CN112322561A

CN112322561A - Klebsiella and application thereof in prevention and control of fruit tree pear fire blight

Info

Publication number: CN112322561A
Application number: CN202011532729.5A
Authority: CN
Inventors: 罗明; 韩剑; 郁帆; 贺旭; 盛强; 古丽孜热; 包慧芳; 黄伟; 朱小琼
Original assignee: Xinjiang Agricultural University
Current assignee: Xinjiang Agricultural University
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2021-02-05
Anticipated expiration: 2040-12-23
Also published as: CN112322561B

Abstract

The invention discloses a Klebsiella strain and its application in the control of fruit tree pear fire blight, belonging to the technical field of plant disease biological control. From the endophytic bacteria isolated from healthy Korla fragrant pear branches, a TN50 strain with strong competition and significant inhibitory effect on the growth of Erwinia amylovor was identified as Klebsiella ( Klebsiella sp.), deposited in the General Microbiology Center of China Microorganism Culture Collection Management Committee, the preservation date is November 18, 2020, and the preservation number is CGMCC No.21204. The fermentation broth of Klebsiella TN50 strain and the active metabolites in the fermentation broth of the present invention have good preventive and therapeutic effects on fire blight of pome fruit trees such as Rosaceae pears, apples, hawthorns, etc. It is a biocontrol potential strain with high control efficiency, good environmental safety and development and application prospects.

Description

Klebsiella and application thereof in prevention and control of fruit tree pear fire blight

Technical Field

The invention belongs to the technical field of biological control of plant diseases, and particularly relates to Klebsiella and application thereof in biological control of fruit tree pear fire blight.

Background

The pear fire blight is caused by Erwinia amylovora (A)Erwinia amylovor) The most destructive bacterial diseases caused by infecting various rosaceous plants are a class of crop diseases and agricultural plant quarantine harmful organisms in China. The disease has wide host range, and can harm more than 220 plants of more than 40 genus of Rosaceae, wherein the most serious disease is kernel fruit tree such as fructus Pyri, fructus Mali Pumilae, fructus crataegi and fructus Mali Pumilae. Pathogenic bacteria invade flowers, leaves, young tips, young fruits, branches and trunks to cause withering of flower devices, the leaves cannot wither like being burnt, the young tips die into shepherd whips, the fruits are rotten and black and shrink, the expanding speed is very high when the diseases are serious, the diseased young organs can be expanded to main branches and trunks within a few weeks, the whole plant dies until the roots, and the whole orchard can be destroyed within one to several growing seasons to cause serious economic loss.

Pear fire blight was first discovered in New York, U.S. in 1780 and has spread to nearly 60 countries and regions of the world. In the last decade, the discovery and occurrence of the pear fire blight have been reported in Japan, Korea, Russia, Hassakestan, Gilg-Gerstein, Russia and other countries around China. With the continuous acceleration of global economic integration, the development of new industries such as central European banning, cross-border electronic commerce (Internet +) and the like, the introduction of forest fruit varieties, the allocation and transportation of seedlings and the increase of imported fruit trades, the risk of spreading the pear fire blight is increased, great hidden dangers are brought to the safety production of the forest fruit industry, and the forest fruit industry is worthy of paying high attention and taking preventive measures as soon as possible.

The foreign control technology for the pear fire blight comprises the measures of quarantine, pruning and eradicating diseased plants, medicament control, biological control, breeding disease resistance variety and the like. However, the current production lacks of fruit tree varieties resisting the pear fire blight, the disease control difficulty is high, no special-effect medicament or single control measure exists, the control is not well achieved so far, and the safe and effective control is still a worldwide problem. The agricultural streptomycin spray is used in the early 70 s, the flower organ is effectively protected from infection, but the long-term and large-scale use of the agricultural streptomycin has led to the generation of drug resistance. At present, agricultural streptomycin stops being produced and exits the pesticide market, and no alternative medicament with a considerable control effect exists. In recent years, with the intensive study on the microecology and the infection biology of the pear fire blight pathogenic bacteria, the application of biological control is promoted. Pseudomonas fluorescens developed in the United states (Pseudomonas fluorescens) The A506 commercial microbial inoculum is practically applied, so that the morbidity of the floral organ of the pear fire blight is averagely reduced by 40-60 percent, and the control effect of the agricultural streptomycin is achieved, or the control effect is equivalent to that of other chemical agents. Another biological control agentErwinia herbicolaC9-1 is also approved by the United states environmental protection agency and used in production, so that a good disease prevention effect is achieved. Therefore, the antagonistic strain with remarkable bacteriostatic effect is screened out, the biological agent is developed by using the living body and the active substances thereof to prevent and treat the pear fire blight, and the method has the outstanding advantages of strong selectivity, difficulty in generating drug resistance, safety, high efficiency, environmental friendliness and the like, and has a good application prospect. At present, no report is found on the biological control research of the pear fire blight at home.

