Lactobacillus paracasei with uric acid reducing function and application of lactobacillus paracasei

Abstract

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

Description

Technical Field

[0001] The present invention relates to the field of microorganisms, in particular to a Lactobacillus paracasei strain with uric acid-lowering function and application thereof. Background Art

[0002] Purines are essential components of nucleic acids. Abnormal purine metabolism, particularly excessive or disrupted purine production, can lead to conditions such as hyperuricemia (HUA) and gout, posing a serious threat to human health. Currently, the main treatments for hyperuricemia are dietary adjustments and medications. However, dietary adjustments can deprive people of the pleasure of food, leading to a decline in quality of life. Drugs for HUA are limited (such as allopurinol, probenecid, and benzbromarone), have toxic side effects, and are poorly tolerated.

[0003] Lactic acid bacteria, a multifunctional probiotic widely used in the food and health sectors, play a role in breaking down purine compounds and preventing and alleviating hyperuricemia. They have potential applications in developing specialized foods for people with hyperuricemia. Therefore, screening for lactic acid bacteria with potential uric acid-lowering properties is of great significance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a multifunctional Lactobacillus paracasei and its application. The Lactobacillus paracasei provided by the present invention has the functions of degrading uric acid, inhibiting bacteria and resisting oxidation.

[0005] In order to solve the above 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 is named as: lactobacillus paracasei C125 Lacticaseibacillus paracasei C125 was deposited in the China Center for Type Culture Collection on February 17, 2025, with the deposit number CCTCC M 2025231. The deposit address is: Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0006] The present invention also provides the use of the Lactobacillus paracasei in preparing a uric acid-lowering product.

[0007] The present invention also provides the use of the Lactobacillus paracasei in preparing an antibacterial agent, wherein the antibacterial agent refers to the activity of inhibiting Escherichia coli, Salmonella or Staphylococcus aureus; and the antibacterial application is for non-therapeutic purposes.

[0008] The present invention also provides application of the Lactobacillus paracasei in preparing antioxidants.

[0009] The present invention also provides application of the Lactobacillus paracasei in preparing fermented food.

[0010] Preferably, the fermented food is fermented milk.

[0011] Preferably, the inoculum size of the Lactobacillus paracasei is 3×10 8 CFU / mL~7.0 × 10 8 CFU / mL.

[0012] The Lactobacillus paracasei is used in combination with a commercial starter (such as Lactobacillus bulgaricus and / or Streptococcus thermophilus), and the addition amount of the commercial starter is: 0.01%~0.03% (m / m).

[0013] Preferably, the fermentation conditions of the fermented milk are as follows: fermentation at 34-37° C. for 10-18 hours and refrigeration for 8-15 hours.

[0014] The present invention isolates a strain of Lactobacillus paracasei C125 from fermented chili peppers in Midu County, Dali Prefecture. The fermentation supernatant of strain C125 can significantly inhibit the activity of xanthine oxidase, with an inhibition rate of 83.26% on xanthine oxidase; the nucleoside degradation rate reaches 100%, and has potential uric acid-lowering activity. Strain C125 contains 30 substances that directly inhibit XOD activity and inhibit the synthesis of uric acid; strain C125 has 8 genes related to purine metabolism and can degrade purine and uric acid. The present invention uses strain C125 to prepare fermented milk, and all indicators of the fermented milk meet national standards and have strong purine degradation ability. In addition, the fermentation supernatant of strain C125 also has good antibacterial and antioxidant properties.

[0015] Compared with existing technologies, the present invention has the following advantages: the Lactobacillus paracasei C125 provided by the present invention has strong inhibitory activity against xanthine oxidase, which can be used to inhibit uric acid synthesis, thereby reducing uric acid. Strain C125 is acid-resistant, bile-tolerant, has good gastrointestinal tolerance, and has strong adhesion ability. Strain C125 also has strong antioxidant activity and a wide range of antibacterial activities.

