Paracaseicillus parracasei with function of reducing uric acid and application thereof

Abstract

The application discloses a paracasei with a function of reducing uric acid and application thereof, and the paracasei is named as paracasei (C125) and is preserved in the China Center for Type Culture Collection on February 17, 2025, with a preservation number of CCTCC M 2025231 and a preservation address of Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province. Lacticaseibacillus paracasei The fermentation supernatant of the paracasei has the functions of reducing uric acid, resisting oxidation and inhibiting bacteria, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of microbiology, and more particularly to a strain of Lactobacillus paracasei with uric acid-lowering function and its applications. Background Technology

[0002] Purines are an important component of nucleic acids. Abnormal purine metabolism, especially excessive purine production or metabolic disorders, can lead to diseases such as hyperuricemia (HUA) and gout, seriously threatening human health. Currently, the main methods for preventing and treating hyperuricemia are dietary regulation and drug therapy. However, dietary regulation can lead to a decline in quality of life as people lose the enjoyment of food. Drugs for treating HUA are limited (allopurinol, probenecid, benzbromarone, etc.) and have toxic side effects and low tolerability.

[0003] Lactic acid bacteria, a class of multifunctional probiotics widely used in the food and health industries, play a role in breaking down purine compounds and preventing and alleviating hyperuricemia, and have potential applications in developing food products specifically for people with hyperuricemia. Therefore, screening lactic acid bacteria with potential uric acid-lowering functions is of great significance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multifunctional *Lactobacillus paracasei* and its applications. The *Lactobacillus paracasei* provided by this invention possesses functions of degrading uric acid, inhibiting bacteria, and providing antioxidant effects.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a *Lactobacillus paracasei* with uric acid-lowering function (… Lacticaseibacillus paracasei The *Lactobacillus paracasei* was named *Lactobacillus paracasei* C125. Lacticaseibacillus paracasei C125 was deposited on February 17, 2025, at the China Center for Type Culture Collection (CCTCC) with accession number M2025231. The deposit address is: Wuhan University, No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0006] The present invention also provides the application of the aforementioned *Lactobacillus paracasei* in the preparation of uric acid-lowering products.

[0007] The present invention also provides the application of the aforementioned *Lactobacillus paracasei* in the preparation of antibacterial agents, wherein antibacterial refers to the inhibition of the activity of *Escherichia coli*, *Salmonella*, or *Staphylococcus aureus*; the antibacterial application is for non-therapeutic purposes.

[0008] The present invention also provides the use of the aforementioned *Lactobacillus paracasei* in the preparation of antioxidants.

[0009] This invention isolated a strain of *Lactobacillus paracasei* C125 from *Zao La Zi* (a type of wild chili) in Midu County, Dali Prefecture. The fermentation supernatant of strain C125 significantly inhibited xanthine oxidase activity, achieving an inhibition rate of 83.26%; the nucleoside degradation rate reached 100%, indicating potential uric acid-lowering activity. Strain C125 contains 30 substances that directly inhibit XOD activity, thus inhibiting uric acid synthesis; strain C125 also possesses 8 genes related to purine metabolism, enabling the degradation of purines and uric acid. Furthermore, the fermentation supernatant of strain C125 also exhibits good antibacterial and antioxidant properties.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The *Lactobacillus paracasei* C125 provided by the present invention has good inhibitory activity against xanthine oxidase, which is used to inhibit the synthesis of uric acid, thereby reducing uric acid levels. Strain C125 is acid-resistant, bile-resistant, and has good gastrointestinal tolerance, and possesses strong adhesion ability; strain C125 also exhibits strong antioxidant activity and broad-spectrum antibacterial activity.

[0011] The microbial preservation information is as follows:

[0012] Classification and nomenclature: Lactobacillus paracasei C125 Lacticaseibacillus paracasei C125;

[0013] Accession number: CCTCC NO: M2025231;

[0014] Preservation period: February 17, 2025;

[0015] Deposit location: China Center for Type Culture Collection;

[0016] The address for storage is: No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province, inside the campus of Wuhan University. Attached Figure Description

[0017] Figure 1 The colony morphology of Lactobacillus paracasei C125;

[0018] Figure 2 The inhibition rate of xanthine oxidase XOD by Lactobacillus paracasei C125;

[0019] Figure 3 Chromatographic data and curves of nucleoside degradation by *Lactobacillus paracasei* C125; A is a liquid chromatogram; B is a standard curve for guanosine; C is a standard curve for inosine; D is a chromatogram of the degradation of inosine and guanosine by C125.

