Grifola frondosa polysaccharide GFP22, preparation method therefor, and use thereof in preparation of prebiotic product and auxiliary antibacterial drug

Abstract

A Grifola frondosa polysaccharide GFP22, a preparation method therefor, and the use thereof in the preparation of a prebiotic product and an auxiliary antibacterial drug. The Grifola frondosa polysaccharide GFP22 is mannoglucan polymerized from mannose and glucose in the ratio of mannose to glucose of 2.88:5.24, has the following structure, and has a weight-average molecular weight range of 4.9 kDa. The Grifola frondosa polysaccharide GFP22 can promote the synthesis of intestinal short-chain fatty acids and regulate intestinal flora homeostasis, promote the proliferation of Bifidobacteria, inhibit the proliferation of Klebsiella, and is expected to be developed into a prebiotic product and a carbohydrate drug for assisting with an anti-Klebsiella drug.

Description

Grifola frondosa polysaccharide GFP22, preparation method thereof, and application thereof in the preparation of prebiotic products and auxiliary antibacterial drugs Technical field:

[0001] The invention belongs to the field of biomedicine, and particularly relates to a Grifola frondosa polysaccharide GFP22, a preparation method thereof, and application thereof in the preparation of prebiotic products and auxiliary antibacterial drugs. Background technology:

[0002] The intestinal flora refers to the microorganisms that reside in the human intestine. There are approximately 10 trillion microorganisms in the human intestine. These microorganisms play a vital role in regulating nutrient absorption, maintaining epithelial cell development, and modulating innate immunity. The homeostasis and diversity of the intestinal flora are closely related to host cell proliferation and neural signaling pathways. An imbalance in the intestinal flora, with an overgrowth of harmful bacteria and a decrease in beneficial bacteria, can lead to a range of diseases, including immunosuppression and metabolic disorders.

[0003] Klebsiella pneumoniae (KP), a Gram-negative facultative anaerobic bacterium belonging to the Enterobacteriaceae family and the genus Klebsiella, is commonly found in the environment, such as water, soil, and vegetation. It can colonize the respiratory or intestinal tracts of humans and animals and is a common opportunistic pathogen in both humans and animals. Klebsiella pneumoniae (KP) is currently one of the most prevalent opportunistic pathogens in the world. It is highly pathogenic to humans and livestock, and can cause pneumonia, metritis, mastitis, other suppurative inflammations, and even sepsis.

[0004] Edible fungus polysaccharides are carbohydrate polymers derived from edible fungi. They are resistant to endogenous digestive enzymes and are neither hydrolyzed nor absorbed in the small intestine. Since edible fungus polysaccharides cannot be digested and degraded by the human body itself, and the intestinal flora that colonize the human intestinal lumen are rich in polysaccharide hydrolases, edible fungus polysaccharides are primarily metabolized and degraded by the intestinal flora, affecting them and regulating host health. These health-promoting polysaccharides or dietary fibers are also commonly referred to as prebiotics, which can promote the proliferation of corresponding beneficial bacteria. Taking a certain amount can produce microorganisms that are beneficial to the host's health.

[0005] Grifola frondosa is a fungus of the genus Grifola in the family Polyporaceae. It is one of the rare edible and medicinal fungi that has been developed and utilized in recent years. Grifola frondosa contains chemical components such as polysaccharides, sterols, and polyphenols, and has anti-tumor, immunomodulatory, and hypoglycemic and blood lipid-lowering effects. The Grifola frondosa strain HMGIM-W151021 is a high-polysaccharide-producing strain collected from the wild and successfully domesticated by the Institute of Microbiology, Guangdong Academy of Sciences. The deposit number of this strain is GDMCC No: 61165, which has been disclosed in Chinese Patent ZL 202210673582.4. However, its polysaccharide structure and its regulatory effect on intestinal flora have not yet been reported. Summary of the invention:

[0006] This invention utilizes a simple and effective process and method for extracting and purifying edible fungus polysaccharides. Using the proprietary strain Grifola frondosa HMGIM-W151021 as raw material, a mixed polysaccharide extract is obtained. Further purification is performed to obtain Grifola frondosa polysaccharide GFP22, which exhibits uniform charge and molecular weight. In vitro experiments have demonstrated that this polysaccharide can regulate intestinal flora balance, inhibit intestinal pathogenic Klebsiella, and promote the growth of probiotics such as Bifidobacterium. Furthermore, anaerobic fermentation of this polysaccharide in the intestine produces short-chain fatty acids, which can regulate immunity and metabolic homeostasis. This polysaccharide has the potential to be developed into a novel prebiotic or a carbohydrate drug to aid in the fight against Klebsiella pneumonia and related diseases.

