Lactobacillus plantarum SMU-KDLP2312 and application thereof

Abstract

The invention discloses a strain of lactobacillus plantarum SMU-KDLP2312 and application thereof, the strain of lactobacillus plantarum SMU-KDLP2312 is classified and named as Lactobacillus plantarum, the strain of lactobacillus plantarum SMU-KDLP2312 is named as Lactobacillus plantarum, and the strain of lactobacillus plantarum SMU-KDLP2312 is named as Lactobacillus plantarum. The strain is preserved in Guangdong Microbial Culture Collection Center on March 21, 2025, with the preservation number of GDMCC No.66040. The strain is preserved in the Guangdong Microbial Culture Collection Center. The lactobacillus plantarum SMU-KDLP2312 system is obtained by being separated and screened from intestinal tracts of Tibetan sheep, and has relatively strong stress resistance and in-vitro antibacterial ability. Meanwhile, the lactobacillus plantarum SMU-KDLP2312 has a relatively high survival rate in an acid environment, has relatively good tolerance to bile salt, has the effect of reducing cholesterol, and has the potential of becoming a good probiotic effect regulator. As one of feed additive strains, when applied to daily ration, the strain can promote the growth performance of Tibetan sheep to a certain extent, adjust the balance of animal intestinal flora and enhance the proliferation of beneficial bacteria.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a strain of Lactobacillus plantarum SMU-KDLP2312 and its applications. Background Technology

[0002] The challenge in Tibetan sheep farming lies in improving growth performance, increasing feed conversion rate, while reducing antibiotic overuse and the incidence of infectious diseases. Microecological preparations, or probiotics, can colonize or persist in the intestinal lumen, thereby improving feed digestibility, increasing weight gain, improving the quality of sheep milk and meat, reducing methane emissions, benefiting lamb growth and development, and reducing diarrhea rates. The gut microbiota is closely related to animal health and production performance. Microecological preparations are live microbial preparations made using normal microorganisms or substances that promote microbial growth. They are well-known eco-friendly probiotics and have been widely used in livestock and poultry farming. Probiotics can colonize the target intestinal segment and secrete various active metabolites (such as short-chain essential fatty acids, lactic acid, antimicrobial peptides, etc.), activate immune cell-related inflammatory factor signals, thereby participating in regulating the balance of the gut microbiota and the body's active defense system, enhancing immunity and disease resistance. Simultaneously, they can enhance the body's absorption and metabolic rate of nutrients (feed conversion rate), improve animal growth index and production performance, and provide high-quality feed additives.

[0003] Developing more, safer, and more effective probiotics has significant clinical application implications. Summary of the Invention

[0004] The purpose of this invention is to provide a strain of Lactobacillus plantarum SMU-KDLP2312 and its applications.

[0005] To address the problems existing in the prior art, the technical solution adopted in this invention is: In the first aspect, the present invention provides a strain of *Lactobacillus plantarum* SMU-KDLP2312, classified and named as follows: Lactiplantibacillus plantarum The accession number is GDMCC No.66040, and it is deposited at the Guangdong Provincial Center for Microbial Culture Collection on March 21, 2025.

[0006] In a second aspect, the present invention provides a preparation comprising Lactobacillus plantarum SMU-KDLP2312 as described in the first aspect above, wherein the preparation comprises fermentation broth, fermentation broth supernatant, fermentation broth precipitate, live bacteria and / or dead bacteria.

[0007] Thirdly, the present invention provides the use of Lactobacillus plantarum SMU-KDLP2312 or the preparation described in the first aspect above in the preparation of livestock and poultry feed additives.

[0008] Furthermore, the livestock and poultry include sheep and rabbits.

[0009] Furthermore, the feed additive is used to improve the daily weight gain of livestock and poultry and the forage conversion rate.

[0010] Furthermore, the viable count of *Lactobacillus plantarum* SMU-KDLP2312 in the feed additive is 1 × 10⁻⁶. 8 ~5×10 9 CFU / ml.

