A kind of antagonistic xanthomonas campestris against ralstonia solanacearum, biocontrol preparation and application thereof

Abstract

The present application relates to a kind of antagonistic chryseobacterium of ralstonia solanacearum, biocontrol preparation and its application, belong to the field of agricultural environmental microorganism technology.The Chryseobacterium wanjuense of the present application is classified as Chryseobacterium wanjuense, and the strain preservation number is CGMCC NO.29539.The Chryseobacterium wanjuense X201 described in the present application is isolated from the sample on the root surface of tobacco infected with tobacco bacterial wilt, and the inhibition zone diameter of tobacco bacterial wilt pathogen is 31.77mm.The strain can secrete a variety of bacteriostatic substances including flexirubin analogues, and the fermentation liquor using the strain can directly inhibit the growth of ralstonia solanacearum in rhizosphere, effectively reduce the incidence of tobacco bacterial wilt.Currently, there is no report on the application of the strain to the prevention and treatment of bacterial wilt, which can add new resources to tobacco bacterial wilt biocontrol strains.

Description

Technical Field

[0001] This invention relates to a *Ralstonia solanacearum* antagonistic to *Ralstonia solanacearum*, a biocontrol agent, and its application, belonging to the field of agricultural environmental microbiology technology. Background Technology

[0002] Bacterial wilt disease is a soil-borne bacterial disease caused by *Ralstonia solanacearum* (commonly known as Bacillus wilt), a member of the Solanaceae family. It is one of the most destructive soil-borne bacterial diseases in the world. Bacillus wilt is highly diverse and has a wide host range, infecting over 450 species of plants from more than 50 families, including tobacco, tomato, peanut, and potato. Extensive proliferation of Bacillus wilt can lead to soil microecological imbalance, seriously threatening global agricultural production. After infection, the fine roots of the plant first turn brown, followed by wilting of the tender tissues at the top (such as young leaves, shoots, and new leaves). Before the leaves turn yellow and dry, the plant rapidly dehydrates, wilts, and withers. Cutting the diseased stem near the ground reveals browning of the vascular tissue and the secretion of a white bacterial sap from this area. In dry, high-temperature conditions, the plant will wither and die within a few days, with only the leaves fading in color while the rest of the stem and leaves remain green. Ralstonia solanaceae is particularly harmful to plants in the Solanaceae family (such as tobacco, tomato, eggplant, pepper, potato, etc.).

[0003] Tobacco is one of my country's important economic crops, and disease occurrence has always been a significant limiting factor affecting its high-quality and stable yield. Moreover, in recent years, with the continuous increase in the number of consecutive years of tobacco cropping, the prevalence and spread of Tobacco bacterial wilt have accelerated, with the incidence rate reaching 100% in severely affected fields. It has become a serious and difficult-to-control soil-borne disease in current tobacco production. It typically occurs in tobacco-growing areas south of the Yangtze River in my country and is a plant disease that urgently needs to be addressed in actual production.

[0004] Bacterial wilt fungus, due to its high genetic variability and environmental adaptability, complex flora, severe damage, and difficulty in control, is a significant limiting factor in tobacco production. Effective control measures have always been a key focus and challenge in production. Currently, the main control measures for bacterial wilt in production include breeding resistant varieties, chemical control, and biological control. Although chemical pesticides can control plant diseases to some extent, over-reliance on chemical pesticides and their unscientific use can damage the original ecological structure of the soil, causing soil acidification and other problems, leading to latent degradation of soil organisms. With the rise of the global trend towards green agriculture and sustainable development, the biological control of plant diseases using microorganisms or their metabolites has become an important development trend. Therefore, in recent years, research on biocontrol bacteria for controlling tobacco bacterial wilt has been extensive, and the development and widespread application of biological agents for tobacco bacterial wilt control are of great significance for improving tobacco yield and quality.

