An erwinia amylovora bacteriophage pEa_SHZU_4 and application thereof

Abstract

The application discloses an erwinia amylovora bacteriophage pEa_SHZU_4 and application thereof, and belongs to the technical field of bacteriophages. The erwinia amylovora bacteriophage pEa_SHZU_4 is preserved in the China Center for Type Culture Collection on April 22, 2026, the preservation address is Wuhan University, Wuhan, China, and the preservation number is CCTCC NO: M 2026758. The application discloses an erwinia amylovora bacteriophage pEa_SHZU_4 and application thereof, the bacteriophage pEa_SHZU_4 can efficiently and specifically lyse erwinia amylovora and drug-resistant strains thereof, the genome of the bacteriophage pEa_SHZU_4 does not carry virulence genes and drug resistance genes, and the bacteriophage pEa_SHZU_4 has good environmental adaptability.

Description

Technical Field

[0001] This invention relates to the field of bacteriophage technology, and in particular to an Erwinia amyloliquefaciens bacteriophage pEa_SHZU_4 and its applications. Background Technology

[0002] Fire blight is caused by Erwinia amyloliquefaciens (… Erwinia amylovora Fire blight is a serious bacterial disease that primarily affects Rosaceae fruit trees such as pears, apples, and hawthorns. The pathogen invades the host through flowers, young shoots, and wounds, proliferating rapidly within plant tissues and blocking the vascular system, leading to vascular necrosis, blackening and death of leaves and fruits. Typical symptoms include flower rot, branch dieback, and cankers; in severe cases, it can cause the death of the entire plant. Since its first report in the Ili region of Xinjiang Uygur Autonomous Region in 2015, the disease has rapidly spread to multiple prefectures and cities in Xinjiang and Gansu Province, with the Korla fragrant pear production area being particularly affected, posing a significant economic loss and a persistent threat to the local pear industry. Currently, conventional control methods for fire blight mainly rely on physical pruning to remove diseased branches and the application of antibiotics and copper-containing chemical pesticides to prevent new infections. However, with the long-term use of chemical agents, the continuous emergence of antibiotic-resistant strains, and the food safety and environmental pollution risks posed by copper-containing pesticides, traditional control strategies face significant bottlenecks. Given this, phage-based biocontrol strategies, due to their safety and environmental friendliness, are gradually becoming a new option for green fire disease control.

[0003] Bacteriophages, as the most abundant viruses in nature capable of specifically infecting bacteria, have shown great potential in the control of agricultural diseases. Based on their replication strategies, bacteriophages can be divided into virulent and mild types, with current biotherapy primarily favoring virulent phages. Virulent phages, in the later stages of host infection, specifically degrade bacterial cell walls by encoding cell wall-lysing enzymes or cell-lysing enzymes, thereby efficiently lysing pathogens. Because their bactericidal mechanism is distinctly different from traditional antibiotics, phages are equally effective against drug-resistant strains; simultaneously, they have a narrow host range and high specificity, with no significant negative impact on normal microbial communities in the environment. Although single phages exhibit good antibacterial effects under laboratory conditions, in actual field applications, single phage preparations often face the problem of rapid resistance mutations in host bacteria, leading to a significant decline in control efficacy in the short term. To overcome this limitation, the development of highly efficient phage cocktail combinations has become a current research hotspot. Studies have shown that combining multiple phages to construct cocktails can not only effectively reduce the rate at which host bacteria develop resistance to phages but also expand the host range, thereby better inhibiting the growth and spread of pathogens. Currently, the types and quantities of highly lytic Erwinia amyloliquefaciens bacteriophages are relatively scarce, making it difficult to meet the diversified control needs in the field. Summary of the Invention

[0004] The purpose of this invention is to provide an Erwinia amyloliquefaciens phage pEa_SHZU_4 and its applications. This phage pEa_SHZU_4 can efficiently and specifically lyse Erwinia amyloliquefaciens and its drug-resistant strains, and its genome does not carry virulence genes or drug resistance genes, and it has good environmental adaptability.

