Lactobacillus gasseri BN9 for improving sweetness perception ability, fermented food therewith, and use thereof

Abstract

Disclosed are Lactobacillus gasseri BN9 for improving the sweetness perception ability, a fermented food therewith, and use thereof. The present invention relates to the technical field of microorganisms. Taking the Lactobacillus gasseri BN9 can significantly enhance the sweetness perception ability of healthy organisms and regulate the metabolism of intestinal amino acids. Moreover, taking the Lactobacillus gasseri BN9 can significantly enhance the sweetness perception ability of obese and diabetic organisms, reduce the body weight of obese mice, and improve the blood glucose homeostasis of obese and diabetic individuals. In conclusion, the Lactobacillus gasseri BN9 can be used in the preparation of functional foods, health care products, and drugs for improving and enhancing the sweetness perception ability of individuals and has very wide application prospects in regulating taste impairment caused by diseases such as obesity and diabetes, controlling blood glucose in an individual, and other aspects.

Description

Lactobacillus gasseri BN9, which enhances the perception of sweetness, its fermented foods and applications Technical Field

[0001] This invention relates to Lactobacillus gasseri BN9, which enhances the perception of sweetness, its fermented foods, and their applications, and belongs to the field of microbial technology. Background Technology

[0002] Humans have an innate love for sugar, and my country's sugar consumption is currently enormous and increasing year by year. In recent years, the relationship between sugar intake and adverse health effects has received much attention, making sugar intake control an increasingly important topic. Excessive sugar intake is a significant risk factor for metabolic diseases characterized by imbalances in glucose and lipid metabolism, such as type 2 diabetes, obesity, and cardiovascular disease. Methods for controlling sugar intake for different populations, including adolescents, adults, and the elderly, mainly include reducing added sugar, controlling diet, using sweeteners, and taking specific medications to suppress appetite. However, these methods have certain drawbacks. For example, reducing added sugar can worsen the taste of food; controlling diet is difficult to maintain long-term and can lead to nutritional imbalances; sweeteners and medications are expensive and have potential side effects. Furthermore, these methods prevent people from enjoying the pleasure of food, potentially triggering various mental health issues. Controlling sugar intake by enhancing individual sweetness perception can avoid these drawbacks and has significant advantages. It does not require changing dietary structure; sugar control can be achieved simply by reducing added sugar, while providing a pleasant taste experience and ultimately reducing the incidence of obesity, diabetes, and other diseases. Furthermore, diseases such as obesity and diabetes can lead to the degeneration or damage of a patient's sense of taste, causing them to find food tasteless or develop a greater craving for sweetness. However, there are currently no safe and effective drugs to improve an individual's ability to perceive sweetness. Therefore, enhancing the body's ability to perceive sweetness can not only effectively control sugar intake and reduce the occurrence of diseases such as diabetes and obesity, but also play an important role in the adjunctive treatment of taste degeneration or damage.

[0003] The gut microbiota, often referred to as the "internalized external environment," participates in various physiological activities of the host, including digestion, metabolism, and immunity. The gut-brain axis is a bidirectional communication system between the gut microbiota and the brain; the gut microbiota can influence host brain function and behavior through this axis. For example, research has found that gut microbiota can regulate the host's sensory decision-making, influencing responses to odors and food choices; it can also affect the host's perception of sweetness. Therefore, regulating the gut microbiota through probiotics, thereby modulating an individual's sweetness perception and reducing active sugar intake, represents a novel and potential approach.

[0004] Currently, the known functions of probiotics are mainly to regulate intestinal function and improve host nutrient metabolism, but very few types of probiotics are known to enhance the ability to perceive sweetness. Therefore, screening for probiotics that can improve an individual's ability to perceive sweetness and developing products that can help reduce or control sugar intake or treat taste impairment has extremely broad application prospects.

[0005] Summary of the Invention

[0006] [Technical Issues]

[0007] Currently known functions of probiotics mainly involve regulating intestinal function. No research has reported that any probiotic can improve an individual's ability to perceive sweetness. The technical problem to be solved by this invention is to provide a probiotic that can effectively improve an individual's ability to perceive sweetness and its application.

