Burkholderia gladioli LJ04 and application of burkholderia gladioli LJ04 in antagonism of durian disease pathogenic bacteria

Abstract

The invention discloses burkholderia gladioli LJ04 and application of the burkholderia gladioli LJ04 in antagonism of durian disease pathogenic bacteria, and relates to the technical field of microorganisms, and the preservation number of the burkholderia gladioli LJ04 is GDMCC No: 67473. The strain LJ04 disclosed by the invention has a very strong inhibition effect on the epidemic disease pathogenic bacteria of the elaeagnus wilsonii, and can obviously inhibit the growth of the hypha of the epidemic disease pathogenic bacteria of the elaeagnus wilsonii, the plate inhibition rate of the LJ04 bacterial liquid on the epidemic disease pathogenic bacteria of the elaeagnus wilsonii within 7 days reaches 100%, and the control effect of the LJ04 bacterial liquid reaches 96.57% after the LJ04 bacterial liquid is inoculated for 5 days. As a disease-resistant strain, the burkholderia gladioli LJ04 has very good potential of preventing and treating plant diseases caused by the durian blight pathogenic bacteria, provides an environment-friendly, simple and effective way for preventing and treating the plant diseases caused by the durian blight pathogenic bacteria, and is beneficial to environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microbial technology, and more particularly to a Burkholderia gladioli LJ04 and its application in antagonizing the pathogenic bacteria of Elaeocarpus venosus blight. BACKGROUND

[0002] Elaeocarpus venosus Blume is one of the important representative types of local tree species in South China and Southwest China, with straight trunk, obvious layered tree shape, red color of new leaves before shedding, white and peculiar flower type, and blue-green pearl-shaped fruits, which are unique in landscape tree species. Elaeocarpus Elaeocarpus venosus blight is a serious branch and trunk disease of Elaeocarpus venosus Blume, and its pathogenic bacteria is Elsinoe venosae Bitant. Pseudocryphonectria elaeocarpicola The disease mainly causes branch and trunk rot and ulcer, and eventually leads to branch and trunk dryness, and even whole plant death.

[0003] At present, there is still a lack of effective technical measures for preventing and treating Elaeocarpus venosus blight in production. It mainly relies on conventional branch and trunk fungal disease management methods, such as scraping off diseased tissues, pruning diseased branches, and spraying chemical agents.

[0004] Therefore, screening of Elaeocarpus venosus blight highly antagonistic biocontrol strains is a problem to be solved by those skilled in the art. SUMMARY

[0005] The present application provides a Burkholderia gladioli LJ04 and its application in antagonizing the pathogenic bacteria of Elaeocarpus venosus blight. The Burkholderia gladioli LJ04 is isolated from a dead forficula, and can efficiently inhibit the pathogenic bacteria of Elaeocarpus venosus blight, which has very important significance for the prevention and treatment of Elaeocarpus venosus blight.

[0006] To solve the above technical problems, the technical scheme is as follows:

[0007] The Burkholderia gladioli LJ04 is preserved in Guangdong Microbial Culture Collection Center, located at No. 59, Building 5, Guangdong Academy of Microbiology, 100 Xianlie Road, Guangzhou, with a preservation date of December 11, 2025, a preservation number of GDMCC NO: 67473, and a classification and naming of Burkholderia gladioli . Burkholderia gladioli

[0008] Another object of the present application is to provide a microbial agent, which comprises the above-mentioned Burkholderia gladioli LJ04. ​

[0009] Another object of the present invention is to provide the application of the above-mentioned Burkholderia gladioli LJ04 or the above-mentioned microbial agent in the prevention and control of Echinococcus salina disease caused by the pseudocryptoclast red shell of Echinococcus salina.

[0010] Another object of the present invention is to provide the application of the above-mentioned Burkholderia gladioli LJ04 or the above-mentioned microbial agent in antagonizing the pseudocryptoclast red shell of Elaeocarpus decipiens.

[0011] Another objective of this invention is to provide a biocontrol agent for *Elaeagnus pungens*, wherein the biocontrol agent comprises *Burkholderia calamus* LJ04 or its fermentation product.

