Pediococcus acidilactici MR21 and application thereof

Abstract

The invention belongs to the technical field of functional microorganisms, and provides pediococcus acidilactici MR21 and application thereof. The pediococcus acidilactici MR21 provided by the invention is preserved in the China General Microbiological Culture Collection Center (CGMCC) on December 3, 2024, and the preservation number is CGMCC NO. 32896. The pediococcus acidilactici MR21 disclosed by the invention has efficient in-vitro cholesterol removal capacity, excellent safety and remarkable probiotic characteristics, and has the effects of restoring liver functions, reducing liver fat accumulation and regulating expression of fat and cholesterol metabolism related genes by remarkably reducing the content of serum total cholesterol and low-density lipoprotein cholesterol. Therefore, the function of relieving hypercholesterolemia is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional microorganisms, and particularly relates to a strain of Pediococcus acidilactici MR21 and its application in lowering cholesterol and alleviating hypercholesterolemia. Background Art

[0002] With the rise and prevalence of fast food and instant food culture in modern society, various diseases are becoming increasingly common, with a growing trend of younger people becoming increasingly vulnerable. Among them, hypercholesterolemia, induced by genetic factors and excessive cholesterol and fat intake, has become a major health threat. Hypercholesterolemia not only leads to atherosclerosis and cardiovascular disease, but also increases the risk of metabolic diseases such as diabetes and fatty liver. Cholesterol, in particular, is the "raw material" for the formation of atherosclerotic plaques. Numerous studies have confirmed that lowering cholesterol levels can significantly reduce the risk of cardiovascular and cerebrovascular diseases. Currently, drug intervention remains the mainstay of treatment for hypercholesterolemia, primarily including statins, bile acid sequestrants, fibrates, niacin, and drugs that inhibit cholesterol absorption. However, these drugs generally require long treatment courses and are expensive. Long-term use can also cause side effects such as liver and kidney damage and gastrointestinal discomfort.

[0003] Lactic acid bacteria have excellent safety and probiotic properties. A large number of studies have shown that lactic acid bacteria have multiple functions such as improving intestinal flora, preventing diarrhea, and enhancing the body's immunity and antioxidant capacity. In addition, the role of lactic acid bacteria in lowering cholesterol and alleviating hypercholesterolemia has been confirmed by research. Compared with drug treatment of hypercholesterolemia, intervention with lactic acid bacteria has the significant advantages of being precise, efficient and without side effects. Breast milk is rich in lactic acid bacteria and is a treasure trove of natural lactic acid bacteria resources. Accurately screening and discovering lactic acid bacteria that can efficiently remove cholesterol from breast milk is of great significance for enriching the new functional microbial resource library and exploring safe and efficient treatment options for metabolic diseases. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a strain of Pediococcus acidilactici MR21, which has high efficiency in vitro cholesterol clearance ability, excellent safety and significant prebiotic properties. It can alleviate hypercholesterolemia by significantly reducing serum total cholesterol and low-density lipoprotein cholesterol levels, restoring liver function, reducing liver fat accumulation, and regulating the expression of genes related to fat and cholesterol metabolism.

[0005] The technical solution of the present invention is: A strain of Pediococcus acidilactici MR21 ( Pediococcus acidilactici), the bacteria was screened from breast milk and was deposited in the General Microbiology Center of China Culture Collection Administration on December 4, 2024. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. Its deposit number is CGMCC NO. 32896, and its classification name is: Pediococcus acidilactici Pediococcus acidilactici .

[0006] Preferably, the full-length sequence of 16S rDNA of Pediococcus acidilactici MR21 is shown as SEQ ID No: 1.

[0007] The upstream primer and downstream primer for amplifying the nucleotide sequence shown in SEQ ID NO: 1 are: 5'-GAGAGTTTGATCCTGGCTCAG-3' and 5'-AAGGAGGTGATCCAGCCGCA-3'.

[0008] The application of the above-mentioned Pediococcus acidilactici MR21 in the preparation of cholesterol-lowering products and products for alleviating hypercholesterolemia is also the key protection content of the present invention.

