Bifidobacterium adolescentis YF-01 and application thereof in fermented milk

Abstract

The invention relates to the technical field of biological medicine, and discloses bifidobacterium adolescentis YF-01 and application thereof in fermented milk. The bifidobacterium adolescentis YF-01 is separated from adult excrement and is preserved in the China Center for Type Culture Collection, and the preservation number is CCTCC NO: M 20251308. Experiments prove that the bifidobacterium adolescentis YF-01 has good gastrointestinal fluid tolerance, the survival rate of the bifidobacterium adolescentis YF-01 can reach 90.1% after simulated gastric fluid treatment for 3 h, and the survival rate of the bifidobacterium adolescentis YF-01 can reach 72% after simulated intestinal fluid treatment for 4 h The strain has the self-aggregation rate of 88.83% and the hydrophobicity of 79.41%, has remarkable scavenging capacity on DPPH free radicals and hydroxyl free radicals, shows good antioxidant activity and adhesion capacity, and provides a theoretical basis for application of the strain in fermented milk. The strain and metabolites thereof can be used for preparing food, medicines or health care products capable of regulating intestinal flora and enhancing oxidation resistance, and have remarkable application potential in development of functional fermented milk products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological medicine, in particular to a Bifidobacterium adolescentis YF-01 and application thereof in fermented milk. BACKGROUND

[0002] Probiotics have important physiological functions on the body, such as adjusting intestinal flora balance, reducing cholesterol, resisting oxidation, resisting infection and enhancing human immunity, and have broad application prospects in the fields of food and medicine and health.

[0003] As the dominant microorganism in the gastrointestinal tract, Bifidobacterium plays an irreplaceable role in maintaining intestinal health. In recent years, various clinical, in vivo and in vitro studies have shown that Bifidobacterium can play an important role in inflammatory bowel disease, irritable bowel syndrome, cancer, diarrhea, lactose intolerance and other diseases, and protect the integrity of the intestinal barrier, thereby maintaining the body in a healthy and stable state.

[0004] Fermented milk is rich in protein, calcium and various nutrients. After fermentation by lactic acid bacteria, protein is decomposed into peptides and amino acids, lactose is hydrolyzed into galactose and glucose and converted into lactic acid, and the fine clots formed are more conducive to gastrointestinal digestion and absorption, and are suitable for people with "lactose intolerance". At the same time, fermented milk performs well in regulating intestinal flora, preventing and treating diabetes, cardiovascular and cerebrovascular diseases, and liver diseases, and is a popular functional food.

[0005] As the dominant bacteria in the intestinal tract of healthy humans, Bifidobacterium adolescentis has various physiological functions. It can specifically induce Th17 cells in the intestinal tract, regulate immunity and not cause inflammation; supplementing Bifidobacterium adolescentis can reduce the sequelae of bone fracture, enhance intestinal barrier function, inhibit systemic inflammatory response, and accelerate bone fracture healing; its metabolites and antibacterial substances can antagonize pathogenic bacteria and promote the recovery of intestinal microecology. In addition, Bifidobacterium adolescentis can also treat chronic diarrhea and constipation, has anti-aging effect, can regulate intestinal flora, and relieve non-alcoholic fatty liver, metabolic syndrome, type 2 diabetes and other metabolic diseases. However, Bifidobacterium adolescentis has poor oxygen tolerance, is difficult to culture, is not resistant to high temperature and is easily contaminated, which limits its industrial development. At present, the key technical direction is to domesticate the strain to adapt to different physicochemical environments, protect the bacterial body to ensure sufficient number of viable bacteria, and develop products that meet the taste and nutritional needs of consumers. Application of Bifidobacterium adolescentis in fermented milk is expected to further improve the nutritional value and functional properties of fermented milk and meet the needs of consumers for healthy food. SUMMARY

[0006] The application aims to provide a Bifidobacterium adolescentis YF-01 and its application in fermented milk, the strain has excellent characteristics such as acid and bile salt tolerance and utilization of various carbohydrates, and is used for preparing fermented milk by compounding with commercial starter cultures to improve the viable cell count, texture, sensory quality and storage stability of the fermented milk.

[0007] To achieve the above-mentioned purpose, the application provides an application of a Bifidobacterium adolescentis YF-01 in preparing a product for regulating intestinal flora, promoting intestinal health or enhancing the antioxidant capacity of the body, the Bifidobacterium adolescentis YF-01 is preserved in the China Center for Type Culture Collection, the preservation number is CCTCC NO: M 20251308, the preservation time is June 9, 2025, the preservation address is Wuhan University in Wuhan, China, and the classification and naming is Bifidobacterium adolescentis YF-01, the 16S rDNA sequence of which is shown as SEQ ID NO. 1.

[0008] Further, the product includes fermented milk.

[0009] Further, when applied, the Bifidobacterium adolescentis YF-01 is compounded with a commercial starter culture PYS-010, and when applied to fermented milk, the fermentation time can be shortened, the texture and flavor of the fermented milk can be improved, and the viable cell count is high and the properties are stable during storage.

[0010] Further, when the Bifidobacterium adolescentis YF-01 is compounded with the commercial starter culture PYS-010, the inoculation amount of the Bifidobacterium adolescentis YF-01 is 1×10 6 CFU / mL, and the inoculation amount of the commercial starter culture PYS-010 is 0.03 ‰.

[0011] Further, the application also provides a product containing the viable cells, inactivated cells and / or metabolites of the above-mentioned Bifidobacterium adolescentis YF-01, and the viable cell count of the Bifidobacterium adolescentis YF-01 in the product is not less than 1×10 8 CFU / mL or 1×10 8 CFU / g.

[0012] Further, the product is fermented milk, dairy products or solid beverages.

[0013] Further, the product has the functions of regulating intestinal flora, promoting intestinal health or enhancing the antioxidant capacity of the body.

[0014] Further, the application also provides application of the secondary metabolites of Bifidobacterium adolescentis YF-01 in preparation of products for regulating intestinal flora, promoting intestinal health or enhancing antioxidant capacity of the body, wherein the secondary metabolites include Lucidenolactone, Ampeloside Bs1, Lucidenic acid F, one strain of Bifidobacterium adolescentis YF-01 is preserved in China Center for Type Culture Collection, the preservation number is CCTCC NO: M20251308, the preservation time is June 9, 2025, the preservation address is Wuhan University in Wuhan, China, and the classification and naming is Bifidobacterium adolescentis YF-01, and the 16S rDNA sequence is shown as SEQ ID NO. 1.

[0015] Further, in application, the viable cell count of the Bifidobacterium adolescentis YF-01 is not less than 1 x 10 8 CFU / mL or 1 x 10 8 CFU / g.