[0012] Preferably, the fermentation product is the filtrate of the fermentation culture broth, or a solid or semi-solid product prepared by adding excipients to the filtrate of the fermentation culture broth.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a strain of *Burkholderia gladioli* LJ04 and its application in antagonizing the pathogen of *Elaeocarpus decipiens* blight. *Burkholderia gladioli* LJ04, antagonizing *Elaeocarpus decipiens* blight, exhibits a highly significant effect in controlling *Elaeocarpus decipiens* blight, showing a strong inhibitory effect on the pathogen and significantly inhibiting the mycelial growth of the pathogen. The bacterial suspension of strain LJ04 achieved a 100% inhibition rate against *Elaeocarpus decipiens* blight on plate after 7 days, and its control effect reached 96.57% after 5 days in pot experiments. As a disease-resistant strain, *Burkholderia gladioli* LJ04 has excellent potential for controlling plant diseases caused by *Elaeocarpus decipiens* blight, providing an environmentally friendly, simple, and effective approach to control plant diseases caused by this pathogen, thus benefiting environmental protection. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0015] Figure 1 The results of the confrontation culture test for detecting the inhibitory effect of strain LJ04 on the pathogen of *Elaeocarpus decipiens* are shown. Among them, A represents the growth of *Elaeocarpus decipiens* without inoculation of strain LJ04 and only inoculated with the pathogen of *Elaeocarpus decipiens*; B represents the growth results of plate confrontation culture of strain LJ04 and *Elaeocarpus decipiens* after streaking.

[0016] Figure 2The images show the colony and cell morphology of strain LJ04, where A represents the culture morphology of strain LJ04 on LB medium; and B is a scanning electron microscope image of the morphology of strain LJ04 (scale bar = 0.001 mm).

[0017] Figure 3 This is a phylogenetic tree of strain LJ04 based on its 16S rDNA sequence; the Latin name in the figure is followed by the corresponding GenBank number.

[0018] Figure 4 The images show the plate inhibition effect of LJ04 bacterial suspension on the pathogen of *Elaeocarpus decipiens* blight; where A is the plate culture image of the blank control group; and B is the plate inhibition effect of LJ04 bacterial suspension on the pathogen of *Elaeocarpus decipiens* blight.

[0019] Figure 5 The images show the plate inhibition effect of the filtrate of LJ04 fermentation broth on *Elaeocarpus decipiens* blight pathogen; where A is the plate culture of the blank control group; and B is the plate culture of LJ04 fermentation broth filtrate on *Elaeocarpus decipiens* blight pathogen.

[0020] Figure 6 The images show the control effect of LJ04 bacterial solution on potted plants against *Elaeocarpus decipiens* blight. A represents the control group inoculated only with blank PDA blocks; B represents the control effect of simultaneously inoculating with LJ04 bacterial solution and *Elaeocarpus decipiens* blight pathogen; and C represents the control group inoculated only with *Elaeocarpus decipiens* blight pathogen. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0023] Example 1: Obtaining Burkholderia gladioli LJ04 1. Isolation of strain LJ04 Collected dead cicadas in Tianhe District, Guangzhou ( Platypleura kaempferi A bacterial strain capable of effectively inhibiting the pathogen of *Elaeocarpus decipiens* blight was isolated from the fungi of the cicada nymph, named LJ04. The strain was purified by streaking on LB agar plates and then stored at 4 °C for later use.

[0024] Plate confrontation experiment: The pathogen of *Elaeocarpus decipiens* blight was placed on a plate. Pseudocryphonectria elaeocarpicola DY-01 (accession number GDMCC No: 62516, see patent 202210744848.X) was inoculated onto potato agar PDA plates (containing 200 g potato, 20 g glucose, 17 g agar powder, pH 7.0-7.2 per 1000 mL). After incubation at 28℃ for 5 days, the mycelial cake was punched out with a 6 mm punch. A fresh mycelial cake with a diameter of 6 mm was placed in the center of another PDA plate and incubated at 28℃ for 1 day. Then, a small amount of bacterial strain LJ04 was picked up with an inoculation loop and gently streaked 2.0 cm away from the mycelial cake. The plate was then placed in an incubator and incubated upside down at 28℃ for 5 days. The presence and size of the inhibition zone were then observed and recorded. The inhibition experiment was repeated 3 times in parallel.