[0009] Preferably, the above-mentioned product is a medicine.

[0010] The above-mentioned products can alleviate hypercholesterolemia by reducing serum total cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase and aspartate aminotransferase levels, restoring serum high-density lipoprotein cholesterol levels, reducing liver fat accumulation, and regulating the expression of FAS, SCD1, ACC, HMGCR, CPT1 and CYP7A1 in the fat and cholesterol metabolic pathways, thereby improving hypercholesterolemia.

[0011] The Pediococcus acidilactici provided by the present invention has the following advantages and effects: (1) The in vitro cholesterol clearance rate of Pediococcus acidilactici MR21 provided by the present invention was as high as 56.66% as determined by o-phthalaldehyde colorimetry; (2) The Pediococcus acidilactici MR21 provided by the present invention is non-hemolytic, sensitive to multiple antibiotics, and has good acid and bile salt resistance, and has excellent overall safety and probiotic properties; (3) The Pediococcus acidilactici MR21 provided by the present invention can significantly reduce the serum total cholesterol and low-density lipoprotein cholesterol levels in hypercholesterolemia mice and restore the serum high-density lipoprotein cholesterol level; (4) The Pediococcus acidilactici MR21 provided by the present invention can significantly reduce the serum alanine aminotransferase and aspartate aminotransferase levels in hypercholesterolemia mice and significantly reduce liver fat accumulation; (5) The lactic acid bacteria MR21 provided by the present invention can alleviate hypercholesterolemia by regulating the expression of FAS, SCD1, ACC, HMGCR, CPT1 and CYP7A1 in the fat and cholesterol metabolic pathways. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the hemolytic detection chart of Pediococcus acidilactici MR21; Figure 2 Four indicators of blood lipids in mice in each treatment group: (A) serum total cholesterol (TC) level; (B) serum triglyceride (TG) level; (C) serum low-density lipoprotein cholesterol (LDL-C) level; (D) serum high-density lipoprotein cholesterol (HDL-C) level; * p < 0.05; ** p < 0.01; *** p < 0.001; Figure 3 Liver function indicators of mice in each treatment group: (A) serum total bile acid (TBA) level; (B) serum alanine aminotransferase (ALT) level; (C) serum aspartate aminotransferase (AST) level; All data are expressed as mean ± standard error (SEM); *p < 0.05; **p < 0.01; ***p < 0.001; Figure 4 The following are Oil Red O staining images of liver sections of mice in each treatment group: ND: normal diet group; HCD: high cholesterol group; PAM: high cholesterol + MR21 group; Prav: high cholesterol + pravastatin group; Figure 5 The results of qRT-PCR detection of livers of mice in each treatment group, (A) genes related to fat and cholesterol metabolism; (B) genes related to inflammation; ND: normal diet group; HCD: high cholesterol group; PAM: high cholesterol + MR21 group; Prav: high cholesterol + pravastatin group * p < 0.05; ** p < 0.01; *** p < 0.001. DETAILED DESCRIPTION

[0013] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in conjunction with specific embodiments.

[0014] Example 1 Screening of Pediococcus acidilactici MR21 The bacteria are screened from breast milk, and the specific screening process is as follows: Sample enrichment: 1 ml of breast milk sample was added to MRS liquid culture medium and cultured at 37°C for 48 hours; Screening of lactic acid bacteria strains: Strains were isolated using the dilution plate method. First, the enriched bacterial solution was serially diluted and plated onto MRS-CaCO3 medium. The plates were incubated at 37°C for 48 hours. Strains with calcium-soluble rings were selected based on colony morphology, color, size, and other characteristics, and then purified by triple streaking. Preservation of bacterial strains: Add the activated bacterial solution and 30% glycerol in equal proportions into a bacterial preservation tube and store it at -80℃.