[0016] Further, the application also provides a product for regulating intestinal flora, promoting intestinal health or enhancing antioxidant capacity of the body, comprising the secondary metabolites of the above-mentioned Bifidobacterium adolescentis YF-01, and the product is a capsule, a tablet, a dry powder, a food or a beverage.

[0017] Therefore, the Bifidobacterium adolescentis YF-01 and the application thereof in fermented milk have the following beneficial effects:

[0018] The application provides a Bifidobacterium adolescentis YF-01, and the preservation number of the Bifidobacterium adolescentis YF-01 is CCTCC NO: M20251308. Experimental results prove that the Bifidobacterium adolescentis YF-01 has good tolerance to simulated gastrointestinal fluid, can shorten fermentation time and improve fermented milk quality when being compounded with commercial starter cultures, has suitable acidity, good water retention and viscosity, excellent texture characteristics and high viable cell count during storage period. The secondary metabolites include Lucidenolactone, Ampeloside Bs1 and Lucidenic acid F, can regulate body health, and the good performance in the fermentation process and the positive regulation on body health make the Bifidobacterium adolescentis YF-01 have great application prospect in preparation of products such as food or medicine with functions of regulating intestinal flora, promoting intestinal health and / or enhancing antioxidant capacity of the body. In addition, the Bifidobacterium adolescentis YF-01 belongs to intestinal beneficial bacteria and is in the list of food-grade bacterial strains, so the Bifidobacterium adolescentis YF-01 and products with the Bifidobacterium adolescentis YF-01 as the effective component have the advantage of food safety, and long-term use is beneficial to human health.

[0019] The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Phylogenetic tree of Bifidobacterium adolescentis YF-01;

[0021] Figure 2 Gram staining diagram of Bifidobacterium adolescentis YF-01;

[0022] Figure 3 A is the self-aggregation rate diagram of Bifidobacterium adolescentis YF-01, and B is the hydrophobicity diagram of Bifidobacterium adolescentis YF-01;

[0023] Figure 4 A is the DPPH clearance rate diagram of Bifidobacterium adolescentis YF-01, and B is the hydroxyl radical clearance rate diagram of Bifidobacterium adolescentis YF-01;

[0024] Figure 5 A is the metabolic PCA diagram of Bifidobacterium adolescentis YF-01 before and after fermentation, and B is the metabolic PLS-DA diagram of Bifidobacterium adolescentis YF-01 before and after fermentation, wherein YN is before fermentation, and B is after fermentation;

[0025] Figure 6 A is the metabolic volcano diagram of Bifidobacterium adolescentis YF-01 before and after fermentation (gray for no significant change in metabolites, red for up-regulated metabolites, and purple for down-regulated metabolites, and the darker the color, the more significant the change), and B is the metabolic bubble diagram of Bifidobacterium adolescentis YF-01 before and after fermentation (the size of the circle represents the number of metabolites in the pathway, and the color represents the size of the p value, the smaller the p value, the more red the color, indicating the more significant enrichment);

[0026] Figure 7 A is the starch and sucrose metabolic pathway of Bifidobacterium adolescentis YF-01 before and after fermentation, B is the galactose metabolic pathway, C is the pyruvate metabolic pathway, and D is the pyruvate metabolic pathway diagram;

[0027] Figure 8 A is the metabolic PCA diagram of Bifidobacterium adolescentis YF-01 and the mixed group of commercial starters, and B is the metabolic PLS-DA diagram of Bifidobacterium adolescentis YF-01 and the mixed group of commercial starters, wherein B is the mixed group of Bifidobacterium adolescentis and commercial starters, and S is the group of commercial starters;

[0028] Figure 9A is the metabolic volcano of B. adolescentis YF-01 during storage, B is the metabolic bubble plot of B. adolescentis YF-01 during storage (the size of the dot represents the number of metabolites in the pathway, and the color represents the size of the p value, the smaller the p value, the more significant the color, indicating the degree of enrichment);

[0029] Figure 10 A is the change of pH of B. adolescentis YF-01 during storage, B is the change of pH of B. adolescentis YF-01 during storage titration acidity change;

[0030] Figure 11 B. adolescentis YF-01 during storage;

[0031] Figure 12 A is the change of water holding capacity of B. adolescentis YF-01 during storage, B is the change of water holding capacity of B. adolescentis YF-01 during storage change of viscosity;

[0032] Figure 13 B. adolescentis YF-01 during storage;

[0033] Figure 14 B. adolescentis YF-01 before and after storage of fermented milk principal component analysis chart;

[0034] Figure 15 B. adolescentis YF-01 before and after storage of fermented milk heat map cluster analysis;

[0035] Figure 16 B. adolescentis YF-01 before and after storage of fermented milk differential metabolites metabolic pathway enrichment chart;

[0036] Figure 17 B. adolescentis YF-01 TIC chart, A is in anion mode, B is in cation mode; blue is total ion flow chart, pink is XIC chart after dynamic background subtraction.

[0037] Biological material preservation information

[0038] B. adolescentis YF-01, B. adolescentis YF-01 is preserved in China Center for Type Culture Collection, the preservation number is CCTCC NO: M 20251308, the preservation time is June 9, 2025, the preservation address is Wuhan University, Wuhan, China, and the classification and naming is Bifidobacterium adolescentis YF-01. DETAILED DESCRIPTION

[0039] The technical solutions of the present application are further described below by means of the drawings and examples. Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those with ordinary skills in the art to which the present application pertains. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present application. The experimental methods in the following examples, unless otherwise specified, are generally determined according to national standards. The experimental instruments, equipment and reagents in the following examples, unless otherwise specified, are all commercially available raw materials.

[0040] Unless otherwise defined or explained, all professional and scientific terms used in the present application have the same meanings as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to those described can be applied in the method of the present application. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict.

[0041] The detection method of viable bacterial count involved in the following examples is: using the national standard "GB 4789.35-2016 Food Safety National Standard Food Microbiological Detection Lactic Acid Bacteria Detection".

[0042] The Bifidobacterium adolescentis YF-01 of the present application is isolated from the feces of a volunteer, which has been preserved in the China Center for Type Culture Collection on June 9, 2025, with the preservation number of CCTCC NO: M 20251308, the preservation address of Wuhan University in Wuhan, China, and the classification and naming of Bifidobacterium adolescentis YF-01.

[0043] Example 1: Isolation and identification of Bifidobacterium adolescentis YF-01

[0044] 1.1 Isolation of Bifidobacterium adolescentis YF-01.