[0005] To achieve the above objectives, the present invention provides the following solution: A type of Erwinia amylolytica phage ( Erwinia phage pEa_SHZU_4, the Erwinia phage pEa_SHZU_4, was deposited on April 22, 2026 at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026758.

[0006] Preferably, Erwinia amyloliquefaciens Ea102 and / or Ea915 is used as the host bacteria.

[0007] The present invention also provides an Erwinia amyloliquefaciens phage preparation, which is prepared using the Erwinia amyloliquefaciens phage pEa_SHZU_4.

[0008] Preferably, the dosage form includes powder, solution, granules, gel, or lyophilized agent.

[0009] This invention also provides the application of the aforementioned Erwinia amyloliquefaciens phage pEa_SHZU_4 or the aforementioned Erwinia amyloliquefaciens phage preparation in the prevention and control of fire blight.

[0010] Preferably, the fire blight is a fire blight disease of Rosaceae fruit trees caused by Erwinia amyloliquefaciens.

[0011] The present invention also provides a biocontrol phage composition for treating fire-related diseases, the biocontrol phage composition comprising the aforementioned Erwinia amyloliquefaciens phage pEa_SHZU_4, and one or two of the following: Erwinia amyloliquefaciens-specific phage, antagonistic bacteria, and antibiotics.

[0012] Preferably, the titer of the Erwinia amyloliquefaciens phage pEa_SHZU_4 is not less than 10. 3 PFU / mL(g).

[0013] The present invention also provides the application of the described Erwinia amyloliquefaciens phage pEa_SHZU_4, the described Erwinia amyloliquefaciens phage preparation, or the described biocontrol phage composition in the preparation of pesticides, biological control agents, or pollination aids for the prevention, treatment, or elimination of fire blight pathogens.

[0014] The present invention discloses the following technical effects: (1) This invention discloses an Erwinia amyloliquefaciens bacteriophage pEa_SHZU_4 and its application. pEa_SHZU_4 replicates in its host bacterium Erwinia amyloliquefaciens via a lytic cycle, with a burst size of 73 PFU / cell. Under co-culture conditions with Erwinia amyloliquefaciens, it can significantly limit the maximum proliferation of pathogenic bacteria, thereby effectively reducing the pathogenicity of the pathogen to Pyrus pyrifolia seedlings, Pyrus pyrifolia flowers, and tender branches.

[0015] (2) In in vitro and field trials, phage pEa_SHZU_4, as a component of phage cocktail, showed better control effect than single phage and comparable to the control effect of traditional chemical pesticide kasugamycin, showing good potential for reducing antibiotic use and replacing chemical pesticides.

[0016] (3) The phage pEa_SHZU_4 has good safety and stability. The phage genome does not contain virulence genes or drug resistance genes, and has high biosafety; it is stable below 55℃ and in the pH range of 4.0-10.0.

