Lactococcus lactis F44 and application of lactococcus lactis F44 in preparation of anti-inflammatory drugs or fat-reducing drugs

Abstract

The invention discloses lactococcus lactis F44 and application thereof in preparation of anti-inflammatory drugs or fat-reducing drugs, experiments prove that the lactococcus lactis F44 has the preservation number of CGMCC No.30924, can produce nisin in high yield, inhibits mouse inflammation, especially acute ulcerative colitis, reduces fat accumulation of caenorhabditis elegans, and has a fat-reducing effect, the preservation number of the lactococcus lactis F44 is CGMCC No.30924, the preservation number of the lactococcus lactis F44 is CGMCC No.30924, the preservation number of the lactococcus lactis F44 is CGMCC No.30924, and the preservation number of the lactococcus lactis F44 is CGMCC No.30924.

Description

Technical Field

[0001] The present invention belongs to the technical field of probiotics, and more specifically relates to Lactococcus lactis F44 and its application in the preparation of anti-inflammatory drugs or fat-reducing drugs. Background Art

[0002] With the accelerated pace of modern life and changing dietary habits, obesity, cardiovascular disease, and a range of health issues caused by chronic inflammation are becoming increasingly prominent concerns. Inflammation is the body's natural defense against injury or infection, but when persistent or excessive, it can lead to a variety of chronic diseases. Furthermore, rising obesity rates worldwide not only impact individual quality of life but also place a significant burden on public health systems. Therefore, developing products that can effectively regulate inflammation and promote healthy fat loss is crucial.

[0003] Lactococcus lactis is an important species of lactic acid bacteria, widely used in the food fermentation industry. Studies have shown that L. lactis not only has strong acid resistance and tolerance to the gastrointestinal environment, but also produces a variety of biologically active metabolites, such as lactic acid, bacteriocins, and exopolysaccharides. These metabolites have significant effects on inhibiting pathogens, improving intestinal health, and enhancing immune function. Furthermore, L. lactis has been found to exert anti-inflammatory effects by regulating immune function, offering potential value for disease intervention and health maintenance.

[0004] The potential of Lactococcus lactis in intestinal health and immune regulation makes it an ideal microbial resource for the development of anti-inflammatory products. However, there are significant differences in the biological functions of different strains. Currently, there are no reports that Lactococcus lactis can be used for both anti-inflammatory and fat-reducing applications. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide Lactococcus lactis F44.

[0006] The second object of the present invention is to provide the use of the above-mentioned Lactococcus lactis in preparing nisin.

[0007] The third object of the present invention is to provide the use of the above-mentioned Lactococcus lactis in the preparation of anti-inflammatory drugs.

[0008] The fourth object of the present invention is to provide the use of the above-mentioned Lactococcus lactis in the preparation of fat-reducing medicines.

[0009] The technical solution of the present invention is summarized as follows:

[0010] Lactococcus lactis F44, whose deposit number is CGMCC No.30924.

[0011] The application of the above-mentioned Lactococcus lactis in the preparation of nisin.

[0012] Application of the above Lactococcus lactis in the preparation of anti-inflammatory drugs.

[0013] A preferred inflammation is acute ulcerative colitis.

[0014] The application of the above-mentioned Lactococcus lactis in the preparation of fat-reducing medicine.

[0015] The present invention has the following beneficial effects:

[0016] Experiments have shown that the Lactococcus lactis F44 of the present invention, whose deposit number is CGMCC No. 30924, can produce high levels of nisin, inhibit inflammation in mice, especially acute ulcerative colitis, and reduce fat accumulation in Caenorhabditis elegans, thus having a fat-reducing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the nisin production capacity of F44.

[0018] Figure 2 The effect of F44 supernatant and live bacteria on LPS-induced NO in RAW264.7.

[0019] Figure 3 The effect of F44 supernatant and live bacteria on LPS-induced IL-6 in RAW264.7.

[0020] Figure 4 The effect of feeding F44 on the colon length of mice.

[0021] Figure 5 HE staining of colon tissues of mice in different groups.

[0022] Figure 6 The effect of feeding F44 on the fat content of nematodes. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0024] The reagents or formulations used in the following examples are:

[0025] Lactococcus lactis seed liquid culture medium: 20 g potassium dihydrogen phosphate, 15 g yeast extract, 15 g peptone, 15 g glucose, 1.5 g sodium chloride, 0.15 g magnesium sulfate heptahydrate, add distilled water to 1 L, and sterilize by autoclaving at 115°C for 30 min.

