after standing at 37 ℃ for 1 h, and measure the absorbance of the water phase at 600 nm wavelength, denoted as A. Calculate the surface hydrophobicity of the strain according to the formula. Repeat 3 independent experiments and take the average value.

[0059] ;

[0060] In the formula: A0 and A respectively represent the absorbance of the Lactobacillus plantarum SWUN3927 bacterial suspension and the water phase after mixing the two phases.

[0061] Lactobacillus plantarum SWUN3927 needs to have the ability to colonize the host intestinal tract and prevent pathogenic bacteria from colonizing the intestinal tract. The self-aggregation ability is an important indicator for evaluating the ability to adhere to intestinal cells in vitro. The self-aggregation ability is generally divided into the following three categories: weak (16%~35%), moderate (35%~50%), and strong (more than 50%). The self-aggregation and hydrophobicity of Lactobacillus plantarum SWUN3927 were determined in the present application, which were 58.98% and 74.67% respectively, indicating that the strain has good intestinal adhesion.

[0062] 4. Determination of the in vitro antioxidant capacity of yak colostrum-derived Lactobacillus plantarum SWUN3927

[0063] Determination of total antioxidant capacity (T-AOC) and superoxide dismutase (T-SOD) of Lactobacillus plantarum SWUN3927: The T-AOC and T-SOD activities of the supernatant of Lactobacillus plantarum SWUN3927 were determined using a kit, and the specific method was strictly according to the kit instructions.

[0064] The results showed that the total antioxidant capacity (T-AOC) was 1.230 U / mL; the superoxide dismutase (T-SOD) was 116.976 U / mL. It is shown that Lactobacillus plantarum SWUN3927 has certain antioxidant properties and can improve the antioxidant capacity of animal body.

[0065] Example 4 Safety of yak colostrum-derived Lactobacillus plantarum SWUN3927 strain

[0066] (1) Hemolytic experiment of Lactobacillus plantarum SWUN3927: After centrifugation, Lactobacillus plantarum SWUN3927 was inoculated on blood agar in the form of streaks, and incubated at 37 ℃ for 48 h. The hemolysis was observed, and the strains producing green bands around the colonies (α-hemolysis) or not producing any hemolysis on the blood agar (γ-hemolysis) were considered to be non-hemolytic. The strains producing hemolytic bands (transparent bands) around the colonies were classified as microorganisms with hemolytic (β-hemolytic) properties. The transparent β-hemolytic ring was hemolytic phenotype positive. Hemolytic Staphylococcus was used as a positive quality control strain.

[0067] The results show that the hemolysis result of Lactobacillus plantarum SWUN3927 is negative, and the safety is high, and the specific results are shown in Table 1. Figure 2 Table 1 Hemolysis results of Lactobacillus plantarum SWUN3927

[0068] (2) Antibiotic sensitivity test of Lactobacillus plantarum SWUN3927: K-B paper method was used to detect the sensitivity of the screened strain to common antibiotics. 200 μL of seed liquid was inoculated in 8 mL of MRS broth, and incubated at 37°C for 24 h. The concentration of the bacterial liquid was adjusted to 10 8 CFU / mL, and the bacterial liquid was evenly coated on the MH culture medium with a sterile cotton swab. The antibiotic sensitivity sheet was taken out with sterile tweezers and pasted on the surface of the culture medium in turn. The antibiotic sensitivity sheet was pressed with tweezers to make it tightly adhere to the culture medium. Four antibiotic sensitivity sheets were pasted on each flat plate. After incubation at 37°C for 16 h, the diameter of the inhibition zone was measured with a ruler, and the results were recorded.

[0069] Table 2 Drug sensitivity results ; "S" sensitive, "R" resistant, "I" intermediate

[0070] According to the test standards of the American Clinical and Laboratory Standards Association (CLSI), the antibiotic resistance was evaluated by Kirby-Bauer paper disc diffusion method. The drug sensitivity test results were divided into the following three levels: resistant, intermediate and susceptible. As shown in Table 2, the Lactobacillus plantarum SWUN3927 is sensitive to most antibiotics and has high safety.