[0011] Fourthly, the present invention provides the use of Lactobacillus plantarum SMU-KDLP2312 or the preparation described in the first aspect above in the preparation of antibacterial agents.

[0012] Furthermore, the antibacterial agent is used to inhibit any one or more of Escherichia coli, Staphylococcus aureus, or Salmonella.

[0013] Fifthly, the present invention provides an antibacterial agent comprising Lactobacillus plantarum SMU-KDLP2312 as described in the first aspect above or the preparation described in the second aspect above.

[0014] In a sixth aspect, the present invention provides the use of Lactobacillus plantarum SMU-KDLP2312 or the preparation described in the first aspect above in the preparation of a medicament for reducing serum cholesterol.

[0015] The advantages and beneficial effects of this invention are: The *Lactobacillus plantarum* SMU-KDLP2312 strain of this invention was screened from the intestines of Tibetan sheep and can grow on LBS agar at a culture temperature of 35–38°C. It exhibits in vitro antibacterial activity, acid resistance, and bile salt tolerance.

[0016] The *Lactobacillus plantarum* SMU-KDLP2312 of this invention exhibits good antibacterial activity, effectively regulating and inhibiting the growth of harmful bacteria in the intestines, promoting intestinal flora balance, and helping to improve the growth performance and feed conversion rate of livestock and poultry, as well as the utilization rate of nutrients in feed. By competitively inhibiting the colonization of pathogenic bacteria (such as *Escherichia coli*, *Salmonella*, and *Staphylococcus aureus*), it reduces the incidence of intestinal diseases and maintains flora balance.

[0017] The *Lactobacillus plantarum* SMU-KDLP2312 strain of this invention exhibits strong stress resistance and in vitro antibacterial activity. Furthermore, *Lactobacillus plantarum* SMU-KDLP2312 shows high survival rate in acidic environments and good tolerance to bile salts, demonstrating its potential as a beneficial probiotic modifier. It can promote intestinal mucosal cell proliferation, reduce serum cholesterol levels, and effectively improve the daily weight gain and forage conversion rate of livestock such as sheep and rabbits. As a feed additive strain, its application in diets can, to some extent, promote the growth performance of Tibetan sheep, adjust the balance of intestinal flora, and enhance the proliferation of beneficial bacteria.

[0018] This strain has the ability to degrade cholesterol both in vivo and in vitro, thereby maintaining cholesterol balance in animals, promoting cardiovascular and intestinal health, and indirectly improving the growth performance and forage conversion rate of sheep and rabbits.

[0019] Preservation instructions: Strain name: Lactiplantibacillus plantarum SMU-KDLP2312; Accession number: GDMCC No. 66040; Category Naming: Lactiplantibacillus plantarum ; Deposit date: March 21, 2025; Preservation institution: Guangdong Provincial Center for Microbial Culture Collection; Address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. Attached Figure Description

[0020] Figure 1 The colony morphology on LBS agar in this embodiment of the invention; Figure 2 The image shows the Gram staining oil immersion microscopic examination result (100×) of an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the phylogenetic analysis of the isolated strains in an embodiment of the present invention; Figure 4 This is a schematic diagram of the growth curve of the isolated strain in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0023] Example 1

[0024] 1. Separation and Identification 1.1 Sample Intestinal contents sample of Tibetan goats in Kangding City, Ganzi Tibetan Autonomous Prefecture, Sichuan Province.

[0025] 1.2 Reagents and Instruments Lactobacillus broth, LBS agar (selective medium for Lactobacillus), MH broth, MH agar, and Gram stain were all purchased from Qingdao Haibo Biotechnology Co., Ltd., and the culture media were prepared according to the instructions. A rapid bacterial genomic DNA extraction kit was purchased from Tiangen Biotech; antibiotic susceptibility testing tablets were purchased from Hangzhou Microbial Reagent Co., Ltd.

[0026] Nucleic acid gel imaging instrument (Shanghai Furi Technology Co., Ltd.), PCR instrument (Thermo Fisher Scientific Co., Ltd.)

