Bifidobacterium animalis subsp. Lactis QY-19, probiotic beer prepared from bifidobacterium animalis subsp. Lactis QY-19 and application

Abstract

The invention provides bifidobacterium animalis subsp. Lactis QY-19, probiotic beer prepared from the bifidobacterium animalis subsp. Lactis QY-19 and application of the probiotic beer. The classification name of the bifidobacterium animalis subsp. Lactis QY-19 is Bifidobacterium animalis subsp. Lactis, the bifidobacterium animalis subsp. Lactis QY-19 is preserved in the China Center for Type Culture Collection, and the preservation number of the bifidobacterium animalis subsp. Lactis QY-19 is CCTCC NO: M 20242174. The bifidobacterium animalis subsp. Lactis QY-19 has no pathogenicity, has no acute toxicity and is safe and reliable, and experiments prove that the immune performance of animals can be remarkably improved by adding a certain viable count of the bifidobacterium animalis subsp. Lactis QY-19 into beer, and the bifidobacterium animalis subsp. Lactis QY-19 has a unique effect in the aspects of improving immunity and the like, so that the bifidobacterium animalis subsp. Lactis QY-19 has a very good application value.

Description

Technical Field

[0001] The present invention relates to the technical fields of probiotics and beer fermentation, and particularly relates to a Bifidobacterium animalis subsp. lactis QY-19, a probiotic beer prepared therefrom, and applications thereof. Background Art

[0002] The rapid development of modern society has continuously improved people's living standards. Excessive intake of nutrients over a long period and a decline in immunity may cause various diseases, such as influenza, bronchitis, and diseases related to skin infections. Even more seriously, infection with hepatitis B or C viruses can damage the liver and lead to liver cancer, and infection with the AIDS virus can paralyze the entire immune system.

[0003] As a widely popular fermented beverage, compared with other alcoholic beverages, beer, especially craft beer, has become a health-beneficial medium because of its low ethanol content and more antioxidants such as phenols. Although it has traditionally been rich in various yeasts, the application of functional probiotics is still in the preliminary research stage.

[0004] Probiotics are a class of beneficial active microorganisms that colonize the human body and change the composition of the flora in a certain part of the host. Traditional fermented foods such as yogurt, soy sauce, and vinegar contain a rich microbiota, and probiotics extracted from such natural fermentation products have both probiotic effects and safety. The colonization of probiotics in the intestine helps the human body build a probiotic barrier to protect the intestine, and can also improve the intestinal environment through its own metabolism, reduce the oxidative stress of the human body, and inhibit the proliferation of harmful bacteria to a certain extent. With the continuous development of the craft beer industry, the types of beer are becoming increasingly diverse, and fresh (raw) beer containing live yeast can already be purchased in daily life. Its unique flavor and refreshing taste are quite popular. In addition to yeast, some lactic acid bacteria can also grow normally in the beer fermentation broth, which also provides a practical basis for using beer as a carrier to deliver probiotics. By controlled and limited biacidification, probiotics can be introduced without significantly affecting the original flavor of the beer, and the purpose of supplementing probiotics can be achieved when drinking. Bifidobacterium animalis subsp. lactis, as an important probiotic, has been widely proven to have a significant effect on the balance of the human intestinal microecology and the improvement of immunity. Therefore, the development of a probiotic beer is of great significance for enhancing human immunity. Summary of the Invention

[0005] The object of the present invention is to provide a Bifidobacterium animalis subsp. lactis QY-19, a probiotic beer prepared therefrom, and applications thereof. By adding a process of probiotic-assisted fermentation to the traditional beer-making process, the present invention can obtain a probiotic beer that can enhance immunity while retaining the characteristic flavor of the beer, meeting the dual needs of consumers for beer and health.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A strain of Bifidobacterium animalis subsp. lactis QY-19, whose taxonomic name is Bifidobacterium animalis subsp. lactis, is deposited in the China Center for Type Culture Collection with the deposit number CCTCC NO: M 20242174.