[0007] The present invention provides a Grifola frondosa polysaccharide GFP22, which is a mannoglucan with a weight-average molecular weight of 4.90 kDa and has the following structure:

[0008] R:β-D-Glcp-(1→6)-β-D-Manp-(1→.

[0009] The Grifola frondosa polysaccharide GFP22 is a polysaccharide polymerized from mannose and glucose, and the ratio (molar ratio) of mannose to glucose is 2.88:5.24.

[0010] The present invention also provides a method for preparing the above-mentioned Grifola frondosa polysaccharide GFP22, comprising the following steps:

[0011] (1) Polysaccharide extraction: The fruiting bodies of Grifola frondosa were extracted with boiling water. The extract was collected and concentrated, centrifuged, and then the supernatant was dialyzed and centrifuged with alcohol to collect the precipitate to obtain the crude polysaccharide GFP.

[0012] (2) Polysaccharide purification: crude polysaccharide GFP was purified by DEAE Sepharose TMThe crude secondary polysaccharide GFP2 was obtained by separation using a Fast Flow anion exchange column; the crude secondary polysaccharide was further purified using a Sephacryl S-200HR gel column to obtain the Grifola frondosa polysaccharide GFP22.

[0013] Preferably, in step (1), the ethanol used for precipitation is 95% ethanol by volume, and the volume of ethanol used for precipitation is 3 to 5 times that of the concentrated solution.

[0014] Preferably, in step (1), before ethanol precipitation, the concentrate is first centrifuged and then the supernatant is dialyzed to remove water-soluble impurities and small molecular components.

[0015] Preferably, in step (2), deionized water, 0.1 M and 0.2 M NaCl solutions are sequentially used for gradient elution during the anion exchange column separation, and the elution peak component eluted with 0.1 M NaCl solution is collected to obtain the secondary crude polysaccharide GFP2.

[0016] Preferably, in step (2), during further purification on a Sephacryl S-200HR gel column, 0.15 M NaCl solution (containing 0.05 M phosphate buffer, pH = 6.8) is used for elution, and the eluted fraction collected is Grifola frondosa polysaccharide GFP22.

[0017] The identification of the obtained Grifola frondosa polysaccharide GFP22 in the present invention comprises the determination of molecular weight and monosaccharide composition, and then the structural characteristics thereof are analyzed by methods such as methylation combined with GC-MS and nuclear magnetic resonance.

[0018] The present invention also provides use of the Grifola frondosa polysaccharide GFP22 in preparing prebiotic products or auxiliary antibacterial drugs.

[0019] Preferably, the prebiotic product can promote the production of short-chain fatty acids in the intestine and regulate the homeostasis of intestinal flora.

[0020] Preferably, the short-chain fatty acids include acetic acid, propionic acid and butyric acid; and the regulating intestinal flora homeostasis includes promoting the proliferation of intestinal Bifidobacterium and inhibiting the proliferation of intestinal Klebsiella.

[0021] Preferably, the antibacterial targets of the auxiliary antibacterial drug include Klebsiella pneumoniae.

[0022] The present invention also provides a prebiotic product or an auxiliary antibacterial drug, which comprises the above-mentioned Grifola frondosa polysaccharide GFP22 as an active ingredient.

[0023] The present invention has the following beneficial effects:

[0024] The present invention utilizes Grifola frondosa polysaccharide GFP22 to prepare intestinal prebiotics, promotes the enrichment of bifidobacteria in the intestine, inhibits intestinal Klebsiella, and can promote intestinal microorganisms to produce short-chain fatty acids. Grifola frondosa polysaccharide GFP22 does not directly exert the activity of inhibiting harmful bacteria, but Grifola frondosa polysaccharide GFP22 can significantly inhibit Klebsiella pneumoniae and inhibit pathogenic microorganisms after fermentation. Although the antibiotics currently used can significantly inhibit pathogenic bacteria, they also inhibit beneficial bacteria, causing intestinal flora disorder. Exogenous supplementation of probiotics may not necessarily achieve the expected effect of specific probiotic colonization, and some probiotics need to be stored at low temperatures, and the transportation and storage costs are high. The intestinal prebiotics of the present invention are of great application value in the field of biomedicine. Description of the drawings:

[0025] FIG1 is a purity chart of Grifola frondosa polysaccharide GFP22 obtained in Example 1 by high performance gel permeation chromatography.