[0026] Lactococcus lactis seed solid culture medium: 20 g potassium dihydrogen phosphate, 15 g yeast extract, 15 g peptone, 15 g glucose, 1.5 g sodium chloride, 0.15 g magnesium sulfate heptahydrate, 20 g agar, add distilled water to 1 L, and sterilize by autoclaving at 115°C for 30 min.

[0027] LB liquid medium: 5 g yeast extract, 10 g tryptone, 10 g sodium chloride, dilute to 1 L with distilled water, and sterilize by autoclaving at 115°C for 30 min.

[0028] Lactococcus lactis fermentation medium: 20 g potassium dihydrogen phosphate, 15 g yeast extract, 15 g peptone, 20 g sucrose, 3 g corn steep liquor, 2.6 g cysteine, 1.5 g sodium chloride, 0.15 g magnesium sulfate heptahydrate, distilled water to 1 L, autoclave at 115 °C for 30 min.

[0029] Nisin titer test medium: 0.8 g tryptone, 0.5 g glucose, 0.2 g disodium hydrogen phosphate, 0.25 g yeast extract, 0.5 g sodium chloride, 1.5 g agar powder, dilute to 100 mL with distilled water, and sterilize by autoclaving at 115°C for 30 min.

[0030] RPMI 1640 complete medium: Under sterile conditions, add 50 mL of RPMI 1640 medium, 5 mL of fetal bovine serum, and 500 μL of penicillin-streptomycin solution.

[0031] 1 M potassium phosphate buffer: 3.56 g of dipotassium hydrogen phosphate, 10.83 g of potassium dihydrogen phosphate, dilute to 100 mL with distilled water, and adjust the pH to 6.

[0032] NGM solid medium: 2.5 g tryptone, 3 g sodium chloride, 17 g agar powder, 25 mL 1 M potassium phosphate buffer, 1 mL 1 M CaCl₂ aqueous solution, 1 mL 1 M MgSO₄ aqueous solution, dilute to 1 L with distilled water, and autoclave at 115°C for 30 min. Once the temperature drops to approximately 60°C, add 1 mL of 5 mg / mL cholesterol solution (95% ethanol in water by volume), shake well, and pour onto plates.

[0033] M9 buffer: 6 g disodium hydrogen phosphate, 3 g dipotassium hydrogen phosphate, 5 g sodium chloride, 1 mL 1 M magnesium sulfate aqueous solution, dilute to 1 L with distilled water, and sterilize by autoclaving at 115°C for 30 min.

[0034] Lysis solution: 0.1 g of sodium hydroxide, 500 μL of 1% sodium hypochlorite solution. After heat dissipation, add 4 mL of M9 buffer and dissolve and mix thoroughly.

[0035] The nitric oxide (NO) content detection kit was purchased from Beyotime Biotechnology Co., Ltd.

[0036] Mouse IL-6 ELISA kit was purchased from Yikesai Biotechnology (Taicang) Co., Ltd.;

[0037] Wild-type Caenorhabditis elegans N2 and Escherichia coli OP50 were purchased from Fujian Shangyuan Bioscience Technology Co., Ltd.

[0038] Example 1 Mutagenesis and identification of strains

[0039] 1. Mutagenesis of strains

[0040] Lactococcus lactis subsp. lactis YF11 (CGMCC No. 12429) was subjected to two rounds of chemical mutagenesis using diethyl sulfate to obtain strains H1, H2, and H3. Lactococcus lactis subsp. lactis YF11 was subjected to two rounds of UV mutagenesis followed by acclimation using high concentrations of nisin and glucose to obtain strains U1, U2, and U3. Using these six strains as starting strains, four rounds of recursive protoplast fusion were performed to screen and identify a high-nisin-producing strain, F44.

[0041] 2. Molecular Biology Identification

[0042] (1) The frozen nisin high-producing strain F44 was taken out and inoculated into 1 mL of Lactococcus lactis seed liquid culture medium at a 1% inoculum size. The culture was placed in a 30°C incubator for 24 h. 3 μL of the bacterial liquid (i.e., template) was taken out and PCR reaction was performed according to the reaction system and procedure in Tables 1 and 2 to amplify the 16S region and perform DNA sequencing.