[0008] [Technical Solution]

[0009] To address the technical problems of this invention, this invention provides Lactobacillus gasseri BN9, which was deposited on January 28, 2024, at the Guangdong Provincial Microbial Culture Collection Center with accession number GDMCC No:64320. The deposit address is Guangdong Institute of Microbiology, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0010] The present invention also provides a microbial preparation containing the above-mentioned Lactobacillus gasseri BN9.

[0011] In one embodiment of the present invention, the viable count of *Lactobacillus gasseri* BN9 in the microbial preparation is not less than 1 × 10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g.

[0012] The present invention also provides a product containing the above-mentioned Lactobacillus gasseri BN9 or the above-mentioned microbial preparation.

[0013] In one embodiment of the present invention, the product includes food, medicine, or health products.

[0014] In one embodiment of the present invention, the food includes fermented food or feed additive; the fermented food includes dairy products, soy products, fruit and vegetable products or other fermented foods containing Lactobacillus gasseri BN9.

[0015] In one embodiment of the present invention, the viable count of the aforementioned Lactobacillus gasseri BN9 in the product is not less than 1 × 10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g.

[0016] In one embodiment of the present invention, the dairy products include milk, sour cream, and cheese.

[0017] In one embodiment of the present invention, the fruit and vegetable products include one or more products made from cucumbers, carrots, beets, celery, cabbage, and other edible fruits and vegetables.

[0018] In one embodiment of the present invention, the fermented food further contains additives, which are selected from one or more combinations of spices, fruit and vegetable juices, flower tea juices, colorants, acidity regulators, preservatives, antioxidants, thickeners, and sweeteners.

[0019] In one embodiment of the present invention, the fermented food is processed into solid food, liquid food, or semi-solid food.

[0020] The present invention also provides the use of the above-mentioned Lactobacillus gasseri BN9 or the above-mentioned microbial preparation in the preparation of drugs that enhance the ability to perceive sweetness.

[0021] The present invention also provides the use of the above-mentioned Lactobacillus gasseri BN9 or the above-mentioned microbial preparation in the preparation of pharmaceuticals or health products that help maintain healthy blood sugar levels.

[0022] The present invention also provides the application of the above-mentioned Lactobacillus gasseri BN9 or the above-mentioned microbial preparation in the preparation of products that reduce the weight of obese individuals. Beneficial effects:

[0023] The Lactobacillus gasseri BN9 provided by this invention has excellent intestinal colonization ability, can significantly improve the sweet taste perception ability of healthy individuals, obese individuals, and diabetic individuals, and has the effect of lowering blood sugar.

[0024] 1. For healthy individuals, taking Lactobacillus gasseri BN9 of the present invention can significantly improve the body's ability to perceive sweetness, significantly increase the content of amino acids such as glutamic acid (7.99 times), glycine (6.02 times), and lysine (6.74 times) in the intestine, and significantly increase the content of amino acids such as glutamine (6.68 times), serine (4.81 times), and glycine (7.02 times) in the blood;

[0025] 2. In obese and diabetic individuals, administration of Lactobacillus gasseri BN9 of this invention significantly improves the body's sweet taste perception, reduces the weight of obese mice, and improves blood glucose homeostasis. Feeding Lactobacillus gasseri BN9 can increase the preference of obese and diabetic mice for low-concentration sucrose solutions (10 mmol / L and 15 mmol / L sucrose solutions) to normal levels, reduce the weight of obese mice by approximately 21%, reduce peak blood glucose levels by approximately 23.75%, and reduce the area under the oral glucose tolerance test curve by approximately 29.40%; and reduce peak blood glucose levels in diabetic mice by approximately 26.87% and reduce the area under the oral glucose tolerance test curve by approximately 31.58%.

[0026] In summary, the Lactobacillus gasseri BN9 described in this invention can improve an individual's sweet taste perception ability and can be used to prepare related functional foods, health products and pharmaceuticals to reduce an individual's sugar intake. It has a very broad application prospect in regulating taste impairment caused by diseases such as obesity and diabetes and controlling an individual's blood sugar and weight.

[0027] Preservation of biological materials

[0028] A strain of Lactobacillus gasseri BN9, taxonomically named Lactobacillus gasseri, was deposited on January 28, 2024, at the Guangdong Provincial Microbial Culture Collection Center (GDMCC No.: 64320), located at the Guangdong Institute of Microbiology, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. Attached Figure Description

[0029] Figure 1 shows the effect of Lactobacillus gasseri BN9 on the sweet taste perception ability of individual bumblebees. Lactobacillus gasseri BN9 significantly improved the sweet taste perception ability of individuals; while the control strains Lactobacillus gasseri CN3 and Lactobacillus rhamnosus did not affect the sweet taste perception ability of individuals; **P<0.01.