[0027] 1.3 Isolation of Lactobacillus plantarum Weigh 1g of Tibetan sheep intestinal chyme sample and add it to 99 mL of sterile distilled water. Shake on a constant temperature shaker for 1 h. Spread 100 μL of the homogenate onto Lactobacillus selective medium and incubate at 37 ℃ for 24 h. Pick a single milky white suspected colony with smooth and regular edges and a calcium dissolution zone and continue to isolate it onto LBS agar until a simple colony is formed.

[0028] 1.4 Morphological observation The isolated strains were stained using the conventional Gram staining method, and their cell morphology was observed using an optical microscope to perform preliminary identification of the strains.

[0029] Result: One target lactic acid bacteria strain was screened, such as Figure 1 As shown, suspected colonies on LBS agar appear as white or creamy-yellow colonies with neat edges, a raised center, and a smooth surface. Figure 2 As shown, Gram staining and microscopic examination revealed Gram-positive rod-shaped bacteria.

[0030] 1.5 Biochemical Characteristic Analysis The physiological and biochemical characteristics of the strains were determined according to the methods described in "Classification, Identification and Experimental Methods of Lactic Acid Bacteria".

[0031] Use bacterial micro-biochemical identification tubes according to the instructions, record and interpret the results.

[0032] Results: The bacterium showed positive reactions in the biochemical identification reactions for esculin, cellobiose, maltose, salicin, sucrose, lactose, and raffinose. It showed negative reactions in the biochemical identification reactions for sorbitol and mannitol.

[0033] 1.6 Molecular biological identification of 16S rDNA Bacterial DNA was extracted using a rapid bacterial genomic DNA extraction kit for PCR amplification. Based on the bacterial genome sequence, universal primers for bacterial 16S rDNA identification, 27F (SEQ ID NO.1: 5'-AGAGTTTGATCCTGGCTCAG-3') and reverse primer 1492R (SEQ ID NO.2: 5'-TACGGCTACCTTGTTACGACTT-3'), were synthesized at Sangon Biotech (Shanghai) Co., Ltd. PCR reaction parameters were set as follows: 95 ℃ pre-denaturation for 5 min, 95 ℃ for 30 s (denaturation), 52 ℃ for 30 s (annealing), and 72 ℃ for 5 min (extension), followed by storage at 4 ℃. The amplified products were purified by 1% gel electrophoresis and gel recovery, and then sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. Sequencing results were compared with the GenBank database, and a phylogenetic tree of the strains was constructed using the Neighbor-joining method with MEGA11 software.

[0034] Table 1 PCR reaction system

[0035] Results: One selected lactic acid bacteria strain was identified as *Lactiplantibacillus plantarum* through sequencing and comparison. Its sequenced gene sequence is shown in SEQ ID NO.3. This strain was named *Lactiplantibacillus plantarum* SMU-KDLP2312 and deposited at the Guangdong Provincial Microbial Culture Collection Center (GDMCC No. 66040) on March 21, 2025. The address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. The phylogenetic tree was constructed as follows. Figure 3 As shown.

[0036] SEQ ID NO. 3 1.7 Growth Curve Plotting The target strain was inoculated into 100 mL of Lactobacillus broth at a 1% (v / v) inoculation rate and cultured on a shaker at 37℃ and 220 rpm / min for 20 h. OD was measured every 2 h. 600nm The absorbance value was measured at the specified location. Finally, a growth curve was plotted with time on the x-axis and OD value on the y-axis.

[0037] The results are as follows Figure 4 As shown, when the culture temperature is 37 ℃, Lactiplantibacillus plantarum SMU-KDLP2312 enters the logarithmic growth phase after 6 h of culture and enters the growth plateau phase after 15 h.