[0026] FIG2 is an ion chromatogram of the monosaccharide composition in the Grifola frondosa polysaccharide GFP22 prepared in Example 1.

[0027] FIG3 is a GC-MS spectrum of glycosidic bonds in Grifola frondosa polysaccharide GFP22 prepared in Example 1.

[0028] Figure 4 is the GFP22 of Grifola frondosa polysaccharide prepared in Example 1 1 H NMR and 13 C NMR spectrum.

[0029] FIG5 shows the effect of 24 h fermentation of Grifola frondosa polysaccharide GFP22 prepared in Example 1 on the composition and structure of intestinal microorganisms.

[0030] Figure 6 shows the SCFA content of the Grifola frondosa polysaccharide GFP22 prepared in Example 1 after 24 hours of in vitro fecal microbial fermentation. (A) Total carbohydrate concentration; (B) pH value; (C) Acetic acid concentration; (D) Propionic acid concentration; (E) Butyric acid concentration. Compared with the Con group, the acetic acid, propionic acid, and butyric acid contents were statistically significantly different. ** P<0.01, *** P<0.001.

[0031] FIG7 shows the inhibitory effect of Grifola frondosa polysaccharide GFP22 and fermentation broth prepared in Example 1 on Klebsiella pneumoniae (A) and the promoting effect of Grifola frondosa polysaccharide GFP22 on Bifidobacterium longum (B. longum) and Bifidobacterium pseudocatenulatum (B, C). Specific implementation method:

[0032] The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention.

[0033] Example 1 Extraction, separation, purification and structural characterization of Grifola frondosa polysaccharide GFP22

[0034] 1. Extraction and separation of polysaccharides

[0035] Fruiting bodies of the Grifola frondosa strain HMGIM-W151021 were extracted multiple times using boiling water. The sugar content of the extracts was determined using the sulfuric acid-phenol method until a sugar reaction became obscured. The extracts were combined, concentrated under reduced pressure, and centrifuged to remove the precipitate. The supernatant was dialyzed against flowing water for two days. The dialyzed solution was precipitated with 95% ethanol at a volume ratio of 1:4 (v / v) and allowed to stand overnight. The upper ethanol solution was discarded, the precipitate was centrifuged, and dried to obtain crude Grifola frondosa polysaccharide GFP (4.2%).

[0036] 2. Purification of Polysaccharides

[0037] (1) Each time, 4.0 g of crude polysaccharide GFP was dissolved in 45 mL of deionized water, stirred overnight, centrifuged, and the supernatant was loaded onto DEAE Sepharose. TM A Fast Flow anion exchange column was used for gradient elution using deionized water and different concentrations of NaCl (0.1 M and 0.2 M) at a flow rate of 3 mL / min. The elution was collected using an automated collector. 50 μL of the solution from each tube was developed using the sulfuric acid-phenol method and its absorbance was measured at 490 nm using a microplate reader. An elution curve was plotted using absorbance and elution volume. The separated polysaccharides were collected according to the elution curve, concentrated under reduced pressure, dialyzed, and freeze-dried. The eluted fractions in the 0.1 M NaCl eluate were dried to yield the secondary crude polysaccharide GFP2 (1.65 g).

[0038] (2) 50 mg of the secondary crude polysaccharide GFP2 was dissolved in 3 mL of 0.15 M NaCl, pH 6.8 phosphate buffer, and centrifuged (12,000 r / min). The supernatant was loaded onto a Sephacryl S-200HR gel column and eluted with 0.15 M NaCl solution (containing 0.05 M phosphate buffer, pH = 6.8) at a flow rate of 0.5 mL / min using an automatic collector. After color development using the sulfuric acid-phenol method and absorbance detection using a microplate reader, an elution curve was plotted. The desired fractions were collected, concentrated, dialyzed, and freeze-dried to obtain uniform Grifola frondosa polysaccharide GFP22 (21.2 mg, 42.4%).