[0005] Chinese invention patent application CN115960766A, published on April 14, 2023, discloses a microorganism for controlling bacterial wilt and its application. Specifically, it discloses that *Pseudomonas aeruginosa* (CGMCC No. 25601), *Bacillus belyceae* (CGMCC No. 25602), or a combination of both strains, exhibit good inhibitory effects against *Ralstonia solanacearum*. However, analysis of specific embodiments shows that the maximum diameter of the inhibition zone against *Ralstonia solanacearum* by these two strains or the mixed inoculum is only about 20 mm, indicating that its antibacterial effect still needs improvement. Summary of the Invention

[0006] The first objective of this invention is to provide a *Ralstonia solanacearum* antagonistic to *Ralstonia solanacearum*, thereby addressing the problem that the antimicrobial inhibitory ability of antagonistic bacteria against *Ralstonia solanacearum* in the prior art needs to be improved.

[0007] The second objective of this invention is to provide a biocontrol agent antagonizing Ralstonia so as to solve the problem that the antibacterial ability of biocontrol agents antagonizing Ralstonia so as to improve the existing technology.

[0008] The third objective of this invention is to provide an application of *Aureobacillus thuringiensis* or a biocontrol agent in the prevention and control of bacterial wilt in plants, and to provide a new and effective method for preventing and controlling bacterial wilt in plants.

[0009] The fourth objective of this invention is to provide an application of *Rhizobium chrysogenum* in the preparation of *Rhizobium bacillus* inhibitors, in order to solve the problem that the antibacterial ability of *Rhizobium bacillus* inhibitors in the prior art needs to be improved.

[0010] To achieve the above objectives, the technical solution of the present invention for antagonizing *Ralstonia solanacearum* with *Cryptotympany* is as follows:

[0011] A *Chryseobacterium wanjuense* strain antagonistic to *Ralstonia solanacearum*, the strain being classified as *Chryseobacterium wanjuense* and having the strain preservation number CGMCC NO.29539.

[0012] The beneficial effects of the above technical solution are as follows: This invention, which describes a Chryseobacterium wanjuense antagonistic to Ralstonia solanacearum, is a pioneering invention. This invention isolates a strain X201, an antagonistic bacterium with strong inhibitory effects on Ralstonia solanacearum, from the root surface soil of tobacco plants. After physiological, biochemical, and molecular biological identification, this bacterium is identified as Chryseobacterium wanjuense, classified as such.

[0013] To achieve the above objectives, the technical solution of the biocontrol agent antagonizing Ralstonia solanacearum in this invention is as follows:

[0014] A biocontrol agent antagonizing Ralstonia solanacearum, the biocontrol agent comprising Chlorella vulgaris and / or Chlorella vulgaris bacterial suspension.

[0015] The beneficial effects of the above technical solution are as follows: This invention isolated a strain X201 from the root surface soil of tobacco plants. After physiological, biochemical, and molecular biological identification, this bacterium was identified as *Chryseobacterium wanjuense*. Furthermore, through plate confrontation screening experiments, it was found that the inhibition zone diameter of *Chryseobacterium wanjuense* X201 against the pathogen of tobacco bacterial wilt reached 31.77 mm. Simultaneously, the tobacco bacterial wilt inhibition experiment demonstrated that the bacterial suspension of *Chryseobacterium wanjuense* X201 can effectively reduce the incidence of tobacco bacterial wilt. Moreover, through whole-set sequencing analysis and secondary metabolite prediction, it was found that *Chryseobacterium wanjuense* X201 can secrete various antibacterial substances, including flexirubin analogues. The above results indicate that *Chryseobacterium wanjuense* X201 or its bacterial suspension of this invention can be used as a biocontrol agent antagonizing *Ralstonia solanacearum*.

[0016] To achieve the above objectives, the technical solution of this invention for the application of *Aureobacillus yunnanensis* or a biocontrol agent in the prevention and control of bacterial wilt in plants is as follows:

[0017] Application of a type of *Aureobacillus* or biocontrol agent in the control of bacterial wilt in plants.