[0030] Figure 2 shows the effects of feeding Lactobacillus gasseri BN9 on amino acids in the gut and hemolymph of bumblebees. (A) Differences in hindgut amino acids; (B) Differences in hemolymph amino acids.

[0031] Figure 3 shows the effect of feeding Lactobacillus gasseri BN9 on sucrose preference in obese mice; *P<0.05.

[0032] Figure 4 shows the effects of feeding Lactobacillus gasseri BN9 on body weight and glucose tolerance in obese mice; (A) body weight; (B) glucose tolerance test; **P<0.01.

[0033] Figure 5 shows the effect of feeding Lactobacillus gasseri BN9 on sucrose preference in diabetic mice; *P<0.05.

[0034] Figure 6 shows the effect of feeding Lactobacillus gasseri BN9 on glucose tolerance in diabetic mice; **P<0.01. Detailed Implementation

[0035] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0036] The culture media involved in the following examples are as follows:

[0037] MRS solid medium: tryptone 10.00 g / L, yeast extract 5.00 g / L, beef extract 10.00 g / L, glucose 20.00 g / L, triammonium citrate 2.00 g / L, anhydrous sodium acetate 5.00 g / L, magnesium sulfate 0.10 g / L, manganese sulfate 0.05 g / L, dipotassium hydrogen phosphate 2.00 g / L, Tween 80 1.00 mL / L, agar powder 15.00 g / L, pH adjusted to 6.5.

[0038] MRS liquid culture medium: tryptone 10.00 g / L, yeast extract 5.00 g / L, beef extract 10.00 g / L, glucose 20.00 g / L, triammonium citrate 2.00 g / L, anhydrous sodium acetate 5.00 g / L, magnesium sulfate 0.10 g / L, manganese sulfate 0.05 g / L, dipotassium hydrogen phosphate 2.00 g / L, Tween 80 1.00 mL / L, pH adjusted to 6.5.

[0039] The ordinary feed involved in this invention was purchased from Jiangsu Xietong Pharmaceutical Biotechnology Co., Ltd., product number XTCON50J; the high-fat feed was purchased from Jiangsu Xietong Pharmaceutical Biotechnology Co., Ltd., product number XTHF60. The blood glucose meter and test strips involved in this invention were purchased from Roche Pharmaceuticals Ltd., model number ACCU-CHEK Guide.

[0040] The Lactobacillus gasseri CN3 and Lactobacillus rhamnosus involved in the following examples are self-selected strains.

[0041] Other experimental materials involved in the following examples can be obtained through conventional channels.

[0042] Example 1: Strain Screening and Identification

[0043] (I) Isolation and screening of Lactobacillus gasseri:

[0044] (l) Take breast milk from healthy lactating women, dilute it serially, spread it on MRS solid medium, and incubate it at 37°C for 72 hours in an anaerobic environment.

[0045] (2) Observe and record the colony morphology, and pick colonies for streaking and purification;

[0046] (3) Pick a single colony, incubate it in MRS liquid medium at 37°C for 48 hours, and then collect the bacterial cells for strain identification.

[0047] (II) Molecular biological identification of Lactobacillus gasseri:

[0048] (l) Extract single-strain genomic DNA using the EZNAStool DNA kit (Omega Bio-tek);

[0049] (2) Amplify 16S rDNA using universal primers for bacterial strain identification;

[0050] (3) Prepare 1% agarose gel, mix the PCR product with loading buffer and load the sample, run at 150V, 100mA for 20min, observe and cut the gel;

[0051] (4) The obtained PCR product was sent to a professional sequencing company for sequencing. The sequencing results were searched and compared for similarity in the GeneBank database using BLAST. The sequencing results identified the strain as belonging to Lactobacillus gasseri and named it Lactobacillus gasseri BN9. The strain was stored at -80℃ for later use.

