Uric acid reducing probiotics based on rapid and high-throughput screening of bombyx mori and application of uric acid reducing probiotics

Abstract

The invention relates to uric acid reducing probiotics obtained by high-throughput screening based on a silkworm model, in particular to a strain SWU-MY69, which is classified and named as Pediococcus pentosaceus, is preserved in China General Microbiological Culture Collection Center (CGMCC), has a preservation number of CGMCC No.31926, and is preserved in September 10, 2024. The pediococcus pentosaceus SWU-MY69 screened through a bombyx mori model has an excellent uric acid reducing effect, the inhibition rates of bacterial suspension, contents and metabolites of the strain on xanthine oxidase in vitro are all 80% or above, and the pediococcus pentosaceus SWU-MY69 also has an excellent inhibition effect on xanthine oxidase in vivo; uric acid in hemolymph is remarkably reduced, excretion of uric acid by intestinal tracts is promoted, and therefore the concentration of uric acid in serum is reduced, and burdens of kidneys and livers are reduced.

Description

Technical Field

[0001] The present invention relates to the field of microbial technology, and in particular to a uric acid-lowering probiotic based on rapid high-throughput screening of silkworms and an application thereof. Background Art

[0002] Hyperuricemia (HUA) is a metabolic disease caused by uric acid metabolism disorder. With the change of lifestyle and eating habits, the prevalence of hyperuricemia in China continues to rise, and hyperuricemia is increasingly considered to be the fourth largest health risk factor after hypertension, hyperlipidemia and diabetes. At present, the clinical treatment methods for hyperuricemia mainly include increasing the excretion function of uric acid and reducing the production process of uric acid. Commonly used drugs include allopurinol, febuxostat, benzbromarone, etc. Xanthine oxidase inhibitors such as allopurinol and febuxostat are mainly used to reduce uric acid production, while benzbromarone and probenecid are used to increase uric acid excretion. However, these drugs may cause a series of side effects, such as severe adverse reactions including abnormal liver and kidney function, headache, vomiting and diarrhea, and are expensive in the market. Therefore, it is urgent to develop new hyperuricemia prevention and treatment drugs with fewer side effects to meet clinical needs.

[0003] In recent years, the potential of probiotics in regulating human health has gradually been discovered by scientific researchers, showing preventive and therapeutic effects on a variety of health problems such as diabetes, hypertension and hyperuricemia. There are more and more studies on the alleviating effect of probiotics on hyperuricemia. It is reported in the prior art that Lactobacillus plantarum PA-3 reduces the synthesis of uric acid by degrading uric acid precursors such as purine, adenosine, and AMP. After 21 days of treatment of hyperuricemia mice with Lactobacillus paracasei MJM60396, the serum uric acid level of mice was significantly lower than that of the HUA model group. After Lactobacillus brevis DM9218 intervened in hyperuricemia mice, the serum uric acid level was reduced by 20%.

[0004] Based on this, screening out probiotic strains with excellent uric acid-lowering effects not only provides new ideas for the screening of drugs for hyperuricemia, but also provides theoretical support and probiotic strain support for microbial therapy of hyperuricemia. Summary of the invention

[0005] The present invention aims to obtain a uric acid-lowering probiotic based on high-throughput screening of a silkworm model.

[0006] Another object of the present invention is to provide the application of the above-mentioned probiotics.

[0007] The purpose of the present invention is achieved through the following technical solutions: A probiotic strain for lowering uric acid obtained by high-throughput screening based on a silkworm model, characterized in that: the probiotic strain is strain SWU-MY69, classified and named Pediococcus pentosaceus ( Pediococcus pentosaceus), which is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.31926 and the deposit date September 10, 2024.

[0008] Since humans lack the uricase gene, the results of commonly used animal models such as mice may not be well adapted to humans. Silkworms, as lepidopteran insects that excrete uric acid, do not have uricase in their bodies, and their uric acid metabolism pathway is similar to that of humans. Therefore, it is feasible to screen probiotics for the uric acid-lowering effect based on the silkworm model. Compared with probiotics screened from other animal models, the screened probiotics are more feasible for application to humans.

