Lactobacillus plantarum ylw67 with function of reducing uric acid, probiotic composition containing same and application

Abstract

This invention relates to a strain of *Lactobacillus plantarum* with uric acid-lowering function (…). Lactobacillus plantarum YLW67 and its applications: This strain was isolated from red sour soup, a traditional fermented food from Guizhou, and is deposited at CGMCC, accession number No. 37373. This strain exhibits excellent tolerance to the gastrointestinal environment, with a survival rate exceeding 40% after treatment in simulated gastric fluid at pH 3.0 and simulated intestinal fluid at pH 8.0. In vitro experiments show that it can completely degrade inosine and guanosine within 9 hours. Animal experiments have confirmed that it can effectively reduce serum uric acid levels in hyperuricemia model mice. This invention also provides a probiotic composition containing this strain and its preparation method, including steps such as large-scale culture, cell collection, freeze-drying, and formulation. This strain and composition can be used to prepare uric acid-lowering functional foods, health foods, or dietary supplements, and have promising applications in improving hyperuricemia and related metabolic diseases.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a strain of Lactobacillus plantarum YLW67 with uric acid-lowering function, a probiotic composition containing this strain, and its application in the preparation of products that regulate uric acid metabolism. Background Technology

[0002] Hyperuricemia is a metabolic disease caused by purine metabolism disorders, leading to elevated blood uric acid levels. It is the direct biochemical basis for gout and is associated with an increased risk of kidney and cardiovascular diseases. Current clinical interventions mainly involve drugs that inhibit uric acid production (such as allopurinol) or promote uric acid excretion. However, long-term use may be accompanied by adverse reactions such as liver and kidney damage, which is not conducive to the long-term management of the disease.

[0003] In recent years, the role of gut microbiota in host metabolism has received increasing attention. Studies have shown that gut microbes can participate in the breakdown and absorption of exogenous purines, affecting uric acid metabolism pathways. Probiotics, as an effective means of regulating gut microecological balance, have shown potential in the intervention of metabolic diseases. However, the number of publicly available probiotic strains with uric acid-lowering potential is limited, and functional verification mainly focuses on in vitro purine-lowering ability or single in vivo uric acid-lowering effects. Comprehensive data supporting the evaluation of the systemic safety, gastrointestinal fluid tolerance, and long-term application potential of these strains are lacking.

[0004] Guizhou red sour soup is a traditional naturally fermented food rich in lactic acid bacteria. However, existing technologies do not disclose the targeted isolation and screening of lactobacillus strains with clear uric acid-lowering functions and excellent probiotic properties from the Guizhou red sour soup ecosystem. Summary of the Invention

[0005] To address the aforementioned technical problems, the first objective of this invention is to provide a novel strain of *Lactobacillus plantarum* that has a clear origin, high safety, and the ability to lower uric acid and improve related indicators of kidney function, in order to overcome the shortcomings of existing probiotic strains that have limited functionality and require further verification of source safety.

[0006] A second objective of the present invention is to provide a probiotic composition comprising the uric acid-lowering Lactobacillus plantarum YLW67.

[0007] A third object of the present invention is to provide a method for preparing the probiotic composition.

[0008] A fourth object of the present invention is to provide the use of the uric acid-lowering Lactobacillus plantarum YLW67 and its composition in the preparation of products that lower blood uric acid levels.

[0009] To achieve the first objective of this invention, the following technical solution is adopted:

[0010] A strain of *Lactobacillus plantarum* YLW67 with uric acid-lowering function was deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 37373 on January 13, 2026. This *Lactobacillus plantarum* strain YLW67 originated from Guizhou Hongsuantang (a local specialty). Its survival rate after treatment in artificial gastric fluid at pH 3 was greater than 40%, and its survival rate after treatment in artificial intestinal fluid at pH 8 was also greater than 40%.