[0016] The microbial deposit information is as follows: Classification name: Lactobacillus paracasei C125 Lacticaseibacillus paracasei C125; Deposit number: CCTCC M 2025231; Deposit date: February 17, 2025; Deposit address: China Center for Type Culture Collection; The storage address is: Wuhan University, No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the colony morphology of Lactobacillus paracasei C125; Figure 2 is the inhibition rate of Lactobacillus paracasei C125 on xanthine oxidase XOD; Figure 3 Nucleoside degradation chromatograms and curves of Lactobacillus paracasei C125; A is the liquid chromatogram; B is the guanosine standard curve; C is the inosine standard curve; D is the degradation chromatogram of inosine and guanosine by C125; Figure 4 is the antioxidant activity of Lactobacillus paracasei C125; A is the DPPH free radical scavenging rate (%); B is the ABTS free radical scavenging rate (%); C is the hydroxyl free radical scavenging rate (%); Figure 5 This is a diagram of the hemolytic test of Lactobacillus paracasei C125; A is Staphylococcus aureus ATCC25923; B is Lactobacillus paracasei C125; Figure 6 is the growth curve of Lactobacillus paracasei C125; Figure 7 This is a heat map of metabolites in Lactobacillus paracasei C125 that can directly inhibit the degradation of purine by xanthine oxidase; Figure 8 are the fermented milk of Lactobacillus paracasei C125 and the XOD inhibition rate; A is the fermented milk of C125, and B is the XOD inhibition rate of the fermented milk. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described in detail below in conjunction with specific embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0019] The indicator bacteria used in the following examples are: Staphylococcus aureus ( Staphyloccocus aureus ATCC25923) was purchased from the American Type Cell / Strain Collection Center; multidrug-resistant Staphylococcus aureus ( Staphyloccocus aureusDC.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. Escherichia coli ( Escherichia coli CICC10389) was purchased from China Industrial Microbiological Culture Collection; salmonella( Salmonella WX29) was screened by Yunnan Agricultural University and identified as Salmonella by 16s rDNA gene sequence analysis.

[0020] Example 1 Isolation and purification of bacterial strains

[0021] Take the fermented chili peppers from Midu County, Dali Prefecture as samples. Take 10g of the sample, add it to 90mL of selective culture medium MRS broth, shake it evenly, and enrich it at 37℃ for 24h. The enriched sample is diluted with sterile saline for a gradient (10 -6 to 10 -8 ) Spread 200 μL of the dilution onto MRS solid medium and incubate at 37°C for 24 hours. Select colonies from the solid medium and repeatedly streak them onto MRS solid medium for purification until the strain has consistent colony morphology. Select a single colony, C125, and inoculate it into MRS liquid medium at 37°C for 24 hours for storage and identification.

[0022] Morphological characteristics of the strain The strain C125 stored at -80℃ was activated in MRS solid medium and cultured at 37℃ for 24 h. The colony morphology was observed. Figure 1 shown.

[0023] like Figure 1 As shown, after strain C125 was cultured in MRS solid medium for 24 h, the colony morphology was milky white, opaque, with a smooth surface, neat edges, and obvious protrusions.

[0024] Molecular biological identification of bacterial species 16S rDNA gene sequencing

[0025] The 16S rRNA sequence was amplified using the DNA of strain C125 as a template 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) and sent to Shanghai Meiji Biopharmaceutical Technology Co., Ltd. for sequencing. The sequencing results were compared with the NT database BLAST for homology, and the strain was identified as Lactobacillus paracasei, which was named Lactobacillus paracasei C125. Lacticaseibacillus paracasei C125 and deposited it in the China Center for Type Culture Collection.

[0026] Example 2 Activity determination of Lactobacillus paracasei C125 Determination of xanthine oxidase (XOD) inhibition rate

[0027] 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 / cellular contents, and 200 μL of 4°C XOD solution, mix thoroughly, and incubate at 37°C for 10 minutes to allow the solution to reach equilibrium. Then, add 200 μL of 37°C pre-warmed xanthine solution to initiate the reaction. Use UV spectrophotometer kinetic software to record the change in absorbance at a wavelength of 295 nm over time, recording results every 30 seconds for a total of 6 minutes. Plot the reaction time against the absorbance value on the ordinate, and calculate the slope of the curve, i.e., the reaction rate As. Calculate the enzymatic reaction rate Ac by replacing the sample with the same volume of blank MRS medium / phosphate buffer solution as a blank control. The relative inhibition rate of XOD is calculated as follows: Relative inhibition rate of XOD = ×100 %