[0025] The results showed that the pathogen of *Elaeocarpus decipiens* blight grew normally in the control group. Figure 1 The treatment group (A), namely the LJ04 strain group, showed a strong inhibitory effect on the pathogen of *Elaeocarpus decipiens* blight. Figure 1 (B), the antibacterial band width reaches 20.00 mm.

[0026] 2. Identification of strain LJ04 The LJ04 strain was identified using the methods described in the "Manual of Systematic Identification of Common Bacteria" (Beijing: Science Press, 2001: 349-398) edited by Dong Xiuzhu et al. and the "Microbiology Experiment Manual" (Shanghai: Science and Technology Press, 1986: 1-137) edited by Zhou Deqing et al., as well as 16S rDNA.

[0027] (1) Morphological identification Strain LJ04 appears as a white to pale yellow-white circle on LB agar plates, with a smooth, slightly raised surface and intact edges. Figure 2 (A) Observations using optical and scanning electron microscopy showed that the size of strain LJ04 was approximately 0.41-0.61 µm × 0.75-2.65 µm. Figure 2 (B) Gram staining is negative.

[0028] (2) Biochemical identification Biochemical experiments showed that strain LJ04 was aerobic, growing at 4℃ and 1% NaCl, but not growing at 8% NaCl. It tested positive for ONPG, aesculin hydrolysis, and gelatin hydrolysis. It tested negative for nitrate reduction, denitrification, indole reaction, glucose acidification, arginine dihydrolase, and urease. It could utilize glucose, arabinose, mannose, D-mannitol, D-arabinol, gluconate, L-alanine, adipic acid, citric acid, phenylacetic acid, L-glutamic acid, and L-arginine, but could not utilize maltose and sucrose (see Table 1). Table 1. Morphological and basic physiological and biochemical characteristics of strain LJ04

[0029] Note: "+" indicates positive, and "-" indicates negative.

[0030] (3) Molecular identification A small number of single colonies were picked and placed in an EP tube containing 20 µL of sterile water. The tube was incubated at 100 °C for 5 min, then centrifuged (10,000 rpm, 2 min). The supernatant was collected and stored at 4 °C, yielding the genomic DNA of strain LJ04. Using the genomic DNA of strain LJ04 as a template, PCR amplification was performed using primers 27F / 1492R (27F: 5'-AGAGTTTGATCCTGGCTCAG-3', SEQ ID NO.1; 1492R: 5'-TACGGCTACCTTGTTACGACTT-3'; SEQ ID NO.2).

[0031] The amplification system consisted of 25 µL containing 12.5 μL of 2×Magic Green Taq Mix, 6.5 μL of ddH2O, 2 μL each of forward and reverse primers (10 mM), and 2 μL of DNA template. The amplification conditions were: 95 ℃ for 3 min; 95 ℃ for 30 s, 56 ℃ for 30 s, 72 ℃ for 1.5 min, for 30 cycles; and 72 ℃ for 10 min.

[0032] The PCR amplification products were sequenced by Beijing Qingke Biotechnology Co., Ltd., and the PCR amplification yielded a product fragment of approximately 1.4 kb (as shown in SEQ ID NO.3).

[0033]

[0034] The sequence was subjected to homology alignment analysis in the NCBI database (http: / / blast.ncbi.nlm.nih.gov / ). A phylogenetic tree was constructed using the Neighbor-Joining method with Mega X software for phylogenetic analysis. The values ​​on each branch represent the percentage of support from 1000 Bootstrap resampling analyses.