[0009] First, the existing strains in the laboratory were screened for in vitro uric acid-lowering effects and in vitro resistance tests, and the strains with better overall effects were selected and then screened in silkworm model experiments to evaluate their uric acid-lowering effects in silkworms. Finally, their effects were compared through in vitro fermentation of feces from patients with hyperuricemia to further improve the credibility of the silkworm model and screen out uric acid-lowering probiotics suitable for humans.

[0010] During the initial in vitro screening, the strains were tested for their ability to degrade inosine and guanosine in vitro, and strains with a degradation efficiency greater than 60% were selected and applied to subsequent silkworm model screening.

[0011] The cell lysis supernatant and cell precipitate of the strain SWU-MY69 screened in the present invention have certain nucleoside degradation ability, have good inhibition effect on xanthine oxidase (XOD) in vivo, the inhibition rate in vitro reaches more than 80%, and the xanthine oxidase activity in vivo decreases by 45.31%. The tolerance test shows that the survival rate of the four strains in artificial gastric juice with pH 3.0 is greater than 100%, and the survival rate in 0.3% bile salt is greater than 80%, and the four strains have good gastric acid and bile salt resistance.

[0012] The use of the above-mentioned strain SWU-MY69 in the preparation of uric acid-lowering drugs.

[0013] Application of the strain SWU-MY69 in the preparation of uric acid-lowering food.

[0014] The present invention has the following technical effects: The Pediococcus pentosaceus SWU-MY69 screened through the silkworm model in the present invention has excellent uric acid-lowering effect, and the bacterial suspension, contents and metabolites of the strain have an inhibition rate of more than 80% on xanthine oxidase in vitro, and also have an excellent inhibitory effect on xanthine oxidase in vivo; it significantly reduces uric acid in hemolymph, promotes the excretion of uric acid in the intestine, thereby reducing the uric acid concentration in serum and reducing the burden on the kidneys and liver. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : Results of inosine and guanosine degradation rates of various probiotics in vitro.

[0016] Figure 2 : The results of inhibition of XOD activity by bacterial suspension, contents and metabolites of strain SWU-MY69.

[0017] Figure 3 :The effect of different strains on uric acid in silkworm hemolymph.

[0018] Figure 4 :The effect of different strains on uric acid excretion in silkworm.

[0019] Figure 5 :Effects of different strains on xanthine oxidase activity in silkworm hemolymph. DETAILED DESCRIPTION

[0020] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0021] Example 1 In vitro screening of uric acid-lowering strains: First, 10 strains were screened from traditional fermented kimchi and cheese. The information obtained after strain sequencing was analyzed and compared using BLAST. Sequences with high similarity were downloaded and compared using MEGA 11.0. Combined with morphological analysis, the information of the 10 strains was shown in Table 1.

[0022] Table 1: Screening strain information

[0023] The above strains were tested for their ability to degrade inosine and guanosine: The strain was inoculated into MRS liquid medium and incubated at 37 °C for 24 hours. 2 mL of bacterial suspension was centrifuged at 4000 r / min for 10 minutes. The suspension was washed three times with 1 mL of 0.85% NaCl solution and the bacterial concentration was adjusted to 10 using a bacterial turbidity meter. 9 cfu / mL, 1 mL of bacterial suspension was centrifuged at 4000 r / min for 10 min, the supernatant was discarded, the cells were resuspended in 750 μL of 1 mmol / L inosine-guanosine solution and incubated at 37 °C for 120 min. After the incubation was completed, the solution was centrifuged at 4000 r / min for 10 min, the supernatant was taken, and the supernatant was mixed with 0.1 M HCLO 4 Add HCLO in a volume ratio of 9:1 4The solution was added to terminate the reaction. After mixing, the mixture was filtered through a 0.22 μm filter membrane for testing. The residual inosine and guanosine in the solution were determined using a high performance liquid chromatography (HPLC) system. The chromatographic conditions were: reverse phase column ThermoFisher-C18 (4.6 mm×250 mm, 5 μm), mobile phase gradient of 10 mmol / L potassium dihydrogen phosphate solution (pH5.0) and methanol in a volume ratio of 90:10, flow rate of 1 mL / min, column temperature of 25 °C, wavelength of 254 nm, and elution time of 30 min. The degradation rate was calculated according to the formula: Degradation rate = ×100% Where C 0 : Initial concentration of guanosine (inosine) standard solution, mmol / L; C: Residual concentration of guanosine (inosine) standard solution after reaction, mmol / L.