Disclosure of Invention

Aiming at the technical problems of the existing control of the fire blight of pears, the invention provides a high-efficiency antagonistic strain Klebsiella (Klebsiella pneumoniae) separated and screened from endophytic bacteria of healthy bergamot plants in bergamot orchard in Kurler city in XinjiangKlebsiellasp.) TN50, and the strain and the metabolite thereof are utilized to carry out safe, effective and environment-friendly biological control on the pear fire blight.

The invention provides a strain of Klebsiella (Klebsiella)Klebsiellasp.) TN50 strain. The strain has been deposited in the Budapest treaty International Collection of microorganisms: china general microbiological culture Collection center (CGMCC for short). And (4) storage address: the institute of microbiology, national academy of sciences No. 3, Xilu No. 1, Beijing, Chaoyang, Beijing. The preservation date is 11 months and 18 days in 2020, and the preservation number is CGMCC No. 21204.

Klebsiella bacterium (B) of the present inventionKlebsiellasp.) TN50 or the filtrate thereof in biological control of fruit tree pear fire blight.

The application of the invention is preferably to the Klebsiella pneumoniaeKlebsiellasp.) TN50 to obtain strain fermentation culture solution or filtrate of the fermentation culture solution; the obtained strain fermentation culture solution, the filtrate of the fermentation culture solution or the combination of any one or more of the fermentation solution freeze-drying or spray-drying powder is applied to the biological control of the pear fire blight.

Klebsiella bacterium (B) of the present inventionKlebsiellasp.) TN50 or the filtrate thereof in preventing and treating pear fire blight of fruit trees, wherein the fruit trees include Rosaceae pome fruit trees such as pear tree, apple, hawthorn, and crabapple, preferably pear tree.

Klebsiella bacterium (B) of the present inventionKlebsiellasp.) TN50 or the filtrate thereof in preventing and treating pear fire blight, wherein the application method comprises spraying the fermentation culture solution or the filtrate thereof to inflorescence, branch, leaf and stem of fruit tree or irrigating root through the fermentation culture solution or the filtrate thereof to prevent and treat pear fire blight.

The invention has the beneficial effects that: the Klebsiella TN50 strain separated and screened from the bergamot pear branches of the invention is used for treating erwinia amylovora of pathogenic bacteria of erwinia amylovoraErwinia amylovora)Has strong competitive action and obvious antagonistic action, has good control effect on the fire blight of rosa-kernel fruit trees, especially pears, apples, hawthorns, crabapples and the like, and has control effect on streptomycesThe elements are equivalent. The invention has obvious disease prevention effect, no pollution to the environment, simple fermentation process for large-scale production and low production cost, is beneficial to the production of green and pollution-free fruits and the ecological environment protection of orchards, is a biocontrol strain with good application prospect, and can be used for preparing a functional biocontrol microbial inoculum for preventing and treating the pear fire blight.

Drawings

FIG. 1 shows that Klebsiella TN50 competes with the erwinia amylovora on the plate medium for growth.

FIG. 2 is a graph showing the effect of Klebsiella TN50 fermentation filtrate on the inhibition of erwinia amylovora.

FIG. 3 shows the colony morphology of Klebsiella TN50 on NA medium.

FIG. 4 shows the morphology of cells of Klebsiella TN50 after gram-staining under a light microscope.

FIG. 5 shows a phylogenetic tree of Klebsiella TN50 constructed based on the 16S rDNA gene.

FIG. 6 shows the effect of applying Klebsiella TN50 fermentation broth to the in vitro floral sequences of pear to prevent the floral rot of pear fire blight. Wherein panel a is a healthy bergamot inflorescence; FIG. B shows the disease condition of 3 days after TN50 fermentation broth is sprayed on the inflorescence of pear and then the pear fire blight bacterial suspension is inoculated; and the picture C shows the disease condition after 3 days of spraying sterile water on the pear inflorescence and then inoculating the pear fire blight bacterium suspension.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are commercially available products.

The media used in the following examples are specifically as follows:

NA medium: 3.0 g/L of beef extract powder, 10.0 g/L of peptone, 5.0 g/L of sodium chloride, 18.0 g/L of agar powder, 1000 mL of distilled water and pH 7.2.