[0011] In this invention, the *Lactobacillus plantarum* YLW67 strain was observed under a microscope to be Gram-positive, non-spore-forming, rod-shaped bacteria. Under simulated gastrointestinal stress, its survival rate was greater than 40% after treatment in artificial gastric fluid at pH=3 and also greater than 40% after treatment in artificial intestinal fluid at pH=8. This indicates that *Lactobacillus plantarum* YLW67 has the potential to pass through the upper digestive tract in an active state and colonize the intestine.

[0012] In this invention, preferably, the *Lactobacillus plantarum* strain YLW67 exhibits a 100% degradation rate of inosine and guanosine within 9 hours in vitro. Whole-genome sequencing analysis shows that the genome of this *Lactobacillus plantarum* strain YLW67 does not contain any known virulence genes or drug resistance genes, thus possessing an inherent biosafety basis.

[0013] To achieve the second objective of this invention, the following technical solution is adopted:

[0014] A probiotic composition comprising the aforementioned Lactobacillus plantarum YLW67 as an active ingredient.

[0015] Preferably, the viable count of *Lactobacillus plantarum* YLW67 in the composition is 1 × 10⁻⁶. 7 ~1×10¹² CFU / dose unit. In this invention, the dosage range of viable Lactobacillus plantarum YLW67 is determined based on the results of in vitro degradation experiments and in vivo animal model efficacy assessments. This dosage range ensures that sufficient live bacteria are ingested to achieve the expected functions of degrading exogenous purines, regulating intestinal microecology, and reducing blood uric acid levels.

[0016] More preferably, the viable count of the *Lactobacillus plantarum* YLW67 is 1 × 10⁻⁶. 8 ~1×10¹¹CFU / dose unit.

[0017] Preferably, the composition further comprises a freeze-drying protectant and / or other excipients. In this invention, the freeze-drying protectant ensures the viability and stability of Lactobacillus plantarum YLW67 strain during processing (e.g., freeze-drying, tableting) and storage. Preferably, the freeze-drying protectant is one or more of trehalose, sucrose, skim milk powder, and glycerol. These freeze-drying protectants can effectively reduce damage to the cell membrane and proteins of the bacteria during freeze-drying, maintaining the survival rate and metabolic activity of Lactobacillus plantarum YLW67 strain.

[0018] The other excipients include prebiotics and / or pharmaceutical carriers. In this invention, prebiotics can enhance the probiotic effect because they are substances that are not digested by the host but can selectively promote the growth or activity of beneficial bacteria in the intestine. In this invention, the preferred prebiotics are one or more of inulin, fructooligosaccharides, galactooligosaccharides, and resistant dextrin. By adding prebiotics, nutritional support can be provided for the colonization and proliferation of Lactobacillus plantarum YLW67 in the intestine, which may enhance the overall probiotic function of Lactobacillus plantarum YLW67.

[0019] In this invention, the pharmaceutical carrier is a carrier or excipient that is pharmaceutically or food-grade. For example, when preparing solid dosage forms (such as capsules, tablets, granules), microcrystalline cellulose, pregelatinized starch, etc. can be added as fillers or disintegrants. When preparing liquid or semi-solid dosage forms, water, glycerin, edible oil, etc. can be used as carriers, which can assist in the formulation of the final product.

[0020] Preferably, the composition further comprises one or more other probiotic strains selected from the genera *Lactobacillus* or *Bifidobacterium*. In this invention, the other probiotic strains form a compound probiotic preparation with the *Lactobacillus plantarum* YLW67 of this invention, thereby achieving multiple health benefits. The *Lactobacillus* genus can be *Lactobacillus*, *Lactococcus*, *Pediococcus*, or other genera; the *Bifidobacterium* genus can be *Bifidobacterium adolescentis*, *Bifidobacterium longum*, *Bifidobacterium animalis*, or other bacilli.