[0024] The results are as follows Figure 1 As shown, 5 lactic acid bacteria strains with the ability to degrade inosine and guanosine in vitro were selected from the above 10 strains, and their degradation rates of inosine and guanosine were all greater than 60%, namely Lactobacillus plantarum A2, Pediococcus acidilactici A4, Lactobacillus acidophilus A5, Pediococcus pentosaceus A8 and Pediococcus pentosaceus A9. Among them, A2 had the highest degradation rate of inosine and guanosine, almost reaching 100%, followed by A9, reaching more than 80%. Therefore, the above 5 probiotics were studied later.

[0025] In the present invention, strain A8 is numbered and recorded as SWU-MY69, and a biological deposit is made. The classification name of the strain SWU-MY69 is Pediococcus pentosaceus ( Pediococcus pentosaceus ), which is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.31926 and the deposit date September 10, 2024.

[0026] Ability of cell lysis supernatant and lysis precipitate to degrade inosine and guanosine: Preparation of lysis supernatant and lysis precipitate: The strain was inoculated into MRS liquid medium and incubated at 37°C for 24 hours. 2 ml of bacterial suspension was centrifuged at 4000r / min for 10 minutes. After washing 3 times with 1 ml of 0.85% NaCl solution, the bacterial concentration was adjusted to 10 using a bacterial turbidity meter. 9 cfu / mL, take 1 mL of bacterial suspension, and perform ultrasonic disruption at 200 W ultrasonic power, working for 5 seconds and stopping for 5 seconds for 30 min. The sonicated bacterial suspension was centrifuged at 4°C, 4000 r / min for 10 min, and the supernatant was taken to prepare the lysis supernatant and lysis precipitate.

[0027] The lysate supernatant and lysate pellet were resuspended in 750 μL of 1 mmol / L inosine-guanosine solution and incubated at 37°C for 120 minutes. After the incubation, the solution was centrifuged at 4000 r / min for 10 minutes to obtain the supernatant, and the supernatant was mixed with 0.1 M HCLO. 4 Add HCLO in a volume ratio of 9:1 4 The solution was added to terminate the reaction. After mixing, the mixture was filtered through a 0.22 μm filter membrane for testing. The effects of live cells, cell lysis precipitates, and cell lysis supernatants on nucleoside degradation were determined as shown in Table 2.

[0028] Table 2: Degradation rates of inosine and guanosine in the supernatant and precipitate of strain SWU-MY69

[0029] After cell lysis, the degradation ability of the lysis supernatant and lysis precipitate of the strain SWU-MY69 that completely degraded in living cells was significantly reduced (P < 0.05). However, both the lysis supernatant and the lysis precipitate had good nucleoside degradation ability, and the cell lysis supernatant contained intracellular soluble substances, such as proteins, nucleic acids, metabolites, etc. The cell lysis precipitate contained insoluble components of the cell, such as cell membranes, organelles, cytoskeleton, etc. This shows that its degradation of nucleosides is the result of the combined action of intracellular enzyme degradation and cell wall adsorption.