NB medium: 3.0 g/L of beef extract powder, 10.0 g/L of peptone, 5.0 g/L of sodium chloride, 1000 mL of distilled water and pH 7.2.

Example 1 isolation, purification and screening of an endophytic antagonistic bacterium TN50 of bergamot pear

(1) Separation of fragrant pear endophytic bacteria: washing collected branches, flowers, leaves and fruits of healthy bergamot pears under tap water for 1-2 h, washing with sterile water, and weighing petals, branches (cut into small sections of 0.5-1 cm) and leaves and fruits (cut into 4 mm)²Tissue blocks) of 1 g, soaking in 75% alcohol for 1 min, soaking in 1% sodium hypochlorite for 2-5 min, and washing with sterile water for 3-5 times. And (3) respectively coating 0.l mL of the last sterile water washing liquid on an NA culture medium, placing the NA culture medium in a thermostat at 28 ℃ for culturing for 2-3 d, observing whether sterile colonies grow out, and detecting whether the surface of the sample is sterilized completely. And (3) putting the sample with the thoroughly-sterilized surface into a sterilized mortar, adding l0 mL of PBS buffer solution into each 1 g of the sample to fully grind the tissue, standing for 10 min, sucking the supernatant by using a pipette gun, adding the supernatant into test tube sterile water, and fully and uniformly mixing to prepare diluents with different dilutions. And (3) sucking 100 muL of sample diluent, injecting the sample diluent onto an NA culture medium flat plate, uniformly coating, and putting the sample diluent into a constant-temperature incubator for 28 ℃ culture for 2-3 d. Selecting single colony according to different forms, colors and sizes of the colony grown on the plate, repeatedly streaking and purifying, transferring to the slant of NA culture medium, and preserving at 4 ℃.

(2) Preparing fermentation liquor of a strain to be detected: inoculating pure culture of the strain to be tested into NB culture solution with bottling amount of 80 mL/250 mL, shaking at 28 deg.C for 24 h to OD₆₀₀And (d) = 1.0-1.2 fermentation liquor. Diluting the fermentation liquid to obtain viable bacteria with concentration of 10⁹cfu/mL of the bacterial fermentation broth.

(3) Preparing fermentation filtrate of the strain to be detected: collecting 200 mL fermentation liquor, centrifuging at 10000 r/min for 20 min at 4 ℃, collecting supernatant, filtering and sterilizing through a 0.22 mu m microporous filter membrane, and storing at 4 ℃ for later use.

(4) Preliminary screening of pear fire blight bacterium antagonistic strains: taking a pear fire blight bacterium suspension (the concentration is 10)⁷cfu/mL) 0.1 mL was plated on NA media plates. Dipping a ring of thalli on a single colony activated by the endophytic bacterial strain to be detected by using an inoculating ring, and carrying out point inoculation on 4 points at equal distance on the circumference of 2 cm of the edge of a bacterium coating plate, wherein each bacterial strain is repeated for 3 times. Culturing at 26-28 deg.C for 2-3 days to obtain crossThe size of the relative inhibition zone is measured by a cross method.

(5) Rescreening pear fire blight bacterium antagonistic strains: re-screening adopts a paper filter disc method, 0.1 mL of pear fire blight bacterium suspension is uniformly coated on an NA flat plate, 4 sterilization paper filter discs (diameter is 4 mm) are placed at equal distance positions on the circumference of 2 cm away from the edge of the bacteria coating flat plate, a liquid transfer gun is used for sucking 5 mu L of primary screening antagonistic bacterium suspension to be dripped on the paper filter discs, NB liquid culture medium with equal sterilization is added as a control, and after 2-3 d cultivation is carried out at 28 ℃, the size of a bacteriostatic circle is measured by a cross method. Each strain was replicated in 3 dishes.

(6) And (3) testing the antagonistic action of TN50 fermentation filtrate on pear fire blight bacteria: taking 0.1 mL of pear fire blight bacterium suspension to evenly spread on an NA flat plate, punching 3 round holes in the positions with equal distances on the circumference of 2 cm away from the edge of the bacterium spreading flat plate by using a puncher (with the diameter of 5 mm), sucking 100 mu L TN50 fermentation filtrate by using a liquid transfer gun, dropwise adding the fermentation filtrate into the holes, taking NB liquid culture medium with the same amount of sterilization as a control, and measuring the size of a bacteriostatic ring by using a cross method after culturing for 2-3 d at 28 ℃. Each strain was replicated in 3 dishes. And measuring the diameter of the inhibition zone, and counting the inhibition rate. Bacteriostasis rate (%) = [ (diameter of bacteriostasis zone-5 mm)/(diameter of bacteriostasis zone) ] × 100%.