[0039] 3. Structural Identification of Polysaccharides

[0040] (1) The characteristic spectrum of Grifola frondosa polysaccharide GFP22 on a series of TSKgel G5000SWXL and G3000SWXL analytical gel columns is shown in Figure 1. The chromatographic conditions were as follows: mobile phase: 0.1M NaNO3 solution; flow rate: 0.5mL / min; column temperature: 30℃; Agilent 1260 liquid chromatograph; detectors: differential detector and UV detector. The weight-average molecular weight of the sample was calculated based on the polysaccharide standard curve: a series of standard dextran products with known molecular weights (2kDa, 5kDa, 12kDa, 20kDa, 50kDa, 120kDa, 200kDa, 500kDa, 670kDa) were dissolved in the mobile phase to prepare a solution with a concentration of 5mg / mL, centrifuged, and the supernatant was collected and automatically injected for analysis. The standard curve was drawn using GPC software, and the weight-average relative molecular mass of Grifola frondosa polysaccharide GFP22 was determined to be 4.90kDa. The gel permeation chromatogram of the homogeneity and average weight average molecular weight of Grifola frondosa polysaccharide GFP22 is shown in FIG1 .

[0041] (2) Take 5 mg of Grifola frondosa polysaccharide GFP22, add 2 mL of 2M TFA, and hydrolyze at 120°C for 3 h. Accurately transfer the acid hydrolysis solution to a tube and blow dry it with a nitrogen blower. Add 5 mL of water and vortex to mix. Take 50 μL and add 950 μL of deionized water. Centrifuge at 12000 rpm for 5 min. Take the supernatant and analyze it with ion chromatography. Chromatographic column: Dionex Carbopac TM PA20 (3 x 150 mm); mobile phase: A: H2O; B: 15 mM NaOH-100 mM NaOAC; flow rate: 0.3 mL / min; injection volume: 5 μL; column temperature: 30°C; detector: electrochemical detector. The ion chromatogram of the monosaccharide composition of Grifola frondosa polysaccharide GFP22 is shown in Figure 2.

[0042] (3) Take 10 mg of Grifola frondosa polysaccharide GFP22, place it in a glass reaction bottle, add 1 mL of anhydrous DMSO, quickly add methylation reagent A solution, seal, dissolve under ultrasonication, and then add methylation reagent B solution. React in a magnetic stirring water bath at 30°C for 60 minutes. Finally, add 2 mL of ultrapure water to the above mixture to terminate the methylation reaction. Take the methylated polysaccharide, add 1 mL of 2M trifluoroacetic acid (TFA) and hydrolyze for 90 minutes, and evaporate to dryness on a rotary evaporator. Add 2 mL of double-distilled water to the residue, reduce 60 mg of sodium borohydride for 8 hours, add glacial acetic acid to neutralize, rotary evaporate, dry in a 100°C oven, then add 1 mL of acetic anhydride to acetylate at 100°C for 1 hour, and cool. Then add 3 mL of toluene, concentrate under reduced pressure and evaporate to dryness, repeat 4-5 times to remove excess acetic anhydride. Dissolve the acetylated product with 3 mL of CH2Cl2 and transfer to a separatory funnel. Add a small amount of distilled water and shake thoroughly, then remove the upper aqueous solution, and repeat this 4 times. The CH₂Cl₂ layer was dried with an appropriate amount of anhydrous sodium sulfate, brought to a volume of 10 mL, and placed in a liquid phase vial. Acetylation product samples were analyzed using a Shimadzu GCMS-QP 2010 gas chromatograph-mass spectrometer. GC-MS conditions included an RXI-5 SIL MS column (30 m × 0.25 mm × 0.25 μm) with a temperature program of 120°C, ramping from 3°C / min to 250°C / min, and holding for 5 min. The inlet temperature was 250°C, the detector temperature was 250°C / min, and the carrier gas was helium at a flow rate of 1 mL / min. The GC-MS spectrum of the glycosidic bonds in the Grifola frondosa polysaccharide GFP22 is shown in Figure 3.

[0043] (4) The physicochemical constants of Grifola frondosa polysaccharide GFP22 are as follows:

[0044] GFP22: white powder; 30 mg of Grifola frondosa polysaccharide GFP22 was dissolved in 0.5 mL of D2O and 2.5 μL of acetone was added as internal standard (δ H =2.29ppm, δ C =31.5ppm), and one-dimensional NMR spectra were measured at 25°C on a Bruker AVANCE III 600M NMR spectrometer. 1 H NMR and 13 The C NMR spectrum is shown in Figure 4. 13 C and 1 The H NMR data are shown in Table 1. The specific structure of GFP22 polysaccharide is:

[0045] R:β-D-Glcp-(1→6)-β-D-Manp-(1→

[0046] It is a polysaccharide with a new structure that has not been reported in the literature.