[0021] To achieve the third objective of this invention, the following technical solution is adopted:

[0022] A method for preparing the probiotic composition described above includes the following steps:

[0023] S1. Expand the culture of the Lactobacillus plantarum YLW67;

[0024] S2. Collect bacterial cells;

[0025] S3. The collected bacterial cells are mixed with the freeze-drying protectant and then freeze-dried to obtain bacterial powder;

[0026] The conditions for freeze-drying are as follows:

[0027] Freezing stage: Freeze the mixture to -40°C to -80°C and keep it at that temperature for 2 to 4 hours to allow the cells to freeze completely;

[0028] Sublimation stage: The sublimation process is carried out under vacuum conditions at low temperature (-20℃ to -40℃) for 10 to 24 hours to ensure that the water in the sample is converted into gaseous water through sublimation.

[0029] Drying stage: Raise the temperature to 10℃ to 25℃ and dry in an environment below atmospheric pressure for 12 to 48 hours to completely remove the remaining moisture in the sample and ensure the long-term stability of the bacteria.

[0030] S4. Mix the bacterial powder with the other excipients to prepare the probiotic composition of the desired dosage form.

[0031] In this invention, in step S1, the preserved or activated Lactobacillus plantarum YLW67 strain is inoculated into MRS liquid medium or other suitable proliferation medium at an inoculation rate of 1%-3% (v / v). The culture conditions are 37℃±1℃, and the culture is carried out under anaerobic or microaerophilic conditions with static or gentle shaking. The culture time is preferably when the bacteria enter the late logarithmic growth phase or the early stationary phase, usually 16 to 48 hours, at which time the bacterial biomass and activity are relatively high.

[0032] In this invention, in step S2, bacterial cells are collected by centrifugation or filtration. Specifically, after the expansion culture of *Lactobacillus plantarum* YLW67 in step S1 is completed, bacterial cells are collected using centrifugation or membrane filtration. The centrifugation conditions are 4-10℃, a centrifugation rate of 5000 rpm, and a time of 5-15 min. The collected bacterial sludge is washed with sterile physiological saline or isotonic solution such as phosphate buffer to remove residual components of the culture medium. This washing step can be repeated 1-3 times to finally obtain high-purity wet *Lactobacillus plantarum* YLW67 bacterial cells.

[0033] In this invention, in step S3, the washed wet cells of *Lactobacillus plantarum* YLW67 are resuspended in a solution containing a freeze-drying protectant to form a uniform bacterial suspension. The bacterial suspension needs to be thoroughly mixed to ensure sufficient contact between the cells and the protectant. Subsequently, the bacterial suspension is transferred to a freeze dryer for primary drying and desorption drying under low-pressure conditions to obtain freeze-dried *Lactobacillus plantarum* YLW67 bacterial powder. Step S3 can improve the stability of the strain under room temperature storage.

[0034] Preferably, between S3 and S4, there is a step of microencapsulating or enteric-coating the bacterial cells. Specifically, this step can further improve the tolerance of the strain to gastric acid and bile salts after oral administration, and ensure that more live bacteria reach the intestine. Microcapsules can be prepared by emulsification, spray drying or extrusion, and the bacterial powder is encapsulated in the microcapsules to form microencapsulated bacterial powder with enteric or sustained-release properties.

[0035] In this invention, in step S4, the obtained *Lactobacillus plantarum* YLW67 bacterial powder (or microencapsulated bacterial powder) is used as the active ingredient and uniformly mixed with other excipients in the formulation under a dry and clean environment. The uniformly mixed material is then formulated into various oral dosage forms using conventional pharmaceutical techniques. For example, it can be made into hard capsules or soft capsules using a capsule filling machine; tablets or chewable tablets using a tablet compression machine; granules using granulation, drying, and sizing equipment; or mixed with a soluble carrier and packaged into solid beverages.

[0036] It should be noted that, regardless of the dosage form, the viable count of *Lactobacillus plantarum* YLW67 per unit of this dosage form must be controlled at 1×10⁻⁶ as mentioned above. 7 Between 1×10¹² CFU / dose unit, the preferred viable count of *Lactobacillus plantarum* YLW67 is 1×10¹² CFU / dose unit. 8 Between 1×10¹¹ CFU / dose unit.

