Complex microbial inoculant, functional yoghurt capable of reducing uric acid and repairing oxidative damage, and preparation method and application of functional yoghurt

Abstract

The invention belongs to the field of food processing, and particularly relates to a complex microbial inoculant, functional yoghurt capable of reducing uric acid and repairing oxidative damage, and a preparation method and application of the functional yoghurt. The complex microbial inoculant comprises the following components in parts by weight: 60-85 parts of lactobacillus delbrueckii subsp. Lactis powder, 5-20 parts of streptococcus salivarius subsp. Thermophilus powder and 5-15 parts of thermally inactivated lactobacillus delbrueckii subsp. Lactis powder, and the lactobacillus delbrueckii subsp. Lactis is a lactobacillus delbrueckii subsp. Lactis Dangxiong LB VIII carrying a related gene with an antioxidant function. And related genes capable of improving hyperuricemia are carried. The lactobacillus delbrueckii subsp. Lactis powder, the streptococcus salivarius subsp. Thermophilus powder, the thermally inactivated lactobacillus delbrueckii subsp. Lactis powder, the prebiotics and the raw milk are mixed and fermented to obtain the functional yoghourt, and the functional yoghourt has relatively strong uric acid reducing or auxiliary uric acid reducing capability and also has an anti-oxidation effect.

Description

Technical Field

[0001] The invention belongs to the field of food processing, and specifically relates to a composite bacterial agent, a functional yogurt capable of lowering uric acid and repairing oxidative damage, and a preparation method and application thereof. Background Art

[0002] Uric acid is a product of purine metabolism. Abnormal purine metabolism in the human body will cause hyperuricemia. Long-term hyperuricemia will significantly increase the risk of gout attacks, is an important cause of renal damage, and is also an important comorbidity of obesity, metabolic syndrome, and lipid metabolism disorders. Oxidative stress refers to the process in which the redox balance in cells or organisms is destroyed due to excessive production of oxidative substances or weakened clearance ability, which in turn causes a series of harmful effects. These oxidative substances mainly include free radicals, peroxides, etc., which are highly reactive and can attack biological macromolecules in cells. High uric acid may promote the occurrence and development of various diseases by enhancing oxidative stress reactions. Therefore, for patients with hyperuricemia, taking measures to reduce uric acid levels while maintaining redox balance has a synergistic effect on the treatment of the disease.

[0003] The Chinese patent application with publication number CN112021407 B discloses a drinkable fermented probiotic yogurt capable of reducing blood uric acid and a preparation method thereof. The patent provides a drinkable fermented probiotic yogurt capable of reducing blood uric acid, which is prepared by fermentation of Lactobacillus fermentum 2644, contains fermentation products and live bacteria of Lactobacillus fermentum 2644, and also includes adding chicory, gardenia, mulberry leaf extract to participate in the fermentation. However, the fermented probiotic yogurt obtained in the patent has a poor ability to reduce uric acid, and the fermented probiotic yogurt is not found to have an antioxidant effect. Summary of the invention

[0004] The problem existing in the prior art is that there is a lack of yogurt having strong uric acid lowering or auxiliary uric acid lowering ability and also having antioxidant effect.

[0005] In view of the above problems existing in the prior art, the present invention provides a composite bacterial agent, a functional yogurt having the functions of lowering uric acid and repairing oxidative damage, and a preparation method and application thereof.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a composite bacterial agent, comprising, by weight, 60-85 parts of Lactobacillus delbrueckii subsp. lactis powder, 5-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder, and 5-15 parts of heat-killed Lactobacillus delbrueckii subsp. lactis powder.

[0008] Preferably, by weight, 70-85 parts of Lactobacillus delbrueckii subsp. lactis powder, and / or 10-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder, and / or 5-10 parts of heat-killed Lactobacillus delbrueckii subsp. lactis powder,

[0009] Preferably, by weight, 75-85 parts of Lactobacillus delbrueckii subsp. lactis powder and / or 10-15 parts of Streptococcus salivarius subsp. thermophilus powder are used.

[0010] Preferably, the viable count of the Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 CFU / g, and / or the number of viable bacteria of Streptococcus salivarius thermophilus powder is 1-3×10 11 CFU / g, and / or the number of heat-killed Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 Pieces / g.

[0011] Preferably, the Lactobacillus delbrueckii subspecies lactis is Lactobacillus delbrueckii subspecies lactis Dangxiong LBⅧ, and its deposit number is CCTCC NO:M 2023396.

[0012] Preferably, the Lactobacillus delbrueckii subspecies Dangxiong LBⅧ carries a gene related to antioxidant function, wherein the gene related to antioxidant function contains a gene sequence as shown in SEQ ID NO:1.

[0013] Preferably, the Lactobacillus delbrueckii subspecies Dangxiong LBⅧ carries genes related to improving hyperuricemia, wherein the genes related to antioxidant function contain the gene sequence shown in SEQ ID NO:2.

[0014] Preferably, the thermophilic Streptococcus salivarius subsp. thermophilus is Streptococcus salivarius subsp. thermophilus Jiacha.ST-685, and the deposit number is CCTCC NO:M 20231495.

[0015] Preferably, the Lactobacillus delbrueckii subsp. lactis powder is prepared by a method comprising the following steps:

[0016] (1) inoculating the activated Lactobacillus delbrueckii subsp. lactis into a liquid culture medium to obtain a seed liquid of Lactobacillus delbrueckii subsp. lactis;

[0017] (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis;

[0018] (3) After centrifuging the fermentation liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (2), collecting bacterial mud, mixing the bacterial mud with a lyophilization protective agent, and performing vacuum freeze-drying to obtain Lactobacillus delbrueckii subsp. lactis bacterial powder.

[0019] Preferably, the Streptococcus salivarius thermophilus subspecies bacterial powder is prepared by a method comprising the following steps:

[0020] (1) inoculating the activated thermophilic subspecies of Streptococcus salivarius into a liquid culture medium to obtain a seed liquid of the thermophilic subspecies of Streptococcus salivarius;

[0021] (3) inoculating the seed liquid of the thermophilic subspecies of Streptococcus salivarius obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of the thermophilic subspecies of Streptococcus salivarius;

[0022] (4) After centrifuging the fermentation liquid of the thermophilic subspecies of Streptococcus salivarius obtained in step (2), collecting bacterial sludge, mixing the bacterial sludge with a lyophilization protective agent, and performing vacuum freeze-drying to obtain thermophilic subspecies of Streptococcus salivarius bacterial powder.

