Bifidobacterium dentium capable of utilizing DFA-I and application thereof

Abstract

The application discloses a Bifidobacterium dentium capable of utilizing DFA-I and an application thereof. The Bifidobacterium dentium WZL-S1 is preserved in the Guangdong Microbial Culture Collection Center on October 14, 2024, has a preservation number of GDMCC No: 65257, and has a preservation address of the 5th floor of Building 59, the Institute, 100, Middle Liangma Street, Guangzhou, China. The Bifidobacterium dentium DFA-I fermentation liquor prepared from the strain has good antioxidant, preservative and oral bacteriostatic effects, and can be used for developing functional products such as antioxidants, green preservatives and oral bacteriostatic agents.

Description

Technical Field

[0001] This invention belongs to the field of microbiology, specifically relating to a Bifidobacterium denticulatum strain that can utilize DFA-I and its applications. Background Technology

[0002] Currently, the importance of gut microbiota in human health is receiving increasing attention. Studies have shown that gut microbiota are closely related to the host's nutrient absorption, immune regulation, and disease prevention.

[0003] In recent years, probiotics, especially Bifidobacteria, have gained popularity due to their positive effects on gut health. As a common probiotic, Bifidobacteria are widely used in various functional foods, health products, and pharmaceuticals. Among the many Bifidobacteria species, *Bifidobacterium dendritum* has attracted significant attention due to its strong colonization ability and metabolic activity in the oral and intestinal environment. *Bifidobacterium dendritum* can produce a variety of beneficial metabolites, such as short-chain fatty acids (SCFAs), which play an important role in regulating intestinal pH, inhibiting the growth of harmful bacteria, and promoting the health of intestinal epithelial cells.

[0004] Difructose anhydride I (DFA-I) is a novel functional oligosaccharide produced by the degradation of inulin (inulose) using inulin glycosyltransferase type I (IFTase I). DFA-I possesses potential benefits such as promoting probiotic growth, regulating gut microbiota, and enhancing immune function. However, DFA-I is relatively rare in nature, and most gut microbiota cannot directly utilize it.

[0005] Existing screening methods mostly target the growth ability of probiotics under common carbon sources such as glucose and lactose, while there is little research on screening strains that utilize specific functional oligosaccharides such as DFA-I. In addition, there are still many technical bottlenecks in how to apply the screened probiotics that efficiently utilize DFA-I to the development of functional foods and pharmaceutical products. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a strain of Bifidobacterium dentium WZL-S1.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: Bifidobacterium dentium WZL-S1 was deposited at the Guangdong Provincial Center for Microbial Culture Collection on October 14, 2024, with accession number GDMCC No: 65257, and the deposit address is Guangdong Provincial Center for Microbial Culture Collection, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, China.

[0010] As a preferred embodiment of the Bifidobacterium dentium WZL-S1 of the present invention, wherein the Bifidobacterium dentium WZL-S1 efficiently utilizes type I difructan.

[0011] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of Bifidobacterium dentium WZL-S1 in the preparation of antioxidants, green preservatives, and oral antibacterial agents.

[0012] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing Bifidobacterium dentium DFA-I fermentation broth, comprising inoculating a culture of Bifidobacterium dentium WZL-S1 into a DFA-I fermentation liquid culture medium and fermenting it under anaerobic conditions to obtain the Bifidobacterium dentium DFA-I fermentation broth.

[0013] As a preferred embodiment of the preparation method described in this invention, the formulation of the DFA-Ⅰ fermentation liquid culture medium is as follows:

[0014] Tryptone 10.00 g / L, yeast extract 5.00 g / L, DFA-I 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, adjust the pH of the culture medium to 6.5.

[0015] As a preferred embodiment of the preparation method described in this invention, the bacterial concentration in the DFA-Ⅰ fermentation liquid culture medium is 1×10⁻⁶. 6 CFU / mL.

[0016] As a preferred embodiment of the preparation method described in this invention, the fermentation conditions are: fermentation at 37°C under anaerobic conditions for 48 hours.

[0017] Another objective of this invention is to overcome the shortcomings of the prior art and provide a Bifidobacterium denticulatum DFA-Ⅰ fermentation broth.