[0045] The collected volunteer feces were plated to isolate the strain. First, the sample was diluted by a factor of 10, 10 -5 and 10 -6 Diluted gradient sample 200 μL was uniformly plated in RCM solid culture medium flat dishes, and after uniform plating, it was placed in an anaerobic tank with an anaerobic gas production bag and taken back to the laboratory. Anaerobic culture was carried out at 37℃ in an A35 anaerobic workstation (80% N2, 10% H2, 10% CO2) for 72-96h. Single colonies with different morphologies, sizes and colors were picked and inoculated in liquid culture medium, and incubated in a 37℃ constant temperature incubator for 24-36h. After the strain grew well, gram staining and microscopic examination were performed. The isolated strain was preserved, and the strain genomic DNA was extracted for subsequent determination and analysis.

[0046] The composition of RCM medium is: 10 g of proteose peptone, 10 g of beef extract powder, 3 g of yeast powder, 5 g of glucose, 1 g of soluble starch, 5 g of sodium chloride, 3 g of sodium acetate, 0.5 g of L-cysteine hydrochloride, 1 L of distilled water, pH is adjusted to about 6.8, 15 g of agar, sterilized at 121°C for 15 min.

[0047] 1.2 physiological and biochemical identification, 16S rRNA molecular identification.

[0048] The frozen test strain was inoculated in ML liquid medium and incubated at 37°C for 24-36 h, and then subcultured for 2-3 generations. 30 mL of bacterial culture at the end of logarithmic growth was centrifuged in a sterile tube at 8000 x g for 5 min (4°C), and the bacterial cells were collected. The supernatant was discarded, and the genomic DNA of the strain was extracted by the CTAB freeze-thaw method.

[0049] The composition of the ML liquid medium is: 10 g of proteose peptone, 4 g of yeast extract powder, 8 g of beef extract powder, 20 g of glucose, 5 g of anhydrous sodium acetate, 2 g of citric acid triamine, 2 g of dimethyl hydrogen phosphate, 1 mL of Tween-80, 0.2 g of magnesium sulfate heptahydrate, 0.05 g of manganese sulfate tetrahydrate, 1 L of distilled water, 0.5 g of L-cysteine salt, pH is adjusted to about 6.2, sterilized at 21°C for 15 min.

[0050] The isolated strain was subjected to physiological and biochemical identification and 16S rRNA molecular identification. According to the "Berger Bacterium Identification Manual", the bacterial API50CH (Biomerieux Company) was used for identification. The DNA sample of the strain was extracted, and the sample was subjected to 16S rRNA molecular identification by Shanghai Meiji Biomedicine Technology Co., Ltd. The molecular sequence was compared by blastn in NCBI database, and it was confirmed that Bifidobacterium adolescentis YF-01 was Bifidobacterium adolescentis YF-01, and its 16S rRNA sequence is shown in SEQ ID NO. 1.

[0051] SEQ ID NO. 1

[0052] TGTGGGGGGGGTCTACCATGCAGTCGACGGGATCCCAGGAGCTTGCTCCTGGGTGAGAGTGGCGAACGGGTGAGTAATGCGTGACCGACCTGCCCCATACACCGGAATAGCTCCTGGAAACGGGTGGTAATGCCGGATGCTCCAGTTGACCGCATGGTCCTCTGGGAAAGCTTTTGCGGTATGGGATGGGGTCGCGTCCTATCAGCTTGATGGCGGGGTAACGGCCCACCATGGCTTCGACGGGTAGCCGGCCTGAGAGGGCGACCGGCCACATTGGGACTGAGATACGGCCCAGACTCCTACGGGAGGCAGCAGTGGGGAATATTGCACAATGGGCGCAAGCCTGATGCAGCGACGCCGCGTGCGGGATGACGGCCTTCGGGTTGTAAACCGCTTTTGACTGGGAGCAAGCCCTTCGGGGTGAGTGTACCTTTCGAATAAGCACCGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGGTGCAAGCGTTATCCGGAATTATTGGGCGTAAAGGGCTCGTAGGCGGTTCGTCGCGTCCGGTGTGAAAGTCCATCGCTTAACGGTGGATCCGCGCCGGGTACGGGCGGGCTTGAGTGCGGTAGGGGAGACTGGAATTCCCGGTGTAACGGTGGAATGTGTAGATATCGGGAAGAACACCAATGGCGAAGGCAGGTCTCTGGGCCGTCACTGACGCTGAGGAGCGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGGTGGATGCTGGATGTGGGGACCATTCCACGGTCTCCGTGTCGGAGCCAACGCGTTAAGCATCCCGCCTGGGGAGTACGGCCGCAAGGCTAAAACTCAAAGAAATTGACGGGGGCCCGCACAAGCGGCGGAGCATGCGGATTAATTCGATGCAACGCGAAGAACCTTACCTGGGCTTGACATGTTCCCGACAGCCGTAGAGATACGGTCTCCCTTCGGGGCGGGTTCACAGGTGGTGCATG.

[0053] 1.3 Colony morphological characteristics.

[0054] The Bifidobacterium adolescentis YF-01 of the present application forms a round, convex, rough, opaque colony with uneven edges, with a diameter of 1-2 mm on RCM solid medium.

[0055] In a clean bench, the purified Bifidobacterium slurry was smeared with an inoculating loop, and after drying, it was subjected to Gram staining. Figure 2 ).

[0056] The Bifidobacterium adolescentis YF-01 of the present application has the following morphological characteristics: the bacterial body is observed under a microscope to be short root-shaped, with rounded ends, arranged singly or in clusters.

[0057] 1.4 Optimum growth temperature and pH.

[0058] The Bifidobacterium adolescentis YF-01 was inoculated at 2% (v / v) in ML liquid medium for activation, and temperature gradients of 28, 32, 37, 41, and 45°C were set, with a pH of 6.0, and after constant temperature culture for 24 h, the OD value was determined at 600 nm, and three groups of parallel were set for each temperature condition to determine the optimum growth temperature range. The pH gradient of the ML medium was set to 4, 5, 6, 7, 8, and 9, and the strain was inoculated at 2% (v / v) in the ML liquid medium for activation, and the inoculated ML liquid medium was incubated at 37°C for 24 h, and the OD value was determined at 600 nm, and three groups of parallel were set for each pH condition to determine the optimum pH for growth of the strain. From the experimental results, the optimum growth temperature of the Bifidobacterium adolescentis YF-01 was 37°C, and the optimum growth pH was 7.0. Cy5.5-NH2 and GRb1 nanoparticles were mixed at a ratio of 1:10. The mixture was ultrasonicated at room temperature and stirred in the dark overnight. Then the solution was transferred to an ultrafiltration tube with a molecular weight cutoff of 3000 Da. After centrifugation at 6000 rpm for 10 minutes, the upper solution was collected for further use.