[0020] Figure 4 Antioxidant activity of *Lactobacillus paracasei* C125; A represents DPPH radical scavenging rate (%), B represents ABTS radical scavenging rate (%), and C represents hydroxyl radical scavenging rate (%).

[0021] Figure 5 Diagram showing the hemolytic activity of Lactobacillus paracasei C125; A represents Staphylococcus aureus ATCC25923; B represents Lactobacillus paracasei C125.

[0022] Figure 6 The growth curve of Lactobacillus paracasei C125;

[0023] Figure 7 A heatmap of metabolites from Lactobacillus paracasei C125 that can directly inhibit the degradation of purines by xanthine oxidase. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below with reference to specific embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0025] The indicator bacteria used in the following examples are: Staphylococcus aureus ( Staphyloccocus aureus ATCC25923) was purchased from the US Model Cell / Strain Collection Center; Multidrug-resistant Staphylococcus aureus ( Staphyloccocus aureus DC.RB-015 was screened by Yunnan Agricultural University (Reference: Prabakusuma, AS; Zhu, J.; Shi, Y.; Ma, Q.; Zhao, Q.; Yang, Z.; Xu, Y. Prevalence and antimicrobialresistance profiling of Staphylococcus aureus isolated from traditional cheese in Yunnan, China. 3 Biotech 2021, 12, 1.). This multidrug-resistant Staphylococcus aureus showed resistance to penicillin, oxacillin, erythromycin, clindamycin, tetracycline, and cefoxitin.

[0026] Escherichia coli ( Escherichia coli CICC10389 was purchased from the China Industrial Microbial Culture Collection Center.

[0027] salmonella( Salmonella WX29 was screened by Yunnan Agricultural University and identified as Salmonella by 16S rDNA gene sequence analysis.

[0028] Example 1 Isolation and purification of bacterial strains

[0029] Pickled chili peppers from Midu County, Dali Prefecture, were used as samples. 10g of the sample was added to 90mL of selective MRS broth, shaken well, and incubated at 37℃ for 24h. The enriched sample was then serially diluted with sterile physiological saline (10-10). -6 Up to 10 -8 ), take 200 μL of the diluted solution and spread it on MRS solid medium, and incubate at 37°C for 24 h. Select colonies from the solid medium and repeatedly streak them on MRS solid medium for purification until the colony morphology of the strains is consistent. Pick a single colony C125 and inoculate it in MRS liquid medium and incubate at 37°C for 24 h for preservation and identification.

[0030] Morphological characteristics of fungal strains

[0031] The C125 strain, preserved at -80℃, was activated in MRS solid medium and incubated statically at 37℃ for 24 h. Colony morphology was then observed. Results are as follows: Figure 1 As shown.

[0032] like Figure 1 As shown, after culturing strain C125 on MRS solid medium for 24 hours, the colony morphology is milky white, opaque, smooth, with neat edges and obvious protrusions.

[0033] Molecular biological identification of bacterial strains

[0034] 16S rDNA gene sequencing

[0035] Using primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3' as shown in SEQ ID No. 1) and 1492R (5'-TACGGCTACCTTGTTACGACTT-3' as shown in SEQ ID No. 2), the 16S rRNA sequence was amplified using DNA from strain C125 as a template, as shown in SEQ ID No. 3, and sent to Shanghai Meiji Biotechnology Co., Ltd. for sequencing. Homology comparison of the sequencing results using the NT database BLAST identified the strain as *Lactobacillus paracasei*, and it was named *Lactobacillus paracasei* C125. Lacticaseibacillus paracasei C125 was deposited at the China Center for Type Culture Collection.

[0036] Example 2: Activity determination of Lactobacillus paracasei C125

[0037] Determination of xanthine oxidase (XOD) inhibition rate

[0038] Prepare a 1.0 mL enzymatic reaction system: Add 560 μL of pH 7.5 phosphate buffer, 40 μL of fermentation broth supernatant / extracellular metabolites / cell contents, and 200 μL of XOD solution at 4°C to the system sequentially. Mix thoroughly and incubate at 37°C for 10 min to allow the solution to reach equilibrium. Then add 200 μL of xanthine solution pre-warmed at 37°C to initiate the reaction. Use UV spectrophotometer kinetic software to record the change in absorbance at 295 nm wavelength over a certain period of time, recording the results every 30 s for a total of 6 min. Plot the reaction time on the x-axis and absorbance on the y-axis to obtain the slope of the curve, i.e., the reaction rate As. Use the same volume of blank MRS medium / phosphate buffer solution as a blank control to calculate its enzymatic reaction rate Ac. The relative inhibition rate of XOD is calculated as follows:

[0039] The relative inhibition rate of XOD = ×100%

[0040] Inhibiting xanthine oxidase can lower uric acid levels and alleviate hyperuricemia. Results are as follows: Figure 2 As shown, with allopurinol as a positive control, allopurinol inhibited XOD by 88%. The fermentation supernatant of *Lactobacillus paracasei* C125 showed an XOD inhibition rate of 83.26%, the extracellular metabolite showed an XOD inhibition rate of 9.53%, and the cell contents showed an XOD inhibition rate of 14.84%. These results indicate that the fermentation supernatant of *Lactobacillus paracasei* C125 exhibits good xanthine oxidase inhibitory activity, and both the extracellular metabolites and cell contents possess certain xanthine oxidase inhibitory activity. Therefore, strain C125 has a good ability to inhibit XOD activity.

[0041] Determination of nucleoside degradation capacity

[0042] Lactic acid bacteria can competitively reduce the absorption of nucleosides by the intestinal epithelium by degrading or absorbing nucleosides, thereby reducing uric acid production. An appropriate amount of activated second-generation bacterial culture was centrifuged at 4500 r / min for 10 min at 4 ℃, the supernatant was discarded, and the bacterial cells were collected. The lactic acid bacteria were washed twice with 0.85% sterile physiological saline, and the OD600 of the bacterial culture was adjusted to 1.5 with physiological saline. After washing, 750 µL of inosine-guanosine-neutral potassium phosphate solution was added, and the culture was incubated at 120 r / min for 1 h at 37 ℃. After incubation, the obtained bacterial culture was centrifuged at 4500 r / min for 10 min at 4 ℃. The obtained supernatant was mixed with a reaction terminator (0.1 mol / L HClO4) at a volume ratio of 9:1, filtered through a 0.22 µm filter membrane, and 5 µL was absorbed for HPLC detection. The residual inosine and guanosine content in the supernatant was calculated using the standard curve method, and then the degradation rate of inosine or guanosine by strain C125 was calculated. The calculation formula is as follows: A = (C1 - C2) / C1 × 100%;

[0043] In the formula: A is the degradation rate, C1 is the initial amount of guanosine (inosine) (g / L), and C2 is the residual amount of guanosine (inosine) (g / L).

[0044] The chromatogram of nucleoside degradation by Lactobacillus paracasei C125 is shown below. Figure 3 As shown, Figure 3 Under these chromatographic conditions, the retention time of inosine A was 7.324 min, and the retention time of guanosine was 8.563 min. For example... Figure 3 The standard curve for β-guanosine is f(x) = 3.20145e+0.06*x + 172204 (R 2 =0.9998693); for example Figure 3 The standard curve for C-inosine is f(x) = 2.71893e+0.06*x + 102492 (R 2 =0.9999556). And Figure 3 Chromatogram D shows the degradation of inosine and guanosine by strain C125, with both guanosine and inosine showing a 100% degradation rate. These results further confirm the uric acid-lowering potential of strain C125.

[0045] Determination of antibacterial activity by perforation method

[0046] The experiment was conducted using the perforation method to measure the antibacterial activity of *Lactobacillus paracasei* C125 against *Staphylococcus aureus* ATCC25923, *Staphylococcus aureus* DC.RB-015, *Escherichia coli* CICC10389, and *Salmonella* WX29. An appropriate amount of activated second-generation strain C125 was centrifuged at 4500 rpm for 5 min at 4℃. The supernatant was collected and concentrated 10-fold by rotary evaporation. Approximately 20-30 mL of LB solid medium was poured into a sterile plate. After solidification, 180 μL of indicator bacteria was rapidly and evenly spread on the plate. Perforations were made using a sterile perforator, and the plate was removed with tweezers. 200 μL of the concentrated sample solution was added, and the plate was incubated at 37℃ for 10 h. The antibacterial activity was then observed and measured. Unconcentrated sample solution and uninoculated MRS liquid medium concentrate served as blank controls. The size of the inhibition zone was used to determine the strength of the antibacterial activity of the test sample solution.