[0023] Preferably, the heat-inactivated Lactobacillus delbrueckii subsp. lactis powder is prepared by a method comprising the following steps:

[0024] (1) inoculating the activated Lactobacillus delbrueckii subsp. lactis into a liquid culture medium to obtain a seed liquid of Lactobacillus delbrueckii subsp. lactis;

[0025] (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis;

[0026] (3) spray-drying the fermented liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (2) to obtain heat-inactivated Lactobacillus delbrueckii subsp. lactis powder.

[0027] In a second aspect, the present invention provides a method for preparing the composite bacterial agent, comprising the following steps: uniformly mixing Lactobacillus delbrueckii subsp. lactis powder, Streptococcus salivarius subsp. thermophilus powder and heat-inactivated Lactobacillus delbrueckii subsp. lactis powder to prepare the composite bacterial agent.

[0028] In a third aspect, the present invention provides an application of the composite bacterial agent or the composite bacterial agent prepared by the preparation method in the preparation of functional yogurt, wherein the functional yogurt is a functional yogurt that lowers uric acid or assists in lowering uric acid, and repairs oxidative damage.

[0029] In a fourth aspect, the present invention provides a functional yogurt for lowering uric acid or assisting in lowering uric acid, and repairing oxidative damage, which is prepared by a method comprising the following steps: mixing raw cow's milk, prebiotics and the composite bacterial agent or the composite bacterial agent prepared by the preparation method, and then fermenting to obtain the functional yogurt.

[0030] Preferably, the mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 900-1500L: 1-10g: 85-105g,

[0031] More preferably, the mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 950-1200L: 1-5g: 85-95g,

[0032] Most preferably, the mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 1000-1200L: 1-5g: 90-95g.

[0033] Preferably, the prebiotic is fructo-oligosaccharide.

[0034] In a fourth aspect, the present invention provides a method for preparing the functional yogurt, comprising the following steps: mixing raw milk, a composite bacterial agent and prebiotics and then fermenting the mixture.

[0035] Preferably, the method comprises the following steps:

[0036] (1) homogenizing, sterilizing and cooling raw milk;

[0037] (2) mixing the raw milk, the composite bacterial agent and the prebiotics obtained in step (1) uniformly to obtain a mixture;

[0038] (3) fermenting the mixture obtained in step (2) and then refrigerating it to obtain the yogurt.

[0039] Preferably, in step (1), the homogenization temperature of the raw milk is 55-65°C.

[0040] Preferably, the homogenization high pressure is 10-30 MPa and the low pressure is 3-5 MPa.

[0041] Preferably, in step (1), the sterilization temperature is 85-95°C and the sterilization time is 10-15 minutes. And / or in step (1), the temperature is cooled to 40-45°C, and / or in step (3), the fermentation temperature is 40-45°C, and / or in step (3), the fermentation is terminated when the acidity value of the mixture reaches 65-75°T.

[0042] In a fifth aspect, the present invention provides the use of the composite bacterial agent or the composite bacterial agent prepared by the preparation method, or the functional yogurt or the functional yogurt obtained by the preparation method in the preparation of health products. Preferably, the health product is a health product for lowering uric acid or assisting in lowering uric acid, and repairing oxidative damage.

[0043] In a sixth aspect, the present invention provides a health product containing the composite bacterial agent or the composite bacterial agent prepared by the preparation method, or the functional yogurt or the functional yogurt obtained by the preparation method. Preferably, the health product is a health product for lowering uric acid or assisting in lowering uric acid, and repairing oxidative damage.

[0044] Beneficial effects of the present invention:

[0045] The invention adopts Lactobacillus delbrueckii subsp. lactis powder, Streptococcus salivarius thermophilus subsp. lactis powder and heat-inactivated Lactobacillus delbrueckii subsp. lactis powder, prebiotics and raw cow milk, and then ferments them to obtain functional yogurt. The functional yogurt has strong uric acid lowering or auxiliary uric acid lowering ability and also has antioxidant effect.

[0046] Bacteria material information

[0047] Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ used in the present invention was deposited in the China Center for Type Culture Collection on March 23, 2023, with a deposit number of CCTCCNO: M 2023396, and a deposit address: Wuhan University, Wuhan, China, postal code: 430072; telephone: 02768754052. It has been recorded in the Chinese patent with publication number CN116948884A.

[0048] The Streptococcus salivarius subsp. thermophilus Jiacha.ST-685 strain used in the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on August 17, 2023, with a deposit number of CCTCC NO: M 20231495, and a deposit address: Wuhan University, Wuhan, China, postal code: 430072; telephone: (027)-68754052. It has been recorded in the Chinese patent publication number CN118872730A. DETAILED DESCRIPTION

[0049] In order to better understand the above technical solution, the technical solution of the present invention is clearly and completely explained in conjunction with the specific implementation method below. It should be noted that the content in the specific implementation method is only a specific implementation and explanation of the technical solution of the present invention, and should not be understood as limiting the scope of protection of the present invention.

[0050] In some specific embodiments, the present invention provides a composite bacterial agent, comprising, by weight, 60-85 parts of Lactobacillus delbrueckii subsp. lactis powder, 5-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder, and 5-15 parts of heat-killed Lactobacillus delbrueckii subsp. lactis powder.

[0051] Preferably, in some specific embodiments, the content of Lactobacillus delbrueckii subsp. lactis powder can be 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight or 85 parts by weight, or the content of Lactobacillus delbrueckii subsp. lactis powder within the numerical range constituted by any two of the above specific numerical values ​​as endpoints.

[0052] Preferably, in some specific embodiments, the content of the thermophilic subspecies of Streptococcus salivarius powder may be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight or 20 parts by weight, or the content of the thermophilic subspecies of Streptococcus salivarius powder within a numerical range consisting of any two of the above specific values ​​as endpoints.

[0053] Preferably, in some specific embodiments, the heat-killed Lactobacillus delbrueckii subsp. lactis powder is 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight or 15 parts by weight, or the heat-killed Lactobacillus delbrueckii subsp. lactis powder is within the numerical range consisting of any two of the above specific values ​​as endpoints.

[0054] In some specific embodiments, the present invention provides a composite bacterial agent, which comprises, by weight, 60-85 parts of Lactobacillus delbrueckii subsp. lactis powder, 5-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder, and 5-15 parts of heat-inactivated Lactobacillus delbrueckii subsp. lactis powder, wherein the number of viable bacteria of Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 CFU / g, and / or the number of viable bacteria of Streptococcus salivarius thermophilus powder is 1-3×10 11 CFU / g, and / or the number of heat-killed Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 Pieces / g.