[0015] Example 2 Determination of cholesterol clearance ability of strains in vitro Prepare cholesterol stock solution: Accurately weigh 0.2 g cholesterol and 0.4 g porcine bile salt into a beaker, add a small amount of anhydrous ethanol and fully dissolve, then dilute to 50 mL to make the final concentration of cholesterol 4 g / L and bile salt 8 g / L.

[0016] Prepare cholesterol medium MRS-CHOL: Filter-sterilize the cholesterol mother solution and add 5% by volume to sterilized MRS liquid medium to make the final cholesterol concentration in the MRS liquid medium 0.2 g / L and the final bile salt concentration 0.4 g / L.

[0017] Prepare o-phthalaldehyde working solution (1 mg / mL): Accurately weigh 50.0 mg of o-phthalaldehyde, dilute to 50 mL with anhydrous ethanol, and refrigerate at 4°C until use.

[0018] Prepare a mixed acid solution: thoroughly mix sulfuric acid and glacial acetic acid in a volume ratio of 1:1 to prepare a mixed acid solution.

[0019] The strains to be tested, screened from breast milk, were streaked and activated on MRS-CaCO3 plates. A single colony was placed in MRS liquid medium and incubated at 37°C for 24 hours. A 5% inoculum was then inoculated into MRS-CHOL medium. A 5% blank sterile medium was added to the MRS-CHOL medium as a control and incubated at 37°C for 24 hours. After 24 hours of incubation, the bacterial and control solutions (collectively referred to as the test solutions) were subjected to the following procedures: ① Take 1 mL of the test solution and centrifuge at 8000 r / min for 10 min, then take the supernatant; ② Mix 80 μL of supernatant with 32 μL of o-phthalaldehyde solution, add 688 μL of mixed acid solution, mix well and let stand for 30 minutes for color development, and measure the absorbance at 550 nm. Each group should be repeated three times.

[0020] Substitute the absorbance value into the standard curve formula to calculate the cholesterol concentration.

[0021] Cholesterol clearance rate (%) = (CA) / C × 100% Where, C is the cholesterol content corresponding to the absorbance value at 550nm wavelength of the control group; A is the cholesterol content corresponding to the absorbance value of the test strain at a wavelength of 550nm.

[0022] After testing, MR21 showed the highest in vitro cholesterol clearance rate of all tested strains, reaching 56.66%. Morphological and molecular biological identification confirmed that the strain was Pediococcus acidilactici and named Pediococcus acidilactici MR21. Pediococcus acidilactici MR21 was deposited with the General Microbiology Center of the China Culture Collection Administration on December 4, 2024, at No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number CGMCC No. 32896.

[0023] Example 3 Safety Assessment of Pediococcus acidilactici MR21 3.1 Hemolysis assay Sterile defibrinated sheep blood was added to sterilized Columbia blood agar at a ratio of 5% (V / V) to prepare blood agar plates.

[0024] Staphylococcus aureus (positive control) and Pediococcus acidilactici MR21 were spotted on different areas on the surface of Columbia blood agar medium. After constant temperature incubation at 37°C for 48 hours, the changes around the colonies were observed.

[0025] By the attached Figure 1 It can be seen that Staphylococcus aureus, a positive control, has a transparent hemolytic ring around it, while Pediococcus acidilactici MR21 does not have a hemolytic ring around it, indicating that it is non-hemolytic.

[0026] 3.2 Antibiotic sensitivity test Evenly spread the activated Pediococcus acidilactici MR21 bacterial suspension onto the surface of MRS solid culture medium. Then, divide the plate into five equal areas, each corresponding to an antibiotic. Place a drug-susceptibility paper disc in the center of each area. After incubation at 37°C for 48 hours, observe and record the size of the inhibition zone. The antibiotic susceptibility of the strain is determined based on the diameter of the inhibition zone.

[0027] The results of antibiotic sensitivity tests are shown in Table 1 below. Table 1 Antibiotic sensitivity test results

[0028] As shown in Table 1 above, Pediococcus acidilactici MR21 was sensitive or moderately sensitive to a variety of antibiotics including cefuroxime sodium and cefoperazone, and had good safety.