[0018] The beneficial effects of the above technical solution are as follows: Firstly, through a plate confrontation method screening experiment, this invention found that *Rhizobium chrysogenum* X201 exhibits an inhibition zone diameter of 31.77 mm against the pathogen of tobacco bacterial wilt, indicating that this bacterium has a good inhibitory effect on *Rhizobium chrysogenum*. Furthermore, through tobacco bacterial wilt inhibition experiments, it was demonstrated that the bacterial suspension of *Rhizobium chrysogenum* X201 can effectively reduce the incidence of tobacco bacterial wilt. This invention provides a new microbial resource for the prevention and control of plant bacterial wilt, laying the foundation for further improving the biological control of plant bacterial wilt.

[0019] As a further improvement, the plants were treated with a solution of Aureobacillus oryzae for root irrigation.

[0020] As a further improvement, the amount of *Aureobacillus* bacterial solution per plant is 10–15 mL.

[0021] As a further improvement, the OD of the *Cyclocarya paliurus* bacterial solution... 600 The value is not less than 0.5.

[0022] As a further improvement, the plant is tobacco.

[0023] To achieve the above objectives, the technical solution of this invention for the application of *Ralstonia solanacearum* in the preparation of *Ralstonia solanacearum* inhibitor is as follows:

[0024] Application of a type of *Ralstonia solanacearum* in the preparation of an inhibitor of *Ralstonia solanacearum*.

[0025] The beneficial effects of the above technical solution are as follows: the experimental results of the present invention fully demonstrate that *Rhizobium chrysogenum* X201 can effectively inhibit *Rhizobium bacillus*, providing a new microbial resource for *Rhizobium bacillus* inhibitors. Attached Figure Description

[0026] Figure 1 This is a graph showing the plate confrontation experiment results of antagonistic bacteria X201 in Example 1 of the present invention;

[0027] Figure 2 This is a colony morphology diagram of the antagonistic bacterium X201 in Example 2 of the present invention;

[0028] Figure 3 This is the phylogenetic tree constructed based on the 16S rRNA gene sequence of strain X201 in Example 2 of the present invention;

[0029] Figure 4 This is a statistical analysis of the control effect and incidence rate of tobacco bacterial wilt by the fermentation broth of strain X201 in Example 3 of the present invention;

[0030] Figure 5 This refers to the genomic information of strain X201 in Example 4 of the present invention;

[0031] Figure 6 The results show the predicted secondary metabolites of strain X201 in Example 4 of this invention. Detailed Implementation

[0032] Ralstonia solanacearum lives in the soil and invades plant roots through wounds, root tips, or secondary roots, then migrates to the stems and leaves. During its migration, Ralstonia solanacearum overcomes multiple barriers to penetrate the plant interior. The rhizosphere microbial community is the first line of defense against pathogen invasion. Therefore, most current research is limited to the isolation and screening of rhizosphere microorganisms. The root surface is in closest contact with the plant root system and is the site of most direct interaction between plants and microorganisms. When plants secrete metabolites into the environment, they first affect the species composition and function of microorganisms on the root surface. Therefore, it is easier to screen for microorganisms with specific functions from the root surface. Based on previous data analysis, this invention learned that the structure and function of the microbial community on the tobacco root surface are most affected by Ralstonia solanacearum. A strain of *Chryseobacterium wanjuense* X201 with good inhibitory ability against Ralstonia solanacearum was isolated from the root surface soil of tobacco plants.

[0033] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto; unless otherwise specified, all reagents, instruments and other items used in the embodiments are commercially available products.

[0034] The culture medium and reagent components involved in the following embodiments of the present invention:

[0035] NA liquid culture medium: glucose 2.5 g / L, beef extract 3.0 g / L, peptone 5.0 g / L, add 1000 mL of distilled water, natural pH, autoclave at 115℃ for 30 min.