[0018] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of Bifidobacterium denticulatum DFA-Ⅰ fermentation broth in the preparation of food or pharmaceuticals with antioxidant properties.

[0019] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of Bifidobacterium denticulatum DFA-Ⅰ fermentation broth in the preparation of green preservatives and oral antibacterial agents.

[0020] Beneficial effects of this invention:

[0021] (1) This invention provides a method for screening intestinal microorganisms that can utilize DFA-I from human intestinal microorganisms. By isolating and screening the intestinal flora of healthy adults, a strain of Bifidobacterium dentium WZL-S1 that can efficiently utilize DFA-I was obtained. The Bifidobacterium dentium WZL-S1 was deposited at the Guangdong Provincial Center for Microbial Culture Collection on October 14, 2024, with the accession number GDMCC No: 65257. The deposit address is Guangdong Provincial Center for Microbial Culture Collection, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, China.

[0022] The fermentation broth of Bifidobacterium denticulatum DFA-Ⅰ prepared using this strain has good antioxidant, preservative and oral antibacterial effects, and can be used to develop functional products such as antioxidants, green preservatives and oral antibacterial agents.

[0023] (2) This invention not only expands the application scope of Bifidobacterium densiflorum, but also provides a new technical approach for developing novel functional probiotic products. In particular, the technology of this invention has significant application prospects for applications that require regulating intestinal flora balance, enhancing immunity, or improving oral health. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1This is a diagram showing the pH changes of Bifidobacterium dentata WZL-S1 during fermentation with different carbon sources in an embodiment of the present invention.

[0026] Figure 2 The OD of Bifidobacterium dentata WZL-S1 during fermentation with different carbon sources in this embodiment of the invention. 600 Change diagram.

[0027] Figure 3 This is a graph showing the change in carbon source concentration of Bifidobacterium dentata WZL-S1 during fermentation with different carbon sources in an embodiment of the present invention.

[0028] Figure 4 This is a graph showing the change in acetic acid concentration of Bifidobacterium denticulatum WZL-S1 during fermentation with different carbon sources in an embodiment of the present invention. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0032] The Bifidobacterium dentium WZL-S1 of the present invention was deposited on October 14, 2024 at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC No: 65257, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, China.

[0033] The culture media involved in the embodiments of the present invention are as follows:

[0034] DFA-Ⅰ screening solid medium: tryptone 2.00 g / L, yeast extract 1.00 g / L, DFA-Ⅰ 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.

[0035] DFA-Ⅰ screening liquid culture medium: tryptone 2.00 g / L, yeast extract 1.00 g / L, DFA-Ⅰ 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.

[0036] MRS liquid culture medium: tryptone 10.00 g / L, yeast extract 5.00 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.

[0037] DFA-Ⅰ fermentation broth medium: tryptone 10.00 g / L, yeast extract 5.00 g / L, DFA-Ⅰ 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.

[0038] Example 1

[0039] DFA-I can be used for gut microbiota screening and identification:

[0040] (a) Collection of fecal samples

[0041] Fresh fecal samples were obtained from 5 healthy volunteers (aged 20–30 years) who maintained a normal diet, had not used antibiotics for at least 3 months, and had a normal body mass index. The feces were resuspended in sterile saline and then filtered through four layers of sterile gauze to obtain a 10% (w / v) fecal suspension.

[0042] (ii) Screening of gut microbiota using DFA-I:

[0043] (1) Dilute 10% (w / v) fecal suspension with physiological saline 5000 times and spread it on DFA-Ⅰ screening solid medium and incubate in an anaerobic workstation for 48 h;

[0044] (2) Pick single colonies and incubate them in DFA-Ⅰ screening liquid medium for 48 hours in an anaerobic workstation;

[0045] (3) The supernatant of the fermentation broth was used to determine the DFA-I content by high performance liquid chromatography to identify human intestinal microorganisms that can efficiently utilize DFA-I.

[0046] (4) Extract single-strain genomic DNA using the EZNAStool DNA kit (OmegaBio-tek);

[0047] (5) 16S rDNA was amplified using universal primers for bacterial strain identification, 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3').

[0048] (6) 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;

[0049]

[0050] The sequencing results obtained by BLAST were searched and compared with similarity in the GeneBank database. The results showed that the similarity with Bifidobacterium dentium 2337 was as high as 99.72%.