[0059] 1.5 Carbohydrate utilization.

[0060] Bifidobacterium adolescentis YF-01 was inoculated into ML liquid medium at 2% (v / v) and activated for 2 passages at the optimum temperature and pH, then centrifuged for 10 min, the bacterial slurry was collected, and the bacterial slurry was repeatedly washed with 0.85% sterile normal saline and centrifuged until no residue was left. The small grooves in the culture box were first filled with sterile distilled water to create a humid environment. The bacterial solution was taken and added to sterile normal saline, shaken uniformly, and then compared with the turbidity tube. After the turbidity was consistent, the bacterial solution was inoculated into an ampoule containing the culture medium, then the inoculated culture medium was added to the tube of the reagent strip according to the API 50CHL operation instruction manual, and the tube was sealed with sterile liquid stone alcohol. After anaerobic culture at the optimum temperature for 48 h, the results were observed and the color change of the reagent strip was recorded by taking pictures, and the carbon metabolism ability of the strain was judged.

[0061] The API 50CHL carbon utilization results of the strain showed that Bifidobacterium adolescentis YF-01 could utilize 18 kinds of carbohydrates, which were D-xylose, D-galactose, D-glucose, D-fructose, sorbitol, methyl-α-D-glucopyranoside, amygdalin, salicin, maltose, D-lactose, inulin, D-raffinose, starch, glycogen, D-gentio-biose, and D-turanose.

[0062] 1.6 Gastrointestinal fluid tolerance of Bifidobacterium adolescentis YF-01.

[0063] Preparation method of simulated gastrointestinal fluid: after sterilization of PBS, adjust the pH value to 2.5 with 1 mol / L HCL, add 3.0 mg / ml pepsin, filter sterilization with 0.22 μm microporous filter membrane, and prepare simulated artificial gastric juice; after sterilization of PBS, adjust the pH value to 8.0 with 0.1 mol / L NaOH, add 0.1% trypsin and 1.8% oxgall, filter sterilization with 0.22 μm microporous filter membrane, and prepare artificial simulated pancreatic juice.

[0064] Gastrointestinal fluid tolerance: the isolated and purified strain was activated and cultured for two generations, centrifuged and washed twice, and the bacterial cells were collected. 0.5 mL of the rescreening bacterial suspension was added to 4.5 mL of pH 2.5 simulated artificial gastric juice, and the viable cell count was determined by the ML solid culture medium pouring method at 0 h and 3 h at 37°C. Then, 0.5 mL of the 3 h digested artificial bacterial-containing gastric juice was added to 4.5 mL of artificial intestinal juice, and the culture was continued at 37°C in a water bath. The viable cell count was determined by the ML solid culture medium pouring method at 4 h and 8 h, and each sample was done in quadruplicate. The survival rate = [N1 / N0] x 100%. Wherein, N0 represents the viable cell count at 0 h; N1 represents the viable cell count after simulated digestion for 3 h or 8 h.

[0065] Tolerance effect: After Bifidobacterium adolescentis YF-01 was treated with simulated gastric fluid and simulated intestinal fluid, the results are shown in Table 1 below:

[0066] Table 1 Survival of Bifidobacterium adolescentis YF-01 in simulated gastrointestinal digestive fluid

[0067] Strain Survival rate in simulated gastric juice (pH 2.5, 3 h) (%) Survival rate in simulated intestinal juice (pH 8.0, 4 h) (%) Bifidobacterium adolescentis YF-01 90.1 72

[0068] As shown in Table 1, Bifidobacterium adolescentis YF-01 has good tolerance, with a survival rate of 72% after 4 hours of treatment with simulated intestinal fluid. The gastrointestinal fluid tolerance effect of this example shows that Bifidobacterium adolescentis YF-01 has good tolerance to gastrointestinal fluid in the intestine and has probiotic properties.

[0069] 2.1 Self-aggregation ability of Bifidobacterium adolescentis YF-01.

[0070] Self-agglutination of strains refers to the phenomenon that bacteria of the same species aggregate with each other to form multicellular clusters. Figure 3 From Figure A, we can see that the self-aggregation rate of Bifidobacterium adolescentis YF-01 is higher, significantly higher than that of the other three strains (P<0.05), with a self-aggregation rate of 88.83%, which indicates that the tested strain has a strong adhesion ability.

[0071] 2.2 Hydrophobicity of Bifidobacterium adolescentis YF-01.

[0072] The strength of probiotic adhesion ability is a prerequisite for its probiotic effect, so determining the initial screening index of probiotic adhesion is of great significance for the research of probiotics. Figure 3 From B, we can see that the hydrophobicity of Bifidobacterium adolescentis YF-01 is significantly higher than that of the other three strains (P<0.05), accounting for 79.41%, and has a better intestinal colonization ability.

[0073] 2.3 DPPH free radical scavenging ability of Bifidobacterium adolescentis YF-01.

[0074] DPPH free radical is a very stable artificially synthesized nitrogen-centered free radical. The DPPH method is a very common and effective method for screening and evaluating antioxidant effects. Figure 4 A shows that the fermentation supernatant of YF-01 has the highest DPPH scavenging capacity of 60.32%. The fermentation supernatant of the same strain has a significantly higher DPPH scavenging capacity than the cell suspension (P < 0.05).

[0075] 2.4 Hydroxyl radical scavenging ability of Bifidobacterium adolescentis YF-01.

[0076] Hydroxyl free radicals are the most active and oxidizing free radicals. They have a strong binding ability to DNA, proteins and lipids, and are the main factor causing oxidative damage in the body.Figure 4 The scavenging rate of the fermentation supernatant of the strains with different B was significantly lower than that of the positive control VC group (P<0.05), and the scavenging rate of the strains on hydroxyl radicals was more than 65%, and the scavenging rate of YF-01 was the highest, which was 67.51%. The scavenging rate of the cell suspension of different strains on hydroxyl radicals was significantly different, and the scavenging rate was significantly lower than that of the positive VC control group, and the cell suspension of YF-01 had the highest scavenging ability on hydroxyl radicals, which was 66.13%.

[0077] 2.5 Drug sensitivity of Bifidobacterium adolescentis YF-01.

[0078] Antibiotic sensitivity detection is the focus of probiotic research, and different probiotics are obtained through antibiotic sensitivity analysis. The paper disc diffusion method was used to detect the drug resistance of YF-01 to 20 kinds of antibiotics, and the size of the inhibition zone was measured to evaluate the sensitivity of the antibiotics, and the sensitivity of the antibiotics was evaluated according to the provisions of the American Clinical and Laboratory Standards Institute (CLSI). The experimental results are shown in Table 2, and YF-01 has strong sensitivity to 14 kinds of antibiotics such as penicillin, ampicillin, and carbenicillin, and obvious inhibition zone appears. It has resistance to 6 kinds of antibiotics such as oxacillin, amikacin, and gentamicin.