[0037] The beneficial effects of this invention are:

[0038] This invention successfully isolated a new strain of Lactobacillus plantarum YLW67 from Guizhou red sour soup, a traditional fermented food. This strain has good tolerance to gastrointestinal fluid and high efficiency in degrading inosine and guanosine, and showed good uric acid-lowering effects in animal experiments.

[0039] The preparation method of the probiotic composition using this bacterium as an active ingredient is simple, and the dosage form of the probiotic composition is diverse, making it suitable for food, health food and other products with uric acid-lowering function that are safe and suitable for long-term consumption. Attached Figure Description

[0040] Figure 1 Flowchart of bacterial classification for Guizhou Red Sour Soup culture group;

[0041] Figure 2 A graph showing the percentage of different bacterial strains in Guizhou red sour soup;

[0042] Figure 3 The complete genome of Lactobacillus plantarum YLW67;

[0043] Figure 4 High-performance liquid chromatography (HPLC) peak chromatogram of a mixed standard solution of inosine and guanosine;

[0044] Figure 5 This is the standard curve of inosine by high performance liquid chromatography (HPLC).

[0045] Figure 6 This is a high-performance liquid chromatography (HPLC) standard curve for guanosine.

[0046] Figure 7 The growth curve and pH change of Lactobacillus plantarum YLW67 after 48 hours of culture in MRS liquid medium;

[0047] Figure 8 The image shows the results of the hemolysis test for Lactobacillus plantarum YLW67.

[0048] Figure 9 This is a schematic diagram of the antibiotic susceptibility test for Lactobacillus plantarum YLW67.

[0049] Figure 10 Flowchart for the construction and intervention experiment of a mouse model of hyperuricemia;

[0050] Figure 11 This is a graph showing the change in the average body weight of mice in each group over the weeks during the experiment.

[0051] Figure 12 The bar chart shows the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in each group of mice at the end of the experiment.

[0052] Figure 13 The bar chart shows the serum levels of uric acid (UA), blood urea nitrogen (BUN), and creatinine (Cr) in each group of mice at the end of the experiment. Detailed Implementation

[0053] The invention can be further understood through the specific embodiments given below, but they are not intended to limit the invention.

[0054] Lactobacillus plantarum YLW67 was deposited on January 13, 2026 at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 37373. The deposit address is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0055] Example 1

[0056] Isolation, screening and identification of Lactobacillus plantarum YLW67

[0057] (1) Sample processing and strain isolation

[0058] according to Figure 1 Follow the flowchart shown below for the bacterial classification of the Guizhou Red Sour Soup culture group.

[0059] Six samples of Guizhou red sour soup were taken and serially diluted using sterile phosphate buffer under aseptic conditions. Appropriately diluted bacterial cultures were then spread onto MRS solid agar plates and incubated at 37°C for 48 hours. Single colonies exhibiting morphological and color differences were picked from the plates and subjected to multiple streak purification processes to obtain pure cultures.

[0060] (2) Preliminary analysis of microbial distribution

[0061] A total of 600 bacterial strains isolated from four Guizhou red sour soup samples were identified, and their relative abundance distribution at the species level is as follows: Figure 2 As shown.

[0062] according to Figure 2 The results showed that *Lactobacillus* was the most dominant genus, with *Lactobacillus paracasei* accounting for the largest proportion. Further molecular biological identification confirmed that it included 39 strains of *Lactobacillus plantarum*.