[0047] Table 1: Carbon and hydrogen spectrum data of GFP22 (in H2O, 1 H for 600MHz, 13 C for 150MHz)

[0048] Table 3 1 H and 13 C NMR assignment of GFP22(in D2O)

[0049] Example 2: Effect of Grifola frondosa polysaccharide GFP22 on regulating intestinal flora homeostasis

[0050] Fresh feces were collected from three volunteers. The uncontaminated portion was taken and placed in a 15 mL sterile centrifuge tube. Sterile phosphate buffer solution (0.1 mol / L, pH = 7.2) was immediately added to obtain a fecal solid-liquid mixture (10%, w / v). The mixture was homogenized and centrifuged, and the supernatant was collected. 2 g of peptone, 2 g of yeast extract, 2 mg of NaHCO3, 0.5 g of bile salts, 0.5 g of cysteine ​​hydrochloride, 0.1 g of NaCl, 40 mg of K2HPO4, 20 mg of heme, 10 mg of MgSO4, 10 mg of CaCl2, 1 mL of Tween 80, 1 mg of resazurin, and 10 μL of vitamin K1 were added to a volume of 1 L with ultrapure water and the pH was adjusted to 7.0 to prepare a minimal nutrient growth medium. The prepared medium was sterilized (121°C, 20 min) and placed on a clean bench for later use. The Con group consisted of 0.5 mL of fecal microbial culture solution plus 4.5 mL of culture medium plus a blank sample. The GFP22 group consisted of 0.5 mL of fecal microbial culture solution plus 4.5 mL of culture medium plus GFP22. The total fermentation volume was 5 mL and placed in sealed vials. Three replicates were used for each group. Anaerobic fermentation was performed in a 37°C anaerobic chamber. The fermentation products were collected at 0 and 24 hours of fermentation and centrifuged. The supernatant was analyzed for polysaccharide content, acidity, and short-chain fatty acids. The precipitate was used for 16S rRNA sequencing analysis (sequencing was commissioned by Shanghai Meiji Biotechnology Co., Ltd.).

[0051] Results showed that after 24 hours of fermentation, the polysaccharide content in the GFP22 group was significantly reduced, indicating that the polysaccharide was utilized by intestinal microorganisms during the fermentation process. The pH of the culture decreased significantly after fermentation, and the content of short-chain fatty acids, including acetic acid, propionic acid, and butyric acid, increased significantly (Figure 6). The Ace index and Shannon and Simpson indices indicated that the GFP22 group increased the richness and diversity of the intestinal microbiota. At the phylum level, after 24 hours of fermentation, compared with the Con group, the GFP22 group significantly suppressed the abundance of Proteobacteria and increased the abundance of Actinobacteria and Firmicutes. At the genus level, the GFP22 group significantly suppressed the abundance of Klebsiella and increased the abundance of Catenibacterium and Bifidobacterium (Figure 5).

[0052] Example 3 Inhibitory Effects of Grifola frondosa Polysaccharide GFP22 and Its Fermentation Broth on Klebsiella pneumoniae

[0053] Bacterial strain: Klebsiella pneumoniae (ATCC BAA-1902, purchased from Guangdong Provincial Microbiological Culture Collection Center).

[0054] The polysaccharide GFP22 fermentation supernatant was obtained by collecting the fermentation product after 24 hours of fermentation according to the method of Example 2, centrifuging the fermentation product, and collecting the supernatant.

[0055] Klebsiella pneumoniae was cultured on BL agar medium. A single colony was picked from the plate and inoculated into 50 mL of BL liquid medium for 3-4 hours. 10 μL of bacterial solution, 90 μL of BL medium, and 100 μL of polysaccharide GFP22 or polysaccharide GFP22 fermentation supernatant were added to each well. The OD value was automatically measured every 30 minutes using a microplate reader. 600 The addition of gentamicin was used as a positive control, and the absence of polysaccharide GFP22 or the fermentation supernatant of polysaccharide GFP22 was used as a blank control.