[0029] Example 4 Acid and bile resistance test of Pediococcus acidilactici MR21 4.1 Acid resistance test of strains Adjust the pH of MRS liquid medium to 3.0 using 1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution, inoculate MR21 bacterial liquid at a 3% (V / V) inoculation volume, mix thoroughly, and immediately take a portion for dilution and coating. The colony count at this time is the 0-hour viable count N0. After culturing at 37°C for 3 hours, take a sample for dilution and coating. The colony count at this time is the 3-hour viable count N3. The strain acid resistance is calculated as follows: Survival rate (%) = N3 / N0 × 100%. N0 is the number of colonies at 0 hours; N3 is the number of colonies after 3 hours of incubation. The unit for both N0 and N3 is CFU / mL.

[0030] The acid resistance of Pediococcus acidilactici MR21 is shown in Table 2: Table 2 Acid resistance of Pediococcus acidilactici MR21 strain number Strain survival rate (%) Pediococcus acidilactici MR21 102.85±10.85

[0031] As shown in Table 2, the survival rate of Pediococcus acidilactici MR21 under the culture condition of pH = 3 is as high as 102.85%, exceeding 100%, indicating that the strain can not only tolerate the culture condition of pH = 3, but also grow.

[0032] 4.2 Bile salt tolerance test First, prepare a bile salt stock solution with a bile salt content of 3% and filter sterilize it. Then, prepare a culture medium with a bile salt content of 0.3% using a ratio of bile salt stock solution to MRS liquid medium of 1:9.

[0033] The bacterial liquid of Pediococcus acidilactici MR21 was inoculated into a liquid culture medium with a bile salt concentration of 0.3% at an inoculum volume of 3% (V / V). After mixing, a sample was immediately taken for dilution and coating. The number of colonies at this time was the 0-hour viable count N0. After culturing at 37°C for 4 hours, a sample was taken for dilution and coating. The number of colonies at this time was the 4-hour viable count N4. The bile salt tolerance of Pediococcus acidilactici MR21 was determined by calculating its survival rate in a culture medium with a bile salt concentration of 0.3%. The calculation formula is as follows: Survival rate (%) = N4 / N0×100%.

[0034] Where N0 is the colony count at 0 hours; N4 is the colony count after 4 hours of incubation. The units of N0 and N4 are both CFU / mL.

[0035] Table 3 Bile salt tolerance of Pediococcus acidilactici MR21 strain number Strain survival rate (%) Pediococcus acidilactici MR21 105.94±16.31

[0036] As shown in Table 3, Pediococcus acidilactici MR21 exhibited excellent bile salt tolerance. Its survival rate exceeded 100% at a bile salt concentration of 0.3%, indicating that the strain was able to grow under these culture conditions.

[0037] Example 5 Artificial Simulated Gastrointestinal Fluid Experiment 5.1 Prepare simulated gastric fluid, simulated duodenal fluid, and simulated intestinal fluid Simulated gastric fluid: Add 3.0 g / L pepsin to sterile PBS buffer, adjust the pH to 3.0 with 1 mol / L HCl, and then filter sterilize with a 0.22 μm filter membrane.

[0038] Simulated duodenal fluid: Add 1% bile salts to sterile PBS buffer, adjust the pH to 8.0 with 0.1 mol / L NaOH, and filter sterilize with a 0.22 μm filter membrane.

[0039] Simulated intestinal fluid: Add 1.0 g / L trypsin and 0.3% bile salts to sterile PBS, adjust the pH to 8.0 with 0.1 mol / L NaOH, and filter sterilize with a 0.22 μm filter membrane.