[0051] After Gram staining of the fermentation broth, the strain was observed under a 100x electron microscope to confirm that it was a Gram-positive rod-shaped bacterium. Based on 16S rDNA and colony morphology, the strain was identified as Bifidobacterium dentium and named Bifidobacterium dentium WZL-S1.

[0052] Example 2

[0053] Fermentation of Bifidobacterium denticulatum under different carbon sources:

[0054] The *Bifidobacterium denticulatum* strains screened in Example 1 were inoculated into MRS liquid medium and DFA-I fermentation liquid medium, respectively, with an initial bacterial concentration of 1 × 10⁻⁶ for each medium. 6 CFU / mL;

[0055] Fermented at 37°C under anaerobic conditions for 48 hours;

[0056] During fermentation, samples were taken every 6 hours to measure the pH value, cell growth concentration (OD600), glucose or DFA-I concentration, and acetic acid concentration of the fermentation broth.

[0057] See [link to Bifidobacterium dentata WZL-S1 pH changes during fermentation with different carbon sources] Figure 1 OD of Bifidobacterium dentata WZL-S1 during fermentation with different carbon sources 600 See changes Figure 2 For the changes in carbon source concentration of Bifidobacterium denticulatum WZL-S1 during fermentation with different carbon sources, please refer to [reference needed]. Figure 3 For the changes in acetic acid concentration of Bifidobacterium denticulatum WZL-S1 during fermentation with different carbon sources, please refer to [reference needed]. Figure 4 ;

[0058] As can be seen, when compared with a culture medium containing only glucose as the sole carbon source, the growth curves and changes in carbon source concentration of Bifidobacterium dendriticum WZL-S1 show that it can efficiently utilize DFA-I for growth. The fermentation process of DFA-I may be more involved in the metabolic pathway of acetic acid, which is of great significance for the development of functional fermentation products based on DFA-I.

[0059] Example 3

[0060] In vitro antioxidant evaluation of fermentation broth:

[0061] (1) DPPH scavenging ability test

[0062] The total antioxidant capacity (T-AOC) was determined using a total antioxidant capacity (T-AOC) assay kit (DPPH method). The fermentation broth of Bifidobacterium denticulatum and the fermentation broth of Bifidobacterium denticulatum DFA-Ⅰ were centrifuged at 5000 rpm for 10 min at 4℃, and the supernatant was then used as the test sample.

[0063] Next, add 50 μL of the extraction solution from the kit to the blank tube, then add 950 μL of reagent one (the main component of which is 1,1-diphenyl-2-picrylhydrazine), and ensure thorough mixing.

[0064] Similarly, 50 μL of the sample to be tested was added to the test tube first, followed by 950 μL of reagent one. After thorough mixing, the mixture was allowed to stand at room temperature in the dark for 20 minutes. The absorbance at 515 nm was then measured using a microplate reader.

[0065] DPPH removal rate calculation formula:

[0066]

[0067] The DPPH free radical scavenging rate of the Bifidobacterium dendriticum fermentation broth was 69.01% according to the formula, while that of the Bifidobacterium dendriticum DFA-Ⅰ fermentation broth was 74.72%. The results show that Bifidobacterium dendriticum has a good DPPH free radical scavenging ability, while Bifidobacterium dendriticum DFA-Ⅰ has a better DPPH free radical scavenging ability.

[0068] (2) Determination of hydroxyl radical scavenging ability

[0069] In a centrifuge tube, add 1 mL of 9 mmol / L FeSO4, 1 mL of the activated bacterial solution, 3 mL of 9 mmol / L salicylic acid-ethanol solution, and 1 mL of 8.8 mmol / L H2O2 solution in sequence.

[0070] The mixed solution was heated in a water bath at 37°C for 15 min, and then the absorbance at a wavelength of 510 nm was measured.

[0071] Equal volumes of distilled water were used to replace the sample solution and H2O2 solution, respectively, to form a blank group and a sample blank group.