[0079] Table 2 Survival of Bifidobacterium adolescentis YF-01 in simulated gastrointestinal juice

[0080] Number Antibiotic Diameter of inhibition zone (mm) Determination result 1 Penicillin 31.29±2.07 S 2 Oxacillin 16.84±0.27 R 3 Ampicillin 30.06±2.43 S 4 Carbenicillin 34.06±3.74 S 5 Piperacillin 25.296±0.73 S 6 Cefalexin 22.84±0.82 S 7 Cefazolin 26.68±1.00 S 8 Cefradine 23.69±1.73 S 9 Cefuroxime 32.95±1.48 S 10 Ceftazidime 24.64±0.85 S 11 Ceftriaxone 37.44±0.97 S 12 Cefoperazone 27.15±3.00 S 13 Amikacin 8.01±0.16 R 14 Gentamicin 8.12±0.54 R 15 Kanamycin 7.07±0.60 R 16 Neomycin 6.83±0.19 R 17 Tetracycline 12.27±0.29 R 18 Doxycycline 17.38±0.97 S 19 Minocycline 17.19±1.46 S 20 Erythromycin 36.96±1.22 S

[0081] 2.6 Hemolytic activity of Bifidobacterium adolescentis YF-01.

[0082] Hemolysis test is to detect whether the strain produces hemolytic toxin to dissolve host red blood cells, which is one of the evaluation indexes for in vitro safety detection of strains. The grass green hemolytic ring around the ɑ-hemolytic colony is also called grass green hemolysis; the transparent hemolytic ring around the β-hemolytic colony is also called complete hemolysis; the γ-hemolytic colony does not form a hemolytic ring, that is, it does not have hemolytic activity. The evaluation results of the hemolytic activity of YF-01 screened in this experiment showed that there was no obvious change around the colonies grown on 5 sheep blood plates after anaerobic culture at 37°C for 72h, indicating that the hemolytic type was γ-hemolytic, that is, it did not have hemolytic activity.

[0083] Example 3: Fermentation characteristics of Bifidobacterium adolescentis YF-01 complex commercial starter

[0084] 3.1 Preparation of fermented milk.

[0085] Bifidobacterium adolescentis YF-01 (high tolerance strain) was mixed with commercial starter PYS-010 (containing Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus). The commercial starter (0.03‰) was used to ferment milk as a control group (group S), and different inoculation amounts of Bifidobacterium adolescentis YF-01 mixed with the commercial starter were set as the fermentation complex groups (group A: Bifidobacterium adolescentis YF-01 inoculation amount 1 x 10 5 CFU / mL + commercial starter (0.03‰), group B: Bifidobacterium adolescentis YF-01 inoculation amount 1 x 10 6 CFU / mL + commercial starter (0.03‰), group C: Bifidobacterium adolescentis YF-01 inoculation amount 1 x 10 7 CFU / mL + commercial starter (0.03‰), and a single strain fermentation group of Bifidobacterium adolescentis YF-01 (group D: Bifidobacterium adolescentis YF-01 inoculation amount 1 x 10 5 CFU / mL). When preparing the fermented milk, commercial pure milk was preheated to 60-65°C, 6.5% (v / v) white granulated sugar was added and mixed for 15 min, then homogenized (pressure 20 MPa), sterilized at 95°C for 30 min and quickly cooled. The starter was inoculated according to the above inoculation amount, and the fermentation was carried out at the optimum growth temperature (37°C). The fermentation was stopped when the pH reached 4.5±0.1, and the fermented milk was stored in a refrigerator at 4°C. During storage, samples were taken every 7 days for detection.

[0086] 3.2 Analysis of the fermentation performance of Bifidobacterium adolescentis YF-01 mixed with commercial starter.

[0087] As shown in Table 3, after the fermentation of the five groups of fermented milk, stable organization state was formed, but there were significant differences in texture characteristics (P<0.05). The hardness of group B was the largest, followed by group A, and then group C, indicating that the gel network structure formed by the complex of A, B and C groups with commercial starter during fermentation was more stable and firm, and the quality of the fermented milk was better. From the consistency, cohesiveness and viscosity index, the related parameters of groups B and C were higher, and the fermentation process produced acid, which caused the pH to decrease, and the casein particles to rearrange, affecting these parameters. Overall, the hardness, consistency, cohesiveness and viscosity index of the complex groups were significantly better than those of the single strain group and the control group (P<0.05). The texture parameters of group B (1 x 10 6 CFU / mL) were the best, and the gel network structure was more stable.

[0088] Table 3 Analysis of texture parameters of fermented milk

[0089] Group Hardness (g) Consistency (g-s) Cohesiveness (g) Viscosity index (g-s) A 54.79±1.34a 437.47±2.96c 28.77±3.20b 12.73±0.18c B 56.06±0.39a 456.86±4.05b 29.60±0.18b 15.70±2.68b C 57.35±2.98a 467.08±2.06a 38.59±3.12a 20.38±4.10a D 20.68±2.00c 162.24±1.48e 9.80±2.80c 5.38±0.56e S 47.37±0.98b 421.37±5.8d 27.99±0.90b 8.62±0.21d

[0090] Note: Different capital letters represent significant differences between groups (P<0.05), and different lowercase letters represent significant differences within groups (P<0.05).

[0091] As shown in Table 4, the degree of preference of the five groups of fermented milk from high to low is B, S, C, A, and D. The sensory score of the complex group B (1 x 10 6 The sensory score of the complex group B (1 x 10

[0092] The fermentation time of the five groups of fermented milk is significantly different (P < 0.05). The fermentation time of the complex group C is the shortest, followed by the groups B and S, and the group D is the longest. Too long fermentation time may lead to contamination of miscellaneous bacteria. In summary, the fermentation time of the complex group is shortened, which is significantly better than that of the control group (6.8 hours) and the single strain group (24 hours). Therefore, the single strain fermented milk does not have practical significance for industrial production, and should be further studied by compounding with commercial starter.

[0093] Table 4 Fermentation time and sensory score

[0094] Group Sensory score Fermentation time A 80.34 ± 0.65 e ]] 6.5 ± 0.02 c ]] B 86.63 ± 1.11 a ]] <![CDATA[6.5+0.02 c ]]> C 82.49 ± 1.20 d ]] 6.0 ± 0.01 d ]] D 72.32 ± 0.81 f ]] 24.0 ± 0.01 a ]] S 84.49 ± 1.25 c ]] 6.8 ± 0.02 b ]]

[0095] Note: Different capital letters represent significant differences between groups (P < 0.05), and different lowercase letters represent significant differences within groups (P < 0.05)

[0096] 3.3 Metabolite analysis before and after fermentation.