[0040] 5.2 Experimental Process and Results Rinse Pediococcus acidilactici MR21 with sterile PBS to prepare a bacterial suspension. After dilution to an appropriate gradient, use the plate count method to count the viable bacteria (N0) at 0 h. Inoculate 10% of the bacterial suspension into simulated gastric fluid and incubate at 37°C for 2 h. Count the viable bacteria (N1). Inoculate 10% of the simulated gastric fluid culture into simulated duodenal fluid and incubate anaerobically at 37°C for 20 min. Count the viable bacteria (N2). Inoculate 10% of the simulated duodenal fluid culture into artificial intestinal fluid and incubate anaerobically at 37°C for 2 h. Count the viable bacteria (N3).

[0041] Survival rate in simulated gastric fluid (%) = N1 / N0 × 100%; Survival rate in simulated duodenal fluid (%) = N2 / N1 × 100%; Survival rate in simulated intestinal fluid (%) = N3 / N2×100%.

[0042] Wherein, the unit of N0, N1, N2, and N3 is CFU / mL.

[0043] Table 4 Experimental results of artificial simulated gastrointestinal fluid

[0044] As shown in Table 4, the survival rates of Pediococcus acidilactici MR21 in simulated gastric fluid, simulated duodenal fluid, and simulated intestinal fluid were all higher than 90%, indicating that the strain has good adaptability to the human gastrointestinal fluid environment and can maintain high activity in the human gastrointestinal fluid environment.

[0045] Example 6: Construction of a hypercholesterolemia mouse model and in vivo experiments 6.1 Model construction and experiments Seven-week-old SPF male C57BL / 6J mice were fed a standard maintenance diet and induced to develop hypercholesterolemia using a high-cholesterol diet. The mice were divided into three groups: a normal diet group, a high-cholesterol group, a high-cholesterol group with MR21, and a high-cholesterol group with pravastatin. Each group consisted of nine mice. The mice were fed the diets listed in Table 5 and received the test solution orally once daily for six weeks. During this period, the mice had free access to food and water.

[0046] Table 5 Experimental groups and feeding and gavage treatments Treatment group Feed type Oral gavage treatment Normal diet group Maintenance feed 0.2 mL normal saline High cholesterol group High cholesterol feed 0.2 mL normal saline High cholesterol + MR21 group High cholesterol feed 0.2 ml MR21 bacterial suspension (109 CFU / ml) High cholesterol + pravastatin group High cholesterol feed 0.2 mL pravastatin (3 mg / kg BW)

[0047] The health and food intake of mice were observed daily during the experiment, and body weight changes were recorded weekly. After the experiment, mice were fasted for 12 hours, but not water. Eyeballs were removed for blood collection, and serum was separated for analysis of four lipid profiles (total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C)) and liver function (total bile acid (TBA), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Liver samples were also collected for Oil Red O staining and qRT-PCR analysis (target genes and primer sequences are shown in Table 6 below).

[0048] Table 6 Target genes and primer sequences used for qRT-PCR detection and analysis target gene Amplification direction Primer sequences FAS Forward 5'-ATCCTGGCTGACGAAGACTC-3' Reverse 5'-TGCTGCTGAGGTTGGAGAG-3' SCD1 Forward 5'-ACCTGCCTCTTCGGGATTTT-3' Reverse 5'-CCATTCGTACACGTCATTCTGG-3' ACC Forward 5'-ATGCTATTTCTTTGTTTGGTCGT-3' Reverse 5'-CCCAGCACTCACATAACCAAC-3' HMGCR Forward 5'-TGATTACCCTGAGTTTAGCCTT-3' Reverse 5'-GGCTCACGTCTACAACAGT-3' CPT1 Forward 5'-GAGACAGACACCATCCACAC-3' Reverse 5'-GAGCCAGACCTTGAAGTAACG-3' CYP7A1 Forward 5'-ACAGAAGCATAGACCCAA-3' Reverse 5'-TGCCAAACAGCGTTAGAT-3' IL-6 Forward 5'-TCCAGCCAGTTGCCTTCTTG-3' Reverse 5'-GGTCTGTTGTGGGTGGTATCC-3' IL-1β Forward 5'-GAAATGCCACCTTTTGACAGTG-3' Reverse 5'-TGGATGCTCTCATCAGGACAG-3' TNF-α Forward 5'-CAGGCGGTGCCTATGTCTC-3' Reverse 5'-CGATCACCCCGAAGTTCAGTAG-3' IFN-γ Forward 5'-ACTGGCAAAAGGATGGTGAC-3' Reverse 5'-TGAGCTCATTGAATGCTT-3' GAPDH Forward 5'-CTCGTCCCGTAGACAAAATGGT-3' Reverse 5'-GAGGTCAATGAAGGGGTCGTT-3'

