A bacteriophage lyophilized powder disinfectant and its preparation method and application

Abstract

This invention provides a lyophilized bacteriophage powder disinfectant, its preparation method, and its application. The disinfectant is composed of lyophilized bacteriophage powder and a reconstitution solvent; the reconstitution solvent, by mass percentage, comprises 0.2-1% skim milk powder, 0.5-2% glycerol, 0.1-0.2% hydroxypropyl methylcellulose, and the balance deionized water. This invention constructs a three-component synergistic system of wall material, antifreeze agent, and film-forming stabilizer, significantly improving the activity recovery rate, reconstitution activity recovery rate, and infection efficiency of the lyophilized bacteriophage powder. Furthermore, the reconstitution operation is simple and quick, completed within 3 minutes. This invention achieves high efficiency and stability in the activity recovery of lyophilized bacteriophage powder during reconstitution, enhancing the biological activity of the reconstituted bacteriophage. It is suitable for scenarios such as farms and food processing where the use of antibiotics and chemical disinfectants is limited, meeting the application requirements of convenience and reliability for on-site immediate disinfection.

Description

Technical Field

[0001] This invention relates to the field of biological disinfection technology, specifically to a phage freeze-dried powder disinfectant, its preparation method, and its application. Background Technology

[0002] Bacteriophages, as biological agents that specifically kill pathogenic microorganisms, have broad application prospects in environmental disinfection, especially in scenarios such as farms and food processing where the use of antibiotics and chemical disinfectants is restricted. Compared with traditional chemical disinfectants, bacteriophages have advantages such as strong targeting, no residue, and low likelihood of inducing drug resistance. Currently, to extend the storage stability of bacteriophages, they are usually prepared as lyophilized powders. However, existing lyophilized bacteriophage products require reconstitution before use, but the activity recovery rate of reconstituted bacteriophages is generally low, and the stability after reconstitution is poor, making it difficult to achieve the expected disinfection effect in a short time. Existing reconstitution media are mostly sterile water or physiological saline, which lack the ability to effectively repair the damage caused by lyophilization of bacteriophages. This leads to the inactivation of bacteriophage capsid proteins during lyophilization and reconstitution due to mechanical stress, ice crystal damage, and other factors, seriously affecting the operability and disinfection reliability of their field application.

[0003] Existing technologies have conducted relevant research on the drying and preservation of bioactive materials. For example, Chinese Patent No. CN102459568A discloses a stable dry powder composition containing bioactive microorganisms and its preparation method. This method involves mixing microorganisms with stabilizers and protectants, followed by vacuum drying at a temperature higher than the freezing point to prepare the dry powder formulation. While this technology improves the survival rate of microorganisms during the drying process to some extent, its focus is on protecting the microorganisms during drying, rather than on restoring their activity during the reconstitution process after freeze-drying. Furthermore, the drying process requires strict control of temperature and vacuum conditions, making the process complex. The final product still needs to be reconstituted under specific conditions for use, and the activity recovery rate after reconstitution is not considered a core optimization indicator, making it difficult to meet the application requirements of rapid on-site reconstitution and efficient sterilization.

[0004] For example, CN101636439A discloses a method for drying biomaterials under vacuum using traveling wave radiation energy (t-REV). This method involves mixing biomaterials with protective agents (such as HPMC, skim milk powder, glycerin, etc.) to form a paste, followed by vacuum radiation drying to obtain a foam-like material. While this method mentions various protective agent components, its core lies in temperature control and foam structure formation during the drying process, aiming to replace traditional freeze-drying or air-drying methods. However, this technology also focuses on the drying process itself, without addressing formulation optimization for activity restoration during the reconstitution of freeze-dried powder. Furthermore, the drying process involves microwave heating, which still poses a potential risk of damage to heat-sensitive biomaterials, and the potency recovery rate after reconstitution has not been effectively verified.

[0005] In summary, existing technologies lack specific solutions for the reconstitution of lyophilized phage powder. Current drying and protection technologies primarily focus on the drying process itself, with insufficient attention paid to activity restoration during reconstitution. Conventional reconstitution media cannot effectively repair the mechanical stress and ice crystal damage suffered by the phage capsid proteins during freeze-drying, resulting in low activity recovery rates after reconstitution, which fails to meet the demands for efficient, stable, and convenient on-site disinfection. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a phage freeze-dried powder disinfectant, its preparation method and application, to solve the technical problem that "existing reconstitution media cannot efficiently repair the mechanical stress and ice crystal damage suffered by phages during freeze-drying, resulting in unstable activity recovery after reconstitution and difficulty in meeting the needs of on-site immediate disinfection".

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a phage lyophilized powder disinfectant, wherein the disinfectant is composed of a mixture of phage lyophilized powder and a reconstituter; the reconstituter, by mass percentage, comprises 0.2-1% of a wall material, 0.5-2% of a low-molecular-weight cryoprotectant, 0.1-0.2% of a high-molecular-weight film-forming stabilizer, and 96.8-99.2% of deionized water; the wall material is skim milk powder; the low-molecular-weight cryoprotectant is glycerol; and the high-molecular-weight film-forming stabilizer is hydroxypropyl methylcellulose.