[0028] Inhibition of xanthine oxidase can reduce uric acid levels and alleviate hyperuricemia. Figure 2 As shown in the results, allopurinol was used as a positive control, and its inhibition rate on XOD reached 88%. The XOD inhibition rates of the fermentation supernatant of Lactobacillus paracasei C125 were 83.26%, 9.53% for extracellular metabolites, and 14.84% for cell contents. These results indicate that the fermentation supernatant of Lactobacillus paracasei C125 exhibits good xanthine oxidase inhibitory activity, and both extracellular metabolites and cell contents have certain xanthine oxidase inhibitory activity. Therefore, strain C125 has a good ability to inhibit XOD activity.

[0029] Determination of nucleoside degradation ability Lactic acid bacteria can competitively reduce nucleoside absorption by the intestinal epithelium by either degrading or absorbing nucleosides, thereby reducing uric acid production. An appropriate amount of activated second-generation bacterial culture was centrifuged at 4500 rpm for 10 minutes at 4°C. The supernatant was discarded and the bacterial cells were collected. The lactic acid bacteria were rinsed twice with 0.85% sterile saline and the OD600 of the culture was adjusted to 1.5 with saline. After washing, 750 µL of inosine-guanosine-neutral potassium phosphate solution was added and incubated at 37°C and 120 rpm for 1 hour. After incubation, the resulting culture was centrifuged at 4500 rpm for 10 minutes at 4°C. The resulting supernatant was mixed with a reaction terminator (0.1 mol / L HClO₄) at a ratio of 9:1 by volume, filtered through a 0.22 µm filter, and 5 µL was absorbed for HPLC analysis. The residual inosine and guanosine contents in the supernatant were calculated using a standard curve method, and the degradation rate of inosine or guanosine by strain C125 was then calculated. The calculation formula is as follows: A=(C1-C2) / C1×100%;

[0030] Where: 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).

[0031] The chromatogram of nucleoside degradation by Lactobacillus paracasei C125 is shown in Figure 2. Figure 3 As shown, Figure 3 A-inosine retention time under this chromatographic condition is 7.324 min, and guanosine retention time is 8.563 min. Figure 3 The standard curve of B-guanosine is f(x)=3.20145e+006*x+172204(R 2 =0.9998693); Figure 3 The standard curve of C-inosine is f(x)=2.71893e+006*x+102492(R 2 =0.9999556). Figure 3 D is the chromatogram of the degradation of inosine and guanosine by strain C125, with a degradation rate of 100% for guanosine and 100% for inosine. This experimental result further confirms the potential of strain C125 to lower uric acid.

[0032] Punch method to determine antibacterial activity A punch assay was used 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 culture was centrifuged at 4500 rpm and 4°C for 5 minutes. 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 quickly and evenly spread on the plate. A sterile punch was used to create a hole in the plate, which was then removed with tweezers. 200 μL of the concentrated sample solution was added and incubated in a 37°C incubator for 10 hours. The sample was then removed and observed for antibacterial activity. Unconcentrated sample solution and uninoculated MRS liquid medium concentrate were used as blank controls. The size of the inhibition zone was used to determine the antibacterial activity of the test sample.

[0033] Antibacterial diameter (mm) = directly measured circle diameter Antibacterial activity of Lactobacillus paracasei C125 The results showed that the inhibition zones of Lactobacillus paracasei C125 were: 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 Staphylococcus aureus DC. RB015): 16.66±0.29 mm, 10-fold concentrated: 30.49±0.34 mm; ③ against E. coli CICC10389 (Escherichia coli CICC10389): 16.77±0.18 mm, 10-fold concentrated: 26.47±0.16 mm; ④ against Salmonella WX29 (Salmonella WX29): 20.03±0.29 mm, 10-fold concentrated: 32.89±0.68 mm. The results showed that strain C125 had good broad-spectrum antibacterial activity.

[0034] Table 1 Inhibition zone size of C125 fermentation broth

[0035] Note: “—” represents no inhibition zone, *** represents extremely significant difference (p<0.001). The concentration of indicator bacteria in the antibacterial experiment of the present invention is fixed at: 10 6 CFU / mL.