[0017] (4) The bacteriophage provided by the present invention, as a biological agent, is compatible with other biological agents, such as bacteriophages, antagonistic bacteria, beneficial microorganisms, pollen suspensions, etc., and is also generally compatible with common fertilizers, non-heavy metal pesticides, antibiotics, plant growth regulators, etc. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The plaque morphology of bacteriophage pEa_SHZU_4; Figure 2 The one-step growth curve of bacteriophage pEa_SHZU_4; Figure 3 The complete genome circular map of bacteriophage pEa_SHZU_4; Figure 4 Phylogenetic tree of bacteriophage pEa_SHZU_4; Figure 5 pH stability test of bacteriophage pEa_SHZU_4, where A is the result of 0 h treatment, B is the result of 0.5 h treatment, C is the result of 1.0 h treatment, and D is the result of 1.5 h treatment. Figure 6Temperature stability test of bacteriophage pEa_SHZU_4, where A is the result of 0 h treatment, B is the result of 0.5 h treatment, C is the result of 1.0 h treatment, and D is the result of 1.5 h treatment; Figure 7 In vitro lysis kinetics curves of bacteriophage pEa_SHZU_4 and its cocktail combination p4+k; Figure 8 An experiment to investigate the therapeutic effect of bacteriophage cocktails on Erwinia amylase-lysing bacteria on Pyrus pyrifolia seedlings; Figure 9 The safety assessment of phage cocktails for fruit trees is presented, where A represents the statistical results of average inflorescence fruit set rate, and B represents the statistical results of average flower fruit set rate. Figure 10 The graph shows the dynamics of disease incidence and the statistical results of control efficacy in the field trial of bacteriophage cocktail. In the graph, A is the cumulative dynamic table of disease incidence, B is the number of new cases per day, C is the statistical results of control efficacy, and D is the statistical results of the average number of diseased branches per tree. Figure 11 The diagram shows the comparison between the field water control group and the phage cocktail treatment group of the present invention, where A is the water control group and B is the phage cocktail treatment group. Figure 12 The field efficacy statistics of phage cocktails. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] Explanation of the test strains and bacteriophage sources: The Erwinia amyloliquefaciens strains Ea102 and Ea915 used in the embodiments of this invention were both isolated from diseased branches of Korla fragrant pear in Xinjiang Uygur Autonomous Region. Their GenBank accession numbers for their genome sequences are as follows: chromosomes: NZ_CP104022.1, NZ_CP104025.1; pEA29 plasmids: NZ_CP104023.1, NZ_CP104026.1; pEA60 plasmids: NZ_CP104024.1.

[0026] The Erwinia amyloliquefaciens bacteriophage Kuerle used in the examples is a known bacteriophage disclosed in non-patent literature (see: Chen Niu, Yu Chengmin, Cui Baiming, et al. Isolation, genome determination and lysis function analysis of Erwinia amyloliquefaciens bacteriophage Kuerle [J]. Chinese Agricultural Science, 2024, 57(2): 295-305).

[0027] Example 1 Phage isolation and purification: This invention uses Erwinia amyloliquefaciens Ea915 as the host bacterium. Topsoil and diseased branches from orchards in Yili, Xinjiang, affected by blight were collected. 5 g of soil sample was weighed and added to 45 mL of sterile SM buffer (NaCl 5.8 g / L, MgSO4·7H2O 2.0 g / L, 2% gelatin 5 mL / L, 1 mol / L Tris-HCl 50 mL / L, pH 7.5). The mixture was suspended and extracted at 28℃ and 180 r / min for 4 h with shaking. The mixture was centrifuged at 4℃ and 8000 r / min for 10 min, and the supernatant was filtered through a 0.22 μm sterile filter. 1 mL of the filtrate was added to 10 mL of bacterial suspension in the logarithmic growth phase and cultured at 28℃ for 16 h to enrich bacteriophages. 100 μL of the enrichment solution was mixed with 100 μL of the host bacterial suspension (10... 8 ~10 9Mix with CFU / mL, let stand for 10 min, then quickly mix with 4 mL of soft agar (containing 0.2% agarose, 50℃) and pour onto LB plates. Incubate at 28℃ for 12 h. Pick well-dispersed phage plaques and transfer them to SM buffer to obtain phage suspension. Purify the phage again using the single-plaque separation method, repeating 3 times. The purified phage pEa_SHZU_4 forms well-defined, completely transparent phage plaques with a diameter of 1-3 mm on bilayer agar plates. Figure 1 ).

[0028] Bacteriophage pEa_SHZU_4 was deposited on April 22, 2026 at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026758.

[0029] Example 2 Determination of optimal multiplicity of infection and one-step growth curve for bacteriophage: Adjust the concentration of Ea102 bacterial culture to 1×10⁻⁶. 8 CFU / mL, the phage suspension was serially diluted and mixed with the host bacterial suspension at MOIs of 10, 1, 0.5, 0.1, 0.05, and 0.01, respectively. After standing at room temperature for 10 min to adsorb, the mixture was transferred to 5 mL LB liquid medium and incubated at 28℃ and 180 r / min for 4 h. The phage titer was determined using the double-layer agar plate method. The results are shown in Table 1; the optimal multiplicity of infection (MOI) for pEa_SHZU_4 was 0.1.