[0047] Inhibition diameter (mm) = Directly measured circle diameter

[0048] Antibacterial activity of Lactobacillus paracasei C125

[0049] The results showed that the inhibition zones of *Lactobacillus paracasei* C125 were as follows: ① Against *S. aureus* ATCC25923: unconcentrated 20.25±0.19 mm, 10-fold concentrated 35.21±0.55 mm; ② Against *S. aureus* DC.RB015 (multidrug-resistant *S. aureus* DC.RB015): unconcentrated 16.66±0.29 mm, 10-fold concentrated 30.49±0.34 mm; ③ Against *E. coli* CICC10389: unconcentrated 16.77±0.18 mm, 10-fold concentrated 26.47±0.16 mm; ④ Against *Salmonella* WX29 (Salmonella WX29): Unconcentrated 20.03±0.29 mm, 10-fold concentrated 32.89±0.68 mm. The results indicate that strain C125 possesses good broad-spectrum antibacterial activity.

[0050] Table 1. Size of the inhibition zone in C125 fermentation broth

[0051]

[0052] Note: "—" indicates no inhibition zone, and *** indicates extremely significant difference (p<0.001). In this invention, the indicator bacteria concentration for the inhibition experiment was fixed at 10... 6 CFU / mL.

[0053] Antioxidant activity of Lactobacillus paracasei C125

[0054] The activated *Lactobacillus paracasei* C125 bacterial suspension was centrifuged at 4℃ and 4000 rpm for 15 min to obtain the fermentation supernatant. The supernatant was filtered through a 0.22 μm microporous membrane to obtain the fermentation supernatant components. The scavenging capacity of free radicals such as DPPH, ABTS, and hydroxyl radicals in the supernatant components was determined.

[0055] The results are as follows Figure 4 As shown in the figure, compared with vitamin C, *Lactobacillus paracasei* C125 exhibited strong scavenging abilities against DPPH, ABTS, and hydroxyl radicals. Specifically, the scavenging rate for DPPH radicals was 88.20%, for ABTS radicals 92.17%, and for hydroxyl radicals 82.51%. These results indicate that C125 possesses good antioxidant activity.

[0056] Safety of Lactobacillus paracasei C125

[0057] (1) Hemolytic activity: The Food and Agriculture Organization of the United Nations stipulates that probiotics used in food must not be hemolytic. Hemolytic strains can lyse cells, causing intrinsic defects in red blood cells and antigen-antibody reactions, leading to sepsis. Therefore, hemolytic activity is an important indicator for screening probiotics in vitro. Lactobacillus paracasei C125 was streaked on Columbia blood agar medium and incubated at 37°C for 48 hours. Staphylococcus aureus ATCC25923 was used as a positive control. The presence of hemolytic zones around the bacteria was observed to determine whether the strain was hemolytic.

[0058] like Figure 5 As shown, transparent hemolytic zones appeared around the colonies of Staphylococcus aureus in the control group, while no hemolytic zones appeared around the colonies of Lactobacillus paracasei C125, indicating that Lactobacillus paracasei C125 is not hemolytic and is a safe strain.

[0059] (2) Antibiotic resistance: Antibiotic resistance was used to assess the safety of lactic acid bacteria applications. 200 μL of strain C125 bacterial suspension was spread on MRS solid plates. Three antimicrobial susceptibility test discs for the same antibiotic were evenly placed on each plate, including 20 antibiotics such as penicillin, chloramphenicol, ciprofloxacin, erythromycin, tetracycline, gentamicin, ceftriaxone, and ampicillin. The plates were incubated at 37°C for 24 h, and the diameter of the inhibition zone was measured using calipers. The results were interpreted using the NCCLS antimicrobial susceptibility standard.

[0060] Table 2 shows the susceptibility results of *Lactobacillus paracasei* C125 to 20 common antibiotics. The results indicate that strain C125 is sensitive to penicillin, piperacillin, tetracycline, minocycline, doxycycline, ceftazidime, cefuroxime sodium, cefazolin, and erythromycin; resistant to ampicillin, kanamycin, gentamicin, streptomycin, amikacin, cefoperazone, cephalexin, polymyxin B, and vancomycin; and moderately sensitive to ceftriaxone and lincomycin. Therefore, this further demonstrates that C125 possesses a certain degree of safety.

[0061] Table 2. Antibiotic susceptibility of Lactobacillus paracasei C125

[0062]

[0063] Note: "S": Sensitive; "I": Moderately sensitive; "R": Resistant; "--" indicates no inhibition zone.