[0036] NA solid medium: glucose 2.5 g / L, beef extract 3.0 g / L, peptone 5.0 g / L, agar 18.0 g / L, add 1000 mL of distilled water, natural pH, autoclave at 115℃ for 30 min.

[0037] TSB liquid medium: 15 g / L tryptone, 5 g / L soybean peptone, 5 g / L NaCl, add 1000 mL distilled water, pH 7.0, autoclave at 115℃ for 30 min.

[0038] TSB solid medium: 15 g / L tryptone, 5 g / L soybean peptone, 5 g / L NaCl, 20 g / L agar, 1000 mL distilled water added, pH 7.0, autoclaved at 115°C for 30 min.

[0039] Specific embodiments of the present invention regarding a *Ralstonia solanacearum* antagonistic to *Ralstonia solanacearum*, a biocontrol agent, and their application:

[0040] The *Chryseobacterium* strain of this invention is named X201, taxonomically *Chryseobacterium wanjuense*, and was deposited on January 8, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC NO. 29539. Furthermore, this invention demonstrates through inhibition zone experiments that *Chryseobacterium* X201 possesses excellent inhibitory ability against *Ralstonia solanacearum*; simultaneously, experiments on the prevention and control of tobacco bacterial wilt demonstrate that *Chryseobacterium* X201 can effectively prevent tobacco bacterial wilt. The specific implementation steps are as follows:

[0041] Example 1: Isolation and Screening of Antagonistic Bacteria

[0042] In this embodiment, an antagonistic bacterium with good inhibitory ability against Ralstonia solanacearum was isolated from the root topsoil of tobacco. The specific implementation operation is as follows:

[0043] 1. Sample collection and strain isolation

[0044] Sample Collection and Root Topsoil Acquisition: The experimental site was Fuquan City, Guizhou Province. The experimental tobacco variety was Yunyan 87. Samples were collected at maturity. Samples were divided into healthy samples (plants with good growth and well-developed root systems) and samples infected with bacterial wilt (plants with withered leaves and blackened xylem in the roots and stems). Using a five-point sampling method, six healthy and six infected plants were randomly selected. The plants were uprooted, and the loose soil adhering to the root surface, as well as stones and clods between the roots, were gently shaken to remove them. The soil on the root surface was then brushed off with a sterile brush (this sample is the rhizosphere soil). The root samples were then placed in a 50mL sterile centrifuge tube, and 10mL of sterile 1×PBS buffer was added. The tubes were shaken for 10 minutes, and the liquid was collected into a new 50mL centrifuge tube. This process was repeated twice, collecting all the liquid into a single centrifuge tube. After centrifugation at 12000rpm / min for 10 minutes, the supernatant was discarded, and the resulting soil precipitate was the root topsoil.

[0045] Strain Isolation: Weigh 5g of each of six parallel tobacco root topsoil samples, mix thoroughly, then weigh 5g of tobacco root topsoil from the mixed sample and add it to an Erlenmeyer flask at a ratio of 5g sample to 90mL of sterile water. Place the flask on a 28℃ constant temperature shaker at 180r / min for 20-30min. Dilute the soil suspension to 10... -2 10 -3 10 -4 10 -5 10 -6 For different gradients, take 100 μL of soil solution with appropriate dilution and place it in TSB solid culture medium, then spread it evenly (in this example, 10 μL of soil solution was selected). -4 10 -5 10-6 (Three gradients were applied). The culture was incubated at 28℃ for 24 hours, and single colonies were picked. The obtained strains were purified using the parallel streak method until single colonies were obtained. The strains were then numbered and stored at 4℃ for later use.