[0008] Furthermore, the colony morphology of the Bifidobacterium animalis subsp. lactis QY-19 has a colony diameter of 1-2 mm, is circular, has a neat edge, is opaque, milky white on the front, convex in the middle, has a smooth, bright surface, is moist in texture, and is easy to pick up; the strain cells are short, curved rod-shaped, and in a bifurcated rod shape.

[0009] The present invention also provides a probiotic beer, which is prepared by fermenting with the above-mentioned Bifidobacterium animalis subsp. lactis QY-19.

[0010] Furthermore, the probiotic beer contains no less than 1×10 7 CFU / g of Bifidobacterium animalis subsp. lactis QY-19.

[0011] Furthermore, the preparation steps of the probiotic beer are as follows:

[0012] S1: After the wort is sterilized and the precipitate is removed, yeast is inoculated for anaerobic fermentation. When the change in the sugar content of the fermentation broth is less than 0.1, the primary fermentation ends, and the primary fermentation broth is obtained;

[0013] S2: Activate Bifidobacterium animalis subsp. lactis QY-19 and inoculate it into the primary fermentation broth for fermentation culture;

[0014] S3: Add isomaltooligosaccharide to the wort, boil it and then perform rotary precipitation, and after cooling, introduce oxygen into the fermentation tank;

[0015] S4: Ferment at constant pressure and temperature. When the diacetyl in the fermentation broth ≤ 0.06 mg / L, acetaldehyde ≤ 8 mg / L, apparent sugar content ≤ 5°P, and the number of Bifidobacterium animalis subsp. lactis QY-19 and yeast ≥ 2×10 6 CFU / mL, seal the tank and increase the pressure. After cooling, perform cold storage for post-fermentation to obtain the probiotic beer raw pulp.

[0016] Furthermore, in S2, the inoculation amount of Bifidobacterium animalis subsp. lactis QY-19 is 4% - 8% of the primary fermentation broth; the culture temperature is 37°C, and the culture time is 48h - 72h.

[0017] Further, in S3, the concentration of isomaltooligosaccharide is 30 g / L, cooled to 18°C - 20°C, and the dissolved oxygen of the wort in the fermenter is controlled at 8 - 10 mg / L;

[0018] Further, in S4, the fermentation temperature is 15°C - 20°C, and the fermentation time is 6 d - 12 d; the pressure is increased to 0.12 MPa - 0.14 MPa, cooled to 0°C, and post-fermentation is carried out at cold storage for 7 d - 10 d.

[0019] Further, the probiotic beer raw pulp stored at 4°C for 30 days is subjected to viable bacteria detection, and the concentration of viable cells of the probiotic Bifidobacterium animalis subsp. lactis QY-19 is higher than 10 8 CFU / mL.

[0020] The present invention also provides the application of the above-mentioned Bifidobacterium animalis subsp. lactis QY-19 in the preparation of drugs and foods for enhancing immunity.

[0021] Compared with the prior art, the positive and progressive effects of the present invention are as follows:

[0022] A strain of Bifidobacterium animalis subsp. lactis QY-19 is screened from dairy starters in the present invention, and probiotic beer is prepared by using this bacterium, which contains a large number of viable cells of Bifidobacterium animalis subsp. lactis, can effectively improve intestinal health problems such as diarrhea and irritable bowel syndrome, and can enhance the immunity of humans and animals. Compared with the beer fermented alone, the addition of probiotic Bifidobacterium animalis subsp. lactis for mixed fermentation of the liquor can enhance the immune function of humans and animals and prevent various adverse side effects of antibiotics on the human body, indicating that the probiotic beer has a more health-beneficial quality, so it has broad application prospects. Description of the Drawings

[0023] Figure 1 It is a microscopic examination photo of the thallus of Bifidobacterium animalis subsp. lactis QY-19. Detailed Embodiments

[0024] The technical solutions of the present invention will be further explained in detail below with reference to specific embodiments and drawings. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments.