[0055] Preferably, in some embodiments, the viable bacterial count of the Lactobacillus delbrueckii subsp. lactis powder may be 1.0×10 11 CFU / g, 1.1×10 11 CFU / g, 1.2×10 11 CFU / g, 1.3×10 11 CFU / g, 1.4×1011 CFU / g, 1.5×10 11 CFU / g, 1.6×10 11 CFU / g, 1.7×10 11 CFU / g, 1.8×10 11 CFU / g, 1.9×10 11 CFU / g, 2.0×10 11 CFU / g, 2.1×10 11 CFU / g, 2.2×10 11 CFU / g, 2.3×10 11 CFU / g, 2.4×10 11 CFU / g, 2.5×10 11 CFU / g, 2.6×10 11 CFU / g, 2.7×10 11 CFU / g, 2.8×10 11 CFU / g, 2.9×10 11 CFU / g or 3.0×10 11 CFU / g, or the number of viable bacteria of Lactobacillus delbrueckii subsp. lactis powder within a numerical range consisting of any two of the above specific numerical values ​​as endpoints.

[0056] Preferably, in some embodiments, the viable count of Streptococcus salivarius thermophilus subspecies powder may be 1.0×10 11 CFU / g, 1.1×10 11 CFU / g, 1.2×10 11 CFU / g, 1.3×10 11 CFU / g, 1.4×10 11 CFU / g, 1.5×10 11 CFU / g, 1.6×10 11 CFU / g, 1.7×10 11 CFU / g, 1.8×10 11 CFU / g, 1.9×10 11 CFU / g, 2.0×10 11 CFU / g, 2.1×10 11 CFU / g, 2.2×10 11 CFU / g, 2.3×10 11 CFU / g, 2.4×10 11 CFU / g, 2.5×10 11 CFU / g, 2.6×10 11 CFU / g, 2.7×10 11 CFU / g, 2.8×10 11 CFU / g, 2.9×1011 CFU / g or 3.0×10 11 CFU / g, or the number of viable bacteria of Streptococcus salivarius subspecies thermophilus powder within a numerical range consisting of any two of the above specific values ​​as endpoints.

[0057] Preferably, in some embodiments, the bacterial count of the heat-killed Lactobacillus delbrueckii subsp. lactis powder may be 1.0×10 11 / g, 1.1×10 11 / g, 1.2×10 11 / g, 1.3×10 11 / g, 1.4×10 11 / g, 1.5×10 11 / g, 1.6×10 11 / g, 1.7×10 11 / g, 1.8×10 11 / g, 1.9×10 11 / g, 2.0×10 11 / g, 2.1×10 11 / g, 2.2×10 11 / g, 2.3×10 11 / g, 2.4×10 11 / g, 2.5×10 11 / g, 2.6×10 11 / g, 2.7×10 11 / g, 2.8×10 11 / g, 2.9×10 11 / g or 3.0×10 11 Pieces / g, or the number of heat-killed Lactobacillus delbrueckii subsp. lactis powder within a numerical range consisting of any two of the above specific numerical values ​​as endpoints.

[0058] In some specific embodiments, the present invention provides a functional yogurt that lowers uric acid or assists in lowering uric acid, and repairs oxidative damage, which is prepared by a method comprising the following steps: mixing raw cow's milk, prebiotics and the composite bacterial agent or the composite bacterial agent prepared by the preparation method, and then fermenting to obtain the functional yogurt, preferably a functional yogurt that assists in lowering uric acid or assists in lowering uric acid, and repairs oxidative damage.

[0059] Preferably, in some specific embodiments, the mixing ratio of the raw cow's milk, the prebiotics and the composite bacterial agent is: 900-1500L: 1-10g: 85-105g.

[0060] More preferably, in some specific embodiments, the content of the raw milk can be 900L, 905L, 910L, 915L, 920L, 925L, 930L, 935L, 940L, 945L, 950L, 955L, 960L, 965L, 970L, 975L, 980L, 985L, 990L, 995L, 1000L, 1005L, 1010L, 1015L, 1020L, 1025L, 1030L, 1035L, 1040L, 1045L, 1050L, 1055L, 1060L, 1065L, 1070L, 1075L The content of raw milk in the range of 150L, ​​150L, ​​1510L, 1520L, 1530L, 1540L, 1550L, 1560L, 1570L, 1580L, 1590L, 1605L, 1610L, 1620L, 1630L, 1640L, 1650L, 1660L, 1670L, 1680L, 1690L, 1705L, 1715L, 1720L, 1730L, 1740L, 1750L, 1760L, 1775L, 1780L, 1790L, 1805L, 1810L, 1820L

[0061] More preferably, in some specific embodiments, the content of the prebiotics may be 1g, 1.5g, 2g, 2.5g, 3g, 3.5g, 4g, 4.5g, 5g, 5.5g, 6g, 6.5g, 7g, 7.5g, 8g, 8.5g, 9g, 9.5g or 10g, or the content of the prebiotics within a numerical range consisting of any two of the above specific numerical values ​​as endpoints. In a specific embodiment, any of the above-mentioned raw milk content ranges can be combined with any prebiotic content range, as long as the functional yogurt required by the present invention can be obtained.

[0062] More preferably, in some specific embodiments, the content of the composite bacterial agent can be 1g, 2g, 3g, 4g, 5g, 6g, 7g, 8g, 9g, 10g, 11g, 12g, 13g, 14g, 15g, 16g, 17g, 18g, 19g, 20g, 21g, 22g, 23g, 24g, 25g, 26g, 27g, 28g, 29g, 30g, 31g, 32g, 33g, 34g, 35g, 36g, 37g, 38g, 39g, 40g, 41g, 42g, 43g, 44g, 45g 7g, 78g, 79g, 80g, 81g, 82g, 83g, 84g or 85g, or the content of the composite bacterial agent within the numerical range constituted by any two of the above specific numerical values ​​as endpoints.

[0063] It should be noted that, in some specific embodiments, any of the above contents of the raw cow's milk can be combined with any of the above contents of the prebiotics and / or any of the above contents of the composite bacterial agent, as long as the functional yogurt required by the present invention can be obtained. Alternatively, any of the above content ranges of the raw cow's milk can be combined with any of the above content ranges of the prebiotics and / or any of the above content ranges of the composite bacterial agent, as long as the functional yogurt required by the present invention can be obtained.

[0064] It should be noted that, when only the mixing weight ratio of Lactobacillus delbrueckii subspecies lactis powder, Streptococcus salivarius thermophilic subspecies lactis powder and / or heat-killed Lactobacillus delbrueckii subspecies lactis powder in the composite bacterial agent is changed; without changing the mixing ratio of raw cow's milk, prebiotics and composite bacterial agent to 900-1500L:1-10g:85-105g, the functional yogurt prepared by mixed fermentation of raw cow's milk, prebiotics and composite bacterial agent has the ability to lower uric acid or assist in lowering uric acid and also has antioxidant effect.