[0046] 2. Screening of antagonistic bacteria

[0047] Antagonistic bacteria were initially screened using the plate confrontation method. The preserved strains were inoculated into TSB liquid medium and cultured at 28°C and 200 rpm for 24 h on a shaker. Ralstonia solanacearum (Rs) stored at -80°C were inoculated into NA liquid medium and cultured overnight at 30°C and 200 rpm on a shaker. The activated Rs. solanacearum was then cultured at a ratio of Rs. solanacearum suspension to medium of 1:600 ​​(30 mL medium to 50 μL bacterial suspension, viable count 2.0 × 10⁻⁶). 8 Add the culture medium (cfu / mL) to NA solid medium at approximately 45°C (the temperature should not be too high, otherwise the bacteria will be easily killed; nor should it be too low, to prevent the generation of a large number of air bubbles during mixing). Mix well and pour into plates. After the plates solidify, use an 8mm diameter punch to make a hole in the center of the plate. Use sterile forceps or a toothpick to remove any remaining culture medium from the hole. Add the bacterial suspension of the test strain (viable count 1.0 × 10⁻⁶) to the plate. 8 Add 100-120 μL of cfu / mL to the central well (ensuring no overflow of sterile solution), incubate at 28℃ for 24 h, observe for the formation of inhibition zones, and measure the diameter of inhibition.

[0048] 3. Analysis of the antibacterial effect of antagonistic bacteria

[0049] The strain with the best antibacterial effect was selected, strain numbered X201, and its plate confrontation test results are shown below. Figure 1 The width and diameter of the inhibition zone were statistically analyzed (Table 1). The results showed that the width of the inhibition zone of X201 reached 11.89±0.78mm and the diameter of the inhibition zone reached 31.77±1.56mm.

[0050] Table 1 Results of inhibition zone determination

[0051]

[0052] Example 2: Morphological observation and molecular biological identification of antagonistic bacteria X201

[0053] This embodiment utilizes morphological and molecular biological methods to identify the antagonistic bacterium X201 screened in Example 1. The specific implementation steps are as follows:

[0054] 1. Colony characteristics and cell morphology

[0055] The colony and cell characteristics of the antagonistic bacterium X201 are as follows: After culturing on TSB medium for 24 hours, the colonies are round, with neat edges, opaque, yellow on the front, raised in the middle, smooth, moist, and easily picked up. Figure 2 ).

[0056] 2. Molecular biological identification

[0057] 16S rDNA assay and analysis of antagonistic bacteria X201: Antagonistic bacteria X201 were streaked on TSB plates, and single colonies were picked from the plates and activated in TSB liquid medium. The colonies were incubated at 28°C and 200 rpm for 24 h until the logarithmic growth phase, and the bacterial cells were collected. Bacterial DNA was extracted using a bacterial genomic DNA extraction kit. PCR amplification was performed using universal primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3', SEQ ID No. 1) and 1492R (5'-TACGGCTACCTTGTTACCACTT-3', SEQ ID No. 2).

[0058] The amplification reaction system was 50 μL: 2 μL each of primers 27F and 1492R, 2 μL of DNA template, 25 μL of 2×TransTaq HiFiPCR SuperMixⅡ, and 19 μL of ddH2O.

[0059] The reaction program was as follows: 95℃ for 2 min; 95℃ for 30 s, 55℃ for 30 s, 72℃ for 90 s, 30 cycles; 72℃ for 10 min.

[0060] PCR amplification products were detected by 1% agarose gel electrophoresis and then sent to Beijing Liuhe BGI Genomics Co., Ltd. for 16S rDNA gene sequence analysis. The sequencing results are shown in SEQ ID NO.3 of the nucleotide sequence listing. The sequencing results were compared with the sequences in the GeneBank database, and a phylogenetic tree was constructed using MEGA 6.0 software (see...). Figure 3 Based on the above identification results, the antagonistic bacterium strain X201 belongs to Chryseobacterium wanjuense and was deposited on January 8, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with the accession number CGMCC NO.29539.