[0035] Homology comparison analysis performed in the NCBI (http: / / blast.ncbi.nlm.nih.gov / ) gene bank revealed that strain LJ04 is related to strain [unclear - possibly a specific strain or model]. Burkholderia gladioli The strains of this species showed the highest homology. Based on phylogenetic analysis ( Figure 3 ), and strain LJ04 was found to be similar to strain Burkholderia gladioli CFBP 2427 was most closely related and clustered in the same branch, while being more distantly related to other strains. This indicates that the strain is *Burkholderia gladioli*.

[0036] Based on the morphological characteristics, physiological and biochemical properties, and 16S rDNA results of the strain, strain LJ04 was finally identified as Burkholderia gladioli (…). Burkholderia gladioli ).

[0037] 3. Preservation of strain LJ04 Burkholderia gladioli ( Burkholderia gladioli LJ04 is deposited at the Guangdong Provincial Center for Microbial Culture Collection, located at the Institute of Microbiology, Guangdong Academy of Sciences, 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. Deposit date: December 11, 2025; Accession number: GDMCC NO:67473; Classification and nomenclature: Burkholderia gladioli .

[0038] Example 2: Antagonistic effect of Burkholderia gladioli LJ04 bacterial suspension on Eucommia ulmoides blight pathogens on agar plates. 1. Preparation of LJ04 bacterial culture Select one loop of activated Burkholderia gladioli ( Burkholderia gladioli LJ04 was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of KSB liquid medium (containing 20 g peptone, 15 mL glycerol, 1.5 g K₂HPO₄, 1.5 g MgSO₄•7H₂O per 1000 mL, pH 7.0-7.2). The flask was then placed on a shaker and cultured at 28℃ and 200 rpm for 2 days to obtain the desired product. Burkholderia gladioli LJ04 bacterial culture was prepared to a concentration of 1.0 × 10⁻⁶. 5 cfu / mL bacterial culture

[0039] 2. Flat Plate Standoff Experiment The LJ04 bacterial suspension prepared above was mixed into a sterilized PDA plate solid culture medium cooled to about 45 °C, wherein the volume ratio of bacterial suspension to PDA plate solid culture medium was 1:10. After mixing, the mixture was poured into plates, and then a fresh *Elaeocarpus decipiens* blight pathogen with a diameter of 6 mm was inoculated in the center of the plate. Pseudocryphonectria elaeocarpicola The mycelial cakes (prepared using the same method as in Example 1) served as the treatment group; the control group consisted of PDA medium with an equal volume of sterile water, mixed thoroughly, poured into plates, and then a fresh mycelial cake of *Elaeocarpus decipiens* blight pathogen with a diameter of 6 mm was inoculated in the center of the plate; each treatment was repeated in triplicate and incubated at 28 ℃ until the colony diameter in the control group reached more than 3 / 4 of the diameter of the petri dish. The colony diameter was then measured, and the inhibition rate was calculated. The colony diameter was determined using the cross-multiplication method. The formula for calculating the inhibition rate using the colony diameter method is as follows: Inhibition rate = (Net colony growth diameter of control group - Net colony growth diameter of treatment group) / Net colony growth diameter of control group × 100%.

[0040] Among them, the net growth diameter of colonies is the diameter of the hyphae of pathogenic fungi growing on the culture medium. The calculation method is: net growth diameter of colonies = colony diameter - diameter of the fungal cake.

[0041] The test results showed that Burkholderia gladioli ( Burkholderia gladioli The bacterial suspension completely inhibited the growth of the pathogen causing *Elaeocarpus decipiens* blight, achieving a 100% inhibition rate after 7 days of culture. Figure 4 (B) Figure 4 Image A shows the plate culture of the control group.

[0042] Table 2 Burkholderia gladioli Antagonistic activity of LJ04 bacterial suspension against the pathogen of *Elaeocarpus decipiens* on agar plates

[0043] Example 3: Antagonistic effect of the filtrate of *Burkholderia gladioli* LJ04 fermentation broth on *Elaeocarpus decipiens* blight pathogens on agar plates. 1. Preparation of filtrate from LJ04 fermentation broth Select one loop of activated Burkholderia gladioli ( Burkholderia gladioli LJ04 was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of KSB liquid medium. The flask was then placed on a shaker and cultured at 28°C and 200 rpm for 2 days, adjusting the concentration to 1.0 × 10⁻⁶. 5 cfu / mL, prepared Burkholderia gladioli LJ04 seed solution.