Adding 100 muL of each of the erwinia amylovora bacterial suspension and TN50 fermentation filtrate into 50 mL/200 mL of bottled NB culture solution, co-culturing at 30 ℃ and 160 r/min for 24 h, measuring the viable count of pathogenic bacteria by using a dilution plate counting method by taking the culture solution only inoculated with the same amount of the erwinia amylovora bacterial suspension as a control, and counting the reduction rate of the viable count. The reduction rate of the viable count of pathogenic bacteria (%) = (viable count of pathogenic bacteria culture solution-viable count of pathogenic bacteria culture solution added with TN50 fermentation filtrate)/viable count of pathogenic bacteria culture solution x 100%.

Test results show that the TN50 strain does not generate a bacteriostatic zone on a plate culture medium, but has high growth speed and strong competitive power, and can quickly cover the erwinia amylovora bacterial colonies within 24 hours (see figure 1). The TN50 strain fermentation filtrate has obvious inhibition effect on the erwinia amylovora (see figure 2 and table 1), the diameter of an inhibition zone reaches 26.27 mm, and the inhibition rate is 80.96%; the TN50 strain fermentation filtrate and the erwinia amylovora are co-cultured, the reduction rate of the viable count of the erwinia amylovora reaches 99.99 percent (see table 2), and the antibacterial effect is strongest in the determined antagonistic strain.

TABLE 1 antagonistic action of partial antagonistic bacterial strain fermentation filtrate on erwinia amylovora

TABLE 2 reduction rate of partial antagonistic bacterial strain fermentation filtrate on viable bacteria of erwinia amylovora

Example 2 identification of TN50 Strain

Strain TN50 was streaked onto NA medium, incubated at 28 ℃ for 24 h, and its colony morphology was observed and described. Meanwhile, gram staining is carried out, and the size, the shape, the existence, the shape, the implantation position and the like of the thalli of the test strains are observed, and the physiological and biochemical processes mainly refer to a common bacteria system identification manual.

(1) Bacterial colony characteristics and thallus morphology characteristics

TN50 has the colony characteristics shown in FIG. 3, and has round shape, luster viscosity, uniform edge, opacity, light yellow color, and rod-like shape shown in FIG. 4, G^-No spores, no flagella.

(2) Physiological and biochemical property identification

The determination is carried out by referring to the method in the handbook of identifying common bacteria systems, and the test results are shown in Table 3.

TABLE 3 physiological and biochemical characteristics of TN50

(3) 16S rDNA gene sequence determination and analysis

PCR amplification is carried out by taking total DNA of TN50 strain extracted by a thermal cracking method as a template, and primers are bacterial 16S rRNA universal primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1429R (5'-CTACGGCTACCTTGTTACGA-3'). The PCR reaction system is 25 muL: 1.0 muL of DNA template, 1.0 muL of 10 mumol/L27F/1429R, 1.5 muL of 10 mmol/L dNTPs, 2.5 muL of 10 XPCR Buffer (2.5 mmol/L MgCl2), 0.5 muL of 2.5U/muL TaqDNA polymerase, and supplementing sterilized ultrapure water to 25 muL. The reaction conditions are as follows: pre-denaturation at 94 ℃ for 5 min; denaturation at 94 ℃ for 45 s, annealing at 58 ℃ for 45 s, extension at 72 ℃ for 1.5 min, and 35 cycles; extension at 72 deg.C for 7 min, and storage at 4 deg.C. After the amplification product is detected by 10 g/L agarose gel electrophoresis, the PCR product is subjected to clone sequencing by Shanghai biological engineering Co., Ltd, and the sequencing result is shown as SEQ ID No. 1.