[0038] 1.8 Evaluation of the Probiotic Properties of Lactobacillus plantarum 1.8.1 In vitro antibacterial test of Lactobacillus plantarum The antibacterial effect of *Lactobacillus plantarum* against *Escherichia coli*, *Staphylococcus aureus*, and *Salmonella* was detected using an agar diffusion assay. The target strain was inoculated into *Lactobacillus* broth at a 1% (v / v) inoculum and cultured at 37 °C on a shaker at 220 rpm / min for 15 h. The culture was then centrifuged at 5000 rpm for 20 min, and the supernatant was collected. An appropriate amount of catalase (10 mg / mL) was added, and the culture was incubated at 30 °C for 1 h to eliminate the antibacterial effect of hydrogen peroxide. *Escherichia coli*, *Staphylococcus aureus*, and *Salmonella* were adjusted to a bacterial concentration of 10⁻⁶ with sterile water. 7 CFU / mL, 100 μL of each solution was evenly spread onto MH agar medium, and then gently pressed into sterile Oxford cups. 200 μL of the treated *Lactobacillus plantarum* supernatant was added to each Oxford cup, and the cups were incubated at 37 ℃ for 12 h. The diameter of the inhibition zone was then measured.

[0039] Results: Lactiplantibacillus plantarum SMU-KDLP2312 showed good antibacterial activity against Escherichia coli, Staphylococcus aureus, and Salmonella. The diameter of the inhibition zone was no less than 16 mm (Table 2).

[0040] Table 2. Diameter of the inhibition zone of Lactobacillus plantarum (mm)

[0041] 1.9 Analysis of Antibiotic Resistance Phenotypes Adjust the bacterial suspension concentration during the logarithmic growth phase to 0.5 McFarland turbidity. Use a sterile cotton swab to collect the bacterial suspension and spread it evenly on the LBS agar surface. Let it stand for 10 minutes until the surface moisture is absorbed. Then, attach an antimicrobial susceptibility plate (purchased from Hangzhou Microbiology) to the center of the medium. Place the plate in a 37°C incubator and incubate for 18 hours. Measure the diameter of the inhibition zone to determine the results.

[0042] The results show: Lactiplantibacillus plantarum SMU-KDLP2312 is resistant to kanamycin, ciprofloxacin, norfloxacin, vancomycin, and gentamicin, but sensitive to nine other antibiotics (Table 3). The antibiotic resistance phenotypic analysis of this strain indicates that it is sensitive to commonly used antibiotics and does not exhibit resistance; therefore, feeding it to animals will not induce resistance to commonly used antibiotics. Furthermore, it will not transmit resistance to other bacteria in the gut. These results confirm the safety of the strain described in this application.

[0043] Table 3. Sensitivity of Lactobacillus plantarum to antimicrobial agents

[0044] Note: R—resistant; M—moderately sensitive; S—sensitive.

[0045] 1.10 Acid and bile salt resistance tests To evaluate the acid tolerance of *Lactobacillus plantarum*, autoclaved *Lactobacillus* broth was adjusted to pH values ​​of 1, 2, 3, and 4, and bacterial cells (3 × 10⁶ cells / mL) were resuspended in broth at different pH values. 8 To evaluate the bile salt tolerance of *Lactobacillus plantarum*, ox bile salts were added to prepared *Lactobacillus* broth (pH 7.2–7.4) at concentrations of 0.1%, 0.2%, and 0.3%, respectively, and the medium was sterilized at 121 °C for 15 min. The prepared bacterial cells (3 × 10⁻⁶ CFU / mL) were then resuspended in the broth. 8 (CFU / mL), incubate at 37 ℃ for 2 h, and count on plates. The bacterial count in the control group is recorded as NC, and the bacterial count in the experimental group is recorded as NT. Survival rate is calculated as: Survival rate (%) = NT / NC × 100%.

[0046] The results are shown in Tables 4 and 5: At pH 3.0 and a ox bile salt concentration of 0.1%, the survival rate of the target bacteria was no less than 80%. At pH 2.0 and a ox bile salt concentration of 0.2%, the survival rate was higher than 50%. Even under strongly acidic conditions at pH 1.0, the survival rate of the target bacteria remained at 48%. These results indicate that *Lactiplantibacillus plantarum* SMU-KDLP2312 possesses good acid and bile salt tolerance characteristics. These good acid and bile salt tolerance characteristics can help it survive in the digestive tract and exert its probiotic properties normally.