[0008] The phage lyophilized powder is one of Salmonella phage WHSATYSB-2501 lyophilized powder, Salmonella phage WHSATYSB-2502 lyophilized powder, and Escherichia coli phage lyophilized powder.

[0009] Secondly, the present invention provides a method for preparing a phage lyophilized powder disinfectant, comprising the following steps: (1) Weigh out the skim milk powder, glycerin and hydroxypropyl methylcellulose by mass percentage, add them to deionized water and stir until all components are completely dissolved to obtain the reconstituted stock solution; (2) The original solution of the reconstituted solvent is sterilized, cooled, and then sealed and stored to obtain the reconstituted solvent; (3) Mix the lyophilized phage powder and the reconstituted solvent to prepare a disinfectant.

[0010] Furthermore, the sterilization temperature in step (2) is 120~125℃, the saturated steam pressure is 0.1~0.15MPa, and the sterilization time is 10~20min.

[0011] Furthermore, the mass-to-volume ratio of the phage lyophilized powder and the reconstituted solvent in step (3) is 1 g: 100 mL.

[0012] Furthermore, in step (3), the temperature for mixing the phage lyophilized powder and the reconstituted solvent is 25°C, and the time is 3 min.

[0013] Thirdly, this invention provides an application of phage freeze-dried powder disinfectant in environmental disinfection in grassroots farms and food processing plants.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) This invention constructs a three-component synergistic system of wall material, antifreeze agent and film-forming stabilizer by compounding skim milk powder, glycerol and hydroxypropyl methylcellulose in a specific ratio. Skim milk powder forms a glassy protective matrix as the wall material, glycerol inhibits ice crystal damage and regulates osmotic pressure as a low molecular weight antifreeze agent, and hydroxypropyl methylcellulose provides physical buffer protection as a high molecular weight film-forming stabilizer during reconstitution. The synergistic effect of the three significantly improves the activity recovery rate of the phage freeze-dried powder. The infection efficiency of this invention is greater than 90%, indicating that the phage freeze-dried powder still has good biological activity after reconstitution and can effectively kill the target pathogens.

[0015] (2) The reconstitution solvent of the present invention can efficiently reconstitute phage freeze-dried powder at room temperature without special equipment in just 3 minutes. The operation is simple and quick, and it is suitable for the on-site rapid disinfection needs of grassroots scenarios such as farms and food processing. The reconstitution timeliness verification results show that the activity recovery rate of the phage freeze-dried powder of the present invention is close to 85% after 2 minutes of reconstitution, and reaches up to 92.8% after 3 minutes of reconstitution.

[0016] (3) When the reconstituted solvent of the present invention is used in combination with the lyophilized phage powder, not only is the activity recovery rate high after reconstitution, but the lyophilized powder also has excellent long-term stability under normal storage conditions. The stability test results show that the potency decay rate after 18 months of storage is less than 8%, indicating that the formulation of the present invention can effectively protect the structural integrity of the phage during the lyophilization and storage process, providing a reliable guarantee for the commercial application of phage disinfectants. Attached Figure Description

[0017] Figure 1 The graph shows the change in activity recovery rate of the phage lyophilized powders in Examples 2, 4, and 5 of this invention within 1-3 minutes after reconstitution.

[0018] Figure 2 This is a schematic diagram showing the potency decay rate of disinfectants after 18 months of storage in various embodiments and comparative examples of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] To address the technical shortcomings of existing reconstitution media in efficiently repairing phage freeze-drying damage, this invention provides a reconstitution solvent composed of skim milk powder, glycerol, and hydroxypropyl methylcellulose in a specific ratio. Its mechanism of action is as follows: First, skim milk powder, acting as a wall material, forms a dense, glassy protective matrix during freeze-drying, replacing the phage capsid proteins in bearing the mechanical stress generated by ice crystal growth and dehydration shrinkage, effectively preventing irreversible collapse of the capsid structure. Second, glycerol, as a low-molecular-weight cryoprotectant, binds to the phage capsid proteins through hydrogen bonds, stabilizing the protein's native conformation during freeze-drying; it also rapidly regulates osmotic pressure during reconstitution, preventing capsid rupture caused by drastic osmotic pressure changes. Finally, hydroxypropyl methylcellulose, as a high-molecular-weight film-forming stabilizer, forms a viscoelastic physical buffer layer during reconstitution, encapsulating the phage particles and significantly reducing secondary mechanical damage caused by liquid flow, shear force, and inter-particle collisions during reconstitution. Through the synergistic effects of structural anchoring during freeze-drying, steady-state regulation of osmotic pressure, and physical buffering during reconstitution, these three technologies systematically solve the problem of phage activity loss caused by mechanical stress, ice crystal damage, and osmotic pressure imbalance during the entire freeze-drying and reconstitution process. This enables rapid, efficient, and stable activity recovery at room temperature, meeting the dual requirements of convenience and reliability for on-site immediate disinfection.