[0030] Determination of the inhibitory effect of bacterial suspension, contents and metabolites on xanthine oxidase (XOD): Preparation of bacterial suspension: The strain was inoculated into MRS liquid medium and incubated at 37°C for 24 hours. 2 ml of bacterial suspension was centrifuged at 4000r / min for 10 minutes. After washing with 0.85% NaCl solution for 3 times, the bacterial concentration was adjusted to 10 using a bacterial turbidity meter. 9 cfu / mL, resuspended in NaCl for later use; preparation of contents: take the bacterial suspension and perform ultrasonic disruption at 200W ultrasonic power, working for 5 seconds and stopping for 5 seconds for 30 minutes, centrifuge the sonicated bacterial solution at 4000 r / min for 10 minutes, take the supernatant, filter it with a 0.22μm filter membrane, and keep it for later use; preparation of metabolites: culture the bacterial suspension at 37℃ for 24 hours, centrifuge it at 4000 r / min for 10 minutes, take the supernatant, filter it with a 0.22μm filter membrane, and keep it for later use.

[0031] Reaction system: Add PBS buffer, 0.20 U / mL xanthine oxidase solution and sample solution (allopurinol solution) to a 96-well plate, incubate at 37°C for 5 min, add 1.77 mmol / L xanthine solution, use a microplate reader to measure the absorbance at 295n, measure once every 1 min, measure for a total of 5 min, and the reaction is over. The xanthine oxidase inhibition rate is calculated according to the formula:

[0032] Wherein A is the positive experimental group with added samples and enzymes; B is the positive control group with added samples but no enzymes; C is the negative experimental group with added enzymes but no samples; and D is the negative control group with no added enzymes and samples.

[0033] The results are as follows Figure 2 As shown in the results, there was no significant difference in the inhibition rate of XOD between the bacterial suspension, contents and metabolites of the allopurinol group and the strain SWU-MY69 (P>0.05). The inhibition rate of xanthine oxidase by the bacterial suspension, contents and metabolites of the strain was above 80%. It can be inferred that the strain SWU-MY69 has a good uric acid-lowering effect.

[0034] Determination of the self-aggregation of bacterial strain cells: Potential probiotics should have the ability to prevent the colonization of pathogenic bacteria. The self-aggregation ability of cells refers to the aggregation of cells with each other, which has a competitive advantage in harsh environments (such as the human gastrointestinal tract), thereby shielding against external harmful environments or pathogens.

[0035] Test steps: The activated bacterial suspension was centrifuged at 6000r / min for 10min at 4℃ to collect the bacteria. After washing twice with 0.85% NaCl solution, centrifuged, and resuspended with 0.85% NaCl solution to measure OD 600 The absorbance value A0 is adjusted to OD 600 The absorbance was 1. Then, 4 mL of bacterial suspension was taken from each type of bacteria, vortexed for 20 s, and cultured at 37 °C. 0.1 mL of the supernatant of each bacterial suspension was taken at 0.5, 1, 2, 4, and 24 h, added to 3.9 mL of PBS buffer, vortexed for 20 s, and the OD of each bacterial suspension was measured using an enzyme marker. 600 The absorbance value at (At). The formula for calculating the self-aggregation force is:

[0036] Where t represents 0, 0.5, 1, 2, 4 and 24 h respectively. After calculation, there was a positive correlation between the self-aggregation of the strain and the incubation time. The longer the incubation time, the stronger the self-aggregation. After 24 hours of incubation, the self-aggregation of strain SWU-MY69 was 69.92%, showing strong self-aggregation.

[0037] Tolerance test of strains to artificial gastric juice: Tolerating the gastrointestinal environment is a basic requirement for the application of probiotics, otherwise probiotics cannot survive in the host body, let alone effectively exert their effects. Therefore, the survival rate of probiotic A8 (SWU-MY69) in simulated gastrointestinal fluid was tested.