[0056] The results showed that polysaccharide GFP22 did not directly exert antibacterial activity. However, after polysaccharide GFP22 was fermented and cultured by intestinal flora, its fermentation supernatant had antibacterial activity. This may be because polysaccharide GFP22 produced some antibacterial active metabolites after fermentation, thereby exerting an indirect antibacterial effect (Figure 7A).

[0057] Example 4 Growth-promoting effect of Grifola frondosa polysaccharide GFP22 on Bifidobacterium longum and B. pseudocatenulatum

[0058] Pick a single colony on the plate and inoculate it into MRS broth medium, culture it in a shaking incubator at 37°C, with a rotation speed of 150r / min, and culture it continuously for 48h. Prepare the basal culture medium (the preparation of the basal culture medium is the same as the basic nutrient growth medium in Example 2), sterilize it, and inoculate different groups with the cultured bacterial solution at a volume fraction of 10%. Set up the Con group: 0.5mL Bifidobacterium bacterial solution + 4.5mL basal culture medium + blank, GFP22 group: 0.5mL Bifidobacterium bacterial solution + 4.5mL basal culture medium + GFP22, and culture it anaerobically at 37°C. The OD value of the fermentation solution is measured at a wavelength of 600nm using an enzyme marker. 600 The results showed that different concentrations (2.5 mg / mL and 5 mg / mL) of polysaccharide GFP22 promoted the growth of both B. longum and B. pseudocatenulatum (Figure 7B, C).

[0059] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A Grifola frondosa polysaccharide GFP22, characterized in that: The Grifola frondosa polysaccharide GFP22 is a mannoglucan polymerized from mannose and glucose and has the following structure: R:β-D-Glcp-(1→6)-β-D-Manp-(1→.

2. The Grifola frondosa polysaccharide GFP22 according to claim 1, characterized in that The weight average molecular weight of the Grifola frondosa polysaccharide GFP22 is 4.90 kDa, and the ratio of mannose to glucose is 2.88:5.

24.

3. A method for preparing Grifola frondosa polysaccharide GFP22 as claimed in claim 1 or 2, characterized in that: The following steps are involved: (1) Polysaccharide extraction: The fruiting bodies of Grifola frondosa were extracted with boiling water, and the extract was collected and concentrated, centrifuged, and then the supernatant was dialyzed and centrifuged with alcohol to collect the precipitate to obtain the crude polysaccharide GFP; (2) Polysaccharide purification: crude polysaccharide GFP was purified by DEAE Sepharose TM The crude secondary polysaccharide was separated by a Fast Flow anion exchange column to obtain the crude secondary polysaccharide GFP2; the crude secondary polysaccharide was further purified by a Sephacryl S-200HR gel column to obtain the Grifola frondosa polysaccharide GFP22.

4. The preparation method according to claim 3, characterized in that: In step (1), the ethanol used for precipitation is 95% by volume ethanol, and the volume of ethanol used for precipitation is 3 to 5 times that of the concentrated solution.

5. The preparation method according to claim 3, characterized in that: In step (2), when performing the anion exchange column separation, deionized water, 0.1M and 0.2M NaCl solutions are used in sequence for gradient elution, and the elution peak component eluted with the 0.1M NaCl solution is collected to obtain the secondary crude polysaccharide GFP2; when performing the gel column purification, a 0.15M NaCl solution with a pH of 6.8 and containing 0.05M phosphate buffer is used for elution, and the elution component collected is Grifola frondosa polysaccharide GFP22.

6. Use of the Grifola frondosa polysaccharide GFP22 according to claim 1 or 2 in the preparation of prebiotic products or auxiliary antibacterial drugs.

7. The use according to claim 6, characterized in that: The prebiotic product can promote the production of intestinal short-chain fatty acids and regulate the homeostasis of intestinal flora.

8. The use according to claim 7, characterized in that: The short-chain fatty acids include acetic acid, propionic acid and butyric acid; and the regulation of intestinal flora homeostasis includes promoting the proliferation of bifidobacteria and inhibiting the proliferation of Klebsiella.

9. The use according to claim 6, characterized in that: The antibacterial targets of the auxiliary antibacterial drugs include Klebsiella pneumoniae.

10. A prebiotic product or auxiliary antibacterial drug, characterized in that: The invention comprises the Grifola frondosa polysaccharide GFP22 according to claim 1 or 2 as an active ingredient.

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