[0025] Example 1: Strain Isolation and Identification

[0026] 1. Strain Isolation

[0027] Take the dairy starter from the market and add it to 100 ml of MRS liquid shake flask culture medium. After culturing for 24 hours, streak it onto MRS solid culture medium and culture it anaerobically at 37℃ for 48 hours. Inoculate the obtained single colony into MRS liquid culture medium. After culturing it at 37℃ for 24 hours, add physiological saline to make a dilution gradient bacterial suspension to 10 -8 , select three appropriate gradient bacterial suspensions and take 1 mL each, inoculate into selective solid culture medium, and culture at 37℃ under anaerobic conditions for 48 h. Pick the typical colonies on the plate, repeat streaking separation for 3 generations, obtain the purified strains, perform Gram staining and observe under a microscope, select Gram-positive strains, and microscopically observe spherical, rod-shaped, and polymorphic strains. Among the multiple strains screened, a forked rod-shaped bacterium was further screened, and a strain numbered QY-19 was obtained.

[0028] 2. Strain identification and morphological observation

[0029] (1) Microscopic examination: The strain QY-19 was inoculated on a modified MRS solid plate and cultured anaerobically at 37°C for 48 h to observe the morphological characteristics of the colonies. Morphological observation was performed using an optical microscope, such as Figure 1 As shown, the colony morphology is 1-2mm in diameter, round, with neat edges, opaque, milky white on the front, convex in the middle, smooth and bright on the surface, moist in texture, and easy to pick up. The strain cells are short, curved rods, sometimes bifidobacterial rods, and their typical morphological characteristics are bifurcated rods, medium-sized, non-spore-forming, and positive after Gram staining.

[0030] (2) Preservation of bacterial strains: The bacterial suspension was mixed with glycerol in a volume ratio of 7:3 and stored at -80°C ultra-low temperature to ensure its genetic stability and repeatability of subsequent experiments.

[0031] (3) 16S rRNA identification: DNA of strain QY-19 was extracted as a template, and its 16S rRNA gene was amplified using universal primers. The DNA was sent to a biological company for sequencing to obtain a complete 16S rRNA sequence. The PCR amplification primers selected were bacterial universal primers 27F: (5'-AGAGTTTGATCCTGGCTCAG-3') 1429R: (5'-GGTTACCTTGTTACGACTT-3'); PCR reaction conditions: pre-denaturation at 95℃ for 5min; denaturation at 95℃ for 30s, annealing at 56℃ for 30s, extension at 72℃ for 45s for a total of 35 cycles, and annealing and extension at 72℃ for 10 min. The sequencing results are shown in SEQ ID No. 1, and compared with the NCBI database, its taxonomic status was confirmed to be animal Bifidobacterium lactis subsp.

[0032] The screened Bifidobacterium animalis subsp. lactis QY-19 was preserved. The preservation unit of Bifidobacterium animalis subsp. lactis QY-19: China Center for Type Culture Collection (CCTCC); Address: Wuhan University, Wuhan, China; The preservation number of Bifidobacterium animalis subsp. lactis QY-19: CCTCC NO: M 20242174, and the preservation date was October 14, 2024.

[0033] Example 2: Physiological and biochemical properties

[0034] A series of physiological and biochemical tests were carried out on the screened Bifidobacterium animalis subsp. lactis QY-19 strain. The observation of physiological and biochemical characteristics was carried out with reference to the methods in "Handbook of Systematic Identification of Common Bacteria" and "Classification, Identification and Experimental Methods of Lactic Acid Bacteria".

[0035] 1. Antibiotic sensitivity test

[0036] The K-B method was used to determine the sensitivity of the strain to 8 antibiotics. According to the standards of the Clinical and Laboratory Standards Institute (CLSI) of the United States, it was determined as resistant, intermediate, and sensitive. The results are shown in Table 1. In this study, it was found through the K-B method that Bifidobacterium animalis subsp. lactis QY-19 was sensitive to 8 antibiotics and had a low safety risk.

