CN118599718A - A strain of Bifidobacterium animalis subspecies lactis MY9 and its application in the preparation of anti-inflammatory and hypoglycemic food and medicine - Google Patents

Abstract

The invention belongs to the technical field of probiotics and application thereof, and particularly relates to bifidobacterium animalis subspecies lactis MY9 and application thereof in preparation of anti-inflammatory and hypoglycemic foods and medicines. The invention separates and purifies the excrement of a healthy adult in Guangdong province in China to obtain an animal bifidobacterium subspecies (Bifidobacterium animalis subsp.lactis) MY9 strain which can not only produce and secrete 3-hydroxybutyric acid, but also inhibit the activity of alpha-glucosidase, and has the functions of resisting inflammation and improving intestinal flora; reducing blood sugar and weight. Therefore, the animal bifidobacterium lactis MY9 strain obtained by the novel separation has various probiotic effects, can be used in the fields of anti-inflammation, blood sugar reduction and the like, and has important application value and economic value.

Description

A strain of Bifidobacterium animalis subspecies lactis MY9 and its application in the preparation of anti-inflammatory and hypoglycemic food and medicine

Technical Field

The invention belongs to the technical field of probiotics and their application, and particularly relates to a strain of animal Bifidobacterium lactis subspecies MY9 and application thereof in the preparation of anti-inflammatory and blood sugar-lowering food and medicine.

Background Art

Bifidobacterium animalis subsp. lactis is a Gram-positive bacillus belonging to the genus Bifidobacterium. Its colonies are smooth, convex, with complete edges, milky white, shiny and soft. Bifidobacterium animalis subsp. lactis does not form spores, is non-motile, and is an anaerobic organism. Its optimum growth temperature is 3-41°C; its optimum fermentation temperature is 35-40°C; its minimum growth temperature is 25-28°C; and its maximum growth temperature is 43-45°C. Bifidobacterium animalis subsp. lactis is mainly distributed in the human intestines, and is also present in large quantities in the digestive tracts of some warm-blooded animals (such as pigs, dogs, mice and bees), indicating that Bifidobacterium animalis subsp. lactis is a normal strain present in the human body. In addition, Bifidobacterium animalis subsp. lactis has good acid and bile resistance, can survive in the stomach and intestines of humans and animals, and is widely present in the intestines of humans and animals.

Animal Bifidobacterium lactis subspecies is one of the strains that can be used for production and processing, and is widely present in the intestinal tract of humans and animals and is discharged with feces. As a probiotic in the intestinal flora, it is also an edible lactic acid bacteria. Animal Bifidobacterium lactis subspecies can also help intestinal peristalsis, and can also enhance the digestive ability of the human body and improve immunity. Therefore, animal Bifidobacterium lactis subspecies has become a hot topic of research in recent years as a probiotic bifidobacterium with great potential. Thereby animal Bifidobacterium lactis subspecies is widely used in the production of probiotic preparations for humans and animals as a probiotic, and is constantly being used to make probiotic preparations suitable for humans and animals.