[0043] Table 1: PCR reaction system

[0044]

[0045] Table 2: PCR reaction program:

[0046]

[0047] (2) The sequencing results were uploaded to the NCBI database for comparison. The similarity between strain F44 and YF11 was 98%, and strain F44 was identified as Lactococcus lactis. The 16S rDNA is shown in SEQ ID NO. 1.

[0048] 3. Strain preservation

[0049] This strain, designated Lactococcus lactis F44, was deposited on June 11, 2024, at the General Microbiology Center of the China Culture Collection Administration (CMC), Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, under the accession number CGMCC No. 30924. It is hereby referred to as F44.

[0050] Example 2

[0051] F44 high-yield nisin

[0052] 1. Fermentation process and sample processing

[0053] F44 was inoculated into a Lactococcus lactis seed liquid culture medium at a 1% inoculum size. After three consecutive passages, it was inoculated into a Lactococcus lactis fermentation medium at a 5% inoculum size. The culture was placed in a 30°C incubator for static culture. Every 2 hours, 600 μL of fermentation broth and 600 μL of 0.02 M HCl aqueous solution were collected, mixed, and added to a sterile 2 mL EP tube. The tube was placed in boiling water and boiled for 5 minutes for subsequent detection of nisin production.

[0054] 2. Detection of nisin titer by inhibition zone method

[0055] After thawing, 25 mL of nisin titer test medium was cooled to 70°C, preheated Tween-20 (final concentration: 1.5%) was added, and after cooling to 50°C, 6 mL of physiological saline was added to rinse the resulting culture medium containing Micrococcus flavus (ATCC 10240, purchased from Shanghai Yansheng Industrial Co., Ltd.). After mixing thoroughly, the culture medium was inverted and refrigerated at 4°C overnight. The test plate was evenly perforated, and standard samples (containing 200, 100, 50, and 25 IU / mL nisin) and the test sample were added. The plate was then placed in a 37°C incubator for overnight incubation. The diameter of the inhibition zone was accurately measured with a vernier caliper, and the nisin titer of the corresponding fermentation broth was calculated based on the standard curve.

[0056] 3. Results

[0057] The nisin production of F44 showed a trend of increasing first and then decreasing, with the highest nisin production reaching 2884 IU / mL at 8 h ( Figure 1 ).

[0058] Example 3

[0059] Tolerance evaluation of F44

[0060] 1. Evaluation of F44 artificial gastric juice tolerance

[0061] (1) Test method

[0062] Frozen F44 was inoculated into a Lactococcus lactis seed liquid culture medium at a 1% inoculum rate and incubated in a 30°C incubator. After one day of incubation, the culture was transferred to a fresh Lactococcus lactis seed liquid culture medium at a 1% inoculum rate and incubated in a 30°C incubator. After 18 hours of incubation, 5 ml of the culture was collected under sterile conditions and centrifuged at 8000 rpm for 5 minutes to isolate the bacteria. The bacterial pellet was resuspended and mixed with physiological saline and centrifuged at 8000 rpm for 5 minutes to collect the bacteria. The bacterial pellet was resuspended and mixed with 5 mL of artificial gastric juice at pH = 2 and pH = 3, respectively, and incubated at 30°C. The culture solution was collected at 0 hours, 1.5 hours, and 3 hours of incubation, and the culture solution was diluted 10-fold with physiological saline. The appropriate dilution was selected for plating. Two dilutions were selected for each sample, and two plates were made for each dilution. The coated plate was inverted and cultured in a 30°C incubator. After culturing for 2 days, the growth status of the colonies on the plate was observed, the number of colonies was recorded, and the survival rate was calculated.

[0063]

[0064] A0 is the number of colonies at 0 hours of incubation, A n is the number of colonies after incubation for n hours.

[0065] (2) Test results

[0066] The survival of F44 in artificial gastric fluid is shown in Table 3.

[0067] Table 3F44 Artificial gastric juice tolerance statistics

[0068]

[0069] 2. Evaluation of F44 artificial intestinal fluid tolerance

[0070] (1) Test method

[0071] Resuspend the F44 bacterial pellet in 5 mL of artificial intestinal fluid and incubate at 30°C. Prepare a 10-fold serial dilution of the bacterial suspension at 0, 4, and 8 hours of incubation with normal saline. Select the appropriate dilution for plating. Select two dilutions for each sample, and make two plates for each dilution. Place the plated plates upside down in a 30°C incubator. After two days of incubation, observe the growth of the bacterial colonies on the plates, record the number of colonies, and calculate the survival rate.