[0065] In some specific embodiments, the Lactobacillus delbrueckii subsp. lactis powder provided by the present invention is prepared by a method comprising the following steps:

[0066] (1) The activated Lactobacillus delbrueckii subsp. lactis is inoculated into a liquid culture medium to obtain a seed solution of Lactobacillus delbrueckii subsp. lactis. Preferably, the inoculation amount is 1-5%.

[0067] (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis,

[0068] Preferably, the viable count of the fermentation broth of Lactobacillus delbrueckii subsp. lactis is 5-8×10 9 CFU / mL;

[0069] Preferably, the inoculation amount is 1-5%,

[0070] Preferably, the high-density fermentation method is: fermentation culture at 40-42°C under non-ventilated conditions for 10-12 hours, adding a glucose solution with a concentration of 2-2.5wt% during the fermentation culture to maintain the sugar content in the fermentation medium at 10-20g / L, and adding Na2CO3 to maintain the pH of the fermentation medium at 4.5-5.

[0071] (3) centrifuging the fermented liquid of Lactobacillus delbrueckii subsp. lactis and collecting bacterial sludge, mixing the bacterial sludge with a lyophilization protective agent and performing vacuum freeze drying to a moisture content of less than 5% to obtain Lactobacillus delbrueckii subsp. lactis powder;

[0072] Preferably, the viable count of the Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 CFU / g;

[0073] Preferably, the vacuum freeze-drying conditions are: pre-freezing at -35°C to -40°C for 4-5 hours, and then vacuum freeze-drying at -35°C to -40°C for 48-50 hours.

[0074] Preferably, the lyoprotectant comprises: 20-25 g skim milk powder, 5-10 g mannitol, 5-10 g trehalose, 1-5 g sodium glutamate and 2-5 g glycerol.

[0075] Preferably, the weight ratio of bacterial mud to freeze-dried protective agent is 1:2-1:4.

[0076] In some specific embodiments, the Streptococcus salivarius thermophilus subspecies bacterial powder provided by the present invention is prepared by a method comprising the following steps:

[0077] (1) The activated Streptococcus salivarius thermophilus subsp. is inoculated into a liquid culture medium to obtain a seed solution of Streptococcus salivarius thermophilus subsp., preferably, the inoculation amount is 1-5%.

[0078] (2) inoculating the seed liquid of the thermophilic subspecies of Streptococcus salivarius into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of the thermophilic subspecies of Streptococcus salivarius,

[0079] Preferably, the number of viable bacteria in the fermentation broth of Streptococcus salivarius thermophilus subspecies is 3-5×10 9 CFU / mL;

[0080] Preferably, the inoculation amount is 1-5%,

[0081] Preferably, the high-density fermentation method is: the high-density fermentation method is: fermentation culture at 40-42°C under airtight conditions for 10-12 hours, during the fermentation culture process, a glucose solution with a concentration of 2-2.5wt% is added to maintain the sugar content in the fermentation medium at 15-20g / L, and Na2CO3 is added to maintain the pH of the fermentation medium at 4.5-5.

[0082] (3) centrifuging the fermentation liquid of the thermophilic subspecies of Streptococcus salivarius to collect bacterial sludge, mixing the bacterial sludge with a lyophilization protective agent, and then performing vacuum freeze drying to a moisture content of less than 5% to obtain a thermophilic subspecies of Streptococcus salivarius bacterial powder;

[0083] Preferably, the viable count of Streptococcus salivarius thermophilus subspecies powder is 1-3×10 11 CFU / g,

[0084] Preferably, the vacuum freeze-drying conditions are: pre-freezing at -35°C to -40°C for 4-5 hours, and then vacuum freeze-drying at -35°C to -40°C for 48-50 hours.

[0085] Preferably, the lyoprotectant comprises: 20-25 g skim milk powder, 5-10 g mannitol, 5-10 g trehalose, 1-5 g sodium glutamate and 2-5 g glycerol.

[0086] Preferably, the weight ratio of bacterial mud to freeze-dried protective agent is 1:2-1:3.

[0087] In some specific embodiments, the heat-inactivated Lactobacillus delbrueckii subsp. lactis powder provided by the present invention is prepared by a method comprising the following steps:

[0088] (1) The activated Lactobacillus delbrueckii subsp. lactis is inoculated into a liquid culture medium to obtain a seed solution of Lactobacillus delbrueckii subsp. lactis. Preferably, the inoculation amount is 1-5%.

[0089] (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis,

[0090] Preferably, the viable count of the fermentation broth of Lactobacillus delbrueckii subsp. lactis is 5-8×10 9 CFU / mL;

[0091] Preferably, the inoculation amount is 1-5%,

[0092] Preferably, the high-density fermentation method is: fermentation culture at 40-42°C under non-aerated conditions for 10-12 hours, feeding a glucose solution with a concentration of 2-2.5wt% during the fermentation culture to maintain the sugar content in the fermentation medium at 15-20g / L, and feeding Na2CO3 to maintain the pH of the fermentation medium at 4.5-5.

[0093] (3) spray-drying the fermented liquid obtained in step (2) to obtain heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder (with a bacterial count of 1-3×10 11 The conditions for spray drying are as follows: air inlet temperature 160-170°C, air outlet temperature 100-105°C, and flow rate 190-200kg / h.

[0094] In some specific embodiments, the concentration of each component in the liquid culture medium is as follows: peptone 10.0-15.0 g / L, beef extract powder 5.0-10.0 g / L, yeast extract powder 4.0-5.0 g / L, glucose 20.0-25.0 g / L, dipotassium hydrogen phosphate 2.0-5.0 g / L, triammonium citrate 2.0-5.0 g / L, sodium acetate 5.0-10.0 g / L, magnesium sulfate 0.2-0.5 g / L, manganese sulfate 0.01-0.05 g / L, agar 15.0-20.0 g / L and Tween 80 1.0-5.0 g / L.

[0095] The Lactobacillus delbrueckii subspecies Dangxiong LBⅧ used in the present invention carries functional genes for anti-oxidation and improving hyperuricemia, and can affect the activity of the key enzyme (xanthine oxidase) for uric acid synthesis, thereby inhibiting the synthesis of uric acid.