[0047] Table 4. Acid tolerance (survival rate %) of Lactobacillus plantarum under different acidic conditions

[0048] Table 5. Survival rate of Lactobacillus plantarum under different concentrations of bile salts (%)

[0049] 1.11 In vitro cholesterol-lowering capacity assay Cholesterol content was determined using the o-phthalaldehyde method. The bacterial culture concentration was adjusted to 0.5 McFarland turbidity, and 1% (v / v) was inoculated into 5 mL of high-cholesterol Lactobacillus broth (cholesterol concentration 500 μg / mL). The culture was incubated at 37 ℃ for 24 h. The cultured bacterial culture was centrifuged (4000 rpm, 4 ℃, 10 min), and the supernatant was collected. Working solution was prepared according to the instructions of the Shanghai Sangon Biotech Cholesterol Detection Kit. 180 μL of working solution and 20 μL of bacterial supernatant were added to a 96-well plate, thoroughly mixed, and incubated at 37 ℃ for 15 min. OD was then measured. 500nm The cholesterol value was calculated and substituted into the standard curve to calculate the cholesterol concentration, and then the cholesterol degradation rate was calculated. The calculation formula is as follows: Cholesterol degradation rate: Degradation rate (%) = (BS) / B × 100%, B: Cholesterol concentration (μg / mL) in the control group (high-cholesterol Lactobacillus broth culture medium). S: Cholesterol concentration in bacterial supernatant (μg / mL).

[0050] Results: Degradation rate (%) = (499.82 - 297.34) / (499.82) × 100% = 40.51%. This indicates that Lactobacillus plantarum SMU-KDLP2312 has a good in vitro cholesterol-lowering ability.

[0051] 1.12 In vitro adhesion experiment Caco-2 cells (human colorectal adenocarcinoma cells, purchased from the Cell Bank of the Chinese Academy of Sciences) were seeded into 6-well cell culture plates and incubated at 37 ℃ in a 5% CO2 incubator. When the cells reached 80% cell growth, they were washed twice with PBS, and 1 mL of bacterial suspension (1×10⁶ cells / mL) was added. 9 (CFU / mL, denoted as N pairs) and continued to be placed in the incubator for 2 h. After culturing, wash three times with PBS to remove unadhered cells, then lyse with 1 mL of 1% Triton X-100 cell lysis buffer for 20 min. Then perform serial dilution for bacterial plate counting and calculate the number of adherent lactic acid bacteria, denoted as N test. Adhesion index = N pairs / N test × 100.

[0052] Results: Microscopic examination revealed that *Lactobacillus plantarum* adhered well to Caco-2 cells, with an adhesion index of 1 × 10⁻⁶. 9 ) / (11.32×10 7 ) × 100 = 8.83.

[0053] Experimental Example 1 Trial of feeding goats with Lactobacillus plantarum Twenty-eight 3-month-old, clinically healthy Tibetan goats (males, weighing (15.22 ± 0.53) kg) from Kangding City, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, were randomly divided into four groups: a blank control group, a low-dose Lactobacillus plantarum feeding group, a high-dose Lactobacillus plantarum feeding group, and a commercially available lactic acid bacteria feeding group, with seven goats in each group. The control group was fed only a basal diet (lamb concentrate, Sichuan Jingying Agricultural and Animal Husbandry Technology Co., Ltd.). The Lactobacillus plantarum groups were fed the basal diet of the control group, with the low-dose group receiving an additional 150 mg / kg of live bacteria (live bacteria count 1.2 × 10⁻⁶). 9 The high-dose group was supplemented with 300 mg / kg of live bacteria, while the commercially available lactic acid bacteria group was supplemented with Huachu Billion Lactic Acid Bacteria at a rate of 1 g / kg on top of the control group's basal diet. All individuals were kept in the same feeding environment and management conditions. The pre-feeding period was 7 days, and the formal feeding period lasted for 90 days.