[0030] Table 1. Determination of the optimal multiple of infection (MOI) for pEa_SHZU_4 The pEa_SHZU_4 phage suspension was mixed with Ea102 bacterial suspension (MOI=0.1) and adsorbed for 10 min. The supernatant was discarded by centrifugation, and the bacterial pellet was washed twice with LB medium. The bacterial cells were resuspended in 0.1 mL LB medium and transferred to 100 mL LB medium for dilution. The mixture was incubated at 28°C (0 min). Every 10 min, 1 mL of culture was taken to determine the phage titer, and a one-step growth curve was plotted. Figure 2 The incubation period of pEa_SHZU_4 is approximately 30 minutes, and the burst size is 73 phage particles per infected cell.

[0031] Example 3 Genome-wide characterization and biosafety analysis of bacteriophage pEa_SHZU_4 High-throughput sequencing, genome assembly, and annotation were performed on the purified phage DNA. The genome structure is shown below. Figure 3As shown. The pEa_SHZU_4 genome is double-stranded DNA (dsDNA), with a full length of 84535 bp and an average GC content of 43.84%. The predicted genome contains 116 protein-coding genes and 26 tRNA genes. Based on genome structure and sequence alignment, pEa_SHZU_4 is classified into the class Caudataphages (Caudataphages). Caudoviricetes Onavivirinae ( Ounavirinae Klesnik virus genus ( Kolesnikvirus Phylogenetic tree as follows Figure 4 As shown.

[0032] Biosafety analysis showed that no known virulence factors, drug resistance genes, or lysogenization-related genes were detected in the genome, confirming at the genetic level that it is a strictly virulent bacteriophage with high agricultural ecological safety.

[0033] Example 4 pH stability experiment of bacteriophage pEa_SHZU_4 Phage suspension was added to LB liquid medium at different pH values ​​(3.0-12.0) to achieve a final concentration of 1.0 × 10⁻⁶. 7 The PFU / mL concentration was incubated at 28°C, and its potency was measured at 0 h, 0.5 h, 1.0 h, and 1.5 h. The results are as follows: Figure 5 As shown, no phage activity was detected in pEa_SHZU_4 in excessively acidic (pH 3) and excessively alkaline (pH 11, pH 12) environments; the phage was stable in the pH range of 5.0-9.0; at pH 4 and pH 10, the phage activity decreased by about half within 1-1.5 h, indicating that pEa_SHZU_4 can adapt to a wide range of pH environments.

[0034] Example 5 Thermal stability experiment of bacteriophage pEa_SHZU_4 The phage suspension (initial titer approximately 4.0 × 10⁻⁶) 6 PFU / mL was treated in water baths at 45℃, 50℃, 55℃, 60℃, and 65℃, and samples were taken at 0 h, 0.5 h, 1.0 h, and 1.5 h to determine the potency. The results are as follows: Figure 6 As shown, bacteriophage pEa_SHZU_4 can withstand temperatures up to 50°C, and at 55°C, its half-life is approximately 1 hour. At higher temperatures, the bacteriophage rapidly inactivates, indicating that pEa_SHZU_4 is not heat-resistant, but it is stable under ambient temperature conditions.

[0035] Example 6 Antibacterial experiment of bacteriophage pEa_SHZU_4 in test tube The Ea102 strain cultured overnight was transferred to LB liquid medium at a ratio of 1:100 and cultured with shaking until the mid-exponential growth phase (OD2). 600 0.2~0.6). Take an appropriate amount of bacterial culture and adjust its final concentration to 1×10. 7 The bacterial culture was divided into three groups at CFU / mL: group one was treated with pEa_SHZU_4 phage; group two was treated with equal amounts of both pEa_SHZU_4 and Kuerle phages; and group three was treated with SM buffer as a control (containing only the host bacterium Ea102). The final concentration of phage in the phage treatment groups was 1 × 10⁻⁶ CFU / mL. 8 PFU / mL (i.e., MOI=10). All samples were incubated at 27℃ and 120 r / min for 12 h, and the bacterial concentration (OD) was measured every 2 h. 600 (value), the result is as follows Figure 7 As shown. In the absence of bacteriophages, Ea102 continued to grow, and after 12 hours of culture, OD... 600 The concentration reached 0.443; in the presence of phages, the growth of Ea102 was significantly inhibited: after 12 h of culture, the bacterial concentration in the pEa_SHZU_4 phage treatment group was about 1 / 3 of the control; the bacterial concentration in the pEa_SHZU_4 plus kuerle phage treatment group was only 1 / 25 of the control.