Studies have shown that different strains of Bifidobacterium animalis subsp. lactis have different probiotic functions: (1) Bifidobacterium animalis subsp. lactis BB-12, isolated from fermented dairy products collected by Chr. Hansen, has been used in infant formula, complementary foods and fermented dairy products around the world. BB-12 exhibits high gastric acid and bile tolerance and has adhesion in the intestines. Therefore, it has potential application value in maintaining intestinal microecological balance, improving intestinal dysfunction, and alleviating symptoms and signs of allergic diseases (Jungersen M, Wind A, Johansen E, et al. The Science behind the Probiotic Strain Bifidobacterium animalis subsp. lactis BB-12 Microorganisms.2014Mar 28;2(2):92-110.doi:10.3390/microorganisms2020092.PMID:27682233; PMCID:PMC5029483.). (2) Bifidobacterium animalis subsp. lactis strain V9 has good tolerance to gastrointestinal digestive juices and antagonistic effects on intestinal pathogens. It has probiotic functions such as significantly improving the recovery rate of diarrhea and regulating immunity (Sun Z, Chen X, Wang J, et al. Complete genome sequence of probiotic Bifidobacterium animalis subsp. lactis strain V9. J Bacteriol. 2010 Aug; 192(15): 4080-1. doi: 10.1128/JB.00369-10. Epub 2010 May 28. PMID: 20511504; PMCID: PMC2916379.). (3) Bifidobacterium animalis subsp. lactis XLTG11 has the effect of preventing and treating colitis (Wang N, Wang S, Xu B, et al. Alleviation Effects of Bifidobacterium animalis subsp. lactis XLTG11 on Dextran Sulfate Sodium-Induced Colitis in Mice. Microorganisms. 2021 Oct 3; 9(10): 2093. doi: 10.3390/microorganisms9102093. PMID: 34683415; PMCID: PMC8539219.). (4) As people's living standards continue to improve, the nutrition they consume is becoming more abundant, which leads to an increase in serum cholesterol in the body, thereby causing a series of diseases such as hypertension, coronary heart disease, and arteriosclerosis. Animal Bifidobacterium lactis subsp. HCS04-002 has good resistance to adverse environments and can withstand the effects of artificial gastric juice and artificial intestinal juice, and can enter the intestine with a higher survival rate to effectively play a probiotic role. It not only has a high lactase activity, which can alleviate lactose intolerance, but also has triglyceride degradation function, and has certain application prospects in the preparation of lipid-lowering products (Yu Ping, Zhao Di, Zhang Chunyu, et al. Research on the probiotic properties of animal Bifidobacterium lactis subsp. HCS04-002 [J]. China Brewing, 2021, 40(05): 86-90.).

Since animal Bifidobacterium lactis subspecies has diverse sources, it has genetic diversity and functional diversity. However, there are still few studies on the isolation and identification, probiotic properties and metabolic mechanisms of animal Bifidobacterium lactis subspecies, which to a certain extent affects the development and utilization of animal Bifidobacterium lactis subspecies. Therefore, it is necessary to explore more new strains based on the different sources of animal Bifidobacterium lactis subspecies, and then determine their efficacy based on the function of the strain or the probiotic metabolites, clarify their application prospects, and enable them to better play a probiotic role. In summary, the research and application of probiotic animal Bifidobacterium lactis subspecies has broad development space.

Summary of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the present invention isolates and purifies a Bifidobacterium animalis subsp. lactis MY9 strain from the feces of a healthy adult in Guangdong Province, China. The strain can not only produce and secrete 3-hydroxybutyric acid, but also inhibit the activity of α-glucosidase, and has important potential application value in the fields of anti-inflammatory and hypoglycemic.

In order to achieve the above object, the technical solution adopted by the present invention is:

The first aspect of the present invention provides a Bifidobacterium animalissubsp.lactis MY9 strain, which was deposited in the China Center for Type Culture Collection on October 25, 2023, with the accession number: CCTCC NO:M 20232016; the 16SrDNA sequence of the Bifidobacterium animalissubsp.lactis MY9 strain is shown in SEQ ID No: 1.

The second aspect of the present invention provides use of the Bifidobacterium animalis subsp. lactis MY9 strain described in the first aspect in producing 3-hydroxybutyric acid.

Research has found that the probiotic Bifidobacterium animalis subsp. lactis MY9 strain can produce 3-hydroxybutyric acid (3-HB), suggesting that Bifidobacterium animalis subsp. lactis MY9 strain can be used to produce 3-HB, and through the characteristic of producing 3-HB, it can be used to provide energy for various body activities, fight osteoporosis, prevent and treat chronic syndrome, improve brain cognitive function, improve lipid metabolism, and relieve intestinal inflammation.

The third aspect of the present invention provides use of the Bifidobacterium animalis subsp. lactis MY9 strain described in the first aspect in the preparation of an α-glucosidase inhibitor.

Studies have shown that the probiotic Bifidobacterium animalis subspecies MY9 can effectively inhibit the activity of α-glucosidase, which is related to type 2 diabetes. Inhibiting α-glucosidase is one of the methods to control postprandial hyperglycemia, suggesting that Bifidobacterium animalis subspecies MY9 is expected to be used in areas such as lowering blood sugar and inhibiting obesity.

The fourth aspect of the present invention provides a method for preparing 3-hydroxybutyric acid, specifically: the Bifidobacterium animalis subsp. lactis MY9 strain described in the first aspect is inoculated into an MRS liquid culture medium, and after culturing to a stable period, the bacterial suspension is collected, and finally 3-hydroxybutyric acid in the bacterial suspension is separated and purified.