[0049] 6.2 Experimental Results and Analysis Table 7 Four indicators of blood lipids in mice in each treatment group Normal diet group High cholesterol group High cholesterol + MR21 group High cholesterol + pravastatin group Serum total cholesterol (mmol / L) 3.05±0.06*** 5.01±0.24 3.05±0.13*** 3.75±0.14*** Serum triglycerides (mmol / L) 1.18±0.05 1.10±0.20 1.14±0.14 1.39±0.11 Serum low-density lipoprotein cholesterol (mmol / L) 2.00±0.05*** 2.81±0.19 1.76±0.05** 1.43±0.10*** Serum high-density lipoprotein cholesterol (mmol / L) 5.78±0.12** 4.31±0.35 5.35±0.13* 7.75±0.24***

[0050] All data are expressed as the mean ± standard error of the mean (SEM). Data were analyzed using SPSS 26.0 software (IBM, USA) with Student's t-test (n ≥ 3). *P < 0.05 compared with the high cholesterol group; **P < 0.01 compared with the high cholesterol group; ***P < 0.001 compared with the high cholesterol group.

[0051] Table 8 Liver function indicators of mice in each treatment group Normal diet group High cholesterol group High cholesterol + MR21 group High cholesterol + pravastatin group Serum total bile acid (μmol / L) 7.97±0.94 6.49±0.59 7.98±0.52 9.19±0.90* Serum alanine aminotransferase (U / L) 7.94±0.50* 10.57±0.87 3.93±0.61*** 8.73±0.41 Serum aspartate aminotransferase (U / L) 3.07±0.63** 6.81±0.87 3.44±1.19 3.82±0.75*

[0052] All data are expressed as the mean ± standard error of the mean (SEM). Data were analyzed using SPSS 26.0 software (IBM, USA) with Student's t-test (n ≥ 3). *P < 0.05 compared with the high cholesterol group; **P < 0.01 compared with the high cholesterol group; ***P < 0.001 compared with the high cholesterol group.

[0053] Table 9 qRT-PCR test results of mouse liver in each treatment group Normal diet group High cholesterol group High cholesterol + MR21 group High cholesterol + pravastatin group FAS 1.00 ±0.02 1.75±0.19 0.68 ±0.06** 1.47±0.16 SCD1 1.01±0.09* 1.47±0.05 0.61±0.06*** 1.03±0.10* ACC 1.00±0.00* 1.12±0.03 0.68±0.04*** 0.99±0.12 HMGCR 1.10 ±0.01 2.36 ±0.34 0.97±0.06* 0.47±0.03* CPT1 1.00±0.04*** 0.66 ±0.02 1.27±0.06*** 0.85±0.07* CYP7A1 1.00±0.06 2.02±0.32 7.66±1.03** 6.42 ±1.37* IL-6 1.00±0.02 2.10±0.49 0.63 ±0.13* 4.35 ±0.88 IL-1β 1.00±0.06*** 4.07±0.07 2.10±0.36** 0.50±0.08*** TNF-α 1.00±0.02* 9.21±1.40 2.28±0.05* 1.23±0.14* IFN-γ 1.06 ±0.28* 15.38 ±2.92 3.77 ±0.05 6.73±0.32

[0054] All data are expressed as the mean ± standard error of the mean (SEM). Data were analyzed using SPSS 26.0 software (IBM, USA) with Student's t-test (n ≥ 3). *P < 0.05 compared with the high cholesterol group; **P < 0.01 compared with the high cholesterol group; ***P < 0.001 compared with the high cholesterol group.