[0064] Probiotic properties of Lactobacillus paracasei C125

[0065] (1) Adhesion ability: The hydrophobicity and self-aggregation of probiotics can reflect their intestinal adhesion ability to a certain extent. Therefore, hydrophobicity and self-aggregation are often used as indicators for screening and evaluating the probiotic potential of probiotics. The activated bacterial solution was centrifuged at 4000 r / min for 5 min at 4℃, the supernatant was removed, and the bacterial precipitate was washed with PBS buffer and centrifuged at 4000 r / min for 5 min at 4℃. The washing operation was repeated twice. The bacterial cells were resuspended with PBS buffer, and the bacterial solution concentration was adjusted to an absorbance value of approximately 0.4 (denoted as A0) at a wavelength of 600 nm. (1) Take 3 mL of bacterial suspension with an absorbance of 0.4 and mix it with 1 mL of chloroform. Vortex for 30 s and let it stand at room temperature for 30 min. Measure the absorbance of the upper layer at a wavelength of 600 nm (denoted as A1). Repeat the hydrophobicity result 3 times. The calculation formula is shown in ①. (2) Take 4 mL of suspension, vortex for 10 s and let it stand at room temperature for 3 h. Take the upper suspension and measure the absorbance at a wavelength of 600 nm (denoted as A2). Repeat the self-polymerization result 3 times. The calculation formula is shown in ②.

[0066] ① Hydrophobicity / % = (A0-A1) / A0×100

[0067] ② Self-polymerization rate / % = (A0 - A2) / A2 × 100

[0068] The results are shown in Table 3. The hydrophobicity of Lactobacillus paracasei C125 was 76.18% ± 0.41%, and the self-aggregation rate of strain C125 was 63.03% ± 0.01%. Therefore, Lactobacillus paracasei C125 has good intestinal adhesion.

[0069] Table 3 Hydrophobicity and self-polymerization rate of C125

[0070]

[0071] (2) Determination of growth curve

[0072] The activated strain C125 was inoculated into MRS liquid fermentation medium at a 2% inoculum and cultured statically at 37°C for 24 hours. Samples were taken every 2 hours to measure the OD600nm value during fermentation and plot a growth curve. The growth curve of C125 is shown below. Figure 6 As shown, strain C125 exhibits good growth and a defined growth cycle.

[0073] (3) Resistant to acid and bile salts

[0074] The bacterial culture activated to the logarithmic growth phase was inoculated at 2% of the inoculum into MRS liquid medium at pH 2.0, 2.5, 3.0, 3.5, and 6.5, and incubated at 37°C for 24 h. Uninoculated MRS liquid medium served as the blank control for each gradient. Absorbance was measured at 600 nm. The results are shown in Table 4: At pH 2.0, the OD600 of *Lactobacillus paracasei* C125 was 0.181, while the OD600 of uninoculated MRS was 0.093, showing a significant difference (P < 0.01). These results indicate that strain C125 is acid-resistant.

[0075] Table 4. Acid resistance (OD600) of Lactobacillus paracasei C125

[0076]

[0077] The activated bacterial culture, inoculated to the logarithmic growth phase, was inoculated at a 2% inoculum into MRS liquid medium containing 0.0%, 0.1%, 0.2%, and 0.3% bovine bile salts, respectively. The cultures were incubated at 37°C for 24 h. The blank control consisted of uninoculated liquid medium at each bile salt concentration. Absorbance was measured at 630 nm. The results are shown in Table 5: At a bile salt concentration of 0.1%, the OD630 of *Lactobacillus paracasei* C125 was 1.194, while the OD630 of uninoculated MRS was 0.071, a highly significant difference (p < 0.001). These results indicate that strain C125 exhibits bile salt tolerance.

[0078] Table 5. Bile salt tolerance of Lactobacillus paracasei C125 (OD630)

[0079]

[0080] (4) Simulate gastrointestinal digestion

[0081] 1.0 mL of bacterial culture activated to the logarithmic growth phase was inoculated into 9.0 mL of simulated gastric fluid and incubated at 37°C for 3 h. Viable bacteria were counted using the plate count method at 0 h and 3 h. 1 mL of the bacterial culture after 3 h of treatment was transferred to 9 mL of simulated intestinal fluid and incubated at 37°C for 3 h. Viable bacteria were then counted using the plate count method at 0 h and 3 h in the simulated intestinal fluid. The survival rate of the strains was expressed as CFU / mL. The results are shown in Table 6: The viable count of *Lactobacillus paracasei* C125 after 3 h of digestion in simulated gastric fluid was 3.72 × 10⁻⁶. 7 The CFU / mL count yielded a survival rate of 76.70%; the viable bacterial count after 3 hours of digestion in artificial intestinal fluid was 1.6 × 10⁻⁶. 7 The concentration of CFU / mL was 43.01%, indicating good tolerability.