The obtained sequence results were subjected to BLAST search at the National Center for Biotechnology Information (NCBI) of the United states, a model strain having high similarity was selected as a reference strain, and a 16S rDNA gene phylogenetic tree was constructed using the Neighbor-joining method (Neighbor-joining) in MEGA5.0 software, with a self-developed value (Bootstrap) of 1000. The results show (FIG. 5), TN50 strain and model strainKlebsiella variicolaThe strain YD8 (KY 887765.1) is positioned on the same phylogenetic branch, and the similarity reaches 99.7 percent at most. The TN50 strain is identified as the Klebsiella by integrating morphological characteristics, physiological and biochemical characteristics and the developmental analysis result of the 16S DNA systemKlebsiellasp.). The strains have been deposited in the Budapest treaty International Collection of microorganisms: china general microbiological culture Collection center (CGMCC for short). And (4) storage address: the institute of microbiology, national academy of sciences No. 3, Xilu No. 1, Beijing, Chaoyang, Beijing. The preservation date is 11 months and 18 days in 2020, and the preservation number is CGMCC No. 21204.

Example 3 in vitro inflorescence determination of Klebsiella TN50 Strain on the control Effect of Pear fire blight

Collecting flowering branches at the initial flowering stage of a bergamot pear orchard, and inserting the flowering branches into 0.05% NaCl solution for corrosion prevention and moisture preservation. Spraying TN50 fermentation liquor by using a handheld pressure sprayer to inoculate pear inflorescences, spraying bacterial liquid to each flower by about 80 mu L, inoculating 50 inflorescences, and repeating for 3 times; meanwhile, spraying 4000-fold liquid contrast of agricultural streptomycin (produced by North China pharmaceutical factory and containing 72% of active ingredients) and sterile water as blank contrast, and spraying and inoculating pathogen bacterial liquid after culturing for 24 hours in an artificial climate box with 25 ℃ and 70% air humidity, wherein each flower is about 80 mu L. And (3) placing the inoculated inflorescences in an artificial climate box for culturing at 25 ℃ and 70% air humidity, observing and recording the morbidity after 3 days, 5 days and 7 days, counting the floral rot rate, and calculating the control effect. After the test is finished, the plant materials with diseases are destroyed after being sterilized by dry heat. Flower rot rate (%) = (number of diseased flowers/total flowers) × 100%; the control effect of flower rot (%) = (control flower rot rate-treated flower rot rate)/control flower rot rate × 100%.

The results show (table 4, fig. 6), TN50 fermentation broth was sprayed on the isolated bergamot pear inflorescence, then pathogenic bacteria were inoculated, and then the flower rot rate of each treatment of 3 d, 5 d and 7 d was investigated, and the protective effect was calculated. The contrast of the TN50 fermentation liquor which is not sprayed begins to generate the flower rot symptom in the anther, stigma, honey gland, calyx, ovary, flower stalk and the like of the bergamot pear inflorescence on the 2 nd day after the pathogenic bacteria are inoculated, and the treatment of spraying the TN50 fermentation liquor can delay the time of the flower rot symptom to a certain extent, reduce the flower rot rate and realize the difference among different strains. The 7-balance control effect of TN50 reaches 52.36 percent, and is close to that of agricultural streptomycin (60.67 percent).

TABLE 4 TN50 determination of the in vitro inflorescence control effect on pear fire blight

Example 4 Du pear potting test to determine the control effect of Klebsiella TN50 strain on the fire blight of pear

(1) Protective prevention effect of TN50 on pear fire blight

The test was carried out in a laboratory climatic chamber with potted 2-year old birch seedlings as the inoculation material. Spray TN50 fermentation broth with hand-held pressure sprayer until leaves and branches are completely wet, spray 5 pots (about 25 branches) per strain, repeat 3 times. Meanwhile, 4000 times of liquid for spraying agricultural streptomycin (produced by North China pharmaceutical factory, 72% of effective component) is used as a contrast, and sterile water spraying is used as a blank contrast. And (3) culturing the inoculated birch pear seedlings in an artificial climate box with the temperature of 28.5 ℃, the relative humidity of 75% and the illumination of 12 h. And spraying to inoculate pathogen bacteria liquid after 72 h, and continuously culturing in an artificial climate box. Observing the disease condition every day, recording the number of diseased branches, measuring the length of the branch withers, the proportion of the length of the branch withers to the length of the inoculated branches and the disease grade. And calculating the morbidity and disease index according to the statistical result, and counting the prevention effect. After the test is finished, the plant materials with diseases are destroyed after being sterilized by dry heat.

(2) Therapeutic control effect of TN50 on pear fire blight

Therapeutic test the inoculation sequence of pathogenic bacteria and antagonistic bacteria is opposite to that of protective test, i.e. spraying inoculation pathogenic bacteria liquid for 72 h on the birch seedling, then spraying TN50 fermentation liquid, and other test materials, culture conditions, and prevention effect investigation method are all consistent with the protective test.