[0072]

[0073] A0 is the number of colonies at 0 hours of incubation, A n is the number of colonies after incubation for n hours.

[0074] (2) Test results

[0075] The survival of F44 in artificial intestinal fluid is shown in Table 4.

[0076] Table 4F44 Statistics of tolerance to artificial intestinal fluid

[0077]

[0078] Example 4

[0079] Effect of F44 supernatant on NO content in RAW264.7 cells (commercial product) induced by LPS (lipopolysaccharide)

[0080] 1. Test method

[0081] RAW264.7 cells with good growth status were taken and 5×10 4 Cells were plated at 100 μL per well in a 96-well cell culture plate (RPMI 1640 medium). When the cell attachment rate reached 80% to 90%, the RPMI 1640 medium was discarded and the cells were treated. A blank control group (CK group), LPS group, F44 supernatant group, and F44 live bacteria group were set up, with 6 replicates per group.

[0082] For the CK group, 200 μL of RPMI 1640 complete medium was added to each well;

[0083] In the LPS group, 200 μL of RPMI 1640 complete medium containing 2 μg / mL LPS was added to each well;

[0084] In the F44 supernatant group, 200 μL of RPMI 1640 complete medium containing F44 supernatant (25 μL of F44 supernatant was added to 200 μL of RPMI 1640 complete medium, with a F44 supernatant concentration of 12.5%) and 2 μg / mL LPS was added to each well;

[0085] For the F44 live bacteria group, 200 μL of RPMI 1640 complete medium containing F44 live bacteria (200 μL of RPMI 1640 complete medium supplemented with 25 μL of F44 live bacteria, with a F44 live bacteria concentration of 12.5%) and 2 μg / mL LPS was added to each well;

[0086] Culture for 24 hours.

[0087] The NO content in the supernatant of RAW264.7 cells was measured using a nitric oxide detection kit. The detailed steps are as follows:

[0088] (1) 1M NaNO2 standard was serially diluted with RPMI 1640 complete medium to 100, 60, 40, 20, 10, 5, 2, and 1 μM;

[0089] (2) Centrifuge the collected cell culture supernatant at 3000 rpm for 5 min;

[0090] (3) 50 μL / well, three replicates per sample group, added to a 96-well plate, 50 μL Griess reagent I added to each well, reacted for 5 min, then added 50 μL Griess reagent II, tapped the plate gently to mix, and reacted for 5 min;

[0091] (4) Measure the OD value at 540 nm on a microplate reader. After establishing a NO standard curve, the corresponding content in the sample can be calculated.

[0092] 2. Test results

[0093] The results are as follows Figure 2 As shown in the data, the secretion of NO in the LPS group was significantly increased compared with the CK group (p < 0.01). After treatment with F44 supernatant and live bacteria, the secretion of NO in RAW264.7 cells induced by LPS was significantly inhibited, with inhibition rates of 40.2% and 42.8%, respectively (p < 0.01).

[0094] Example 5

[0095] Effect of F44 on LPS-induced IL-6 content in RAW264.7 cells

[0096] 1. Test method

[0097] RAW264.7 cells in good growth condition were used at 2×10 6 2 mL per well was inoculated into a six-well plate. After the cells were firmly attached to the wall, the supernatant was discarded. The blank control group (CK group), LPS group, F44 supernatant group, and F44 live bacteria group were set up.

[0098] For the CK group, 2 mL of RPMI 1640 complete medium was added to each well;

[0099] In the LPS group, 2 mL of RPMI 1640 complete medium containing 2 μg / mL LPS was added to each well;

[0100] In the F44 supernatant group, 2 mL of RPMI 1640 complete medium containing F44 supernatant (250 μL of F44 supernatant added to 2 mL of RPMI 1640 complete medium, with a F44 supernatant concentration of 12.5%) and 2 μg / mL LPS was added to each well;

[0101] For the F44 live bacteria group, 2 mL of RPMI 1640 complete medium containing F44 live bacteria (250 μL of F44 live bacteria added to 2 mL of RPMI 1640 complete medium, with a F44 live bacteria concentration of 12.5%) and 2 μg / mL LPS was added to each well;

[0102] After culturing for 24 h, the cell supernatant was collected and the secretion of IL-6 in the cell supernatant was determined using a mouse IL-6 ELISA kit.