[0097] The experiment used principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) to determine the differences between metabolites before and after fermentation, as shown in Figure 5 The contribution rates of the first and second principal components of PCA were 64.60% and 14.30%, respectively, and the total contribution rate was 78.90%, indicating that principal component analysis could explain the overall situation of the samples. The contribution rates of the first and second principal components of PLS-DA were 63.60% and 12.90%, respectively, and the total contribution rate was 76.50%. There was a clear separation between the two groups of samples, and the samples were clustered between groups, indicating that there were significant differences in metabolites before and after fermentation. As shown in the volcano plot Figure 6 A), a total of 731 differential metabolites were produced before and after fermentation (P < 0.05, VIP > 1), including 211 up-regulated metabolites and 21 down-regulated metabolites. Acetaldehyde, L-lactic acid, and other substances were significantly up-regulated after fermentation.

[0098] Acetaldehyde is an important flavor compound produced by lactic acid bacteria in fermented milk. During the fermentation process of lactic acid bacteria, lactic acid bacteria decompose lactose, amino acids and other components in milk to produce acetaldehyde, which has a unique pungent odor and a refreshing sour aroma characteristic. It is one of the key flavor markers that distinguish fermented milk from raw milk. Studies have shown that the content of acetaldehyde is directly related to the "typical yogurt flavor" intensity of fermented milk. An appropriate amount of acetaldehyde can bring fresh and lively aroma levels to the product, enhancing the taste experience of consumers. In addition, acetaldehyde may also have a synergistic effect on other volatile compounds in the fermented milk system, together forming a complex flavor profile.

[0099] L-lactic acid is the main organic acid product of lactic acid bacteria metabolism in fermented milk. First, in terms of acidity adjustment, the accumulation of L-lactic acid can reduce the pH value of the milk system, causing the moderate coagulation of casein and forming the unique curd structure of fermented milk, which gives the product a smooth and delicate texture. Second, in terms of flavor contribution, L-lactic acid as an organic acid can provide a soft sour taste, which synergizes with other flavor substances (such as acetaldehyde and diacetyl) to balance the sweet and sour taste of the product and enhance the richness of the flavor. In addition, L-lactic acid has antibacterial effects, which can inhibit the growth of intestinal pathogenic bacteria and spoilage bacteria, helping to maintain the microbial stability of fermented milk, and may have beneficial effects on the human intestinal microecology, such as promoting the colonization of probiotics and regulating the intestinal acid-base environment. From a nutritional perspective, L-lactic acid, as a human body isomer that can be directly utilized, can be converted into energy or involved in gluconeogenesis during the metabolic process, and has a certain nutritional value.

[0100] By KEGG annotation of the difference metabolites before and after fermentation, 13 metabolic pathways involved in the fermentation before and after fermentation were found, and further enrichment analysis of the metabolic pathways before and after fermentation was performed Figure 6 Based on the p value, it was found that the enrichment degree of starch and sucrose metabolism, galactose metabolism and pyruvate metabolism was the most significant, and the number of metabolites of galactose metabolism and glutathione metabolism was the most Figure 7 ).

[0101] Example 4: Metabolic characteristics of Bifidobacterium adolescentis YF-01 complex commercial starter fermented milk

[0102] 4.1 Comparison and analysis of metabolites between the complex group and the commercial starter group.

[0103] Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to determine the differences between the metabolites of the commercial starter and the complex group Figure 8) The contribution rates of the first and second principal components of PCA were 56.70% and 22.90%, respectively, and the total contribution rate was 79.60%, indicating that the principal component analysis could explain the overall situation of the samples. The contribution rates of the first and second principal components of PLS-DA were 51.70% and 16.00%, respectively, and the total contribution rate was 67.70%, indicating that there was a clear separation between the two groups of samples, the samples were clustered between groups, and there were significant differences in metabolites before and after fermentation. As can be seen from the volcano plot Figure 9 A), a total of 1514 differential metabolites (P < 0.05, VIP > 1) were produced before and after fermentation, including 14 up-regulated metabolites and 11 down-regulated metabolites.

[0104] Among them, the fermentation milk using the compound starter has unique metabolites of Lucidenolactone, Ampeloside Bs1, and Lucidenic acid F. The fermentation broth containing metabolites was separated and identified using an ultra-high performance liquid chromatograph with a Waters ACQUITY UPLC BEH Amide liquid chromatography column. The retention time is shown in Figure 17 The anion mode, at a retention time of 8.19 minutes, lucidenolactone and ampeloside Bs1 were detected, and the two substances presented a co-elution peak (a single peak appeared at the same retention time) in the TIC graph. The peak abundance was about 3.0e7-3.5e7, and the two substances may flow out at the same time due to similar polarity or consistent retention behavior under chromatographic conditions; at a retention time of 8.34 minutes, lucidenic acid F was detected, corresponding to an independent peak with an abundance of about 3.5e7-4.0e7 in the TIC graph, the peak shape was sharp, and the retention time was consistent with the expected value of the standard substance, indicating that the substance could be effectively ionized and separated in the anion mode. In the positive ion mode, at a retention time of 8.19 minutes, lucidenolactone and ampeloside Bs1 were detected, and the co-elution peak had an abundance of about 6.0e7-6.5e7, which was higher than the response in the anion mode, and the two substances may have higher ionization efficiency in the positive ion mode; at a retention time of 8.34 minutes, lucidenic acid F was detected, corresponding to a peak with an abundance of about 8.0e7-8.5e7, which was one of the high-abundance peaks in the TIC graph in the positive ion mode, and the retention time was consistent with that in the anion mode, indicating that it had good detection response in both positive and negative ion modes.

[0105] Lucidenolactone is a terpene lactone compound with antioxidant, anti-inflammatory, and metabolic regulation functions. Its antioxidant properties can scavenge intestinal free radicals and reduce oxidative stress damage; its anti-inflammatory effect may alleviate intestinal inflammation by inhibiting the NF-κB inflammatory pathway; in addition, terpenoids may also regulate lipid metabolism and help improve metabolic syndrome. The up-regulation of this substance may enhance the health care efficacy of fermented milk, especially for people with antioxidant needs.

[0106] Ampelopsin Bs1 belongs to flavonoid glycosides, which has antibacterial, antiviral and vascular protective effects. Flavonoid glycosides can exert prebiotic effects by inhibiting the adhesion of intestinal pathogenic bacteria and regulating the balance of intestinal flora, and may protect the intestinal mucosal barrier through antioxidant and anti-inflammatory mechanisms. In fermented milk, it may enhance the antibacterial activity of milk proteins and organic acids, especially for the potential prevention of bacterial diarrhea or intestinal infection.