Referring to the method of Paprstein et al and improving, the disease classification standard of the in vitro branch inoculated by the pathogenic bacteria of the erwinia amylovora is established: grade 0, the branch has no disease spots; the length of the lesion of the branch accounts for 1% -5% of the length of the inoculated branch in the level I; grade III, the length of the lesion of the branch accounts for 6% -15% of the length of the inoculated branch; grade V, the length of the lesion of the branch accounts for 16% -30% of the length of the inoculated branch; in the VII level, the length of the lesion of the branch accounts for 31% -50% of the length of the inoculated branch; and the length of the disease spots of the branch accounts for more than 51 percent of the length of the inoculated branch at IX level. And dividing pathogenicity of pathogenic bacteria according to disease indexes of the same time after the isolated branches are inoculated.

Incidence (%) = (number of diseased branches/number of total inoculated branches) × 100%; disease index = (number of diseased branches at each stage × disease-level representative value)/(number of inoculated total branches × highest-level value) × 100; the control effect of the paraquat (%) = (control disease index-treatment disease index)/control disease index is multiplied by 100%.

The protective test results (see table 5) show that the pre-spraying of TN50 on the birch pear seedlings can obviously reduce the branch withering rate and the disease index (P is less than 0.05), and the average protective control effect of 7-15 d is 67.22%. Wherein the control effect is the highest at 10 d (71.33%), and the control effect is still stable at 67.03% at 15 d.

The results of the therapeutic tests show that (see table 6), the spraying of TN50 has obvious therapeutic effect on the paraquat of the birch pear seedlings. The control effect of the TN50 strain with the best control effect is maintained to be more than 65% at 7 d and 10 d, and the average treatment control effect of 7-15 d is 63.88%.

TABLE 5 TN50 protective control of pyretic blight of birch pear

TABLE 6 TN50 therapeutic control of pyretic blight of pyrus betulaefolia

Sequence listing

<110> Sinkiang university of agriculture

<120> Klebsiella and application thereof in prevention and control of fruit tree pear fire blight

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<213> Klebsiella sp (Klebsiella sp.)

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ctggggcggc tacacatgca gtcgagcggt agcacagaga gcttgctctc gggtgacgag 60

cggcggacgg gtgagtaatg tctgggaaac tgcctgatgg agggggataa ctactggaaa 120

cggtagctaa taccgcataa cgtcgcaaga ccaaagtggg ggaccttcgg gcctcatgcc 180

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cgatttggag gttgtgccct tgaggcgtgg cttccggagc taacgcgtta aatcgaccgc 840

ctggggagta cggccgcaag gttaaaactc aaatgaattg acgggggccc gcacaagcgg 900

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Claims

1. The Klebsiella strain is characterized in that the preservation name of the strain is Klebsiella ((Klebsiella) (Klebsiella pneumoniae)) and the application of the Klebsiella strain in preventing and controlling fruit tree pear fire blightKlebsiellasp.) TN50, which has been deposited in China general microbiological culture Collection center (CGMCC), with the deposition address being Beijing CityThe microbial research institute of national academy of sciences No. 3 of Xilu No. 1 of Yang district, the preservation date is 11 months and 18 days in 2020, and the preservation number is CGMCC No. 21204.

2. The application of the fermentation culture solution or the filtrate of the fermentation culture solution of the Klebsiella TN50 according to claim 1 in biological control of fruit tree pear fire blight.

3. The use according to claim 2, wherein the Klebsiella strain TN50 is preferably cultured to obtain a fermentation culture solution of the strain or a filtrate of the fermentation culture solution; the obtained strain fermentation culture solution, the filtrate of the fermentation culture solution or the combination of any one or more of the fermentation solution freeze-drying or spray-drying powder is applied to the biological control of the pear fire blight.

4. The application of the fermentation culture solution or the filtrate of the fermentation culture solution of the klebsiella TN50 in the control of the pear fire blight of fruit trees according to claim 2, wherein the fruit trees include pome fruit trees such as pear trees, apples, hawthorns, and Chinese flowering apple trees, and preferably the pear trees.

5. The application of the fermentation culture solution or the filtrate of the fermentation culture solution of the klebsiella pneumoniae TN50 in preventing and treating the pear fire blight of the fruit trees according to claim 2, wherein the application method comprises the steps of spraying the fermentation culture solution or the filtrate of the fermentation culture solution to inflorescences, branches, leaves and stems of the fruit trees or irrigating roots of the fermentation culture solution or the filtrate of the fermentation culture solution to prevent and treat the pear fire blight.