[0037] Table 1: Results of the antibiotic sensitivity experiment of Lactobacillus plantarum NSL0125 provided by the present invention

[0038] antibiotic penicillin chloramphenicol rifampicin tetracycline clindamycin vancomycin cefaclor sensitivity S S S S S S S

[0039] Note: S is sensitive; M is moderately sensitive; R is resistant.

[0040] 2. Physiological and biochemical detection

[0041] The catalase test, indole test, starch hydrolysis test, nitrate reduction test, gelatin liquefaction test, hydrogen sulfide production test, and fermentation gas production test of strain QY-19 were all negative, which was in line with the characteristics of the genus Lactobacillus. Therefore, it was preliminarily determined to be the genus Lactobacillus, and the results are shown in Table 2.

[0042] Table 2: Results of physiological and biochemical detection

[0043] item catalase test indole test starch hydrolysis test nitrate reduction test gelatin liquefaction test hydrogen sulfide production test fermentation gas production test QY-19 - - - - - - -

[0044] Through this series of tests, Bifidobacterium animalis subsp. lactis with excellent physiological and biochemical characteristics was finally selected, laying a solid foundation for the next step of probiotic beer development and application research.

[0045] Example 3: Simulation of gastrointestinal fluid tolerance

[0046] Preparation of artificial gastric juice: Pepsin was dissolved in sterilized normal saline (0.9% w / v, pH 3.0) to a final concentration of 3 g / L of pepsin, filtered through a 0.22 μm sterile filter membrane, and prepared freshly before use.

[0047] Preparation of artificial intestinal juice: Trypsin was dissolved in sterilized normal saline (0.9% w / v, pH 8.0) to a final concentration of 1 g / L of trypsin, and bile salts were added to a final concentration of 0.3%, filtered through a 0.22 μm sterile filter membrane, and prepared freshly before use.

[0048] After activating the strain QY-19 for 3 generations, 1 mL was taken and placed respectively in 9 mL of artificial gastric juice with a pH of 3.0 that had been sterilized by filtration. It was shaken evenly and cultured at 37 °C. Samples were taken at the beginning and after 4 h of culture to determine the viable cell count. Then, 1 mL of the culture solution after digestion in artificial gastric juice at pH 3.0 for 4 h was taken and inoculated respectively into 9 mL of artificial intestinal juice with a pH of 8.0 that had been sterilized by filtration, and continued to be cultured at 37 °C. The viable cell count was measured at 0 and 4 h respectively. The results are shown in Table 3. The strain QY-19 has a certain tolerance in the gastrointestinal environment, especially stronger survival ability in intestinal juice, and is suitable for the research and development of probiotic products that need to reach the intestine through the stomach to exert their effects.

[0049] Survival rate (%) = (N1 / N0) × 100%;

[0050] Where: N1 is the viable cell count after being treated with artificial digestive juice for 4 h, CFU / mL;

[0051] N0 is the viable cell count after being treated with artificial digestive juice for 0 h, CFU / mL.

[0052] Table 3: Test results of gastrointestinal adaptability

[0053] artificial digestive juice survival rate (%) gastric juice 52.7±3.2 intestinal juice 62.1±2.3

[0054] Example 4: Safety evaluation of Bifidobacterium animalis subsp. lactis QY-19

[0055] Oral acute toxicity test in animals:

[0056] Twenty healthy adult SPF-grade KM mice weighing 18 - 25 g were selected, with 10 males and 10 females. The Bifidobacterium animalis subsp. lactis QY-19 in the growth stage was adjusted to a concentration of 1×10 8CFU / mL, fasting gavage once, each gavage volume of 0.2 mL / 10 g body weight. Immediately after gavage, the activity performance, body weight and physical condition of the animals were observed for 14 days.

[0057] The results showed that during the observation period, the mice had normal activity and appetite, and gained weight. After the experiment, the surviving mice were dissected and no abnormalities were found in their internal organs such as the heart, liver, spleen, lungs, kidneys, and intestines. This shows that animal Bifidobacterium lactis subspecies QY-19 is not acutely toxic to mice, indicating that animal Bifidobacterium lactis subspecies QY-19 is safe.