[0052] Example 2: Effects of Lactobacillus gasseri BN9 on the sweet taste perception ability of individual bumblebees

[0053] Activated *Lactobacillus gasseri* BN9 was anaerobically cultured in MRS liquid medium at 37°C for 48 hours. Control strains *Lactobacillus gasseri* CN3 and *L. rhamnosus* were activated and inoculated into MRS liquid medium, and anaerobically cultured at 37°C for 48 hours. Fresh, stationary bacterial cultures were centrifuged, washed with PBS, and the bacterial pellet was dissolved in 40% (w / w) sucrose water to achieve an OD500 concentration. 600 =1.0.

[0054] Newly emerged worker bees were marked daily. At 3 days old, they were transferred to different small wooden boxes for group feeding, totaling 4 groups with 15 bees in each group. The specific grouping was as follows: (1) Control group: 40% (w / w) sucrose water was provided daily; (2) Lactobacillus gasseri BN9 feeding group: freshly prepared Lactobacillus gasseri BN9 (OD) was provided daily. 600 =1) 40% sucrose water; (3) Lactobacillus gasseri CN3 feeding group: Provide freshly prepared Lactobacillus gasseri CN3 (OD) daily. 600=1) 40% sucrose water (4) Control strain L. rhamnosus feeding group (L.Rh feeding group): Provided daily freshly prepared L. rhamnosus (OD) 600 =1) 40% sucrose water. Provide each group of bumblebees with sufficient sugar water for free drinking every day for a total of 9 days.

[0055] Sweet taste perception tests were conducted on bumblebees at 12 days of age. The specific methods and results are as follows: Individual bumblebees that had been fasted for 12 hours were placed in a tester and given 2 μl of water (0%) and sucrose solutions of 0.1%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, and 40% concentrations, respectively. The feeding behavior of the bumblebees was observed and recorded to assess their sweet taste perception ability. Feeding on sucrose solution indicated that the bumblebees responded to the corresponding concentration of sugar solution. At the interval between each test, the tester was cleaned and wiped with 70% alcohol to ensure that there was no odor or sugar solution residue that could affect the results. The results are shown in Figure 1. Compared with the control group, feeding with *Lactobacillus gasseri* BN9 significantly improved the sweet taste perception ability of individuals, and reduced the concentration of sugar solution the individuals responded to. In the control group, approximately 66.7% of individuals responded to sugar solutions of 1.25% or higher, and only 33.3% responded to sugar solutions of 1% or lower. In contrast, all individuals in the *Lactobacillus gasseri* BN9 group responded to sugar solutions of 1% or lower, meaning that more individuals responded to low-concentration sugar solutions. The control bacteria *Lactobacillus gasseri* CN3 and *Lactobacillus rhamnosus* did not affect the individuals' sweet taste perception ability.

[0056] After the behavioral experiment, the hindgut of bumblebees was collected for quantitative analysis of the gut microbiota. The results showed that *Lactobacillus gasseri* BN9 could colonize the bumblebee gut, with an abundance of approximately 10. 6 It does not affect the total gut microbiota or the amount of other core bacteria.

[0057] Example 3: Effects of Lactobacillus gasseri BN9 on host amino acid metabolism

[0058] Bumblebees in the control group (fed 40% sucrose solution daily) and the Lactobacillus gasseri BN9-fed group were suffocated on dry ice, and their hindgut tissue and hemolymph were subsequently extracted. The tissue samples were weighed using an analytical balance, and the weight was recorded. 500 μl of 5% trichloroacetic acid (m / v) was added, and the samples were then homogenized using an automated sample grinder. After mixing, the samples were sonicated at room temperature for 20 min and allowed to stand for at least 2 h to precipitate proteins. The samples were then centrifuged at 15000 rpm and 25°C for 30 min. The supernatant was filtered through a 0.22 μm water membrane and analyzed by HPLC.