[0063] (3) Screening for tolerance to gastrointestinal fluids

[0064] Artificial gastric fluid (containing pepsin) with pH 3.0 and artificial intestinal fluid (containing pancreatic enzymes and bile salts) with pH 8.0 were prepared. The activated cells of 39 candidate *Lactobacillus plantarum* strains were washed and resuspended, then mixed with the artificial gastric and intestinal fluids respectively. After treatment at 37°C for a period of time, the survival rate was calculated by plate counting to determine the ratio of viable bacteria after treatment to viable bacteria before treatment. The screening criterion was a survival rate greater than 40%. Specific results are shown in Table 1. A total of 12 strains showed a survival rate >40% in the artificial gastric fluid, and 26 strains showed a survival rate >40% in the artificial intestinal fluid. Finally, 31 *Lactobacillus plantarum* strains with acceptable tolerance were selected for further analysis.

[0065] Table 1 Survival rates of artificial gastric and intestinal fluids

[0066]

[0067] (4) Whole genome sequencing and safety analysis

[0068] Whole genome sequencing was performed on the above 31 strains of Lactobacillus plantarum.

[0069] Average nucleotide identity analysis based on sequencing data confirmed that all strains were Lactobacillus plantarum.

[0070] Further comparative analysis using virulence factor databases and antibiotic resistance gene databases showed that no known virulence genes or antibiotic resistance genes were detected in any of the sequenced strains, including *Lactobacillus plantarum* YLW67. The whole genome map of *Lactobacillus plantarum* YLW67 is shown below. Figure 3 As shown, Figure 3 The results showed characteristics such as genome size, GC content, and distribution of coding genes.

[0071] (5) Screening for purine nucleoside degradation capacity

[0072] ① Preparation of standard curve

[0073] Weigh 500 mg each of inosine and guanosine standards, dissolve them in 0.01 mol / L potassium phosphate buffer, and dilute to 1000 mL to prepare a mixed stock solution with a concentration of 500 μg / mL. Serially dilute the stock solution to obtain a series of standard solutions of different concentrations, filter them through a 0.22 μm filter membrane, and then perform HPLC analysis.

[0074] A typical HPLC chromatogram of a mixed standard solution of inosine and guanosine is shown below. Figure 4 As shown, a standard curve was plotted with the standard concentration as the x-axis (X) and the chromatographic peak area as the y-axis (Y).

[0075] The standard curve of inosine is as follows: Figure 5 As shown, by Figure 5 The results show that the linear regression equation and correlation coefficient indicate a good linear relationship;

[0076] The standard curve of guanosine is as follows Figure 6 As shown, by Figure 6 The results show that the linear regression equation and correlation coefficient also indicate a good linear relationship.

[0077] ② Degradation experiment

[0078] After activating the candidate strains (including YLW67), the bacterial cells were collected and resuspended in PBS, and the OD600 was adjusted to 1.0. 2 mL of the bacterial suspension was mixed with 2 mL of a 500 μg / mL inosine-guanosine mixed solution (prepared with potassium phosphate buffer) in a centrifuge tube and incubated anaerobically at 37°C. Samples were taken after 9 and 12 hours of incubation, immediately centrifuged, and the supernatant was collected. The reaction was terminated by adding perchloric acid, filtered, and analyzed by HPLC. The remaining inosine and guanosine concentrations in the solution were calculated based on the standard curve, and the degradation rate was calculated using the formula: Degradation rate (%) = (Initial concentration - Residual concentration) / Initial concentration × 100%.

[0079] ③ Screening results

[0080] In the 12-hour degradation experiment, 13 strains of *Lactobacillus plantarum* achieved degradation rates of over 80% for inosine and guanosine. The specific results are shown in Table 2.

[0081] Table 2. Degradation results of inosine and guanosine after 12 hours

[0082]

[0083] The results of the 9-hour degradation experiment are shown in Table 3. As can be seen from the results in Table 3, Lactobacillus plantarum YLW67 achieved complete degradation of inosine and guanosine within 9 hours, with a degradation rate of 100%, which is the best performance.