Preferably, the culture conditions are: 37°C constant temperature anaerobic.

Preferably, the Bifidobacterium animalis subsp. lactis MY9 strain is first cultured in MRS liquid culture medium to a stable phase, and then expanded into a new MRS liquid culture medium at a dilution multiple of 1:20-100.

The fifth aspect of the present invention provides an α-glucosidase inhibitor, wherein the inhibitor uses the Bifidobacterium animalis subsp. lactis MY9 strain described in the first aspect as a main active ingredient.

Preferably, in the field of medical applications, the inhibitor further includes a pharmaceutically acceptable excipient.

More preferably, the excipients include carriers and excipients. The excipients refer to diluents, adhesives, lubricants, disintegrants, solubilizers, stabilizers, etc. that can be used in the pharmaceutical field, as well as some pharmaceutical matrices. The carrier is a functional pharmaceutical excipient available in the pharmaceutical field, including surfactants, suspending agents, emulsifiers, and some new pharmaceutical polymer materials, such as cyclodextrin, chitosan, polylactic acid (PLA), polyglycolic acid-polylactic acid copolymer (PLGA), hyaluronic acid, etc.

Preferably, in the field of medical applications, the dosage form of the inhibitor includes but is not limited to tablets, granules, capsules, pellets, sustained-release preparations, oral liquid preparations, and injections. The above dosage forms refer to dosage forms commonly used in clinical practice. The pharmaceutical preparation can be administered orally or parenterally (e.g., intravenously, subcutaneously, intraperitoneally or topically). If some drugs are unstable under gastric conditions, they can be prepared into enteric-coated tablets.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention separates and purifies a strain of Bifidobacterium animalis subsp. lactis MY9 from the feces of a healthy adult in Guangdong Province, China. The strain can not only produce and secrete 3-hydroxybutyric acid, but also inhibit the activity of α-glucosidase. Therefore, the Bifidobacterium animalis subsp. lactis MY9 strain has multiple functions such as anti-inflammatory and improvement of intestinal flora; hypoglycemic and weight loss. It can be seen that the newly isolated Bifidobacterium animalis subsp. lactis MY9 strain has multiple prebiotic effects and can be used in the fields of anti-inflammatory and hypoglycemic, for example, it can be made into anti-inflammatory and hypoglycemic medicines, which have important application value and economic value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a phylogenetic tree of Bifidobacterium animalis subsp. lactis MY9 strain (all strains are derived from the Genome database of NCBI);

Figure 2 shows that the animal Bifidobacterium lactis subsp. MY9 strain can produce and secrete 3-hydroxybutyrate

Figure 3 shows that the fermentation broth of Bifidobacterium animalis subsp. lactis MY9 can secrete substances that significantly inhibit the activity of α-glucosidase.

DETAILED DESCRIPTION

The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

The experimental materials involved in the following examples are as follows:

(1) Bifidobacterium animalis subsp. lactis MY9 strain was isolated from the feces of a healthy adult in Guangdong, China by the Runze Laboratory of the Intestinal Microbiology Research Group and stored in glycerol tubes at -80°C. Generally, colonies can be obtained by inoculating it on the surface of an MRS solid culture medium plate and inverting it in a 37°C constant temperature anaerobic incubator for 24 hours, or by shaking it in an MRS liquid culture medium in a 37°C constant temperature anaerobic incubator for 24-48 hours to obtain a fermentation liquid.

(2) Kits: 3-Hydroxybutyrate (3-HB) detection kit (Cloud-Clone Corp., Cat: CEB022Ge), α-glucosidase inhibitor screening kit (abcam, Cat: ab284520).

(3) MRS plate: beef extract 10 g, peptone 10 g, yeast extract 5 g, triammonium citrate 2 g, sodium acetate 5 g, glucose 20 g, dipotassium phosphate 2 g, Tween 80 1 mL, magnesium sulfate 0.58 g, manganese sulfate 0.25 g, agar 15 g, ddH ₂ O to 1 L, adjust pH to 6.2-6.6, autoclave at 121°C for 20 min, and prepare MRS plate.