[0059] The results showed that feeding Lactobacillus gasseri BN9 altered the content of various amino acids, including glycine, lysine, serine, glutamine, and glutamic acid, in the hindgut and hemolymph of bumblebees (Figure 2). Feeding Lactobacillus gasseri BN9 significantly increased the content of amino acids such as glutamic acid, glycine, and lysine in the bumblebee intestine. The glutamic acid content increased from 0.15 mg / g to 1.26 mg / g, an increase of 7.99 times; the lysine content increased from 0.14 mg / g to 0.96 mg / g, an increase of 6.74 times; and the glycine content increased from 0.16 mg / g to 0.98 mg / g, an increase of 6.02 times. Simultaneously, feeding with *Lactobacillus gasseri* BN9 significantly increased the levels of amino acids such as glutamine, serine, and glycine in bumblebee hemolymph. Glutamine levels increased from 0.21 mg / g to 1.44 mg / g, a 6.68-fold increase; serine levels increased from 0.28 mg / g to 1.38 mg / g, a 4.81-fold increase; and glycine levels increased from 0.18 mg / g to 1.26 mg / g, a 7.02-fold increase. Glycine and lysine are associated with maintaining brain function and regulating blood sugar; serine is associated with blood sugar regulation and weight control; glutamine and glutamate can be interconverted in the body, and glutamate plays an important role in the transmission and regulation of taste information in taste receptors. Therefore, *Lactobacillus gasseri* BN9 may enhance the sweet taste perception ability of individual bumblebees by regulating the amino acid content in the hindgut and hemolymph.

[0060] Example 4: Lactobacillus gasseri BN9 can improve the sweet taste perception ability of obese mice.

[0061] In this embodiment, 30 male C57BL / 6J mice were randomly divided into three groups (n=10): a normal group, an obese group, and an obese + Lactobacillus gasseri BN9 group. The normal group mice were fed a standard diet for 12 weeks; the obese and obese + Lactobacillus gasseri BN9 groups were fed a high-fat diet for 12 weeks. Starting from week 9, the obese + Lactobacillus gasseri BN9 group mice underwent Lactobacillus gasseri BN9 intervention, receiving daily gavage containing Lactobacillus gasseri BN9 (OD2000). 600 200 μL of PBS solution (=1) was administered to mice in both the normal and obese groups via gavage daily for 4 weeks. The weight of all mice was recorded every two weeks. From week 13 onwards, all three groups of mice were fed a standard diet, and subsequent tests were conducted.

[0062] A sucrose preference experiment was conducted on each group of mice. Two identical drinking bottles were placed in each cage: one containing a sucrose solution with concentrations of 1, 5, 10, 15, 20, 25, 50, and 100 mmol / L, and the other containing deionized water. The solution volumes in both bottles were kept consistent. To avoid errors caused by positional bias, the positions of the two bottles were swapped every 24 hours. Each sugar solution concentration was tested for 48 hours. During the test, the solution concentration was increased sequentially, and the experimental data were recorded. The sucrose preference rate (%) was calculated using the formula: Sucrose preference rate (%) = (Sucrose solution consumption / (Sucrose solution consumption + Deionized water consumption)) × 100%.

[0063] The results showed that, compared with normal mice, obese mice exhibited a decreased preference for lower concentrations of sucrose solutions (10 mmol / L and 15 mmol / L), while feeding with *Lactobacillus gasseri* BN9 significantly improved this preference. For 10 mmol / L sucrose solution, the preference rate for obese mice fed with *Lactobacillus gasseri* BN9 was 58.13%, compared to 59.21% in the control group and 53.52% in the obese mice. For 15 mmol / L sucrose solution, the preference rate for mice fed with *Lactobacillus gasseri* BN9 was 63.21%, compared to 65.45% in the control group and 55.12% in the obese mice. Feeding with *Lactobacillus gasseri* BN9 restored the preference rate for lower concentrations of sucrose solution in obese mice to a level comparable to that of the control group. This indicates a decreased sweet taste perception in obese mice, while *Lactobacillus gasseri* BN9 can improve this sweet taste perception (Figure 3).

[0064] Example 5: Lactobacillus gasseri BN9 can improve individual obesity symptoms.

[0065] In Example 4, the body weight and oral glucose tolerance test (OGTT) of the three groups of mice were compared. Body weight was recorded every two weeks, and OGTT was measured at week 16 after the glucose preference test. Eight weeks of high-fat diet resulted in significantly higher body weight in the mice compared to the control group. Supplementation with Lactobacillus gasseri BN9 was then initiated at week 9. Compared to the obese group, the obese mice fed with Lactobacillus gasseri BN9 showed an average body weight reduction of 2.03 g and 8.97 g at weeks 10 and 12, respectively. One month of Lactobacillus gasseri BN9 feeding significantly reduced the body weight of obese mice by 21.34% (Figure 4A).