[0096] The present invention evaluates the effects of the functional yogurt on lowering uric acid and repairing oxidative damage by animal experiments, specifically: 20-25 mL of the functional yogurt is gavaged into the stomach for each kg of mouse body weight in the early morning, once a day, for 7 consecutive days. From the 8th day onwards, in addition to gavage of 20-25 mL of the functional yogurt in the morning, triple administration was performed in the afternoon (12 hours apart from the above-mentioned morning gavage), wherein the triple administration method refers to mixing 300 mg-310 mg of hypoxanthine, 250 mg-260 mg of potassium oxonate and 15 g-20 g of yeast extract with distilled water per kg of mouse body weight to form a 20 mL-25 mL mixed solution, and then gavage was performed once a day. After gavage for 7 consecutive days, the uric acid content in mouse serum and the activity of xanthine oxidase (XOD) in mouse liver were detected to evaluate the uric acid-lowering ability of the functional yogurt; and the activity of superoxide dismutase (SOD) in mouse serum, the malondialdehyde (MDA) content in mouse serum, and the activity of glutathione-peroxidase (GSH-PX) in mouse serum were detected to evaluate the antioxidant function of the functional yogurt.

[0097] Preferably, the uric acid content in mouse serum is 40-65 μmol / L, and / or the xanthine oxidase activity in mouse liver (10 wt% liver tissue homogenate) is 20-32 U / L.

[0098] More preferably, the uric acid content in mouse serum is 40-50 μmol / L, and / or the xanthine oxidase activity in mouse liver (10 wt% liver tissue homogenate) is 20-25 U / L.

[0099] Preferably, the activity of superoxide dismutase in mouse serum is 190-251 U / mL, and / or the malondialdehyde content in mouse serum is 8-11 mmol / L, and / or the activity of glutathione-peroxidase in mouse serum is 670-805 activity units, wherein an activity unit refers to: at a temperature of 37° C., the amount of enzyme required (reduced) to catalyze the oxidation of 1 μumol GSH within 1 min per 1 L of serum is one GSH-PX activity unit.

[0100] More preferably, the activity of superoxide dismutase in mouse serum is 237-251 U / mL, and / or the malondialdehyde content in mouse serum is 8-10 mmol / L, and / or the activity of glutathione-peroxidase in mouse serum is 780-805 activity units, wherein an activity unit refers to: at a temperature of 37° C., the amount of enzyme required (reduced) to catalyze the oxidation of 1 μumol GSH within 1 min per 1 L of serum is one GSH-PX activity unit.

[0101] In order to better understand the technical solution of the present invention, the technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0102] Unless otherwise specified, the various reagents / instruments used in the examples of the present invention are conventional commercially available products. The sources of the experimental reagents used in the present invention are shown in Table 1.

[0103] Table 1. Experimental reagent information

[0104]

[0105]

[0106] The concentrations of the components in the MRS liquid medium used in the example (purchased from Qingdao Haibo Biotechnology Co., Ltd.) are as follows: peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, dipotassium hydrogen phosphate 2.0 g / L, triammonium citrate 2.0 g / L, sodium acetate 5.0 g / L, magnesium sulfate 0.2 g / L, manganese sulfate 0.05 g / L, agar 15.0 g / L, and Tween 80 1.0 g / L.

[0107] Example 1

[0108] The whole genome sequencing and comparative genomics analysis of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ were performed according to conventional methods. The results showed that the strain contained a unique gene related to antioxidant, with a gene ID of DB-8GL001342, and the corresponding gene sequence was shown in SEQ ID NO: 1; and the strain contained a unique gene related to improving hyperuricemia, with a gene ID of DB-8GL001908, and the corresponding gene sequence was shown in SEQ ID NO: 2). These two unique genes enable the strain to have a higher antioxidant capacity and the ability to improve hyperuricemia, so that it can better exert its probiotic properties.

[0109]

[0110]

[0111] Example 2 Preparation of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder, preparation of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 bacterial powder, and preparation of heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder

[0112] 1. The preparation method of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder is as follows:

[0113] (1) The bacterial solution of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ preserved in a glycerol tube was inoculated into MRS liquid culture medium at a volume ratio of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ:MRS liquid culture medium=1:50 (i.e., inoculation amount 2%), and the bacterial solution was cultured at 37°C for 12 h for activation to obtain a primary seed solution.

[0114] (2) The first-level seed solution obtained in step (1) is inoculated into MRS liquid culture medium at a volume ratio of first-level seed solution: MRS liquid culture medium = 1:50 (i.e., inoculation amount 2%) to obtain a second-level seed solution.

[0115] (3) The secondary seed liquid obtained in step (2) was inoculated into a fermentation medium at a volume ratio of primary seed liquid to MRS liquid medium = 1:20 (i.e., an inoculation amount of 5%) for high-density fermentation, wherein the high-density fermentation was carried out by fermenting and culturing at 40°C under airless conditions for 12 hours, adding a 2.5wt% glucose solution during the fermentation process to maintain the sugar content in the fermentation medium at 10-20g / L, and adding Na2CO3 to maintain the pH of the fermentation medium at 4.5-5. The obtained fermentation liquid (viable count of 7×10 9 CFU / mL).

[0116] (4) After the fermentation liquid obtained in step (3) is centrifuged, the bacterial sludge is collected, and the bacterial sludge and the lyophilization protective agent are post-vacuum freeze-dried to a moisture content of 5% according to a weight ratio of bacterial sludge to lyophilization protective agent = 1:3, to obtain Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder (viable cell count of 3×10 11 CFU / g). The preparation method of the lyophilized protective agent is to mix 25g skim milk, 5g mannitol, 5g trehalose, 1g sodium glutamate and 2g glycerol to obtain the lyophilized protective agent. The vacuum freeze drying conditions are: pre-freezing at -40°C for 4h, and vacuum freeze drying at -40°C for 48h.

[0117] 2. The preparation method of the thermophilic subspecies Jiacha.ST-685 bacterial powder of Streptococcus salivarius is as follows:

[0118] (1) The bacterial solution of the thermophilic subspecies of Streptococcus salivarius Jiacha.ST-685 preserved in a glycerol tube was inoculated into MRS liquid culture medium at a volume ratio of the bacterial solution of the thermophilic subspecies of Streptococcus salivarius Jiacha.ST-685 to MRS liquid culture medium = 1:50 (i.e., inoculation amount 2%), and the culture was activated at 37° C. for 12 h to obtain a primary seed solution.

[0119] (2) The first-level seed solution obtained in step (1) is inoculated into MRS liquid culture medium at a volume ratio of first-level seed solution: MRS liquid culture medium = 1:50 (i.e., inoculation amount 2%) to obtain a second-level seed solution.