[31] Formula for calculating hydroxyl radical scavenging rate:

[0072]

[0073] The hydroxyl radical scavenging capacity of the Bifidobacterium dendriticum fermentation broth was measured to be 75.26% according to the formula, while that of the Bifidobacterium dendriticum DFA-Ⅰ fermentation broth was 78.63%. The results show that Bifidobacterium dendriticum has a good hydroxyl radical scavenging capacity, while Bifidobacterium dendriticum DFA-Ⅰ has a better hydroxyl radical scavenging capacity.

[0074] (3) Determination of superoxide anion free radical scavenging ability

[0075] Add 3 mL of Tris-HCl (pH 8.2) to a centrifuge tube and incubate at 25°C for 25 min. Then, add 1 mL of pyrogallol and 1 mL of the activated bacterial solution to the tube, mix thoroughly, and continue incubating at 25°C for 10 min. Measure the absorbance at 320 nm. Use an equal volume of physiological saline instead of the sample solution as a blank control, and use this solution instead of Tris-HCl and pyrogallol as a sample blank control. Formula for calculating superoxide anion radical scavenging rate:

[0076]

[0077] The superoxide anion radical scavenging capacity of the Bifidobacterium dendriticum fermentation broth was measured to be 48.74% according to the formula, and the superoxide anion radical scavenging capacity of the Bifidobacterium dendriticum DFA-Ⅰ fermentation broth was 48.97%. The results show that both the Bifidobacterium dendriticum fermentation broth and the Bifidobacterium dendriticum DFA-Ⅰ fermentation broth have good superoxide anion radical scavenging capacity, and the results are not significantly different.

[0078] Example 4

[0079] Determination of the in vitro antibacterial activity of Diplococcus denticulatus:

[0080] (1) Preparation of bacterial suspension: Take an appropriate amount of Escherichia coli strain and inoculate it into a pre-prepared sterile LB liquid medium at an inoculation rate of 2%. Then, place this medium in a constant temperature shaker at 37°C for 12 hours for incubation;

[0081] To further expand the culture, 4 mL of the above culture medium was taken and added to 200 mL of LB liquid medium to adjust the Escherichia coli bacterial concentration to 1 × 10⁻⁶. 8 CFU / mL ~5×10 8 CFU / mL, OD was measured using an enzyme-linked immunosorbent assay (ELISA) reader. 600 The concentration is 0.5–0.65, which is used as the experimental bacterial suspension. It should be stored at 1℃–4℃ and used within 4 hours.

[0082] (2) Preparation of test plates: First, the Escherichia coli suspension was diluted with LB solid medium cooled to about 55°C at a ratio of 1:10.

[0083] Specific operations:

[0084] Take 200 mL of LB solid medium, add 20 mL of Escherichia coli suspension, and mix thoroughly. Then, pour 20 mL of the mixture into a sterile petri dish. Next, gently shake the petri dish clockwise and counterclockwise to ensure that the bacterial suspension is evenly distributed on the plate. Once the culture medium on the plate has solidified, the test plate is ready for subsequent use.

[0085] (3) Determination of antibacterial activity: Place the Oxford cup gently on the prepared test plate;

[0086] Then, 200 μL each of Bifidobacterium denticulatum fermentation broth and Bifidobacterium denticulatum DFA-Ⅰ fermentation broth were precisely added into the corresponding Oxford cups.

[0087] Meanwhile, to establish a blank control, 200 μL of LB liquid medium was added to the Oxford cup. Five parallel groups were performed. The plates were placed upright in a 37°C incubator and incubated for 14 hours. The diameter of the inhibition zone of the test sample and the blank control group was then measured.

[0088] The procedure for Staphylococcus aureus, Streptococcus mutans, and Porphyromonas gingivalis is the same as above. For Staphylococcus aureus, LB medium is used; for Streptococcus mutans, commercially available BHI medium is used; and for Porphyromonas gingivalis, commercially available Columbia blood agar medium is used.

[0089] Staphylococcus aureus was cultured in a 37°C constant temperature incubator, while Streptococcus mutans and Porphyromonas gingivalis were cultured in an anaerobic workstation at 37°C.

[0090] The antibacterial results are shown in Table 1 below.