[0054] After feeding Tibetan goats with Lactobacillus plantarum in their diet for 90 days, the average daily weight gain of the goats in the high-dose Lactobacillus plantarum feeding group was significantly higher than that of the control group. p <0.05), and the average material weight ratio was also better than the control group ( p <0.05%. Compared with the commercially available lactic acid bacteria group, the average daily feed intake and average feed conversion ratio of the high-dose Lactobacillus plantarum feeding group were significantly better than those of the commercially available group. p <0.05%. The average daily weight gain of the low-dose Lactobacillus plantarum feeding group was significantly higher than that of the control group ( p <0.05). This indicates that adding Lactobacillus plantarum to the diet can improve the growth performance of goats (see Table 6).

[0055] Table 6. Growth performance parameters of sheep in each group

[0056] Note: a, b, c, and d represent differences; the same letter indicates no significant difference, and different letters indicate a significant difference. p <0.05).

[0057] Experiment on feeding rabbits with Lactobacillus plantarum Forty clinically healthy 1-month-old New Zealand White rabbits, weighing (805.86 ± 5.25) g, with half males and half females, were randomly divided into four groups: a blank control group, a low-dose Lactobacillus plantarum feeding group, a high-dose Lactobacillus plantarum feeding group, and a commercially available lactic acid bacteria feeding group, with 10 rabbits in each group. The blank control group was fed only basal rabbit diet (Shandong Yavini Feed Factory), the Lactobacillus plantarum group was fed the same diet as the control group, and the low-dose group was fed 150 mg / kg live bacteria (live bacteria count 1.2 × 10⁻⁶). 8 The high-dose group was supplemented with 300 mg / kg of live bacteria, while the commercially available lactic acid bacteria group was supplemented with Huachu Billion Lactic Acid Bacteria at a rate of 1 g / kg on top of the control group's basal diet. All individuals were kept in the same feeding environment and management conditions. The pre-feeding period was 5 days, and the formal feeding period lasted for 60 days.

[0058] After feeding Tibetan rabbits with Lactobacillus plantarum in their diet for 60 days, the average daily weight gain of the rabbits in the high-dose Lactobacillus plantarum feeding group was significantly higher than that of the control group. p <0.05), and the average material weight ratio was also better than the control group ( p <0.05), the average daily weight gain and average feed conversion ratio of the high-dose Lactobacillus plantarum feeding group were also better than those of the commercially available lactic acid bacteria group ( p <0.05). The average daily weight gain and feed conversion ratio of the low-dose Lactobacillus plantarum feeding group were higher than those of the control group ( p <0.05). This indicates that adding Lactobacillus plantarum to the diet can improve the growth performance of rabbits (see Table 7).

[0059] Table 7 Growth performance parameters of rabbits in each group

[0060] Note: a, b, c, and d represent differences; the same letter indicates no significant difference, and different letters indicate a significant difference. p <0.05).

[0061] Five rabbits were randomly selected from each group for blood collection before the start of the feeding experiment and 60 days after feeding. The blood samples were allowed to stand at room temperature until serum separated, then centrifuged at 3000 rpm for 10 minutes. The supernatant serum was separated and sent to Jiangsu Enzyme Immunoassay Biotechnology Co., Ltd. for lipid analysis. The results of the lipid indicators (Table 8) showed that after 60 days of feeding, the total cholesterol, lipoprotein a, apolipoprotein B, low-density lipoprotein, and triglycerides in the high-dose and low-dose *Lactobacillus plantarum* feeding groups were significantly lower than those in the control group. p <0.05). This indicates that adding Lactobacillus plantarum to the diet can reduce blood lipid levels in rabbits.

[0062] Table 8. Changes in blood lipid levels in rabbits before and after feeding in each group.

[0063] Note: a, b, c, and d represent differences; the same letter indicates no significant difference, and different letters indicate a significant difference. p <0.05).