[0120] (3) The secondary seed liquid obtained in step (2) is inoculated into a fermentation medium at a volume ratio of secondary seed liquid to MRS liquid medium = 1:20 (i.e., an inoculation amount of 5%) for high-density fermentation, wherein the high-density fermentation is carried out by fermenting and culturing at 42° C. under airtight conditions for 12 h, adding a 2.5 wt % glucose solution during the fermentation process to maintain the sugar content in the fermentation medium at 15-20 g / L, and adding Na2CO3 to maintain the pH of the fermentation medium at 4.5-5, and obtaining a fermentation liquid (with a viable count of 4×10 9 CFU / mL).

[0121] (4) After the fermentation liquid obtained in step (3) was centrifuged, the bacterial sludge was collected, and the bacterial sludge and the lyophilization protective agent were post-vacuum freeze-dried to a moisture content of 5% according to a weight ratio of bacterial sludge to lyophilization protective agent = 1:2 to obtain Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 bacterial powder (viable cell count of 2×10 11 CFU / g). The preparation method of the lyophilized protective agent is to mix 25g skim milk, 5g mannitol, 5g trehalose, 1g sodium glutamate and 2g glycerol to obtain the lyophilized protective agent. The vacuum freeze drying conditions are: pre-freezing at -40°C for 4h, and vacuum freeze drying at -40°C for 48h.

[0122] 3. The preparation method of heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder (postbiotic) is as follows:

[0123] (1) The bacterial solution of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ preserved in a glycerol tube was inoculated into MRS liquid culture medium at a volume ratio of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ:MRS liquid culture medium=1:50 (i.e., inoculation amount 2%), and the bacterial solution was cultured at 37°C for 12 h for activation to obtain a primary seed solution.

[0124] (2) The first-level seed solution obtained in step (1) is inoculated into MRS liquid culture medium at a volume ratio of first-level seed solution: MRS liquid culture medium = 1:20 (i.e., inoculation amount 5%), and cultured at 37° C. for 12 h to obtain a second-level seed solution.

[0125] (3) The secondary seed liquid obtained in step (2) is inoculated into a fermentation medium at a volume ratio of secondary seed liquid to fermentation medium = 1:20 (i.e., an inoculation amount of 5%) for high-density fermentation, wherein the high-density fermentation is carried out by fermenting and culturing at 42° C. under airtight conditions for 12 h, adding a 2.5 wt % glucose solution during the fermentation process to maintain the sugar content in the fermentation medium at 15-20 g / L, and adding Na2CO3 to maintain the pH of the fermentation medium at 4.5-5, to obtain a fermentation liquid (the number of viable bacteria in the fermentation liquid is 1×10 9 CFU / mL).

[0126] (3) The fermented liquid obtained in step (2) was spray-dried to a moisture content of 5% to obtain heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder (the bacterial count was 1×10 11 The spray drying conditions are as follows: inlet air temperature of 170°C, outlet air temperature of 100°C, and flow rate of 200 kg / h.

[0127] Example 3 Preparation of functional yogurt

[0128] Example 3.1 provides a method for preparing functional yogurt, and the specific steps are as follows:

[0129] (1) Raw milk at 55° C. is homogenized, wherein the high pressure is 20 MPa and the low pressure is 5 MPa, the homogenized raw milk is pasteurized at 90° C. for 12 min, and the sterilized raw milk is cooled to 43° C. at room temperature.

[0130] (2) Preparation of composite bacterial agent: 70 g of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder, 15 g of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 powder and 10 g of heat-killed Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder were mixed to obtain a composite bacterial agent.

[0131] (3) 950 L of cooled raw milk, 95 g of the composite bacterial agent obtained in step (2) and 5 g of oligofructose were mixed uniformly to obtain a mixture.

[0132] (4) The mixture is then fermented at 42°C until the acidity reaches 70°T, and then the fermentation is stopped and refrigerated at 4°C overnight to obtain functional yogurt.

[0133] Example 3.2 provides a method for preparing functional yogurt, and the specific steps are as follows:

[0134] (1) Raw milk at 60° C. is homogenized, wherein the high pressure is 20 MPa and the low pressure is 5 MPa, the homogenized raw milk is pasteurized at 85° C. for 15 min, and the sterilized raw milk is cooled to 40° C. at room temperature.

[0135] (2) Preparation of composite bacterial agent: 80 g of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder, 10 g of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 powder, and 5 g of heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder were mixed to obtain a composite bacterial agent.

[0136] (3) 1000 L of cooled raw milk, 95 g of the composite bacterial agent obtained in step (2) and 5 g of oligofructose were mixed uniformly to obtain a mixture.

[0137] (4) The mixture is then fermented at 45°C until the acidity reaches 75°T, and then the fermentation is stopped and refrigerated at 4°C overnight to obtain functional yogurt.

[0138] Example 3.3 provides a method for preparing functional yogurt, and the specific steps are as follows:

[0139] (1) Raw milk at 65° C. is homogenized, wherein the high pressure is 20 MPa and the low pressure is 5 MPa, the homogenized raw milk is pasteurized at 95° C. for 10 min, and the sterilized raw milk is cooled to 44° C. at room temperature.

[0140] (2) Preparation of composite bacterial agent: 75 g of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder, 10 g of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 powder, and 10 g of heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder were mixed to obtain a composite bacterial agent.

[0141] (3) 1200 L of cooled raw milk, 95 g of the composite bacterial agent obtained in step (2) and 5 g of oligofructose were mixed uniformly to obtain a mixture.

[0142] (4) The mixture is then fermented at 45°C until the acidity reaches 72°T, and then the fermentation is stopped and refrigerated at 4°C overnight to obtain functional yogurt.

[0143] Comparative Example 3.1 provides a method for preparing a functional yogurt, which is different from Example 2.3 in that:

[0144] In step (2), 50 g of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder, 35 g of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 powder, and 10 g of heat-inactivated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ powder are mixed to obtain a composite bacterial agent.

[0145] In step (3), 1200 L of cooled raw milk, 95 g of the composite bacterial agent obtained in step (2) and 5 g of oligofructose are mixed evenly to obtain a mixture.

[0146] Comparative Example 3.2 provides a method for preparing a functional yogurt, which is different from Example 2.2 in that:

[0147] In step (2), 75 g of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ bacterial powder, 20 g of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 bacterial powder and 5 g of oligofructose are mixed to obtain a composite bacterial agent.

[0148] In step (3), 1000 L of cooled raw milk and 95 g of the composite bacterial agent obtained in step (2) are mixed evenly to obtain a mixture.