[0038] Preparation of gastric juice: 0.80% NaCl, 0.02% KCl, 0.02% KH 2 PO 4 and 0.22%Na 2 HPO 4 pH 7.4 phosphate buffered saline (PBS) was prepared, and its pH was adjusted to 3.0 using 1 mol / L HCl, and then sterilized by autoclaving at 121°C for 15 min. Gastric fluid (GJ) was prepared by adding pepsin (1:15000) to supplement PBS (pH 3.0) to a concentration of 3 g / L, and filtered using a 0.22 µm membrane filter for later use; Tolerance experiment: The strain was cultured in MRS broth at 37°C for 18 hours, and then centrifuged at 6000r / min for 10 minutes at 4°C to collect the bacteria. After washing 3 times with 1 ml of 0.85% NaCl solution, the bacteria were incubated in simulated gastric fluid and incubated at 37°C for 0h and 3h. The number of live bacteria at 0h and 3h was calculated by the plate spreading method. The calculation formula is as follows:

[0039] The calculated survival rate of strain SWU-MY69 (A8) in artificial gastric fluid is shown in Table 3.

[0040] Table 3: Survival rate of strain SWU-MY69 in artificial gastric fluid

[0041] It can be seen that the survival rate of strain SWU-MY69 in artificial gastric juice exceeded 100%, that is, the strain had excellent acid resistance and showed a growth trend in gastric juice.

[0042] Tolerance of strains to 0.3% bile salts: Prepare artificial intestinal fluid: Take KH 2 PO 46.8 g was dissolved in 500 mL of distilled water, and the pH was adjusted to 6.8 with 0.4% NaOH solution by weight, and then water was added to 1000 mL, and 0.3 g of pig bile salt (conventional commercial product) was added to every 100 mL of solution. After fully dissolved, it was sterilized at 115 ° C for 15 min to obtain the artificial intestinal fluid.

[0043] The activated strain was inoculated into MRS-THIO medium and 0.3% pig bile salt MRS-THIO medium at a 2% (v / v) inoculation rate, and the OD600 value of each medium was measured after culturing at 37°C for 24 hours. The uninoculated MRS-THIO medium was used as a blank control. The growth rate (C) of the strain in bile salt was calculated according to the following formula:

[0044] The calculation showed that the growth survival rate of strain SWU-MY69 (A8) in 0.3% bile salt concentration medium was 88.92%, which showed good viability.

[0045] Determination of hydrophobicity of bacterial cell surface: Surface hydrophobicity is an important indicator of nonspecific interactions between microorganisms and host cells, and is used to evaluate the adhesion and proliferation abilities of microorganisms in intestinal epithelial cells. According to the hydrophobicity, the hydrophobicity of strains can be divided into three levels: high, medium, and low. The hydrophobicity judgment standard of strains is divided into three levels: hydrophobicity > 50% is high hydrophobicity, hydrophobicity in the range of 20% to 50% is medium hydrophobicity, and hydrophobicity < 20% is low hydrophobicity. In the present invention, xylene (non-polar solution) and ethyl acetate (monopolar, alkaline organic solution, electron donor) were used to measure the hydrophobicity of 5 strains.

[0046] The activated bacterial suspension was centrifuged at 6000r / min for 10min at 4°C to collect the bacteria. After washing twice with 0.85% NaCl solution, the suspension was resuspended with 0.85% NaCl solution and the OD was measured. 600 The absorbance value A 0 , adjust OD 600 The absorbance is 1. Take 4 mL of bacterial suspension, add 1 mL of xylene (organic solvent) or ethyl acetate (organic solvent) to each of the control groups, vortex for 30 seconds, let stand for 10 seconds, then vortex for 30 seconds, let stand for 60 minutes at 37°C, separate the layers, take the aqueous phase, and measure the OD 600 The absorbance value is A. The hydrophobicity is calculated according to the following formula:

[0047] After calculation, the hydrophobicity of strain SWU-MY69 measured in xylene solvent was 39.82%, and the hydrophobicity measured in ethyl acetate was 52.3%, that is, strain SWU-MY69 has good hydrophobic properties.