(4) MRS liquid medium: beef extract 10 g, peptone 10 g, yeast extract 5 g, triammonium citrate 2 g, sodium acetate 5 g, glucose 20 g, dipotassium phosphate 2 g, Tween 80 1 mL, magnesium sulfate 0.58 g, manganese sulfate 0.25 g, make up to 1 L with ddH ₂ O, adjust the pH to 6.2-6.6, and sterilize at 121°C for 20 min to prepare MRS liquid medium.

Example 1 Isolation and Identification of Bifidobacterium animalis subsp. lactis MY9 Strain

Bifidobacterium animalis subsp. lactis MY9 strain was isolated from the feces of a healthy adult (BMI=21.1) in Guangdong Province, China, as follows:

The fecal sample was repeatedly washed 3 times with sterile water, placed in a mortar, 500uL sterile water was added for every 100mg of feces, the slurry was thoroughly ground, an appropriate amount of grinding liquid was taken with a pipette, and it was spread on an MRS plate and cultured at room temperature for 3 days. Then the colonies to be streaked and purified in the separation experiment plate were numbered with a marker, and the strain number was marked on the plate accordingly. After marking, the colonies were picked and inoculated on the MRS plate, and the strains were purified by the plate streaking method. If this method cannot separate the strains, it is necessary to pick the colonies from the enrichment plate, dilute them with the MRS liquid medium gradient, and spread them on the culture medium. Finally, referring to the Bergey Bacterial Identification Manual (Eighth Edition) and the Fungal Classification and Identification Manual, the strains belonging to bacteria were first distinguished. A purified strain was initially isolated, the strain number was MY9, and after 48 hours of culture, the colonies of the strain were observed to be small, smooth, convex, with complete edges and milky white.

Next, the isolated MY9 strain was molecularly identified by 16S rDNA universal primers (27F: AGAGTTTGATCCTGGCTCAG, 1492R: TACGGCTACCTTGTTACGACTT), and then the isolated MY9 strain was sequenced by Beijing Biomaike Biotechnology Co., Ltd. The obtained sequence 16S rDNA sequence (SEQID No: 1) was BLAST aligned in the Genome database of NCBI. The results showed that the homology of the MY9 strain with the known animal Bifidobacterium animalis subsp. lactis 16S rDNA sequence was >99%, and evolutionary analysis was performed with homologous strains (Figure 1), confirming that MY9 is a different strain of the same species of animal Bifidobacterium animalis subsp. lactis.

Finally, the strain MY9 was deposited, and the deposit information is as follows: deposit time: October 25, 2023; name of the depository: China Center for Type Culture Collection (CCTCC); deposit number: CCTCC NO:M 20232016; address of the depository: Wuhan University, Wuhan, China; classification name: Bifidobacterium animalis subsp.lactis.

Bifidobacterium animalis subsp. lactis is a probiotic strain with a wide range of probiotic effects, but strains from different sources have different effects, indicating that the new Bifidobacterium animalis subsp. lactis MY9 isolated from human feces in the present invention can be used as a probiotic and may have new effects and functions.

Bifidobacterium animalis subsp.Lactis MY9 16S rDNA sequence (1397bp, SEQ ID No: 1):