[0084] Table 3. Degradation results of inosine and guanosine after 9 hours

[0085]

[0086] (6) Characterization of probiotic properties

[0087] ① Growth and acid production curves

[0088] Lactobacillus plantarum YLW67 was inoculated into MRS liquid medium and incubated statically at 37°C for 48 hours. Samples were taken at regular intervals to measure the OD600 and pH values. The results are as follows: Figure 7 As shown, Figure 7 It contains two sub-graphs: a growth curve and a pH change curve, by Figure 7 The results showed that the growth curve indicated that the strain rapidly entered the logarithmic growth phase within 0-24 hours; the pH change curve showed that the pH value of the culture medium decreased rapidly in the early stage of culture and eventually stabilized below 4.0, indicating that it has a strong acid production capacity.

[0089] ② Hemolysis test

[0090] Lactobacillus plantarum YLW67 was inoculated onto sheep blood agar plates and anaerobically cultured at 37°C for 24-48 hours. Results were observed as follows: Figure 8 As shown, by Figure 8 The results showed that mild hemolysis occurred around the colony, and the hemolytic activity was low compared to other pathogens, indicating that it may have a good protective effect on the safety of host cells.

[0091] ③ Antibiotic susceptibility testing

[0092] The minimum inhibitory concentrations (MICs) of Lactobacillus plantarum YLW67 against six common antibiotics were determined. The six common antibiotics were: penicillin G, gentamicin, erythromycin, clindamycin, cefuroxime, and linezolid.

[0093] The results of the antibiotic susceptibility test are shown in Table 4. As can be seen from the results in Table 4, Lactobacillus plantarum YLW67 was sensitive (S) to all the tested antibiotics.

[0094] A schematic diagram of antibiotic susceptibility testing is shown below. Figure 9 As shown.

[0095] Table 4. Results of antibiotic susceptibility testing for Lactobacillus plantarum YLW67

[0096]

[0097] Based on the above test and evaluation results, the *Lactobacillus plantarum* YLW67 of the present invention exhibits outstanding gastrointestinal fluid tolerance, excellent purine nucleoside degradation ability, good growth characteristics, and reliable safety. Therefore, *Lactobacillus plantarum* YLW67 of the present invention can be used as a candidate probiotic for lowering uric acid for further animal evaluation.

[0098] Example 2

[0099] Evaluation of the in vivo uric acid-lowering function of Lactobacillus plantarum YLW67

[0100] (1) Animal experimental design

[0101] according to Figure 10 The experiment was conducted according to the procedure shown.

[0102] Forty 8-week-old SPF-grade male C57BL / 6 mice were selected and, after one week of acclimatization, were randomly divided into four groups: blank control group (Control), hyperuricemia model group (HUA), Lactobacillus plantarum YLW67 intervention group (YLW67), and positive control allopurinol group (ALLO), with 10 mice in each group.

[0103] (2) Modeling and Intervention

[0104] The control group was given 0.2 mL of 0.5% CMC-Na solution by gavage daily, followed by an intraperitoneal injection of 0.2 mL of 0.5% CMC-Na solution one hour later.

[0105] The other three groups were administered 0.2 mL of 500 mg / kg hypoxanthine (HY, dissolved in 0.5% CMC-Na) daily by gavage to increase the substrate for uric acid production. One hour later, they were injected intraperitoneally with 0.2 mL of 500 mg / kg potassium oxonate (PO, dissolved in 0.5% CMC-Na) to inhibit uricase activity, thus establishing a hyperuricemia model. From the first day of modeling, the YLW67 group was administered 0.2 mL of bacterial suspension containing 1×10^9 CFU of Lactobacillus plantarum YLW67 daily by gavage; the ALLO group was injected intraperitoneally daily with 5 mg / kg allopurinol solution; and the HUA and Control groups were administered an equal volume of the solvent by gavage. The experiment lasted for 6 weeks.

[0106] (3) Sample collection and indicator detection

[0107] At the end of the experiment, one hour after the last intervention, blood was collected from the orbital fossa and serum was separated. Serum uric acid (UA), creatinine (Cr), blood urea nitrogen (BUN), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were measured using biochemical reagent kits. Mouse body weight was recorded weekly.