[0071] (2) Acute oral toxicity test in mice

[0072] Twelve male SPF KM mice were selected, and 6 mice in each of the experimental group and the control group. After one week of adaptive feeding, the experiment was carried out. The experimental group was given Lactobacillus plantarum SWUN3927 1×10 10 CFU / mL of bacterial liquid per day, and the blank control group was given the same volume of MRS broth. The mice were continuously given for 21 days, and the mental food appetite, feces and other conditions of the mice were observed during the period. After 21 days, the mice were dissected, and the heart, lung, liver, spleen and kidney of the mice were observed for obvious pathological changes, and the activity index of the organs was measured.

[0073] The results show that during the gavage of mice, the spirit, diet, and diarrhea death are good. Autopsy shows that the heart, liver, spleen, lung weight of the blank control group mice has no obvious difference and pathological changes compared with the experimental group. By measuring the organ weight of mice, it is found that the organ index of mice in the experimental group and the blank control group has no significant difference (P>0.05), as shown in Figure 3 The safety experiment results show that the plant lactobacillus SWUN3927 as an animal feed additive has no high risk.

[0074] Example 5 Influence of yak colostrum-derived Weissella DY12 on growth performance, antioxidant capacity and immunity of mice

[0075] The plant lactobacillus SWUN3927 was streaked on a plate, cultured at 37°C for 24 h, and then a single colony was picked and cultured in MRS liquid medium for 24 h. After washing twice with PBS and resuspension, gradient dilution was performed, and the final concentration was determined by plate counting to be 1×10 8 CFU / mL and 1×10 10 CFU / mL. The 10 mL centrifuge tube was divided into 10 mL, and stored in a-20°C refrigerator.

[0076] Select 4-week-old male SPF KM mice with a body weight of 20±2 g. Divide 30 mice into 3 groups, namely the control group, the low-dose group and the high-dose group. The control group: the mice are not treated and are normally raised; the low-dose group: the mice are gavaged with 0.2 mL of 10 8 CFU / mL of plant lactobacillus SWUN3927 liquid per day; the high-dose group: the mice are gavaged with 0.2 mL of 10 10 CFU / mL of plant lactobacillus SWUN3927 liquid per day. The test is conducted for 21 days. During the test, the mice are free to eat and drink water, and the physiological conditions of the mice are observed.

[0077] (1) Measurement of daily weight gain of mice: select 30 male SPF KM mice with a body weight of 20±2 g, and divide them into 3 groups, 20 mice in each group. The low-dose group of mice is gavaged with 0.2 mL of 10 8 CFU / mL of plant lactobacillus SWUN3927 liquid per day; the high-dose group of mice is gavaged with 0.2 mL of 10 10 CFU / mL of plant lactobacillus SWUN3927 liquid per day. The control group is gavaged with 0.2 mL of normal saline, and the gavage is continuously conducted for 21 days. From the start of gavage, the weight of the mice in each group is measured once every 7 days, and the results are recorded.

[0078] The results show that the difference in daily weight gain of mice after 7 days and 14 days of gavage is not significant (P>0.05); after 21 days of gavage, the high-dose group significantly improves the daily weight gain compared with the low-dose group and the control group (P<0.05), as shown in Figure 4 . The results show that Lactobacillus plantarum SWUN3927 has a significant promoting effect on the daily weight gain of mice.

[0079] (2) Effect of feeding Lactobacillus plantarum SWUN3927 from yak colostrum on the antioxidant capacity of mice: On the basis of (1), 5 mice from each of the experimental group and the control group at 21 d were randomly taken, and the orbital blood was collected and stored at 37°C for 2 h, then centrifuged at 3,500 rpm for 15 min at 4°C, and the supernatant was absorbed and stored at 4°C. The SOD detection kit (Lanji Ke Technology Co., Ltd.), AKP kit, and LZM kit (Nanjing Jiancheng Biological Engineering Institute) were used to detect the SOD, AKP activity, and LZM content in the serum.