[0107] Ganoderic acid F is a triterpenoid compound of ganoderic acid, which has hepatoprotective, antitumor and immunomodulatory functions. Triterpenoids can alleviate liver damage by activating liver detoxification enzymes such as glutathione S-transferase, and enhance immune function by regulating immune cells such as enhancing the phagocytic ability of macrophages. In fermented milk, it may have auxiliary conditioning effect on alcoholic liver damage or immunocompromised population, and at the same time endow fermented milk with the functional characteristics of "medicinal and edible".

[0108] By KEGG annotation of the difference metabolites before and after fermentation, 61 metabolic pathways involved in the fermentation before and after fermentation were found, and further enrichment analysis of the metabolic pathways before and after fermentation was performed Figure 9 Based on the p value, it was found that the enrichment degree of arachidonic acid metabolism, steroid biosynthesis, starch and sucrose metabolism was the most significant, and the number of metabolites of nitrogen metabolism, arginine biosynthesis and arachidonic acid metabolism was the most.

[0109] Example 5: Storage characteristics of Bifidobacterium adolescentis YF-01 complex commercial starter in fermented milk

[0110] 5.1 Analysis of storage quality of Bifidobacterium adolescentis YF-01 complex fermented milk.

[0111] As shown in Figure 10 During the 28-day storage period, the pH of the complex groups A, B and C and the control group S showed a general downward trend. The pH of group C was significantly different from that of groups A, B and S after 28 days of storage (P<0.05), because the amount of Bifidobacterium adolescentis added was the most, the acid production was the most, and the pH decreased rapidly. The titratable acidity of the four groups showed a general upward trend. After 28 days of storage, the titratable acidity of the complex groups was significantly higher than that of the control group (P<0.05), and the titratable acidity of group C was the highest. The best production effect can be achieved when the acidity of fermented milk is controlled between 70°T and 110°T. The titratable acidity of groups A, B and S was within this range, and the titratable acidity of group C increased rapidly during the later storage period and was high at the end of storage. Therefore, Bifidobacterium adolescentis and commercial starter strains at 4°C can still continue to decompose lactose to produce lactic acid.

[0112] As shown in Figure 11As shown, the viable count of fermented milk increased first and then decreased during storage at 4℃, reaching a maximum at 14 d of storage, and then showing a downward trend (P < 0.05), because B. adolescentis is a strict anaerobe. At the end of storage, the viable count of the complex groups A, B and C was significantly higher than that of the control group S (P < 0.05), and the viable count of the complex groups remained above 10 8 CFU / mL after 28 d of storage, meeting the standard of probiotic products (>10 6 CFU / mL) and being able to play an active role in health.

[0113] As Figure 12 shown, the water holding capacity and viscosity of the four groups of fermented milk increased first and then decreased with time, and the water holding capacity and viscosity of the complex groups reached a peak at 14 d of storage, being significantly higher than those of the control group (P < 0.05), indicating that the complex B. adolescentis YF-01 can improve the water holding capacity and viscosity of fermented milk and make them stable during storage, which helps to improve the texture of fermented milk. The viscosity and water holding capacity of group B were significantly higher than those of the other groups, so the use of B. adolescentis YF-01 with an inoculum of 1 × 10 6 CFU / ml and commercial starter for fermentation can stabilize the viscosity and water holding capacity of fermented milk and improve the storage stability.

[0114] As shown in Table 5, the hardness, consistency, cohesiveness and viscosity index of the four groups of fermented milk increased first and then decreased during storage, reaching a peak at 14 d of storage, which is consistent with the change trend of water holding capacity and viscosity. The decrease in pH value at the early stage of storage increased the gel strength of fermented milk and improved the texture characteristics; the post-acidification phenomenon at the later stage destroyed the gel structure, leading to a decrease in texture characteristics. During the entire storage period, the hardness, consistency, cohesiveness and viscosity index of the complex fermentation groups B and C were significantly higher than those of the starter group S (P < 0.05), and the texture characteristics of group B were higher than those of the other groups, indicating that YF-01 with an inoculum of 1 × 10 6 CFU / ml and starter for fermentation can help to form a more solid gel network structure and improve the stability of fermented milk.

[0115] Table 5 Texture parameters of fermented milk during storage

[0116]

[0117] As Figure 13As shown in the figure, the sensory evaluation scores of the four groups of fermented milk samples during storage showed that group B had the highest score, followed by group S, and group C had the lowest score. On the 14th day of storage, the sensory scores of each group were the highest. After that, as the storage time prolonged, the sensory scores decreased due to problems such as increased acidity, whey precipitation, and decreased viscosity and water holding capacity of the fermented milk. Overall, the four groups of samples were uniformly milky white at the beginning of storage, with a moderate sweet and sour taste and a delicate texture. Group B had a significantly higher sensory score than the other groups during storage (P < 0.05), and Group S had a better score than Groups A and C, indicating that the inoculum size was 1×10 6 The fermented milk prepared with CFU / mL and commercial starter culture coagulated faster, had moderate viscosity, better water holding capacity, appropriate sour-sweet ratio, and the highest sensory score.

[0118] 5.2 Metabolic characteristics of fermented milk during storage.

[0119] Using a variety of metabolomics analysis methods, the inoculum size was 1×10 6 The metabolic characteristics of fermented milk mixed with YF-01 and commercial starter cultures before and after storage were investigated to explore the differential metabolites and their effects on the quality of fermented milk. 6 Significant differences in the metabolites of fermented milks derived from co-fermentation with YF-01 and a commercial starter culture were observed. A total of 50 differential metabolites were identified, primarily involving carbohydrates and their derivatives, lipids and fatty acid derivatives, short peptides, and amino acid derivatives. The differential metabolites identified in fermented milk were enriched in 16 metabolic pathways, including fatty acid metabolism and arginine metabolism in the pentose phosphate pathway. These metabolite changes were closely correlated with the flavor, stability, and bioactivity of the fermented milk, further revealing the metabolic mechanism of YF-01 in fermented milk and its role in improving product quality.

[0120] The instrument stability and metabolite detection reliability were determined by analyzing the total ion current chromatograms of different fermented milk QC samples. The total ion current curves in the positive and negative ion modes overlapped almost completely, demonstrating the high stability of the instrument analysis system, strong experimental reproducibility, and good data accuracy, meeting the requirements of subsequent analysis.