[0044] At an inoculum rate of 1% (V / V), the LJ04 seed culture prepared in the previous step was inoculated into a 500 mL Erlenmeyer flask containing 100 mL of NBG liquid medium (containing 10 g tryptone, 5 g yeast extract, 2 g glucose, 5 g NaCl, 0.5 g MgSO4•7H2O, 0.01 g FeSO4•7H2O, 1 g KH2PO4, pH 7.0-7.2 per 1000 mL) for expansion culture. The Erlenmeyer flask was then placed on a shaker and cultured at 28 ℃ and 200 rpm for 7 days. The filtrate after culture was centrifuged at 4 ℃ and 12000 rpm for 20 min, and the supernatant was collected. The supernatant was then filtered through a 0.45 μm bacterial filter membrane for sterilization, yielding the product of this invention. Burkholderia gladioli Filtrate of LJ04 fermentation broth.

[0045] 2. Flat Plate Standoff Experiment The filtrate of the LJ04 fermentation broth prepared in the previous step was mixed into a sterilized PDA plate solid medium cooled to about 45 ℃, wherein the volume ratio of bacterial culture to PDA medium was 1:10. After mixing, the mixture was poured into plates, and then a fresh *Elaeocarpus decipiens* blight pathogen with a diameter of 6 mm was inoculated in the center of the plate. Pseudocryphonectria elaeocarpicola The mycelial cakes (prepared using the same method as in Example 1) served as the treatment group; the control group consisted of PDA medium with an equal volume of sterile water, mixed thoroughly, poured into plates, and then a fresh mycelial cake of *Elaeocarpus decipiens* blight pathogen with a diameter of 6 mm was inoculated in the center of the plate; each treatment was repeated in triplicate and incubated at 28 ℃ until the colony diameter in the control group reached more than 3 / 4 of the diameter of the petri dish. The colony diameter was then measured, and the inhibition rate was calculated. The colony diameter was determined using the cross-multiplication method. The formula for calculating the inhibition rate using the colony diameter method is as follows: Inhibition rate = (Net colony growth diameter of control group - Net colony growth diameter of treatment group) / Net colony growth diameter of control group × 100%.

[0046] Among them, the net growth diameter of colonies is the diameter of the hyphae of pathogenic fungi growing on the culture medium. The calculation method is: net growth diameter of colonies = colony diameter - diameter of the fungal cake.

[0047] The test results showed that Burkholderia gladioli ( Burkholderia gladioli The filtrate from the fermentation broth effectively inhibited the growth of *Elaeocarpus decipiens* pathogen, achieving an inhibition rate of 77.74% within 7 days of culture. Figure 5 (B) Figure 5 Image A shows the plate culture of the control group.

[0048] Table 3 Burkholderia gladioli The filtrate of LJ04 fermentation broth exhibited antagonistic activity against the pathogen of *Elaeocarpus decipiens* on agar plates.

[0049] Example 4: Potted plant control effect of Burkholderia gladioli LJ04 against Phytophthora decipiens. 1. Preparation of Burkholderia gladioli LJ04 bacterial suspension and Eucommia ulmoides blight block Select one loop of activated Burkholderia gladioli ( Burkholderia gladioli LJ04 was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of KSB liquid medium. The flask was then placed on a shaker and cultured at 28 °C and 200 rpm for 2 days to obtain the desired product. Burkholderia gladioli LJ04 bacterial culture was prepared to a concentration of 1.0 × 10⁻⁶. 5 cfu / mL bacterial culture

[0050] On the edge of the colony of the blight pathogen of Elaeocarpus decipiens cultured for 3 days (on a PDA plate) and on a blank PDA plate, use a punch to make a 6 mm diameter mycelial cake and a blank PDA block, respectively, for later use; 2. Inoculation Select two-year-old *Ficus microcarpa* (Hainan Elaeocarpus) seedlings with similar diameter at breast height (DBH). Clean the inoculation site on the main stem of the seedling with sterile water, then disinfect the surface with 75% alcohol, and finally rinse the main stem with sterile water. For the treated seedlings, scald them 10-30 cm above the base using a red-hot 6 mm punch.