[0048] Screening of uric acid-lowering probiotics based on the silkworm model: Since the human body lacks the uricase gene, the results of commonly used animal models such as mice may not be well adapted to humans, and the selected probiotics may not achieve the expected effect after being applied to the human body. As a lepidopteran insect that excretes uric acid, silkworms do not have uricase in their bodies, and their uric acid metabolism pathway is similar to that of humans. Therefore, it is feasible to use them as a model organism to quickly screen out probiotics that have the ability to lower uric acid in humans.

[0049] Experimental strains: Lactobacillus plantarum A2, Pediococcus acidilactici A4, Lactobacillus acidophilus A52, Pediococcus pentosaceus A8 and A9 used in this experiment were all from the previously screened probiotics that degrade inosine and guanosine in vitro and were stored in skim milk.

[0050] Experimental animals: Silkworms (Bombyx mori) were purchased from the Tiejia Village Silkworm Base, Yunmen Street, Hechuan District, Chongqing, and fed with fresh mulberry leaves and raised in an artificial incubator at a temperature of 25°C ± 1°C and a humidity of 75% ± 1% to the fourth instar stage.

[0051] Silkworm breeding: Starting from the fifth instar larvae, 1,200 healthy silkworm larvae with synchronized growth stages and similar body sizes were selected and randomly divided into seven groups, with 200 in each group. Each group was fed with a fixed amount of mulberry leaves every day, supplemented every 8 hours, ensuring a feeding frequency of three meals a day, and continued to be raised for six days. The groups are as follows: (1) CK group, fed with 60 mL skim milk and evenly smeared with 600 g mulberry leaves; (2) Group A2, fed with 60 mL of 9×10 10 cfu / mL Lactobacillus plantarum A2 was evenly applied on 600 g mulberry leaves; (3) Group A4 was fed with 60 mL of 9×10 10 cfu / mL of Pediococcus acidilactici A4 was evenly applied on 600g of mulberry leaves; (4) Group A5 was fed with 60 mL of 9×10 10 cfu / mL Lactobacillus acidophilus A5 was evenly applied on 600 g mulberry leaves; (5) Group A8 was fed with 60 mL of 9×10 10 cfu / mL Lactobacillus rhamnosus A53 was evenly applied on 600g mulberry leaves; (6) Group A8 was fed with 60 mL of 9×1010 cfu / mL Lactobacillus rhamnosus A53 was evenly applied on 600g mulberry leaves; (7) AP group: 60 mL of 0.25 mg / mL allopurinol solution prepared with skim milk was added to the diet and evenly applied on 600 g of mulberry leaves.

[0052] Each group was given medication once every morning, and after the silkworms had eaten the mulberry leaves smeared with skim milk, they were allowed to fully eat fresh mulberry leaves. Hemolymph was collected on the 2nd, 4th, and 6th days of feeding at the fifth instar, and the uric acid concentration was measured using a uric acid analyzer. The content of xanthine oxidase (XOD), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) in the hemolymph samples was detected using an analytical kit.

[0053] The results showed that during the second to sixth day of the fifth instar, the uric acid level in the silkworm group treated with AP was significantly lower than that in the control group. This finding supports that the effect of allopurinol in silkworms is consistent with clinical observations and confirms that silkworms can be used as a model to evaluate the effects of anti-hyperuricemia drugs.

[0054] (1) Effects of probiotics on uric acid in silkworm hemolymph: like Figure 3 As shown in the figure, on the second day of the fifth instar, the uric acid content in the silkworms of AP, A2, A5, A8 and A9 groups was significantly lower than that of the blank group (P < 0.05), while there was no significant difference between the A4 group and the blank group (P > 0.05). On the fourth day of the fifth instar, compared with the blank group, the uric acid content in the AP, A4, A5, A8 and A9 groups was significantly reduced (P < 0.05), while there was no significant difference in the A2 group (P > 0.05). Until the sixth day of the fifth instar, the uric acid levels in CK, AP, A2, A4, A5, A8 and A9 were 1.92 mol / L, 1.14 mol / L, 1.83 mol / L, 1.76 mol / L, 1.37 mol / L, 0.955 mol / L and 1.52 mol / L, respectively. The uric acid levels in each group were significantly lower than those in the first four days. This may be because the silkworms are in a period of overeating in the first four days of the fifth instar, and their food intake begins to gradually decrease from the fifth day. Some silkworms gradually mature and stop eating, gradually excreting metabolites from their bodies until they spin silk on the cocoon and finally make cocoons. However, compared with the blank group, the uric acid levels in AP, A5 and A8 groups were still significantly reduced (P < 0.05), while there were no significant differences in A2, A4 and A9 groups. Among them, the uric acid value of A8 decreased most significantly, which was 50.26% lower than that of the CK group and lower than that of the AP group, indicating that A8 has the most significant regulatory effect on the uric acid level of silkworms.