[0036] Example 7 Verification experiment on the control effect of bacteriophage cocktail on pear seedlings Healthy pear seedlings were selected, and a wound was made at the stem tip using a sterile needle. 2.5 μL of treatment solution was inoculated. Four treatment groups were set up: a blank control group (PBS), a pathogen control group (Ea102 bacterial suspension), a drug control group (a mixture of kasugamycin and Ea102), and a phage cocktail experimental group (a mixture of two phages, pEa_SHZU_4 and kuerle, abbreviated as p4+k, and Ea102). On day 6 post-inoculation, the disease situation was as follows: Figure 8 As shown: the first row of five pear seedlings constitutes one group; the first group is the blank control (PBS), the second group is the positive control (Ea102+PBS), the third group is the negative control (Ea102+kasugamycin), and the fourth group is the phage cocktail treatment group (Ea102+p4+k). Statistical analysis revealed that the pathogen control group exhibited the most severe disease, with an average lesion length of 28.3 mm. All treatment groups significantly delayed lesion expansion. P <0.05). Among them, the average lesion length of the control group (kasugamycin) was 6.4 mm; while the average lesion length of the phage cocktail experimental group (p4+k) was only 5.7 mm. The combination of pEa_SHZU_4 and Kuerle has a control effect on live seedlings, which is comparable to that of the traditional chemical pesticide kasugamycin.

[0037] Example 8 Preliminary field trial of bacteriophage cocktail In 2025, a 2-mu (approximately 0.33 hectares) field preliminary experiment was conducted. The Xiangli orchard of the Agricultural Science Research Institute of the Second Division of Xinjiang Production and Construction Corps was selected, and three treatment groups were set up: a disease control group (sprayed with purified water), a pesticide control group (sprayed with kasugamycin), and a phage cocktail experimental group (p4+k, with a total phage titer of 1×10⁻⁶). 9 (PFU / mL). Spray once each when the fruit trees are 20%, 50%, and 75% in bloom.

[0038] Safety assessment of phage cocktails for fruit trees, such as Figure 9 As shown.

[0039] Depend on Figure 9 It was found that the fruit set rate of inflorescences and flowers in each treatment group was not significantly different from that in the water control group. This proves that the biocontrol agent did not cause obvious phytotoxicity to pear trees, and has both effective control and good ecological safety, showing potential for field application and commercialization.

[0040] Disease dynamics and control efficacy statistics of bacteriophage cocktail field trials are as follows: Figure 10 As shown.

[0041] Depend on Figure 10 The data from the final harvest period showed that the phage cocktail experimental group (p4+k) had excellent control effect, with only 3 diseased branches and a control effect of 91.18%, which was significantly better than the disease control group (34 diseased branches) and comparable to the control group (6 diseased branches, control effect of 82.35%). Both groups significantly reduced the incidence of disease in fruit trees.

[0042] The results of the control group of diseased branches in the field water and the phage cocktail treatment group of this invention are as follows: Figure 11 As shown.

[0043] Depend on Figure 11 It can be seen that, compared with the water control group, the diseased tree branches in the phage treatment group showed that the lesions were shorter and the affected area was more limited.

[0044] Example 9 Field control efficacy trial of phage cocktail preparation p4+k In 2026, to verify the practical application results of bacteriophages in the field, an experiment was conducted in a pear orchard in Tiemenguan City, Korla, Xinjiang, involving approximately 720 trees in the treatment group and 280 trees in the control group across 11 mu (approximately 0.8 hectares). Two treatment groups were set up: a disease control group (sprayed with purified water) and a bacteriophage cocktail experimental group (p4+k, with an overall bacteriophage titer of 1×10⁻⁶). 9(PFU / mL). Spray once in early April when the fruit trees are 20%, 50%, and 75% open. Field surveys of disease incidence were conducted on April 27 and May 2, with diseased branches counted using a comprehensive sampling method. The severity of disease in the field was graded according to the van der Zwet (1970) scoring system, and an inverse severity rating (X) was assigned. The specific grading criteria and pathological characteristics are shown in Table 2.