[0058] Embodiment 5: the preparation method of probiotic beer

[0059] The present invention provides a method for preparing probiotic beer, comprising the following steps:

[0060] Step 1: Sterilize the wort at 115°C for 20 min and filter out the precipitate. Add 3-8% yeast seed solution to the wort to make the final yeast concentration reach 2.34×10 9 CFU / mL, the first anaerobic fermentation is carried out at 20°C, during which the sugar content change is continuously monitored, and the initial fermentation is considered to be completed when the sugar content change is less than 0.1 for two consecutive days. The yeast seed liquid preparation method is as follows: after the malt juice is sterilized, the preserved beer yeast is added and cultured at 37°C for 1 to 5 days.

[0061] Step 2: Activate the animal Bifidobacterium lactis subspecies QY-19 in MRS culture, inoculate the activated strain animal Bifidobacterium lactis subspecies into the primary fermentation liquid, inoculate 4-8% of the culture volume, culture temperature is 37°C, culture time is 48 hours, and transfer and expand the activated strain twice; wherein, the concentration of activated bacteria is: animal Bifidobacterium lactis subspecies QY-19 is 3.93×10 11 CFU / mL.

[0062] Step 3: Add 30 g / L isomaltooligosaccharide to 10°P whole wheat wort, boil the wort, swirl and precipitate, cool to 18-20°C, oxygenate and introduce into a 100 L fermenter, and control the dissolved oxygen in the wort at 8-10 mg / L.

[0063] Step 4: The main fermentation temperature is 15-20℃, and the fermentation is carried out at normal pressure and constant temperature. The main fermentation time is controlled at 6-12 days.

[0064] Step 5: During the main fermentation, the apparent sugar content, yeast count and number of live probiotics in the fermentation liquid were tracked and tested. From the 7th day of the main fermentation, diacetyl and acetaldehyde were tracked and tested. When diacetyl in the fermentation liquid was ≤0.06 mg / L, acetaldehyde was ≤8 mg / L, the apparent sugar content was ≤5°P, and the number of active yeasts of animal Bifidobacterium lactis subspecies QY-19 was ≥2×106 CFU / mL, seal the tank and increase the pressure.

[0065] Step 6: Let the pressure in the tank rise naturally to 0.12 - 0.14 MPa, cool down to 0 °C, and the cold storage and post-fermentation time is 7 days to obtain a probiotic raw beer liquid containing active Bifidobacterium animalis subsp. lactis.

[0066] Example 6: Immune performance detection

[0067] 1. Determination indexes and methods

[0068] Select 100 SPF-grade ICR female mice with a body weight of 18 - 22 g. The mice in this experiment are divided into 10 groups, with 10 mice in each group, and every three groups are an experimental group. The recommended human dose is 2 g / 60 kg per day, and a physiological saline control group is set up. Feed continuously for 28 d according to the dose design. Feed the probiotic beer prepared in Example 5 to the mice by gavage, and the gavage volume is 0.4 mL / 20 g.

[0069] 1. Determination of organ-body weight ratio

[0070] Take the initial body weight of the mice and the weight after 28 d of gavage intervention as the initial weight and the final weight respectively. Dislocate and sacrifice the mice, take the spleen and thymus, remove all the fascia, dry the blood stains on the surface of the organs with filter paper, weigh them, and calculate the spleen-body weight ratio and thymus-body weight ratio.

[0071] The results are shown in Table 4. It can be seen from the table that there is no significant difference in the spleen / body weight ratio and thymus / body weight ratio of the mice between the probiotic beer and the control group (p < 0.05), indicating that the probiotic beer has no significant effect on the spleen and thymus of the mice.