[0082] Table 6. Gastrointestinal Tolerance of C125

[0083]

[0084] Example 3: Mining of purine degradation genes in Lactobacillus paracasei C125

[0085] By comparing and screening genomic databases, genes involved in purine metabolism pathways were identified, and the molecular mechanism of purine degradation by strain C125 was analyzed from a genetic perspective. The results are shown in Table 7. In the genomic database of strain C125, a total of 8 genes directly involved in purine metabolism were identified, namely xpt, deoD, hprT, add, guaB, guaA, guaD, and apt.

[0086] Table 7. Analysis of genes related to purine metabolism

[0087]

[0088] Example 4: Mining of purine degradation metabolites from Lactobacillus paracasei C125

[0089] The metabolites of the fermentation supernatant of strain C125 were determined. Based on a review of existing literature, this application identified 30 substances in the metabolites of strain C125 that directly inhibit XOD activity. The results are as follows: Figure 7As shown, the specific ingredients include: DL-arginine (DL-tyrosine), cyclic (leucyl-proline) (Cyclo(Leu-Pro)), histidine-lysine (His-Lys), histidine-proline (His-Pro), phenylalanine-glutamine (Phe-Gln), valine, histidine-isoleucine (His-Ile), histidine-glutamate (His-Glu), histidine-histidine-ornithine (His-His-Arg), glutamine-histidine (Gln-His), histidine-leucine (His-Leu), histidine-valine (His-Val), threonine-valine-leucine (Thr-Val-Leu), DL-tyrosine (DL-tyrosine), histidine-tyrosine (His-Tyr), and glycine-proline-ornithine (Gl). The following are listed: γ-Pro-Arg, Pro-Ala-Arg, Val-His, Val-Leu-Pro-Val-Pro, Isoleucine-Aspartic Acid, Ornithine-Glutamine (Arg-Gln), Lysine, Glycine-Val-Arg, Histidine-Cysine, Asn-Ala-Arg, Aspartic Acid-Threonine-Ornithine (Asp-Thr-Arg), Tryptophan, Genistein, Betaine, and Dihydrokaempferol.

[0090] Example 5: Application of Lactobacillus paracasei C125 in fermented yogurt

[0091] Activated C125 was inoculated into MRS broth at a 1% inoculum and cultured (37℃, 24h) to the third generation, and then acclimated in skim milk. C125 seed culture was added at 3.5% (m / m, 6.5 × 10⁻⁶) 8 CFU / mL ~7.0 × 10 8 The inoculum was prepared by adding 0.014% (m / m) of a commercial starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus 1:1) at CFU / mL, and fermenting at 35℃ for 14 h, followed by refrigeration and ripening for 10 h to obtain fermented milk (denoted as: LBST + C125 fermented milk). The sensory and conventional physicochemical properties of the fermented milk were analyzed. The control group was the group with only the commercial starter culture added (denoted as: LBST fermented milk). The colony count of *Lactobacillus paracasei* C125 was 6.9 × 10⁻⁶. 8CFU / mL. The performance parameters of the fermented milk are shown in Tables 8 and 9.

[0092] (1) Yogurt quality analysis:

[0093] Table 8 Physicochemical characteristics of C125 fermented milk

[0094]

[0095] Note: Different lowercase superscript letters in the same row indicate significant differences (P < 0.05).

[0096] Table 9. Viable Lactic Acid Bacteria Count and Microbial Characteristics of Fermented Milk

[0097]

[0098] Note: Different lowercase superscript letters in the same row indicate significant differences (P < 0.05).

[0099] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A type of Lactobacillus paracasei with uric acid-lowering function, characterized in that, The Lactobacillus paracasei described herein is named Lactobacillus paracasei C125 and was deposited on February 17, 2025, at the China Center for Type Culture Collection (CCTCC) with accession number M2025231. The deposit address is: Wuhan University, No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province.

2. The use of Lactobacillus paracasei according to claim 1 in the preparation of a uric acid-lowering drug.

3. The application of *Lactobacillus paracasei* according to claim 1 in the preparation of an antibacterial agent, characterized in that, in, Antibacterial activity refers to the inhibition of the activity of Escherichia coli, Salmonella, or Staphylococcus aureus.

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