[0091] Table 1

[0092]

[0093] The DFA-I fermentation broth of *Bifidobacterium denticulatum* showed superior antibacterial effects against all tested strains compared to fermentation broth using glucose as a carbon source, with a particularly significant enhancement in its effectiveness against *Porphyromonas gingivalis*. These results suggest that DFA-I, as a carbon source, may stimulate *Bifidobacterium denticulatum* to produce stronger antibacterial substances, indicating potential application value of *Bifidobacterium denticulatum* DFA-I fermentation broth in the development of antibacterial agents and oral care products.

[0094] Example 5

[0095] Determination of drug resistance in Bifidobacterium densiflorum:

[0096] (1) Preparation of drug sensitivity paper discs: First, use a punch to cut the filter paper into circular paper discs with a diameter of 6mm;

[0097] Next, these paper pieces were placed in a clean and dry beaker and then sterilized at 121°C for 20 minutes.

[0098] After sterilization, dry the paper discs and store them properly for later use to prepare antibiotic discs of appropriate concentrations, as shown in Table 2 below. In a clean bench, add 10 μL of the drug solution to each dried paper disc to prepare antibiotic sensitivity discs with the specified concentrations. Allow them to air dry naturally before use.

[0099] Table 2. Antibiotics and their content

[0100]

[0101] Take 30 μL of activated Bifidobacterium denticulatum culture and spread it evenly on an MRS solid plate using a spreader. Carefully place different antibiotic susceptibility test strips on the surface of the culture medium using tweezers. Use a strip containing 10 μL of MRS liquid culture medium as a blank control group. Perform 3 parallel groups to ensure that the distance between the susceptibility test strips is greater than 25 mm and the distance between the center of the susceptibility test strip and the edge of the culture dish is greater than 15 mm. Incubate at a constant temperature of 37℃ in an anaerobic workstation for 18 h. Measure and record the diameter of the inhibition zone. The results are shown in Table 3.

[0102] Table 3. Antibiotic resistance results of Bifidobacterium densiflorum

[0103]

[0104] The drug resistance of *Bifidobacterium dendritum* WZL-S1 was determined, and the results showed significant differences in the sensitivity of this strain to different antibiotics. *Bifidobacterium dendritum* WZL-S1 was highly sensitive to β-lactam antibiotics such as ampicillin and ceftazidime, but exhibited strong resistance to neomycin. This diversity in antibiotic responses provides evidence of its survival and adaptation in an antibiotic environment, and also suggests that its drug resistance characteristics should be considered when developing probiotic preparations.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. Bifidobacterium densiflorum ( Bifidobacterium dentium WZL-S1 was deposited on October 14, 2024, at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC No: 65257. The deposit address is Guangdong Provincial Center for Microbial Culture Collection, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, China.

2. The application of Bifidobacterium dentium WZL-S1 as described in claim 1 in the preparation of antioxidants or oral antibacterial agents, wherein, The oral antibacterial agent is an antibacterial agent that inhibits Porphyromonas gingivalis.

3. A method for preparing Bifidobacterium denticulatum DFA-Ⅰ fermentation broth, characterized in that: Includes the Bifidobacterium denticulatum (as described in claim 1) Bifidobacterium dentium The culture of WZL-S1 was inoculated into DFA-Ⅰ fermentation liquid medium and fermented under anaerobic conditions to obtain the Bifidobacterium denticulatum DFA-Ⅰ fermentation broth.

4. The preparation method according to claim 3, characterized in that: The formulation of the DFA-Ⅰ fermentation liquid culture medium is as follows: Tryptone 10.00 g / L, yeast extract 5.00 g / L, DFA-I 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, and the pH of the culture medium was adjusted to 6.

5.

5. The preparation method according to claim 3 or 4, characterized in that: The concentration of the bacterial liquid in the DFA-I fermentation liquid medium is 1×10 6 CFU / mL.

6. The preparation method according to claim 5, characterized in that: The fermentation conditions were anaerobic fermentation at 37°C for 48 hours.

7. The Bifidobacterium denticulatum DFA-Ⅰ fermentation broth prepared by any of the preparation methods described in claims 3 to 6.

8. The application of the Bifidobacterium denticulatum DFA-Ⅰ fermentation broth according to claim 7 in the preparation of oral antibacterial agents, characterized in that: The oral antibacterial agent is an antibacterial agent that inhibits Porphyromonas gingivalis.

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