[0036] Antioxidant activity of Lactobacillus paracasei C125 The activated Lactobacillus paracasei C125 suspension was centrifuged at 4°C and 4000 rpm for 15 minutes to obtain the fermentation supernatant. The supernatant was filtered through a 0.22 μm microporous membrane to obtain the fermentation supernatant fractions. The scavenging abilities of the supernatant fractions for free radicals, including DPPH, ABTS, and hydroxyl radicals, were determined.

[0037] The results are as follows Figure 4 As shown in the figure, using VC as a control, Lactobacillus paracasei C125 showed strong scavenging abilities against DPPH, ABTS, and hydroxyl radicals, with scavenging rates of 88.20% for DPPH, 92.17% for ABTS, and 82.51% for hydroxyl radicals. These results indicate that C125 possesses strong antioxidant activity.

[0038] Safety of Lactobacillus paracasei C125 (1) Hemolytic activity: The Food and Agriculture Organization of the United Nations stipulates that probiotics used in food cannot be hemolytic. Strains with hemolytic activity can dissolve cells, causing intrinsic defects in red blood cells to react with antigens and antibodies, leading to sepsis. Therefore, hemolytic activity is an important indicator for in vitro screening of probiotics. Streak Lactobacillus paracasei C125 on Columbia blood agar medium and incubate at 37°C for 48 hours. Use Staphylococcus aureus ATCC25923 as a positive control to observe whether a hemolytic zone is formed around the bacterial sand to determine whether the strain is hemolytic.

[0039] like Figure 5 As shown in the figure, a transparent hemolytic zone appeared around the colony of Staphylococcus aureus in the control group, while no hemolytic zone appeared around the colony of Lactobacillus paracasei C125, indicating that Lactobacillus paracasei C125 is not hemolytic and is a safe strain.

[0040] (2) Antibiotic resistance: Antibiotic resistance is used to assess the safety of lactic acid bacteria applications. 200 μL of strain C125 bacterial solution was spread on MRS solid plates, and three antibiotic susceptibility paper discs of the same type were evenly placed on each plate. These included 20 antibiotics, including penicillin, chloramphenicol, ciprofloxacin, erythromycin, tetracycline, gentamicin, ceftriaxone, and ampicillin. The plates were then incubated at 37°C for 24 h, and the diameter of the inhibition zone was measured with a vernier caliper. The results were interpreted using the NCCLS susceptibility standard.

[0041] Table 2 shows the susceptibility of Lactobacillus paracasei C125 to 20 common antibiotics. The results showed that strain C125 was 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. This further demonstrates the safety of strain C125.

[0042] Table 2 Antibiotic susceptibility of Lactobacillus paracasei C125

[0043] Note: “S”: sensitive; “I”: moderately sensitive; “R”: resistant; “--” indicates no inhibition zone.

[0044] Probiotic properties of Lactobacillus paracasei C125 (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 rpm for 5 minutes at 4°C. The supernatant was removed. The bacterial pellet was washed with PBS buffer and centrifuged at 4000 rpm for 5 minutes at 4°C. The washing operation was repeated twice. The bacteria were resuspended in PBS buffer and the bacterial solution concentration was adjusted to an absorbance value of approximately 0.4 at a wavelength of 600 nm (denoted as A0). (1) Take 3 mL of bacterial suspension with an absorbance of 0.4 and mix it with 1 mL of trichloromethane, vortex it for 30 seconds, let it stand at room temperature for 30 minutes, and measure the absorbance of the upper layer solution at a wavelength of 600 nm (denoted as A1). The hydrophobicity result was repeated three times, and the calculation formula is shown in ①; (2) Take 4 mL of the suspension, vortex it for 10 seconds, let it stand at room temperature for 3 hours, and take the upper layer suspension for absorbance measurement at a wavelength of 600 nm (denoted as A2). The self-aggregation result was repeated three times, and the calculation formula is shown in ②.

[0045] ①, Hydrophobicity / %=(A0-A1) / A0×100

[0046] ②, Self-aggregation rate / %=(A0-A2) / A2×100

[0047] 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.

[0048] Table 3 Hydrophobicity and self-aggregation rate of C125

[0049] (2) Determination of growth curve The activated strain C125 was inoculated into MRS liquid fermentation medium at 2% inoculum and cultured at 37℃ for 24 hours. Samples were taken every 2 hours to measure the OD600nm value of the strain during the fermentation process and draw a curve. The growth curve of C125 is shown in Figure 2. Figure 6 As shown in Figure 2, strain C125 has good growth potential and exhibits a definite growth cycle.