[0108] (4) Experimental results and analysis

[0109] ① Weight changes

[0110] The curves showing the changes in body weight of mice in each group during the experiment are as follows: Figure 11 As shown, by Figure 11 The results showed that the body weight of each group increased steadily with each week, and no statistically significant differences were observed between the groups, indicating that the experimental intervention did not affect the normal growth and development of the mice.

[0111] ② Liver function indicators

[0112] Serum ALT and AST levels, as Figure 12 As shown, by Figure 12 The results showed that, compared with the blank group, the ALT and AST levels in the model group (HUA) increased, while the ALT and AST levels in the Lactobacillus plantarum YLW67 intervention group (YLW67) decreased compared with the model group and were similar to those in the positive drug group (ALLO), indicating that YLW67 intervention did not cause liver damage.

[0113] ③ Blood uric acid and related indicators of kidney function

[0114] Serum UA, BUN and CREA levels as follows Figure 13 As shown, by Figure 13 The results showed that the serum UA level in the model group (HUA) was significantly higher than that in the blank group, indicating that the hyperuricemia model was successfully established. The intervention of Lactobacillus plantarum YLW67 could significantly reduce the serum UA level in the model mice, and its effect was comparable to that of the positive control allopurinol group (ALLO). In terms of renal function-related indicators, the levels of BUN and CREA in the model group showed an increasing trend, while the levels of BUN and CREA in the YLW67 intervention group were lower than those in the model group.

[0115] In conclusion, in a mouse model of hyperuricemia, oral administration of Lactobacillus plantarum YLW67 effectively reduced elevated serum uric acid levels without adversely affecting liver function or body weight, and showed a positive regulatory trend on renal function-related indicators, indicating its efficacy and safety in lowering uric acid in vivo.

[0116] Example 3

[0117] The preparation of the probiotic composition includes the following steps:

[0118] S1, Strain expansion culture

[0119] The preserved Lactobacillus plantarum YLW67 was inoculated into MRS liquid medium and activated by static anaerobic culture at 37°C for 18-24 hours. The activated bacterial solution was then transferred to fresh MRS liquid medium at an inoculation rate of 1%-2% and cultured at 37°C until it entered the early stage of the stationary phase.

[0120] S2, Bacterial Collection

[0121] Centrifuge the expanded bacterial culture at 4°C and 5000 rpm for 10 minutes, discard the supernatant, and obtain bacterial sludge. Gently resuspend and wash the bacterial sludge twice with pre-cooled sterile physiological saline or phosphate-buffered saline (PBS) to remove residual culture medium components.

[0122] S3, freeze drying

[0123] The washed bacterial sludge was resuspended in a sterile solution containing a lyophilization protectant. The lyophilization protectant formulation was 10% (w / v) skim milk powder and 5% (w / v) trehalose, ensuring uniform dispersion of the bacteria in the protectant. The bacterial suspension was dispensed into sterile lyophilization bottles and frozen in an ultra-low temperature freezer at -40°C to -80°C for 2-4 hours. The samples were then transferred to a freeze dryer for primary drying and desorption drying to obtain *Lactobacillus plantarum* YLW67 lyophilized bacterial powder. Plate count analysis showed that the viable count of the lyophilized bacterial powder was not less than 1 × 10⁻⁶. 11 CFU / g.

[0124] The specific process of transferring the sample to a freeze dryer for primary drying and analytical drying is as follows:

[0125] Sublimation stage: Sublimation is carried out under vacuum conditions at a low temperature of -20℃ to -40℃ for 10-24 hours to ensure that the water in the sample is converted into gaseous water through sublimation;

[0126] Drying stage: Raise the temperature to 10℃ to 25℃ and dry in an environment below atmospheric pressure for 12-48 hours to completely remove the remaining moisture from the sample and ensure the long-term stability of the bacteria.