[0080] As shown in Figure 5 , wherein 5A is the SOD content; 5B is the AKP content; and 5C is the LZM content. The SOD content in the serum of the mice in the low-dose group and the high-dose group was extremely significantly higher than that in the control group (P<0.01); the AKP content in the serum of the mice in the low-dose group and the high-dose group was extremely significantly higher than that in the control group (P<0.01), and the AKP content in the high-dose group was extremely significantly higher than that in the low-dose group (P<0.01); the LZM content in the serum of the mice in the high-dose group was significantly higher than that in the control group (P<0.05), and the LZM content in the serum of the mice in the low-dose group was significantly higher than that in the high-dose group (P<0.05). The results show that gavage with different doses of Lactobacillus plantarum SWUN3927 bacterial solution can increase the contents of superoxide dismutase, alkaline phosphatase, and lysozyme in the serum. Especially, gavage with 1×10 10 CFU / mL of Lactobacillus plantarum SWUN3927 has better antioxidant effect.

[0081] (3) Effect of feeding Lactobacillus plantarum SWUN3927 from yak colostrum on the blood IgG of mice: On the basis of (1), 5 mice from each of the experimental group and the control group at 21 d were randomly taken, and the orbital blood was collected and stored at 37°C for 2 h, then centrifuged at 3,500 rpm for 15 min at 4°C, and the supernatant was absorbed and stored at 4°C. The ELISA kit was used to detect the IgG content in the blood (Wuhan Doctorde Biological Engineering Co., Ltd.).

[0082] The results show that, after 7 days of gavage, the IgG content in the serum of the low-dose group and the high-dose group has no significant difference compared with the control group (P>0.05); after 14 days of gavage, the IgG content in the serum of the high-dose group is significantly higher than that of the control group (P<0.05); after 21 days of gavage, the difference between the control group and the low-dose group is significant (P<0.05), and the difference between the high-dose group and the low-dose group is extremely significant (P<0.01). It is shown that 1×10 10 CFU / mL can significantly improve the secretion of IgG in the blood of mice, as shown in Table 2. Figure 6 A.

[0083] (4) The effect of feeding yak colostrum-derived Lactobacillus plantarum SWUN3927 on the intestinal mucosal sIgA of mice: (2) On the basis of the experiment, the mice were dislocated and killed, the jejunum of the same length was taken, the contents were washed with sterile normal saline, homogenized on ice, frozen overnight at-20℃, repeated freeze-thawing for 2 times, centrifuged at 5000×g for 5 min at 4℃, and the supernatant was taken. Referring to the instructions of the ELISA kit, the content of intestinal IgA of mice was determined (Wuhan Huamei Biological Engineering Co., Ltd.).

[0084] The results show that, after 7 days of gavage, the sIgA content of the high-dose group and the low-dose group is extremely significantly higher than that of the control group (P<0.01); after 14 days of gavage, the sIgA content of the low-dose group and the high-dose group is extremely significantly higher than that of the control group (P<0.01), and the sIgA content of the high-dose group is significantly higher than that of the low-dose group (P<0.05); after 21 days of gavage, the sIgA content of the low-dose group and the high-dose group is extremely significantly higher than that of the control group (P<0.01), and the sIgA content of the high-dose group is significantly higher than that of the low-dose group (P<0.05). It is shown that 1×10 10 CFU / mL can significantly improve the secretion of sIgA in the jejunum of mice, as shown in Table 3. Figure 6 B.

[0085] It is apparent to those skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments, and that the application can be implemented in other particular forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the application should be defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes and modifications that fall within the meaning and scope of equivalents of the claims. Any reference signs in the claims should not be construed as limiting the claims to which they belong.

Claims

1. Lactobacillus plantarum ( Lactobacillus plantarum SWUN3927, characterized in that: Lactobacillus plantarum was isolated from Tibetan yak colostrum, and its preservation number is CCTCC NO: M 20241631, and the rDNA sequence is shown as SEQ ID NO:

1.

2. Use of the Lactobacillus plantarum SWUN3927 of claim 1 in the preparation of a feed additive or an animal feed.

3. Use of the Lactobacillus plantarum SWUN3927 of claim 1 in promoting animal growth and regulating animal body immunity.

4. Use of the Lactobacillus plantarum SWUN3927 of claim 1 in improving animal antioxidant capacity.

5. A feed additive for promoting the growth of animals, regulating the immunity of animals, and improving the antioxidant capacity of animals, characterized in that: The Lactobacillus plantarum SWUN3927 of claim 1.

6. Animal feed for promoting growth, regulating immunity, and improving antioxidant capacity of animals, characterized in that: The Lactobacillus plantarum SWUN3927 of claim 1 and common animal feed nutritional components or carriers.

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