[0055] The experimental results showed that compared with the normal diet group, the serum TC and LDL-C levels of the high cholesterol group mice were significantly increased, and the HDL-C level was significantly decreased, while the above indicators of the high cholesterol + MR21 group returned to normal levels, with no significant difference from the normal diet group (Appendix Figure 2 Compared with the normal diet group, the serum ALT and AST of mice in the high cholesterol group were significantly increased, indicating that the high cholesterol diet damaged liver function, while the ALT and AST of the high cholesterol + MR21 group were significantly decreased compared with the high cholesterol group (Appendix Figure 3 At the same time, the results of liver oil red O staining showed that the liver fat accumulation of mice in the high cholesterol group was serious, and a large amount of lipid droplets were observed, while the liver fat accumulation in the high cholesterol + MR21 group was significantly reduced (Appendix Figure 4 The above results indicate that Pediococcus acidilactici MR21 can significantly alleviate liver damage induced by a high cholesterol diet. The present invention also preliminarily explored the potential mechanism of MR21 in alleviating hypercholesterolemia (see Appendix). Figure 5 ), a study found that after six weeks of a high-cholesterol diet, the expression of SCD1, ACC, IL-1β, TNF-α, and IFN-γ genes in the liver of mice increased significantly. FAS, HMGCR, and IL-6 also increased, while CPT1 expression decreased significantly. MR21 significantly reversed the abnormal expression of FAS, HMGCR, SCD1, ACC, CPT1, IL-6, IL-1β, and TNF-α genes induced by a high-cholesterol diet, and alleviated the abnormal expression of IFN-γ. MR21 also significantly increased CYP7A1 gene expression in the liver. The genes encoding liver type I transmembrane glycoprotein (FAS) and stearoyl-CoA (SCD1) are lipogenesis genes, while the gene encoding carnitine palmitoyltransferase (CPT1) is involved in fatty acid oxidation. The gene encoding 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) is the rate-limiting enzyme in cholesterol synthesis. The gene encoding cholesterol 7α-hydroxylase (CYP7A1) is the rate-limiting enzyme in the classical bile acid biosynthesis pathway, catalyzing the hepatic breakdown of cholesterol into bile acids. In summary, MR21 may inhibit fat accumulation by inhibiting lipogenesis and promoting β-oxidation, while simultaneously lowering cholesterol levels by inhibiting cholesterol production and enhancing the conversion of cholesterol to bile acids, ultimately improving hypercholesterolemia.

[0056] In summary, the Pediococcus acidilactici MR21 provided by the present invention has the ability to efficiently clear cholesterol in vitro, has good safety and prebiotic properties; in addition, it can also alleviate hypercholesterolemia by lowering serum total cholesterol and low-density lipoprotein cholesterol levels, restoring liver function, reducing liver fat accumulation, and regulating the expression of genes related to fat and cholesterol metabolism.

[0057] The above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A strain of Pediococcus acidilactici MR21, characterized in that: The Pediococcus acidilactici MR21 ( Pediococcus acidilactici ) was deposited in the General Microbiology Center of China Culture Collection Administration on December 4, 2024. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, and the deposit number is CGMCC NO. 32896.

2. Use of the Pediococcus acidilactici MR21 according to claim 1 in preparing a cholesterol-lowering product.

3. Use of the Pediococcus acidilactici MR21 according to claim 1 in preparing a product for alleviating hypercholesterolemia.

4. The Pediococcus acidilactici MR21 according to claim 1, wherein The full-length sequence of 16S rDNA of Pediococcus acidilactici MR21 is shown in SEQ ID No: 1; The upstream primer and downstream primer for amplifying the nucleotide sequence shown in SEQ ID NO: 1 are: 5'-GAGAGTTTGATCCTGGCTCAG-3' and 5'-AAGGAGGTGATCCAGCCGCA-3'.

5. The use according to claim 2 or the use according to claim 3, characterized in that: The product described is a pharmaceutical product.

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