[0066] Further glucose tolerance tests were conducted to evaluate the effect of *Lactobacillus gasseri* BN9 on glycemic homeostasis. Mice were fasted for 14 hours but allowed free access to water. Then, each mouse was administered sterile glucose solution by gavage at a dose of 2 g glucose / kg body weight. Blood was collected from the tail of a lancet, and blood glucose levels were measured at 0, 15, 30, 60, 90, and 120 minutes after gavage (0 min represents the fasting blood glucose level before gavage). OGTT curves were plotted, and the area under the curve (AUC) was calculated. Obese mice exhibited impaired glucose tolerance, while supplementation with *Lactobacillus gasseri* BN9 improved glucose tolerance in obese mice. The peak blood glucose level in all three groups occurred at 15 min, then gradually decreased, returning to normal levels after 2 hours. Compared with the control group, obese mice showed significantly higher peak blood glucose levels at 15 min and a significantly higher AUC in the OGTT, indicating impaired glucose tolerance in obese mice. Obese mice fed with Lactobacillus gasseri BN9 showed improved glucose tolerance, with peak blood glucose levels decreasing by approximately 23.75% compared to the obese group, and the area under the OGTT curve decreasing by approximately 29.4% (Figure 4B). These results indicate that Lactobacillus gasseri BN9 has a good effect on reducing body weight and improving glycemic homeostasis.

[0067] Example 6: Lactobacillus gasseri BN9 can improve the sweet taste perception ability of diabetic mice.

[0068] Thirty male C57BL / 6 mice were randomly divided into a control group (n=10), a diabetic control group (n=10), and a diabetic *Lactobacillus gasseri* BN9 intervention group (n=10). The normal control group mice were fed a standard diet for 12 weeks. The diabetic control group and the diabetic *Lactobacillus gasseri* BN9 intervention group mice were fed a high-fat diet for 12 weeks. After 8 weeks of high-fat diet, the mice fed the high-fat diet were given a single intraperitoneal injection of streptozotocin (STZ, 50 mg / kg) to induce diabetes and obtain diabetic mice. Ten of these diabetic mice were treated with *Lactobacillus gasseri* BN9. Starting from week 9, the diabetic *Lactobacillus gasseri* BN9 intervention group mice were administered *Lactobacillus gasseri* BN9 via gavage daily, containing *Lactobacillus gasseri* BN9 (OD2000). 600 =1) 200 μL of PBS solution (diabetic Lactobacillus gasseri BN9 intervention group); another 10 diabetic mice did not receive Lactobacillus gasseri intervention (diabetic control group); the control group and the diabetic control group mice were gavaged with an equal volume of physiological saline daily for 4 weeks (9-12 weeks). Starting from week 13, the three groups of mice were fed normal diet and subsequent tests were conducted.

[0069] A sucrose preference experiment was conducted on each group of mice. Two identical drinking bottles were placed in each cage: one containing a sucrose solution with concentrations of 1, 5, 10, 15, 20, 25, and 50 mmol / L, and the other containing deionized water. The solution volumes in both bottles were kept consistent. To avoid errors caused by positional preference, the positions of the two bottles were exchanged every 24 hours. Each sucrose solution concentration was tested for 48 hours. During the test, the solution concentration was increased sequentially from low to high. The results showed that diabetic mice exhibited a decreased preference for lower concentrations of sucrose solution, while feeding them with *Lactobacillus gasseri* BN9 significantly improved their preference for lower concentrations of sucrose solution, restoring it to a level comparable to the control group. Specifically, for a 10 mmol / L sucrose solution, the preference rate for diabetic mice fed with *Lactobacillus gasseri* BN9 was 57.96%, compared to 60.32% in the control group and 52.9% in diabetic mice. For a 15 mmol / L sucrose solution, the preference rate for mice fed with *Lactobacillus gasseri* BN9 was 60.21%, compared to 62.53% in the control group and 54.86% in diabetic mice. This indicates a decreased sweet taste perception in diabetic mice, while *Lactobacillus gasseri* BN9 can enhance their sweet taste perception (Figure 5).