[0127] S4, Formulation

[0128] S41, Probiotic Capsules

[0129] The freeze-dried bacterial powder, prebiotic (resistant dextrin), and filler (microcrystalline cellulose) were thoroughly mixed in a mixer at a mass ratio of 30:50:20. The mixed powder was then filled into No. 1 empty capsules using a capsule filling machine to obtain the probiotic capsule product. Each capsule contains approximately 300mg of contents, with a viable count of at least 3 × 10⁻⁶ Lactobacillus plantarum YLW67. 9 CFU / g.

[0130] S42, Probiotic Solid Beverage

[0131] Freeze-dried bacterial culture powder is mixed with maltodextrin, fructooligosaccharides, citric acid, and natural fruit powder flavoring agents in a certain proportion. After granulation, drying, and sizing, the mixture is packaged into aluminum foil bags to produce solid beverage granules. Each bag (approximately 5g) contains no less than 5 × 10⁻⁶ live Lactobacillus plantarum YLW67 bacteria. 9 CFU / g.

[0132] Example 4

[0133] Application of probiotic compositions

[0134] The probiotic capsules prepared in Example 3 were applied to individuals requiring adjunctive management of hyperuricemia. The recommended dosage is one capsule twice daily, after meals. The product's adjunctive regulatory effect was evaluated by regularly monitoring the users' serum uric acid levels.

[0135] The above description is merely an embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A strain of *Lactobacillus plantarum* YLW67 with uric acid-lowering function, characterized in that, The *Lactobacillus plantarum* YLW67 strain is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 37373 and a deposit date of January 13, 2026. This strain was isolated from Guizhou Hongsuantang and exhibits the following characteristics: a survival rate greater than 40% after treatment in simulated gastric fluid at pH 3.0 for 3 hours and a survival rate greater than 40% after treatment in simulated intestinal fluid at pH 8.0 for 4 hours.

2. The *Lactobacillus plantarum* YLW67 according to claim 1, characterized in that, The strain achieved a 100% degradation rate of inosine and guanosine in vitro within 9 hours.

3. A probiotic composition, characterized in that, The composition comprises the uric acid-lowering Lactobacillus plantarum YLW67 as the active ingredient as described in claim 1 or 2.

4. The probiotic composition according to claim 3, characterized in that, The viable count of *Lactobacillus plantarum* YLW67 in the composition is 1 × 10⁻⁶. 7 ~1×10¹²CFU / dose unit.

5. The probiotic composition according to claim 4, characterized in that, The viable count of the *Lactobacillus plantarum* YLW67 was 1 × 10⁻⁶. 8 ~1×10¹¹CFU / dose unit.

6. The probiotic composition according to any one of claims 3-5, characterized in that, The composition further comprises a lyophilization protectant and / or other excipients, the other excipients comprising prebiotics and / or pharmaceutical carriers; the lyophilization protectant is one or more selected from trehalose, sucrose, skim milk powder and glycerin; the prebiotic is one or more selected from inulin, fructooligosaccharides, galactooligosaccharides and resistant dextrin.

7. The probiotic composition according to claim 6, characterized in that, The composition also contains one or more other probiotic strains selected from the genera *Lactobacillus* or *Bifidobacterium*.

8. A method for preparing a probiotic composition according to any one of claims 3-7, characterized in that, Includes the following steps: S1. Expand the culture of the Lactobacillus plantarum YLW67; S2. Collect bacterial cells; S3. The collected bacterial cells are mixed with the freeze-drying protectant and then freeze-dried to obtain bacterial powder; S4. Mix the bacterial powder with the other excipients to prepare the probiotic composition of the desired dosage form.

9. The method for preparing the probiotic composition according to claim 8, characterized in that, Between S3 and S4, there is also a step of microencapsulating or enteric-coating the bacterial cells.

10. The use of a uric acid-lowering Lactobacillus plantarum YLW67 as described in claim 1 or 2, or a probiotic composition as described in any one of claims 3-7, in the preparation of a product for lowering blood uric acid levels.

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