GCAAGTCGAACGGGATCCCTGGCAGCTTGCTGTCGGGGTGAGAGTGGCGAACGGGTGAGTAATGCGTGACCAACCTGCCCTGTGCACCGGAATAGCTCCTGGAAACGGGTGGTAATACCGGATGCTCCGCTCCATCGCATGGTGGGGTGGGAAATGCTTTTGCGGCATGGGATGGGGTCGCGTCCTATCAGCTTGTTGGCGGGGTGATGGCCCACCAAGGCGTTGACGGGTAGCCGGCCTGAGAGGGTG ACCGGCCACATTGGGACTGAGATACGGCCCAGACTCCTACGGGAGGCAGCAGTGGGGAATATTGCACAATGGGCGCAAGCCTGATGCAGCGACGCCGCGT GCGGGATGGAGGCCTTCGGGTTGTAAACCGCTTTTGTTCAAGGGCAAGGCACGGTTTCGGCCGTGTTGAGTGGATTGTTCGAATAAGCACCGGCTAACTACGTGCCAGCCCGCGGTAATACGTAGGGTGCGAGCGTTATCCGGATTTATTGGGCGTAAAGGGCTCGTAGGCGGTTCGTCGCGTCCGGTGTGAAAGTCCATCGCCTAACGGTGGATCTGCGCCGGGTACGGGCGGGCTGGAGTGCGG TAGGGGAGACTGGAATTCCCGGTGTAACGGTGGAATGTGTAGATATCGGGAAGAACACCAATGGCGAAGGCAGGTCTCTGGGCCGTCACTGACGCTGAGGAG CGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGGTGGATGCTGGATGTGGGGCCCTTTCCACGGGTCCCGTGTCGGAGCCAACGCGTTAAGCATCCCGCCTGGGGAGTACGGCCGCAAGGCTAAAACTCAAAGAAATTGACGGGGGCCCGCACAAGCGGCGGAGCATGCGGATTAATTCGATGCAACGCGAAGAACCTTACCTGGGCTTGACATGTGCCGGATCGCCGTGGAGACACGGT TTCCCTTCGGGGCCGGTTCACAGGTGGTGCATGGTCGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAA CCCTCGCCGCATGTTGCCAGCGGGTGATGCCGGGAACTCATGTGGGACCGCCGGGGTCAACTCGGAGGAAGGTGGGGATGACGTCAGATCATCATGCCCCTTACGTCCAGGGCTTCACGCATGCTACAATGGCCGGTACAACGCGGTGCGACACGGTGACGTGGGGCGGATCGCTGAAAACCGGTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGGCGGAGTCGCTAGTAATCGCGGATCAGCAACG CCGCGGTGAATGCGTTCCCGGGCCTTGTACACACCGCCCGTCAAGTCATGAAAGTGGGTAGCACCCGAAGCCGGTGGCCCGACCCTTGTGGGG.

Example 2 Function and application of Bifidobacterium animalis subsp. lactis MY9 strain

(1) Bifidobacterium animalis subsp. lactis MY9 strain can produce and secrete 3-hydroxybutyrate (3-HB)

Animal Bifidobacterium lactis subsp. MY9 cultured to the stable phase in MRS liquid medium was expanded into new MRS liquid medium at a dilution multiple of 1:30. The bacterial suspension was collected at 24 hours after the stable phase, and the fermentation supernatant was collected after centrifugation at 10,000×g and 4°C for 10 minutes. The 3-HB concentration in the fermentation supernatant was then determined by a 3-HB specific ELISA kit (CEB022Ge). The results showed that compared with the absence of 3-HB in the blank medium MRS, the concentration of 3-HB in the supernatant of strain MY9 was 0.063 μg/mL, indicating that animal Bifidobacterium lactis subsp. MY9 strain can produce and secrete 3-hydroxybutyrate in the stable phase (Figure 2).

3-Hydroxybutyric acid (3-HB) can provide energy for various activities of the body and is a potential energy/functional food. It has been added to athletes' drinks, so the probiotic animal Bifidobacterium lactis MY9 strain can be used as an additive for energy products. At the same time, given that 3-HB can effectively fight osteoporosis, prevent and treat chronic syndromes (hypertension, alcoholic fatty liver, enteritis, intestinal cancer), improve brain cognitive function (improve learning and memory ability, protect glial cells, improve Alzheimer's disease), and improve lipid metabolism. Therefore, the probiotic animal Bifidobacterium lactis MY9 strain can play the above multiple uses by producing 3-hydroxybutyric acid.

In addition, 3-HB is an endogenous small molecule naturally produced by the body. It plays an important role in maintaining the integrity of colorectal tissues, and has the functions of maintaining intestinal health, preventing colon diseases and reducing inflammation. 3-HB treatment can promote the proliferation of beneficial intestinal bacteria and relieve the symptoms of multiple sclerosis. It has great potential in regulating the flora and improving health. It can be seen that the probiotic animal Bifidobacterium lactis subspecies MY9 strain can also help improve the intestinal flora and relieve intestinal inflammation.