[0072] Table 4: Body weight and organ ratio of mice

[0073] group spleen / body weight ratio (mg / g) thymus / body weight ratio (mg / g) control group 13.52±0.23 10.64±0.11 experimental group 13.32±0.31 10.53±0.18

[0074] 2. Lymphocyte proliferation ability

[0075] The lymphocyte suspension of mice was added into two wells of a 24-well culture plate, 1 mL per well. 75 μL of ConA solution (equivalent to 7.5 μg / mL) was added to one well, and the other well was used as a control. The plate was incubated at 37 °C in a 5% CO2 incubator for 72 h. 4 h before the end of the culture, 0.7 mL of the supernatant was aspirated, and 0.7 mL of RPMI 1640 culture medium without calf serum and 50 μL of MTT (5 mg / mL) were added per well, and the culture was continued for 4 h. After the culture was completed, 1 mL of acidic isopropanol was added to each well, and the mixture was pipetted and mixed manually to completely dissolve the purple crystals. The solution was transferred to a 96-well culture plate for parallel samples in 3 wells, and the optical density value was measured at a wavelength of 570 nm. The result was expressed as the lymphocyte proliferation ability, and the lymphocyte proliferation ability = the optical density value of the well with ConA - the optical density value of the well without ConA. If the optical density difference of the test group was significantly higher than that of the control group, the experimental result was determined to be positive.

[0076] The results are shown in Table 5. Compared with the control group, after 28 days of administration of the test probiotic beer, the proliferation ability of spleen lymphocytes increased significantly (p < 0.01), indicating that the beer under the experimental conditions could promote lymphocyte proliferation.

[0077] Table 5: Changes in the proliferation ability of mouse lymphocytes

[0078] group OD570 difference control group 0.273±0.022 experimental group 0.301±0.025

[0079] Note: Compared with the control group: P < 0.01

[0080] 3. Detection of NK cell activity

[0081] Under normal circumstances, the LDH contained in the cytoplasm of living cells cannot penetrate the cell membrane. When the cells are killed by NK cells, LDH is released into the extracellular space. LDH can dehydrogenate lithium lactate, thereby reducing NAD to NADH, and the latter is further reduced to a purple-red formazan compound by a hydrogen carrier, and the absorbance value can be measured at 490 nm.

[0082] Animals were continuously intragastrically administered with probiotic beer for 28 d. The target cell YAC-1 was passaged 24 h before the start of the experiment. Before use, it was washed twice with Hank’s solution, and the cell concentration was adjusted to 1 × 10 5 cells / mL (target cells) with RPMI 1640 complete culture medium containing 10% calf serum. After 28 d, the mice were sacrificed by cervical dislocation, the spleen was aseptically removed, and a spleen cell suspension was prepared. It was washed twice with Hank’s solution, centrifuged at 1000 rpm for 10 min, and then resuspended with 2 mL of RPMI 1640 complete medium containing 10% calf serum. The viable cells were stained with trypan blue for counting (the viable cell count should be above 95%), and the cell concentration was adjusted to 1 × 107 cells / mL (effector cells) to make the effector-to-target ratio 100:1. Take 100 μL each of target cells and effector cells and add them to a U-shaped 96-well culture plate. In the natural release wells of the target cells, add 100 μL each of target cells and culture medium. In the maximum release wells of the target cells, add 100 μL each of target cells and 1% NP40. Set up 3 parallel wells for each of the above, culture for 4 h, centrifuge the 96-well culture plate at 1500 rpm for 5 min, aspirate 100 μL of the supernatant from each well and place it in a flat-bottom 96-well culture plate. At the same time, add 100 μL of LDH substrate solution, react for 3 min, then add 30 μL of 1 mol / L HCl solution to each well to terminate the reaction, and measure the OD value at 490 nm using an enzyme-linked immunosorbent assay (ELISA) reader. NK activity is calculated according to the following formula:

[0083] NK cell activity (%) = OD value of reaction wells - OD value of natural release wells

[0084] OD value of maximum release wells = OD value of natural release wells × 100%

[0085] The results are shown in Table 6. It can be seen from the table that compared with the control group, the NK cell activity of the experimental group samples is higher than that of the control group, and the difference is extremely significant (p < 0.05), and the test result is positive. This indicates that the probiotic beer significantly improves the NK cell activity of mice.