[0064] The above experiments show that the *Lactobacillus plantarum* SMU-KDLP2312 of this invention can improve the utilization rate of nutrients in feed by forming beneficial bacteria, promoting the growth of fiber-decomposing bacteria and lactic acid-utilizing bacteria, and improving fiber digestibility; it can also maintain intestinal health, reduce the incidence of intestinal diseases, and improve the balance of intestinal microorganisms by competitively inhibiting the colonization of pathogenic bacteria (such as *Escherichia coli*, *Salmonella*, and *Staphylococcus aureus*); and it can reduce serum cholesterol levels by breaking down cholesterol.

[0065] The *Lactobacillus plantarum* SMU-KDLP2312 of this invention possesses a variety of specific binding proteins on its surface, such as adhesins, S-layer proteins, and adhesion-related molecules. These proteins can specifically bind to receptors (glycoproteins, glycolipids, fibronectin, etc.) on the surface of host cells, enabling the bacteria to adhere firmly to the surface of intestinal epithelial cells or the mucus layer.

[0066] The *Lactobacillus plantarum* SMU-KDLP2312 of this invention exhibits non-specific physical interactions, including electrostatic interactions (attraction / repulsion between the charged bacterial surface and the host cell membrane); hydrophobic interactions (binding of hydrophobic molecules on the bacterial surface to hydrophobic regions of the host membrane lipids); and van der Waals forces (short-range weak interactions). Although these interactions are relatively weak individually, when combined with specific proteins, they can significantly enhance adhesion stability.

[0067] The cell wall of *Lactobacillus plantarum* SMU-KDLP2312 of this invention is rich in lipoteichoic acid (LTA) and extracellular polysaccharides (EPS), which can regulate the charge and hydrophobicity of the bacterial surface and affect its adhesion ability. EPS can both help *Lactobacillus* fix itself to the host surface and form a biofilm, enhancing its persistence.

[0068] In vitro adhesion experiments show that the *Lactobacillus plantarum* SMU-KDLP2312 of this invention may achieve efficient adhesion to in vitro cells through multiple mechanisms such as surface adhesion proteins, non-specific physical action, and surface properties. It can competitively occupy the binding sites of host cells, thereby preventing the adhesion and colonization of pathogens, and thus forming a stable beneficial bacterial community to exert a probiotic effect.

[0069] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A strain of *Lactobacillus plantarum* SMU-KDLP2312, characterized in that, Category naming Lactiplantibacillus plantarum The accession number is GDMCC No.66040, and it is deposited at the Guangdong Provincial Center for Microbial Culture Collection on March 21, 2025.

2. A preparation comprising *Lactobacillus plantarum* SMU-KDLP2312 as described in claim 1, characterized in that, The preparations are fermentation broth, fermentation broth supernatant, fermentation broth precipitate, live bacteria and / or dead bacteria.

3. The use of Lactobacillus plantarum SMU-KDLP2312 as described in claim 1 or the preparation as described in claim 2 in the preparation of livestock and poultry feed additives.

4. The application according to claim 3, characterized in that, The livestock and poultry include sheep and rabbits.

5. The application according to claim 3, characterized in that, The feed additives are used to improve the daily weight gain of livestock and poultry and the forage conversion rate.

6. The application according to claim 3, characterized in that, The viable count of *Lactobacillus plantarum* SMU-KDLP2312 in the feed additive is 1×10⁻⁶. 8 ~5×10 9 CFU / ml.

7. The use of Lactobacillus plantarum SMU-KDLP2312 as described in claim 1 or the preparation as described in claim 2 in the preparation of antibacterial agents.

8. The application according to claim 7, characterized in that, The antibacterial agent is used to inhibit any one or more of Escherichia coli, Staphylococcus aureus, or Salmonella.

9. An antibacterial agent comprising Lactobacillus plantarum SMU-KDLP2312 as described in claim 1 or the preparation as described in claim 2.

10. The use of *Lactobacillus plantarum* SMU-KDLP2312 according to claim 1 or the preparation according to claim 2 in the preparation of a drug, characterized in that, The drug is used to reduce serum cholesterol.

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