[0149] Technical effect evaluation

[0150] 1. Determine the uric acid-lowering ability of the functional yogurts of Example 3.1, Example 3.2, Example 3.3, and Comparative Example 3.1 and Comparative Example 3.2:

[0151] (1) 60 mice (Kunming mice, Three Gorges University Experimental Animal Center) were randomly divided into 6 groups, each with 10 mice, namely blank control group, model group, Example 3.1 group, Example 3.2 group, Example 3.3 group, Comparative Example 3.1 group, and Comparative Example 3.2 group.

[0152] (2) Feeding methods of mice in each group:

[0153] Blank control group: After adaptive feeding, mice were gavaged with 20 mL of saline per kg of mouse body weight at 6 a.m., once a day, for 7 consecutive days. From the 8th day, sodium carboxymethyl cellulose solution was used in the afternoon (12 hours apart from the above morning gavage) on the basis of gavage with 20 mL of saline in the morning, and the intervention continued for another 7 consecutive days.

[0154] Model group: After adaptive feeding, mice were gavaged with 20 mL of saline per kg of mouse body weight in the morning, once a day, for 7 consecutive days. From the 8th day, on the basis of gavage with 20 mL of saline in the morning, triple administration was performed in the afternoon (12 hours apart from the above morning gavage), where the triple administration method refers to mixing 300 mg of hypoxanthine, 250 mg of potassium oxonate and 15 g of yeast extract with distilled water per kg of mouse body weight to make a 20 mL mixed solution and then gavage once a day for 7 consecutive days.

[0155] Example 3.1 group, Example 3.2 group, Example 3.3 group, Comparative Example 3.1 group and Comparative Example 3.2 group: After the mice were adaptively fed, they were gavaged with 20 mL of the functional yogurt of the corresponding example or comparative example per kg of mouse body weight in the morning, once a day, for 7 consecutive days. From the 8th day, on the basis of gavage of 20 mL of functional yogurt in the morning, gavage was performed in the afternoon (12 hours apart from the above-mentioned morning gavage), wherein the triple administration method refers to mixing 300 mg of hypoxanthine, 250 mg of potassium oxonate and 15 g of yeast extract with distilled water per kg of mouse body weight to form a 20 mL mixed solution and then gavage, once a day, for 7 consecutive days.

[0156] (3) Blood was collected from the eyeballs of mice in each group and serum was separated. The mice were killed by spinal dislocation and the livers were removed. After being rinsed with saline, the livers rinsed with saline were frozen with liquid nitrogen and stored at -80°C. Then, ELISA was used to determine the uric acid content in the mouse serum, the results are shown in Table 2, and the activity of xanthine oxidase (XOD), a key uric acid synthase in the mouse liver, was used to evaluate the uric acid-lowering ability of functional yogurt, the results are shown in Table 3. Three parallel experiments were performed in each group.

[0157] (4) The activity of superoxide dismutase (SOD) in the serum of mice was analyzed, and the results are shown in Table 4. The content of malondialdehyde (MDA) in the serum of mice was analyzed, and the results are shown in Table 5. The activity of glutathione-peroxidase (GSH-PX) in the serum of mice was analyzed, and the results are shown in Table 6, in order to evaluate the antioxidant function of functional yogurt. Three parallel experiments were performed in each group.

[0158] Among them, the detection method of the uric acid content in mouse serum, the activity of superoxide dismutase (SOD) in mouse serum, the malondialdehyde (MDA) content and the activity of glutathione-peroxidase (GSH-PX) is as follows: blood is collected from the eyeballs of mice in each group, and after standing for 20 minutes, the blood is centrifuged at 4°C and 3000r / min for 15 minutes to retain the supernatant, and the supernatant is operated according to the corresponding kit instructions to detect the uric acid content, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and glutathione-peroxidase (GSH-PX) activity.

[0159] The liver tissue of each group of mice was taken, mixed and homogenized in a weight ratio of liver tissue: 0.9% saline = 1:9 to obtain a 10wt% liver tissue homogenate, and then centrifuged at 4°C, 3000r / min for 10min to retain the supernatant, and the supernatant was operated according to the instructions of the corresponding kit to detect the activity of xanthine oxidase (XOD).

[0160]

[0161]

[0162] As shown in Table 2 and Table 3, the results showed that compared with the model group, the preventive intervention of Example 3.1, Example 3.2, and Example 3.3 could significantly reduce the uric acid level in the serum of mice and the activity of XOD.

[0163]

[0164]

[0165]

[0166]

[0167] Note: The "activity unit" in the table means: at a temperature of 37°C, the amount of enzyme required (reduced) to catalyze the oxidation of 1 μumol of GSH in 1 minute per 1L of serum is one GSH-PX activity unit.

[0168] It should be noted that the activity of superoxide dismutase (SOD), malondialdehyde (MDA) content and glutathione peroxidase (GSH-Px) in serum are important indicators for measuring antioxidant capacity. SOD and GSH-Px are the main antioxidant enzymes that can remove free radicals in the body, while MDA is a product of lipid peroxidation, and its content can reflect the degree of oxidative stress in the body. If the activity of SOD and GSH-Px is high and the content of MDA is low, it indicates that it has strong antioxidant capacity and can effectively repair oxidative damage.

[0169] As shown in Tables 4, 5 and 6, the results indicate that, compared with the model group, Example 3.1, Example 3.2 and Example 3.3 can significantly increase the activity of SOD and GSH-PX in serum, while reducing the MDA content in serum. This shows that the functional yogurt provided in the present application has the effect of repairing oxidative damage.

[0170] The above embodiments are only for further explanation and understanding of the technical solution of the present invention, and are not limitations of the present invention. Any non-prominent substantial features and non-significant improvements made by those skilled in the art on this basis should fall within the scope of protection of the present invention.

Claims

1. A composite bacterial agent, characterized in that: The invention comprises, by weight, 60-85 parts of Lactobacillus delbrueckii subsp. lactis powder, 5-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder and 5-15 parts of heat-inactivated Lactobacillus delbrueckii subsp. lactis powder.

2. The composite bacterial agent according to claim 1, characterized in that In parts by weight, 70-85 parts of Lactobacillus delbrueckii subsp. lactis powder, and / or 10-20 parts of Streptococcus salivarius thermophilus subsp. lactis powder, and / or 5-10 parts of heat-killed Lactobacillus delbrueckii subsp. lactis powder, Preferably, by weight, 75-85 parts of Lactobacillus delbrueckii subsp. lactis powder and / or 10-15 parts of Streptococcus salivarius subsp. thermophilus powder are used.

3. The composite bacterial agent according to claim 1 or 2, characterized in that: The number of viable bacteria of Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 CFU / g, and / or the number of viable bacteria of Streptococcus salivarius thermophilus powder is 1-3×10 11 CFU / g, and / or the number of heat-killed Lactobacillus delbrueckii subsp. lactis powder is 1-3×10 11 Pieces / g.