[0070] Following the glucose tolerance test, an oral glucose tolerance comparison experiment was conducted at week 16, following the method described in Example 5. The effect of *Lactobacillus gasseri* BN9 on glycemic homeostasis in diabetic mice was evaluated using glucose tolerance testing. Diabetic mice exhibited impaired glucose tolerance, while supplementation with *Lactobacillus gasseri* BN9 improved their glucose tolerance. The peak blood glucose level in all three groups occurred at 15 minutes, then gradually decreased, returning to normal levels after 2 hours. Compared to the control group, diabetic mice showed significantly higher peak blood glucose levels at 15 minutes and significantly increased area under the OGTT curve, indicating impaired glucose tolerance. The glucose tolerance of diabetic mice fed *Lactobacillus gasseri* BN9 was improved, with a peak blood glucose level approximately 26.87% lower and an OGTT area under the curve reduced by approximately 31.58% (Figure 6). These results demonstrate that *Lactobacillus gasseri* BN9 has a good effect on improving glycemic homeostasis.

[0071] Example 7: Application of Lactobacillus gasseri BN9

[0072] Preparation of Lactobacillus gasseri BN9 inoculum:

[0073] Activated Lactobacillus gasseri BN9 was cultured anaerobically at 37°C for 48 hours in MRS liquid medium. 30 mL of the Lactobacillus gasseri BN9 culture was placed in a centrifuge tube and centrifuged at 4°C and 4000 rpm for 10 min. The supernatant was discarded, and the bacterial sludge was collected. After washing 2-3 times with strictly sterilized physiological saline, an appropriate amount of cryoprotectant was added and mixed thoroughly. The mixture was pre-cooled at -80°C for 4 hours and then freeze-dried under the following conditions: cold trap temperature -70°C, drying time 24 hours, and vacuum degree 1 Pa. After freeze-drying, the bacterial powder was immediately collected into aseptic packaging bags and sealed to obtain Lactobacillus gasseri BN9 bacterial agent.

[0074] Preparation of fermented milk using Lactobacillus gasseri BN9:

[0075] Fresh milk and granulated sugar were mixed and homogenized (5:1), sterilized at 140°C for 2 seconds, cooled to 35°C, and then inoculated with the Lactobacillus gasseri BN9 inoculum prepared in this invention. Fermentation was carried out in a sealed container at 35°C for 4 hours, followed by post-fermentation at 4°C for 12 hours to obtain the final fermented product (bacterial concentration 10). 8 (CFU / mL or higher).

[0076] This invention enables the production and preparation of other fermented foods using Lactobacillus gasseri BN9 fermentation. These fermented foods include solid foods, liquid foods, and semi-solid foods. The fermented foods include dairy products, soy products, and fruit and vegetable products. The dairy products include milk, sour cream, and cheese; the fruit and vegetable products include products made from cucumbers, carrots, beets, celery, and cabbage.

[0077] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A strain of Lactobacillus gasseri BN9 was deposited on January 28, 2024, at the Guangdong Provincial Center for Microbial Culture Collection (GDMCC No.: 64320), located at the Guangdong Institute of Microbiology, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

2. A microbial preparation containing Lactobacillus gasseri BN9 as described in claim 1.

3. The microbial preparation according to claim 2, characterized in that, In the microbial preparation described in claim 1, the viable count of Lactobacillus gasseri BN9 is not less than 1 × 10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g.

4. A product characterized in that, The product contains Lactobacillus gasseri BN9 as described in claim 1, or the microbial preparation as described in claim 2 or 3.

5. The product as described in claim 4, characterized in that, The products include food, medicine, or health products.

6. The product as described in claim 5, characterized in that, The food products include fermented foods or feed additives; the fermented foods include dairy products, soy products, and fruit and vegetable products.

7. The product as described in any one of claims 4 to 6, characterized in that, In the product described in claim 1, the viable count of Lactobacillus gasseri BN9 is not less than 1 × 10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g.

8. The use of Lactobacillus gasseri BN9 as described in claim 1, or the microbial preparation as described in claim 2 or 3, in the preparation of a medicament for relieving and / or treating taste degeneration.

9. The use of Lactobacillus gasseri BN9 as described in claim 1, or the microbial preparation as described in claim 2 or 3, in the preparation of pharmaceuticals or health products that help maintain healthy blood sugar levels.

10. The use of Lactobacillus gasseri BN9 as described in claim 1, or the microbial preparation as described in claim 2 or 3, in the preparation of products that reduce the body weight of obese individuals.

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