[0121] like Figure 14 As shown in the figure, principal component analysis of the metabolites of fermented milk stored for 1 and 28 days in Group B revealed a total sample variability of 72.1%, with PC1 contributing 47.7% and PC2 contributing 24.4%. The two groups showed a trend toward separation, with concentrated distribution within each group, indicating significant differences in the metabolites of fermented milk before and after storage.

[0122] like Figure 15 and Figure 16As shown, using MetaboAnalyst 6.0 online website, 50 kinds of differential metabolites of fermented milk before and after storage were screened out with VIP>1, P<0.05 as the standard, mainly including carbohydrates and their derivatives, lipids and fatty acid derivatives, short peptides and amino acid derivatives, and other small molecule metabolites. When stored for 1d, β-lactose was highly expressed, which provided energy for the flora and affected the sweetness of dairy products and had potential anti-tumor activity. When stored for 28d, 1-hexanol arabinoside and other glycosides were highly expressed, which affected the flavor of fermented milk as flavor precursor substances, and also had the effects of antioxidant, prolonging shelf life and affecting texture and taste. When stored for 1d, 3-phosphoglycerate, phosphatidylglycerol and 1-hexanol were highly expressed, which were involved in glycerolipid synthesis, had various application potentials and affected the flavor of fermented milk. When stored for 28d, hydroxyoctanoyl coenzyme A, nonanoyl coenzyme A and acetaldehyde were highly expressed, which were involved in fatty acid metabolism and affected the flavor of fermented milk. When stored for 28d, part of short peptides and amino acid derivatives such as γ-glutamylarginine were highly expressed, which had proteolysis characteristics, could regulate nutrition, play antioxidant effect, and were also related to some metabolic processes. After uploading the differential metabolites to MetaboAnalyst 6.0 online website for analysis, it was found that they were commonly enriched in 16 metabolic pathways such as fatty acid metabolism. Among them, the three metabolic pathways of triacylglycerol biosynthesis, phosphoglycerate metabolism and cardiolipin synthesis were more significant. These metabolite changes are affected by multiple factors and improve the quality of fermented milk through multi-target action, which provides a scientific basis for the development of fermented milk as a functional food.

[0123] The study found through non-targeted metabolomics analysis that the inoculation of 1x10 6 The fermented milk inoculated with 1x10 8 CFU / mL Bifidobacterium adolescentis YF-01 and commercial starter culture identified 50 significant differential metabolites during storage, mainly involving carbohydrates, lipids and short peptides, and was enriched in 16 key metabolic pathways such as fatty acid metabolism and pentose phosphate pathway. The compounding scheme significantly improved the flavor (such as increasing fruity and sweet taste), stability (increasing water holding capacity and viscosity) and biological activity (such as antioxidant and immune regulation function) of fermented milk by synergistically regulating these metabolic pathways, while shortening the fermentation time to 6.5 hours and maintaining the viable count >10 8 CFU / mL after 28 days, providing a theoretical basis and application strategy for the development of high-quality probiotic fermented milk.

[0124] Therefore, the present application adopts the above-mentioned Bifidobacterium adolescentis YF-01 and its application in fermented milk, which has excellent properties such as acid and bile salt tolerance and ability to utilize various carbohydrates, and is used for fermented milk preparation by compounding with commercial starter culture to improve the viable count, texture, sensory quality and storage stability of fermented milk.

[0125] It should be pointed out finally that the above examples are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. Use of a strain of Bifidobacterium adolescentis YF-01 in the preparation of a product for regulating intestinal flora, promoting intestinal health, or enhancing the body's antioxidant capacity, characterized in that: The Bifidobacterium adolescentis YF-01 is deposited in the China Center for Type Culture Collection with a deposit number of CCTCC NO: M 20251308, a deposit date of June 9, 2025, and a deposit address of Wuhan University, Wuhan, China. It is classified and named Bifidobacterium adolescentis YF-01, and its 16S rDNA sequence is shown in SEQ ID NO.1; The survival rate of Bifidobacterium adolescentis YF-01 after 3 hours of treatment with simulated gastric fluid was 90.1%, and the survival rate after 4 hours of treatment with simulated intestinal fluid was 72%. The self-aggregation rate of the strain was 88.83%, the hydrophobicity was 79.41%, the DPPH free radical scavenging rate was 60.32%, and the hydroxyl free radical scavenging rate was 66.13%. When Bifidobacterium adolescentis YF-01 is used to prepare products that regulate intestinal flora, promote intestinal health or enhance the body's antioxidant capacity, the secondary metabolites obtained by fermentation include Lucidenolactone, Ampeloside Bs1, and Lucidenic acid F.

2. The use according to claim 1, characterized in that: The product comprises fermented milk.

3. The use according to claim 2, characterized in that: When used, Bifidobacterium adolescentis YF-01 is compounded with the commercial starter culture PYS-010 and used in the preparation of fermented milk, which can shorten the fermentation time, improve the texture and flavor of the fermented milk, and maintain a high number of live bacteria and stable properties during storage.

4. The use according to claim 3, characterized in that: When Bifidobacterium adolescentis YF-01 was compounded with the commercial starter culture PYS-010, the inoculum size of Bifidobacterium adolescentis YF-01 was 1×10 6 CFU / mL, and the inoculum size of the commercial starter culture PYS-010 was 0.03‰.

5. A product characterized by: The product contains live bacteria, inactivated strains, and / or metabolites of Bifidobacterium adolescentis YF-01 according to claim 1, and the number of live bacteria of Bifidobacterium adolescentis YF-01 in the product is not less than 1×10 8 CFU / mL or 1×10 8 CFU / g.

6. The product according to claim 5, characterized in that The product is fermented milk, dairy product or solid beverage.

7. Use of a secondary metabolite of Bifidobacterium adolescentis YF-01 in the preparation of a product for regulating intestinal flora, promoting intestinal health, or enhancing the body's antioxidant capacity, characterized by: The secondary metabolites include Lucidenolactone, Ampeloside Bs1, and Lucidenic acid F. A strain of Bifidobacterium adolescentis YF-01 is deposited in the China Center for Type Culture Collection with a deposit number of CCTCC NO: M 20251308, a deposit date of June 9, 2025, and a deposit address of Wuhan University, Wuhan, China. It is classified and named Bifidobacteriumadolescentis YF-01, and its 16S rDNA sequence is shown in SEQ ID NO.

1.

8. The use according to claim 7, characterized in that: When used, the viable count of Bifidobacterium adolescentis YF-01 should not be less than 1×10 8 CFU / mL or 1×10 8 CFU / g.

9. A product for regulating intestinal flora, promoting intestinal health or enhancing the body's antioxidant capacity, characterized in that: A secondary metabolite comprising the Bifidobacterium adolescentis YF-01 according to claim 7.

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