[0050] (3) Acid and bile salt resistance Bacterial suspension activated to the logarithmic phase was inoculated at 2% of the inoculum into MRS liquid medium at pH values ​​of 2.0, 2.5, 3.0, 3.5, and 6.5, respectively, and incubated at 37°C for 24 hours. Uninoculated MRS liquid medium served as a blank control for each gradient, and 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, compared to 0.093 for uninoculated MRS liquid medium, demonstrating a significant difference (P < 0.01). These results demonstrate that strain C125 exhibits acid tolerance.

[0051] Table 4 Acid resistance of Lactobacillus paracasei C125 (OD600)

[0052] Bacterial cultures activated to the logarithmic phase were inoculated at a 2% inoculum into MRS liquid culture medium containing 0.0%, 0.1%, 0.2%, and 0.3% ox bile salts, respectively. The cultures were incubated at 37°C for 24 hours. Blank controls consisted of uninoculated liquid culture medium at each bile salt concentration. The 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 that of the uninoculated MRS medium was 0.071, a highly significant difference (p < 0.001). These results demonstrate that strain C125 exhibits bile salt tolerance.

[0053] Table 5 Bile salt tolerance of Lactobacillus paracasei C125 (OD630)

[0054] (4) Simulated gastrointestinal digestion 1.0 mL of activated bacterial suspension was inoculated into 9.0 mL of simulated gastric fluid and incubated at 37°C for 3 hours. Live bacteria were counted using a plate colony count method at 0 and 3 hours. 1 mL of the 3-hour-old bacterial suspension was transferred to 9 mL of simulated intestinal fluid and incubated at 37°C for 3 hours. Live bacteria were counted using a plate colony count method at 0 and 3 hours in the simulated intestinal fluid. Strain survival was expressed as viable cell counts (CFU / mL). The results are shown in Table 6. The viable cell count of Lactobacillus paracasei C125 after 3 hours of digestion in artificial gastric fluid was 3.72 × 10 7 CFU / mL, with a survival rate of 76.70%; the number of viable bacteria after 3 h of digestion in artificial intestinal fluid was 1.6×10 7 CFU / mL, the survival rate was 43.01%, and the tolerance was good.

[0055] Table 6 Gastrointestinal tolerance of C125

[0056] Example 3: Mining of purine-degrading genes in Lactobacillus paracasei C125 By comparing the genome database, we screened genes involved in the purine metabolism pathway and analyzed the molecular mechanism of purine degradation in strain C125 from a genetic perspective. The results are shown in Table 7. In the genome database of strain C125, a total of eight genes directly involved in purine metabolism were identified: xpt, deoD, hprT, add, guaB, guaA, guaD, and apt.

[0057] Table 7 Analysis of purine metabolism-related genes

[0058] Example 4 Mining of Purine Degradation Metabolites of Lactobacillus paracasei C125 Determination of metabolites in the fermentation supernatant of strain C125. By consulting existing literature reports, the present application found 30 substances that directly inhibit XOD activity in the metabolites of strain C125. The results are as follows Figure 7As shown, specifically including: DL-arginine (DL-tyrosine), cyclo (leucyl-proline) (Cyclo (Leu-Pro)), histidyl-lysine (His-Lys), histidyl-proline (His-Pro), phenylalanyl-glutamine (Phe-Gln), valine (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), glycine-proline-ornithine (Gln-His). y-Pro-Arg), Proline-Alanine-Ornithine (Pro-Ala-Arg), Valine-Histidine (Val-His), Valine-Leucine-Proline-Valine-Proline Val-Leu-Pro-Val-Pro), Isoleucine-Aspartic Acid (Ile-Asp), Ornithine-Glutamine (Arg-Gln), Lysine (Lysine), Glycine-Valine-Ornithine (Gly-Val-Arg), Histidine-Cysteine ​​(His-Cys), Asparagine-Alanine-Ornithine (Asn-Ala-Arg), Aspartic Acid-Threonine-Ornithine (Asp-Thr-Arg), Tryptophan, Genistein, Betaine and Dihydrokaempferol.