[0103] Please refer to the kit instructions for the detection steps. The detailed steps are as follows:

[0104] (1) Return the kit to room temperature, dilute the concentrated washing solution with 20 times ultrapure water to obtain a diluted washing solution, dilute the biochemical antibody working solution with 100 times the diluted washing solution to obtain a diluted biochemical antibody working solution; dilute the enzyme conjugate solution with 100 times the diluted washing solution to obtain a diluted enzyme conjugate solution;

[0105] (2) Use the standard diluent in the kit to serially dilute the IL-6 standard to the following concentrations: 1000 pg / mL, 500 pg / mL, 250 pg / mL, 125 pg / mL, 62.5 pg / mL, 31.25 pg / mL, 15.625 pg / mL, and 0 pg / mL. Determine the IL-6 concentration in the sample through preliminary experiments and dilute to the appropriate standard concentration range for subsequent determination.

[0106] (3) The collected cell supernatant was centrifuged at 3000 rpm for 5 min. After centrifugation, gradient dilution was performed according to the results of the preliminary experiment;

[0107] (4) Set up blank wells (i.e., zero wells), standard wells, and sample wells (CK group, LPS group, F44 supernatant group, F44 live bacteria group) on the experimental strips, with three parallel wells for each group. Add different concentrations of standard and sample wells to the corresponding wells, 100 μL per well, and then add 50 μL of diluted biochemical antibody working solution to each well. Do not add to the zero wells, and seal the reaction wells with sealing tape. Incubate at room temperature at 300 rpm for 120 min.

[0108] (5) Shake off the liquid in the wells vigorously, pat dry the remaining liquid on a thick stack of clean absorbent paper, add 350 μL of diluted washing solution to each well, let it stand for 30 seconds, shake off the liquid in the wells vigorously, and repeat the washing five times;

[0109] (6) Add 100 μL of diluted enzyme conjugate solution, leaving the zero well untouched, and seal the reaction wells with sealing tape. Incubate at room temperature and 300 rpm for 120 min.

[0110] (7) Repeat step (5);

[0111] (8) Add 100 μL of chromogenic substrate to each well, including the zero-clear well, and incubate at room temperature in the dark for 15 min.

[0112] (9) Add 100 μL of reaction termination solution to each well, including the zero-clearing well, and measure the OD within 10 minutes after mixing the system. 450 nm value.

[0113] 2. Test results

[0114] The results are as follows Figure 3 As shown, compared to the CK group, induction with 2 μg / mL LPS significantly increased the secretion of the inflammatory factor IL-6 in the cell supernatant (p < 0.01). Regarding the inflammatory factor IL-6, the F44 live bacteria group significantly inhibited the LPS-induced inflammation level by 38.8% (p < 0.01), while there was no significant difference between the F44 supernatant group and the LPS group. This demonstrates that the F44 live bacteria group has an effective therapeutic effect on LPS-induced inflammation in RAW264.7 cells.

[0115] Example 6 Effect of F44 on Acute Ulcerative Colitis in Mice

[0116] 1. Test method

[0117] (1) Establishment of an acute ulcerative colitis mouse model and F44 intervention

[0118] Male C57BL / 6J mice aged 6-8 weeks were randomly assigned to two groups of eight mice: the PBS group and the F44 group. Mice in the PBS group drank 2.5% sodium sulfate dextran (DSS, purchased from MP Biomedicals, catalog number: 0216011050) solution for days 1-3, 4% DSS solution for day 4, and 1.5% DSS solution for days 5-7. They were gavaged with 100 μL of PBS solution daily for 7 days. Mice in the F44 group drank 2.5% DSS solution for days 1-3, 4% DSS solution for day 4, and 1.5% DSS solution for days 5-7. They were gavaged with 100 μL of F44 bacterial solution daily for 7 days.

[0119] (2) Colon length measurement

[0120] After the experiment, the mice were killed by cervical dislocation, the colon was removed by dissection, and the length of the colon was measured and the data were recorded.