(2) The fermentation broth of Bifidobacterium animalis subspecies MY9 can effectively inhibit the activity of α-glucosidase

Animal Bifidobacterium lactis subspecies MY9 cultured to the stable phase with MRS liquid medium was expanded to a new MRS liquid medium at a dilution multiple of 1:30, and the bacterial suspension was collected when the stable phase was reached for 24 hours. The fermentation supernatant was collected after centrifugation at 10,000×g and 4°C for 10 minutes, and then the fermentation supernatant was determined by the α-glucosidase inhibitor screening kit (ab284520) to determine the effect of the fermentation supernatant on the enzymatic activity of α-glucosidase hydrolyzing glucose. The results showed that compared with the blank medium MRS without inhibition, the fermentation supernatant of strain MY9 significantly inhibited the ability of α-glucosidase to hydrolyze glucose, and the inhibition rate was about 18.71%, indicating that the fermentation broth of animal Bifidobacterium lactis subspecies MY9 can effectively inhibit the activity of α-glucosidase (Figure 3).

α-glucosidase is an enzyme that plays a role in the breakdown of carbohydrates and is associated with type 2 diabetes. Inhibiting α-glucosidase is one of the ways to control postprandial hyperglycemia, thereby contributing to the treatment of diabetes. Therefore, α-glucosidase inhibitors help maintain blood sugar balance and can improve diabetic complications. In addition, inhibiting the activity of α-glucosidase can control obesity.

Therefore, the probiotic Bifidobacterium animalis subsp. lactis MY9 strain has an inhibitory α-glucosidase activity, which makes it a potential probiotic for lowering blood sugar and inhibiting obesity.

In summary, the newly isolated Bifidobacterium animalis subsp. lactis MY9 strain of the present invention can not only produce and secrete 3-hydroxybutyric acid, but also inhibit the activity of α-glucosidase. Therefore, the newly isolated Bifidobacterium animalis subsp. lactis MY9 strain of the present invention has important application value and economic value in the fields of anti-inflammatory and hypoglycemic.

The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims (7)

1. Use of a strain of bifidobacterium animalis subsp.lactis (Bifidobacterium animalis subsp. Lactis) MY9 for the production of 3-hydroxybutyric acid, wherein said strain of bifidobacterium animalis subsp.my 9 was deposited in the chinese collection of typical cultures at 10 months 2023 under the accession number: CCTCC NO: M20232016; the 16S rDNA sequence of the animal bifidobacterium lactis MY9 strain is shown as SEQ ID No: 1.

2. Use of a strain of bifidobacterium animalis subsp.lactis (Bifidobacterium animalis subsp. Lactis) MY9 for the preparation of an alpha-glucosidase inhibitor, characterized in that said strain of bifidobacterium animalis MY9 was deposited in the chinese collection of typical cultures at 10 months and 25 days 2023, under the deposit number: CCTCC NO: M20232016; the 16S rDNA sequence of the animal bifidobacterium lactis MY9 strain is shown as SEQ ID No: 1.

3. A method for preparing 3-hydroxybutyric acid is characterized in that an animal bifidobacterium subsp (Bifidobacterium animalis subsp.lactis) MY9 strain is inoculated in an MRS liquid culture medium, a bacterial suspension is collected after the culture is carried out to a stationary phase, and finally the 3-hydroxybutyric acid in the bacterial suspension is separated and purified to obtain the 3-hydroxybutyric acid; the animal bifidobacterium lactis MY9 strain is preserved in China center for type culture Collection (China, with the preservation number: CCTCC NO: M20232016; the 16S rDNA sequence of the animal bifidobacterium lactis MY9 strain is shown as SEQ ID No: 1.

4. A method for preparing 3-hydroxybutyric acid according to claim 3, where the culturing conditions are: anaerobic at a constant temperature of 37 ℃.

5. A method for preparing 3-hydroxybutyric acid according to claim 3, wherein animal bifidobacterium subspecies (Bifidobacterium animalis subsp. Lactis) MY9 strain is first cultured in MRS broth to stationary phase and then expanded to new MRS broth at a dilution of 1:20-100.

6. An alpha-glucosidase inhibitor characterized in that the inhibitor comprises a strain of bifidobacterium animalis subsp.lactis (Bifidobacterium animalis subsp. Lactis) MY9 as the major active ingredient; the animal bifidobacterium lactis MY9 strain is preserved in China center for type culture Collection (China, with the preservation number: CCTCC NO: M20232016; the 16S rDNA sequence of the animal bifidobacterium lactis MY9 strain is shown as SEQ ID No: 1.

7. The α -glucosidase inhibitor of claim 6, wherein the inhibitor further comprises pharmaceutically acceptable excipients in the field of pharmaceutical use.