[0059] Example 5 Application of Lactobacillus paracasei C125 in fermented yogurt

[0060] The activated C125 was inoculated into MRS broth at a 1% inoculum volume and cultured (37°C, 24 h) to the third generation and then acclimated in skim milk. 8 CFU / mL~7.0 × 10 8 CFU / mL) + 0.014% (m / m) of a commercial starter (Lactobacillus bulgaricus and Streptococcus thermophilus, 1:1) were inoculated, fermented at 35°C for 14 hours, and refrigerated for 10 hours to obtain fermented milk (denoted as: LBST + C125 fermented milk). The sensory and general physicochemical indicators of the fermented milk were analyzed. The control group was a group with only the commercial starter (denoted as: LBST fermented milk). The colony count of the Lactobacillus paracasei C125 was 6.9 × 10 8CFU / mL. The performance parameters of fermented milk are shown in Tables 8, 9 and Figure 8 shown.

[0061] (1) Yogurt quality analysis: Table 8 Physicochemical characteristics of C125 fermented milk

[0062] Note: Different lowercase letters in the same row indicate significant differences (P < 0.05).

[0063] Table 9 Live lactic acid bacteria count and microbial characteristics of fermented milk

[0064] Note: Different lowercase letters in the same row indicate significant differences (P < 0.05).

[0065] (2) Determination of XOD inhibition rate in yogurt: The XOD inhibition rate in yogurt was determined as described above. Figure 8 As shown in the figure: when the XOD inhibition rate of allopurinol was 87.18%, the XOD inhibition rate of C125 fermented milk reached 46.4%, indicating that it had a certain ability to degrade uric acid.

[0066] (2) Analysis of yogurt’s ability to lower uric acid Metabolite screening of the two groups of fermented milk revealed three key substances involved in purine metabolism: adenine, guanine, and hypoxanthine, as shown in Table 10. As can be seen from Table 10, the relative quantitative values ​​of adenine, guanine, and hypoxanthine were significantly reduced in C125 + LBST fermented milk, with Fold_Change (the ratio of the quantitative values ​​of the two experimental substances) values ​​of 0.3075, 0.0382, and 0.0499, respectively, and Log_Foldchange (the logarithm of Fold_Change to base 2) values ​​of -1.7013, -4.7109, and -4.3235, respectively. This indicates that these purine metabolites were significantly degraded in C125 + LBST fermented milk, indicating that the added C125 starter culture has purine degradation ability, further demonstrating that Lactobacillus paracasei C125 has certain purine and uric acid degradation capabilities.

[0067] Table 10 Metabolites involved in purine metabolism in fermented milk

[0068] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A Lactobacillus paracasei with uric acid-lowering function ( Lacticaseibacillus paracasei ), characterized in that The lactobacillus paracasei was named lactobacillus paracasei C125 Lacticaseibacillus paracasei C125 was deposited in the China Center for Type Culture Collection on February 17, 2025, with the deposit number CCTCC M 2025231. The deposit address is: Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

2. An application of Lactobacillus paracasei according to claim 1 in preparing a uric acid-lowering product.

3. An application of Lactobacillus paracasei in the preparation of an antibacterial agent according to claim 1, characterized in that, The bacteriostasis refers to the activity of inhibiting Escherichia coli, Salmonella or Staphylococcus aureus; the bacteriostasis application is used for non-therapeutic purposes.

4. Use of Lactobacillus paracasei according to claim 1 in the preparation of antioxidants.

5. Use of Lactobacillus paracasei according to claim 1 in preparing fermented foods.

6. the application of Lactobacillus paracasei in preparing fermented food according to claim 5, is characterized in that, The fermented food is fermented milk.

7. The use according to claim 6, characterized in that The inoculum size of the Lactobacillus paracasei was 3 × 10 8 CFU / mL~7.0 × 10 8 CFU / mL.

8. The use according to claim 7, characterized in that The Lactobacillus paracasei is used in combination with a commercial starter culture, and the addition amount of the commercial starter culture is 0.01% to 0.03% (m / m).

9. The use according to claim 8, characterized in that The fermentation conditions of the fermented milk are as follows: fermentation at 34-37°C for 10-18 hours and refrigeration for 8-15 hours.

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