[0051] The LJ04 bacterial suspension prepared in the previous step was inoculated onto branches along with *Elaeocarpus decipiens* blight pathogen blocks and blank PDA blocks. A total of four inoculation treatments were performed: Treatment group I involved spraying 2 mL of sterile water onto the scalded area of ​​the main trunk of the water lily, then inoculating a blank PDA block, keeping it moist with absorbent cotton soaked in sterile water, and fixing it with plastic wrap. Treatment group II involved spraying 2 mL of sterile water onto the scalded area of ​​the main trunk of the water stone fig, then inoculating it with a fungal cake of the blight pathogen of Elaeocarpus decipiens, keeping it moist with absorbent cotton soaked in sterile water, and fixing it with plastic wrap. Treatment group III involved spraying 2 mL of LJ04 bacterial solution onto the scalded area of ​​the main trunk of the water pine, then inoculating the scalded area with a fungal cake of *Elaeocarpus decipiens* blight pathogen, keeping it moist with absorbent cotton soaked in sterile water, and fixing it with plastic wrap.

[0052] All inoculated seedlings were transferred to a culture room at 25℃ and 70%–80% relative humidity, and cultured under alternating light and dark conditions. After 2 days, the humidity was removed. Five seedlings were inoculated into each treatment group, and the inoculation was repeated three times. The area of ​​lesions on the main stem was investigated after 5 days, and the control effect was calculated. The formulas for calculating the lesion area and control effect are as follows: Lesion area (mm) 2=π × lesion length × lesion width / 4, where π is pi; Control efficacy (%) = (Lesion area of ​​treatment group II - Lesion area of ​​treatment group III) / (Lesion area of ​​treatment group II - Lesion area of ​​treatment group I) × 100%.

[0053] The test results showed that Burkholderia gladioli ( Burkholderia gladioli LJ04 has a good potted plant control effect against Elaeocarpus blight (as shown in Table 4). Figure 6 (As shown). Five days after inoculation, no obvious lesion expansion was observed at the inoculation site in treatment group I (as shown). Figure 6 In group A), large lesions were observed, with an average lesion area of ​​555.32 ± 67.20 mm. 2 ( Figure 6 (C), while Burkholderia gladioli ( Burkholderia gladioli In group III treated with LJ04, only minor lesion expansion was observed, with an average lesion area of ​​74.23 ± 11.67 mm. 2 The prevention and control effect reached 96.57% ( Figure 6 (B)

[0054] Table 4 Burkholderia gladioli LJ04's effect on potted plant control of Elaeocarpus blight

[0055] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Burkholderia gladioli ( Burkholderia gladioli LJ04, characterized in that, Its accession number is GDMCC No: 67473.

2. A microbial inoculant, characterized in that, Includes Burkholderia gladioli LJ04 as described in claim 1.

3. The application of Burkholderia gladioli LJ04 as described in claim 1 or the microbial agent as described in claim 2 in the prevention and control of Elaeocarpus decipiens disease caused by *Elaeocarpus spp.* 4. The application of Burkholderia gladioli LJ04 as described in claim 1 or the microbial agent as described in claim 2 in antagonizing the pseudocryptoclast red shell of Elaeocarpus decipiens.

5. A biocontrol agent for *Elaeocarpus decipiens* with *Cryptocoryne rubrum*, characterized in that, The biocontrol agent includes Burkholderia gladioli LJ04 as described in claim 1 or its fermentation product.

6. The biocontrol agent for *Elaeocarpus decipiens* according to claim 5, characterized in that, The fermentation product is the filtrate of the fermentation culture medium, or a solid or semi-solid product prepared by adding excipients to the filtrate of the fermentation culture medium.

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