[0121] (3) Pathological analysis

[0122] The colon samples were washed twice with normal saline, immersed in 1 mL of 4% paraformaldehyde solution (purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: R20497), embedded in paraffin, sectioned, and stained with HE.

[0123] 2. Test results:

[0124] The results are as follows Figure 4 As shown in the figure, on the 7th day of the experiment, the colon length of the F44 group was 7.0 cm, which was significantly longer than the 5.9 cm of the PBS group, that is, F44 intervention had a certain protective effect on the colon intestinal tract of acute colitis.

[0125] The results are as follows Figure 5 As shown, HE staining of colonic tissue in the PBS group revealed severe intestinal structural abnormalities, with localized mucosal epithelial cell shedding, exposing the lamina propria. Crypts were significantly reduced in number and structure, with extensive inflammatory cell infiltration. HE staining of colonic tissue in the F44 group revealed moderate intestinal structural abnormalities, with tightly packed, non-shedding mucosal epithelial cells. Crypts were reduced in number and partially lost in structure, with only a small amount of inflammatory cell infiltration. These findings suggest that the F44 group exhibited milder pathological changes in colonic inflammation, demonstrating a therapeutic effect against DSS-induced acute ulcerative colitis.

[0126] Example 7 Effect of F44 on Fat Content in Wild-Type Caenorhabditis elegans N2 (hereinafter referred to as Nematode)

[0127] 1. Synchronization of nematodes

[0128] Collect L4 nematodes into a centrifuge tube and add 1 mL of M9 buffer to wash away excess E. coli OP50. Let the tube settle, then remove the supernatant and repeat the wash three times. Then, add 1 mL of lysis buffer and shake thoroughly. Remove the supernatant and wash three times with M9 buffer by centrifugation (3000 rpm, 1 min). Remove the supernatant and retain the eggs. Transfer the eggs to fresh NGM solid medium and incubate in a 20°C biochemical incubator. After approximately 16-18 hours, they will grow into L1 larvae.

[0129] 2. Cultivation of Nematodes and Determination of Fat

[0130] F44 was cultured in a Lactococcus lactis seed liquid medium to the logarithmic phase, and Escherichia coli OP50 was cultured in a LB liquid medium to the logarithmic phase. The cells were centrifuged at 8000 rpm for 10 min at 4°C, and the F44 and Escherichia coli OP50 cells were collected as food. The cells were adjusted to the same OD value using M9 buffer. 600 Value (OD 600=0.5). Each time, 100 μL of the bacterial solution was plated onto a 60 mm NGM solid medium containing worm eggs and cultured in a 20°C biochemical incubator. The nematodes reached the L4 stage in approximately 3-4 days. A control group fed with Escherichia coli OP50 and an experimental group fed with Lactococcus lactis F44 were cultured for 3 days after reaching the L4 stage. After the nematodes reached the L4 stage, they were cultured with both bacterial solutions for another 3 days. Twenty nematodes were randomly selected and stained with Oil Red O to measure fat content. The nematodes were rinsed three times with M9 buffer, the throat was sealed with 25 mM levamisole hydrochloride, and 200 μL of 4% paraformaldehyde solution was added and allowed to stand for 20 minutes. The solution was then removed and the nematodes were frozen and thawed three times with liquid nitrogen. The nematodes were then stained with 60% isopropanol Oil Red O (10 ml of 60% isopropanol + 0.05 g of Oil Red O). After 5 hours, the excess dye was rinsed with M9 buffer and the staining was observed under a light microscope.

[0131] 2. Test results

[0132] Compared with the E. coli OP50 control group, the fat content of nematodes fed with F44 was significantly reduced ( Figure 6 Image J software was used to analyze the red light optical density of fat, and it was found that the red light optical density of nematode fat was significantly weakened after F44 interference, decreasing by 20.4% ( Figure 6 , p<0.05). This indicates that F44 significantly reduces fat deposition in nematodes, thereby affecting their fat metabolism.

Claims

1. Lactococcus lactis F44, whose deposit number is CGMCC No. 30924.

2. Use of the Lactococcus lactis according to claim 1 in preparing nisin.

3. Use of the Lactococcus lactis according to claim 1 in the preparation of anti-inflammatory drugs.

4. The use according to claim 3, characterized in that The inflammation is acute ulcerative colitis.

5. Use of the Lactococcus lactis according to claim 1 in the preparation of fat-reducing medicines.

Images