[0055] (2) The uric acid-lowering properties of the above-mentioned probiotics were further tested. The effects of probiotics on uric acid in silkworm feces were as follows: Figure 4As shown. The uric acid content in the feces of silkworms in the CK group, AP group, A2 group, A4 group, A5 group, A8 group, and A9 group was 0.043 mmol / L, 0.007 mmol / L, 0.053 mmol / L, 0.062 mmol / L, 0.086 mmol / L, 0.113 mmol / L, and 0.057 mmol / L, respectively. The uric acid concentration in the A8 group was the highest, and the AP group was the lowest, and there were significant differences among the four groups (P < 0.05). This shows that strain A8 effectively promotes the excretion of uric acid in the intestine, thereby indirectly reducing the concentration of uric acid in serum and reducing the burden on the kidneys and liver.

[0056] (3) Test on the effect of probiotics on the activity of xanthine oxidase in silkworm: Xanthine oxidase is a molybdenum enzyme that can oxidize hypoxanthine to xanthine and further oxidize xanthine to uric acid, which is of vital importance in the nitrogen metabolism process. Figure 5 As shown in the results, the xanthine oxidase activities of the CK group, AP group, A2 group, A4 group, A5 group, A8 group and A9 group were 0.064mmol / min / mL, 0.033mmol / min / mL, 0.052mmol / min / mL, 0.047mmol / min / mL, 0.044mmol / min / mL, 0.035mmol / min / mL and 0.045mmol / min / mL, respectively. There were significant differences between the CK group and the AP group, A2 group, A4 group, A5 group, A8 group and A9 group (P<0.05), while there was no significant difference between the A8 group and the AP group (P>0.05). Compared with the CK group, the xanthine oxidase activity decreased by 45.31%. Therefore, A8 can control the synthesis of uric acid by inhibiting the activity of xanthine oxidase, thereby reducing the level of uric acid.

[0057] (4) Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are indicators for evaluating liver function and diagnosing liver diseases. When liver cells are damaged or destroyed, the integrity of the cell membrane is destroyed, causing AST and ALT to be released into the surrounding tissue fluid and blood, thereby increasing the levels of AST and ALT in the blood. The effects of various strains on AST and ALT in silkworm hemolymph samples are shown in Table 4.

[0058] Table 4:

[0059] There were no significant differences in AST and ALT between the treatment groups (P>0.05), but the AST and ALT levels of silkworms in the allopurinol group were slightly higher than those in the CK, A2, A4, A5, A8 and A9 groups, probably because allopurinol caused slight damage to the fat body of silkworms. Such results are consistent with the clinical effects, further supporting the feasibility of silkworms as a model for anti-hyperuricemia drug screening. And the strain SWU-MY69 with excellent uric acid-lowering effect was screened.

Claims

1. A strain of uric acid-lowering probiotics obtained by high-throughput screening based on a silkworm model, characterized in that: The probiotic is strain SWU-MY69, classified as Pediococcus pentosaceus ( Pediococcus pentosaceus ), which is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.31926 and the deposit date September 10, 2024.

2. Use of the strain SWU-MY69 as claimed in claim 1 in the preparation of uric acid-lowering drugs.

3. Use of the strain SWU-MY69 as claimed in claim 1 in preparing uric acid-lowering food.

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