[0061] Example 3: Control effect of Chlorella vulgaris X201 on tobacco bacterial wilt

[0062] In this embodiment, the *Chlorella X201* identified in Example 2 was cultured to OD200. 600The concentration was set at 0.5, and the bacterial solution was used as a biocontrol agent to explore its control effect on tobacco bacterial wilt. The specific implementation procedure is as follows:

[0063] 1. Preparation of biocontrol agents

[0064] The X201 strain, stored at -80℃, was transferred to a sterile test tube containing 5 mL of TSB liquid medium and incubated at 28℃ and 200 rpm for 12 h to activate it. Then, it was inoculated into 100 mL of liquid medium at a 1% inoculum rate and incubated at 28℃ and 200 rpm until OD reached [value missing]. 600 =0.5, reserved.

[0065] 2. Greenhouse pest control effect

[0066] Tobacco (Red Flower Dajinyuan) seeds were sown in seedling trays filled with a mixture of nutrient soil and vermiculite. Once the seedlings reached the small cross stage (two true leaves and two cotyledons), they were transplanted into 10×9 seedling trays filled with the same nutrient soil and vermiculite mixture. One seedling was transplanted per tray, and the seedlings were divided into four groups: CK (sterile water treatment), X201 (X201 inoculant only), Rs (Ralstonia solanacearum inoculation only), and X201+Rs (X201 inoculant followed by Ralstonia solanacearum inoculation). Each treatment had three replicates, with 15 seedlings per replicate. After 10 days of cultivation in a greenhouse, the plants in the X201 and X201+Rs treatment groups were inoculated with 10 mL of X201 inoculant by drenching the roots of each plant. Continue culturing for 10 days, and then inoculate the plants in the X201 and X201+Rs groups again using the same method. Four days later, inoculate the plants in the Rs and X201+Rs groups with Ralstonia solanacearum, adding 5 mL of OD400 solution. 600 A 0.5% solution of Ralstonia solanacearum suspension was used to drench the roots of each plant. After the plants in group Rs showed disease characteristics, photographs were taken, and plant height, fresh weight, root weight, and root length were measured and statistically analyzed. The incidence of bacterial wilt was then monitored daily, and the disease incidence rate was calculated after 15 days.

[0067] Incidence rate (%) = Number of infected plants / Total number of plants surveyed × 100%;

[0068] Prevention and control effect = (control incidence rate - treatment incidence rate) / control incidence rate × 100%.

[0069] Fifteen days after inoculation, the incidence of tobacco disease in the Rs treatment group was 84.62%, while the incidence of bacterial wilt in the X201+Rs treatment group was 13.08%, indicating that the application of X201 inoculant significantly reduced the incidence of tobacco disease, with a relative control effect of 84.54% (Table 2). The growth status of tobacco plants in each treatment group is as follows: Figure 4As shown, in the uninoculated Ralstonia solanacearum treatments (CK and X201), compared with the blank control, the application of X201 significantly increased the height of tobacco plants, but had no significant effect on plant fresh weight, root length, and root weight. In the Ralstonia solanacearum treatments (Rs and X201+Rs), the application of X201 significantly enhanced the plant's resistance to Ralstonia solanacearum. The height, fresh weight, root length, and root weight of tobacco plants after the application of X201 significantly increased by 4.25, 10.48, 1.40, and 2.55 times, respectively (Table 3).

[0070] Table 2. Control efficacy of Chlorella vulgaris X201 against tobacco bacterial wilt.

[0071]

[0072] Table 3 Effects of Chlorella X201 on tobacco growth

[0073]

[0074] Example 4: Genomic information and secondary metabolite prediction of Chlorella X201

[0075] This embodiment performs whole-genome analysis and predicts secondary metabolites of Chlorella X201. The specific implementation steps are as follows:

[0076] 1. Whole genome sequencing and analysis

[0077] Strain X201 was inoculated into TSB liquid medium and cultured at 28°C and 200 rpm in a constant temperature shaker until OD600 = 0.6. After centrifugation at 4°C and 3900 rpm for 15 min, the supernatant was discarded, and the precipitate was washed 2–3 times with sterile water before whole-genome sequencing. The protein sequences of the predicted genes were compared with various functional databases using Diamond alignment (evalue ≤ 1 e). -5 For each sequence alignment result, the one with the highest score (default identity≥40%, coverage≥40%) is selected for annotation.