4. The composite bacterial agent according to any one of claims 1 to 3, characterized in that: The Lactobacillus delbrueckii subspecies lactis is Lactobacillus delbrueckii subspecies lactis Dangxiong LBⅧ, and its preservation number is CCTCCNO:M 2023396.

5. The composite bacterial agent according to claim 4, characterized in that: The Lactobacillus delbrueckii subspecies Dangxiong LBⅧ carries a gene related to antioxidant function, wherein the gene related to antioxidant function contains a gene sequence as shown in SEQ ID NO:

1.

6. The composite bacterial agent according to claim 4 or 5, characterized in that: The Lactobacillus delbrueckii subspecies DangxiongLBⅧ carries genes related to improving hyperuricemia, wherein the genes related to antioxidant function contain the gene sequence shown in SEQ ID NO:

2.

7. The composite bacterial agent according to any one of claims 1 to 6, characterized in that: The thermophilic subspecies of Streptococcus salivarius is the thermophilic subspecies of Streptococcus salivarius Jiacha.ST-685, and the deposit number is CCTCC NO:M20231495.

8. The composite bacterial agent according to any one of claims 1 to 7, characterized in that: Lactobacillus delbrueckii subsp. lactis powder is prepared by a method comprising the following steps: (1) inoculating the activated Lactobacillus delbrueckii subsp. lactis into a liquid culture medium to obtain a seed liquid of Lactobacillus delbrueckii subsp. lactis; (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis; (3) After centrifuging the fermentation liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (2), collecting bacterial mud, mixing the bacterial mud with a lyophilization protective agent, and performing vacuum freeze-drying to obtain Lactobacillus delbrueckii subsp. lactis bacterial powder.

9. The composite bacterial agent according to any one of claims 1 to 8, characterized in that: Streptococcus salivarius thermophilus subspecies bacterial powder is prepared by a method comprising the following steps: (1) inoculating the activated thermophilic subspecies of Streptococcus salivarius into a liquid culture medium to obtain a seed liquid of the thermophilic subspecies of Streptococcus salivarius; (2) inoculating the seed liquid of the thermophilic subspecies of Streptococcus salivarius obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of the thermophilic subspecies of Streptococcus salivarius; (3) After centrifuging the fermentation liquid of the thermophilic subspecies of Streptococcus salivarius obtained in step (2), collecting bacterial sludge, mixing the bacterial sludge with a lyophilization protective agent, and performing vacuum freeze-drying to obtain thermophilic subspecies of Streptococcus salivarius bacterial powder.

10. The composite bacterial agent according to any one of claims 1 to 9, characterized in that: Heat-inactivated Lactobacillus germanica subsp. lactis powder is prepared by a method comprising the following steps: (1) inoculating the activated Lactobacillus delbrueckii subsp. lactis into a liquid culture medium to obtain a seed liquid of Lactobacillus delbrueckii subsp. lactis; (2) inoculating the seed liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (1) into a liquid culture medium for high-density fermentation to obtain a fermentation liquid of Lactobacillus delbrueckii subsp. lactis; (3) spray-drying the fermented liquid of Lactobacillus delbrueckii subsp. lactis obtained in step (2) to obtain heat-inactivated Lactobacillus delbrueckii subsp. lactis powder.

11. A method for preparing the composite bacterial agent according to any one of claims 1 to 10, characterized in that: The method comprises the following steps: uniformly mixing Lactobacillus delbrueckii subspecies lactis powder, Streptococcus salivarius thermophilus subspecies lactis powder and heat-inactivated Lactobacillus delbrueckii subspecies lactis powder and then adding the mixture into a composite bacterial agent.

12. Use of the composite bacterial agent according to any one of claims 1 to 10 or the composite bacterial agent prepared by the preparation method according to claim 11 in preparing functional yogurt, wherein: The functional yogurt is a functional yogurt that can lower uric acid or assist in lowering uric acid, and repair oxidative damage.

13. A functional yogurt for lowering uric acid or assisting in lowering uric acid and repairing oxidative damage, characterized in that: The functional yogurt is prepared by a method comprising the following steps: mixing raw milk, prebiotics and the composite bacterial agent described in any one of claims 1 to 10 or the composite bacterial agent prepared by the preparation method described in claim 11, and then fermenting to obtain the functional yogurt.

14. The functional yogurt according to claim 13, characterized in that: The mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 900-1500L: 1-10g: 85-105g, Preferably, the mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 950-1200L: 1-5g: 85-95g, More preferably, the mixing ratio of raw milk, prebiotics and the composite bacterial agent is: 1000-1200L: 1-5g: 90-95g.

15. The functional yogurt according to claim 13 or 14, characterized in that: Prebiotics are fructooligosaccharides.

16. A method for preparing the functional yogurt according to any one of claims 13 to 15, characterized in that: The method comprises the following steps: mixing raw milk, compound bacterial agent and prebiotics and then fermenting.

17. The method for preparing yogurt according to claim 16, characterized in that: The steps include: (1) homogenizing, sterilizing and cooling raw milk; (2) mixing the raw milk, the composite bacterial agent and the prebiotics obtained in step (1) uniformly to obtain a mixture; (3) fermenting the mixture obtained in step (2) and then refrigerating it to obtain the yogurt.

18. The method for preparing functional yogurt according to claim 17, characterized in that: In step (1), the homogenization temperature of the raw milk is 55-65°C.

19. The method for preparing functional yogurt according to claim 18, characterized in that: The homogenization high pressure is 10-30MPa and the low pressure is 3-5MPa.

20. The method for preparing functional yogurt according to claim 17, characterized in that: In step (1), the sterilization temperature is 85-95°C and the sterilization time is 10-15 minutes. And / or in step (1), the mixture is cooled to a temperature of 40-45°C, and / or in step (3), the fermentation temperature is 40-45°C, and / or in step (3), the fermentation is terminated when the acidity of the mixture reaches 65-75°T.

21. Use of the composite bacterial agent according to any one of claims 1 to 10, the composite bacterial agent prepared by the preparation method according to claim 11, or the functional yogurt obtained by the preparation method according to any one of claims 13 to 15 or any one of claims 16 to 20 in preparing health products.

22. A health product, characterized in that: A functional yogurt containing the composite bacterial agent according to any one of claims 1 to 10, or the composite bacterial agent prepared by the preparation method according to claim 11, or the functional yogurt obtained by the preparation method according to any one of claims 13 to 15 or any one of claims 16 to 20.

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