[0045] Table 2. Severity Grading Table Based on actual field survey data, the disease incidence rate (%), disease severity index (DI), and relative efficacy (E) for each group were calculated using the following formulas: Disease incidence rate (%) = (Total number of infections / Total number of strains) × 100%; Disease Index (DI) = [∑(number of cases at each level × corresponding level value) / (total number of plants × highest level value)] × 100; Relative efficacy (E) = [(DI of blank control group - DI of treatment group) / DI of blank control group] × 100%.

[0046] The results are shown in Table 3 and Figure 12 As shown.

[0047] Table 3 Statistical table of field control efficacy test data From Table 3 and Figure 12 It was found that in the disease control group without any phage agent application, 11 out of 280 plants were infected, with a disease incidence rate of 3.93%. Two plants showed moderate disease, one severe disease, and three showed systemic disease, resulting in a disease severity index (DI) of 1.79. In the treatment group treated with the phage cocktail preparation p4+k described in this invention, only 7 out of 720 plants showed mild disease, with no moderate, severe, or systemic cases. The disease incidence rate decreased to 0.97%, and the disease severity index (DI) decreased to 0.16. Based on the relative efficacy formula, the field relative efficacy (E) of the phage cocktail preparation p4+k described in this invention against fruit tree fire blight was 91%.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A type of Erwinia amylolytica phage ( Erwinia phage pEa_SHZU_4, characterized in that, The Erwinia bacteriophage pEa_SHZU_4 was deposited at the China Center for Type Culture Collection (CCTCC) on April 22, 2026, at Wuhan University, Wuhan, China, with accession number CCTCC NO: M 2026758.

2. The Erwinia amyloliquefaciens phage pEa_SHZU_4 according to claim 1, characterized in that, Erwinia amyloliquefaciens Ea102 and / or Ea915 were used as host bacteria.

3. A preparation of Erwinia amyloliquefaciens bacteriophage, characterized in that, It was prepared using Erwinia amyloliquefaciens phage pEa_SHZU_4 as described in claim 1 or 2.

4. The Erwinia amyloliquefaciens phage preparation according to claim 3, characterized in that, It also includes the Erwinia amyloliquefaciens phage pEa_SHZU_4 vector.

5. The Erwinia amyloliquefaciens phage preparation according to claim 3 or 4, characterized in that, Dosage forms include powders, solutions, granules, gels, or lyophilized agents.

6. The application of Erwinia amyloliquefaciens phage pEa_SHZU_4 as described in claim 1 or 2, or the Erwinia amyloliquefaciens phage preparation as described in any one of claims 3-5, in the prevention and control of fire blight.

7. The application according to claim 6, characterized in that, The fire blight mentioned is a fire blight disease of Rosaceae fruit trees caused by Erwinia amyloliquefaciens.

8. A biocontrol bacteriophage composition for treating fire-related diseases, characterized in that, The biocontrol phage composition comprises Erwinia amyloliquefaciens phage pEa_SHZU_4 as described in claim 1 or 2, and one or two of Erwinia amyloliquefaciens-specific phage, antagonistic bacteria, and antibiotics.

9. The biocontrol phage composition according to claim 8, characterized in that, The titer of the Erwinia amyloliquefaciens phage pEa_SHZU_4 is not less than 10. 3 PFU / mL(g).

10. The use of Erwinia amyloliquefaciens phage pEa_SHZU_4 as described in claim 1 or 2, or the Erwinia amyloliquefaciens phage preparation as described in any one of claims 3-5, or the biocontrol phage composition as described in claim 8 or 9, in the preparation of pesticides, biological control agents, or pollination aids for the prevention, treatment, or elimination of fire blight pathogens.

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