[0078] The genome diagram of strain X201 is as follows Figure 5 As shown, sequence assembly alignment and annotation analysis revealed that the X201 genome consists of one chromosome with a size of 4,664,037 bp, a GC content of 35.91%, 4,471 genes, a total length of 4,055,724 bp, an average length of 907 bp, and accounts for 86.96% of the genome. 4,154 protein-coding regions were predicted, with 3,845 annotated genes.

[0079] 2. Prediction of secondary metabolites

[0080] The anti-SMASH (https: / / antismash.secondarymetabolites.org / ) online software was used to analyze the secondary metabolite synthesis gene clusters of the strain genome to predict potential antimicrobial substances.

[0081] The predicted results of secondary metabolites of strain X201 are as follows: Figure 6 As shown, this strain possesses 12 secondary metabolite synthesis clusters, but only 3 are similar to gene clusters of known antimicrobial substances. Of the 12 predicted potential antimicrobial substance gene clusters, 6 (Clusters 2, 3, 5, 8, 11, 12) belong to terpenoids. Among the 3 gene clusters similar to known antimicrobial substances, the antimicrobial active substances in Clusters 1 and 2 are 5-(S-glutathioneyl)-2-tert-butylhydroquinone (methylpendolmycin) and carotenoid, respectively, with a similarity of only 28%, indicating low reference value. The antimicrobial active substance in Cluster 7 shows an 80% similarity to the known antimicrobial substance (flexirubin), suggesting that this gene cluster may produce compounds similar to this substance. Related studies have demonstrated that flexirubin has good antimicrobial activity, and we speculate that the flexirubin analogues produced by this strain may have similar functions. In addition, the genome of this bacterium contains a large number (9) of unknown secondary metabolite synthesis gene clusters, which may synthesize some new substances to inhibit bacteria or fungi.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of *Ralstonia solanacearum* antagonistic to *Ralstonia solanacearum*, characterized in that: The taxonomic name of the *Chryseobacterium wanjuense* is *Chryseobacterium wanjuense*, and its culture preservation number is CGMCC NO.29539.

2. A biocontrol agent antagonizing Ralstonia solanacearum, characterized in that: The biocontrol agent includes *Aureobacterium chrysogenum* and / or *Aureobacterium chrysogenum* bacterial solution as described in claim 1.

3. The application of the *Aureobacillus* as described in claim 1 or the biocontrol agent as described in claim 2 in the control of bacterial wilt of plants.

4. The application of *Aureobacillus yunnanensis* or biocontrol agents according to claim 3 in the control of bacterial wilt of plants, characterized in that: The roots of the plants were treated with a solution of Aureobacillus oryzae.

5. The application of *Aureobacillus yunnanensis* or biocontrol agents according to claim 4 in the control of bacterial wilt of plants, characterized in that: The amount of *Aureobacillus* bacterial solution corresponding to each plant is 10–15 mL.

6. The application of *Aureobacillus yunnanensis* or biocontrol agents according to claim 5 in the control of bacterial wilt of plants, characterized in that: The OD of the *Cyclocarya paliurus* bacterial solution 600 The value is not less than 0.

5.

7. The application of *Aureobacillus yunnanensis* or its biocontrol agent according to any one of claims 3 to 6 in the control of bacterial wilt of plants, characterized in that: The plant in question is tobacco.

8. The use of *Rhizobium chrysogenum* as described in claim 1 in the preparation of *Rhizobium blight* inhibitor.

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