[0086] Table 6: Detection results of NK cell activity

[0087] group cell viability % control group 31.20±2.10 experimental group 42.27±3.17

[0088] Note: Compared with the control group: P < 0.01

[0089] In summary, the Bifidobacterium animalis subsp. lactis QY-19 screened in the present invention has significant efficacy in enhancing immunity, and a novel probiotic beer is prepared using this bacterium. This probiotic-based beer is expected to become an important means of enhancing immunity and has broad market application prospects.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. A strain of Bifidobacterium animalis subspecies lactis QY-19, characterized in that: Its classification name is Bifidobacterium animalis subsp. lactis, and the animal Bifidobacterium lactis subsp. QY-19 is preserved in the China Center for Type Culture Collection with a preservation number of CCTCC NO: M 20242174.

2. The animal Bifidobacterium lactis subspecies QY-19 according to claim 1, characterized in that The colony morphology of the animal Bifidobacterium lactis subspecies QY-19 is that the colony has a diameter of 1-2 mm, is round, has neat edges, is opaque, is milky white on the front, is convex in the middle, has a smooth and bright surface, is moist in texture, and is easy to pick up; the strain cells are short, curved rods, and are bifidobacterial rod-shaped.

3. A probiotic beer, characterized in that: The probiotic beer is prepared by fermenting the Bifidobacterium animalis subspecies lactis QY-19 described in claim 1.

4. The probiotic beer according to claim 4, characterized in that The number of live bacteria in the probiotic beer is not less than 1×10 7 CFU / g of Bifidobacterium animalis subsp. lactis QY-19.

5. The probiotic beer according to claim 4, characterized in that: The preparation steps of the probiotic beer are as follows: S1: After the wort is sterilized and the precipitate is removed, yeast is added for anaerobic fermentation. When the sugar content of the fermentation liquid changes to less than 0.1, the initial fermentation ends and the initial fermentation liquid is obtained; S2: activating the animal Bifidobacterium lactis subspecies QY-19 and inoculating the primary fermentation liquid for fermentation culture; S3: adding isomaltooligosaccharide to the wort, boiling it, swirling it to precipitate, cooling it, aerating it, and introducing it into the fermentation tank; S4: Fermentation at normal pressure and constant temperature, when diacetyl in the fermentation liquid is ≤0.06 mg / L, acetaldehyde is ≤8 mg / L, apparent sugar content is ≤5°P, and the number of animal Bifidobacterium lactis subspecies QY-19 and yeast is ≥2×10 6 CFU / mL, seal the tank and increase the pressure, cool it down, cold store it and then ferment it to obtain the probiotic beer puree.

6. The probiotic beer according to claim 5, characterized in that: In the S2, the inoculation amount of Bifidobacterium animalis subspecies lactis QY-19 is 4% to 8% of the initial fermentation liquid; the culture temperature is 37° C., and the culture time is 48 h to 72 h.

7. The probiotic beer according to claim 5, characterized in that: In the S3, the concentration of isomaltooligosaccharide is 30 g / L, the temperature is cooled to 18° C. to 20° C., and the dissolved oxygen in the wort in the fermenter is controlled at 8 to 10 mg / L.

8. The probiotic beer according to claim 5, characterized in that: In S4, the fermentation temperature is 15°C to 20°C, and the fermentation time is 6 days to 12 days; the pressure is increased to 0.12 MPa to 0.14 MPa, the temperature is reduced to 0°C, and the fermentation is carried out for 7 days to 10 days after cold storage.

9. Use of the animal Bifidobacterium lactis subspecies QY-19 according to claim 1 in the preparation of medicines and foods for improving immunity.

10. The use according to claim 9, characterized in that: The number of viable bacteria in the drugs and foods is not less than 1×10 7 CFU / g of Bifidobacterium animalis subsp. lactis QY-19.

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