[0021] Example 1: Preparation and application of Salmonella bacteriophage WHSATYSB-2501 lyophilized powder disinfectant (1) Preparation of the resolvent: Take 0.2% skim milk powder, 0.5% glycerol, and 0.1% hydroxypropyl methylcellulose (HPMC) by mass percentage, with the remainder being deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 120°C and 0.1 MPa for 20 min. After naturally cooling to room temperature, seal and store it at 0°C for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0022] Example 2: Preparation and application of Salmonella bacteriophage WHSATYSB-2501 lyophilized powder disinfectant (1) Preparation of the resolvent: Take 0.6% skim milk powder, 1.25% glycerol, and 0.15% hydroxypropyl methylcellulose (HPMC) by mass percentage, with the remainder being deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0023] Example 3: Preparation and application of Salmonella bacteriophage WHSATYSB-2501 lyophilized powder disinfectant (1) Preparation of the resolvent: Take 1.0% skim milk powder, 2.0% glycerol, 0.2% hydroxypropyl methylcellulose (HPMC) by mass percentage, and the remainder is deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 125℃ and 0.15MPa for 10 minutes. After naturally cooling to room temperature, seal and store it at 5℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0024] Example 4: Preparation and application of Salmonella bacteriophage WHSATYSB-2502 lyophilized powder disinfectant (1) Preparation of the resolvent: Take 0.6% skim milk powder, 1.25% glycerol, and 0.15% hydroxypropyl methylcellulose (HPMC) by mass percentage, with the remainder being deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2502 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0025] Example 5: Preparation and application of Escherichia coli bacteriophage lyophilized powder disinfectant (1) Preparation of the resolvent: Take 0.6% skim milk powder, 1.25% glycerol, and 0.15% hydroxypropyl methylcellulose (HPMC) by mass percentage, with the remainder being deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 8.5×10 9 PFU / g of Escherichia coli phage lyophilized powder was added to 100mL of the above-mentioned prepared reconstitution solvent. The mixture was gently inverted and mixed 3 times at 25°C, avoiding violent shaking. The mixture was then allowed to stand for 3 minutes to complete the reconstitution and obtain the disinfectant.

[0026] Comparative Example 1; (1) Preparation of the resolvent: Take 1.25% glycerol and 0.15% hydroxypropyl methylcellulose (HPMC) by mass percentage, and the remainder is deionized water. Mix and stir until all components are completely dissolved to obtain the resolvent stock solution. (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0027] Comparative Example 2; (1) Preparation of the resolvent: Take 0.6% skim milk powder, 0.15% hydroxypropyl methylcellulose (HPMC) and the remainder deionized water by mass percentage, mix and stir until all components are completely dissolved to obtain the resolvent stock solution; (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×1010 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0028] Comparative Example 3; (1) Preparation of the resolvent: Take 0.6% skim milk powder, 1.25% glycerin and the remainder deionized water by mass percentage, mix and stir until all components are completely dissolved to obtain the resolvent stock solution; (2) Place the above-mentioned reconstituted stock solution in an autoclave and sterilize it at 121℃ and 0.12MPa for 15min. After naturally cooling to room temperature, seal and store it at 4℃ for later use to obtain the reconstituted solution. (3) Reconstitution of lyophilized powder: Take 1g of the lyophilized powder with a potency of 1.0×10 10 Add 100 mL of the above-mentioned prepared reconstitution solvent to PFU / g of Salmonella phage WHSATYSB-2501 lyophilized powder, gently invert and mix 3 times at 25°C, avoiding violent shaking, and let stand for 3 minutes to complete the reconstitution, thus obtaining the disinfectant.

[0029] Test and Results Analysis Test methods Phage titer determination: The titer of the reconstituted phages from each example and comparative example was determined using the double-layer plate method. Nutrient agar medium was melted and poured into sterile petri dishes, allowed to solidify, and the bottom layer plate was prepared. The target pathogenic bacteria (Salmonella or Escherichia coli) standard strain was inoculated into nutrient broth medium and cultured at 37°C with shaking until the logarithmic growth phase. The bacterial concentration was then adjusted to 1×10⁻⁶. 8 CFU / mL, for later use; take the reconstituted phage sample and perform 10-fold serial dilutions with sterile physiological saline. Take 100 μL of each dilution sample and mix it with 200 μL of host bacterial culture. Add 5 mL of semi-solid nutrient agar medium that has been melted and cooled to about 50°C. Mix quickly and pour it onto the bottom plate. Shake well and spread evenly. After the semi-solid layer solidifies, invert the plate and incubate it in a 37°C constant temperature incubator for 12 h. Observe and count the plaque forming units (PFU). Titer calculation: Titer (PFU / mL) = average number of plaques × dilution factor × 10. The results are expressed as the common logarithm (lg PFU / mL). See Table 1 for specific results.

[0030] Reconstitution time-efficiency verification: The reconstitution solvents from Examples 2, 4, and 5 were mixed with the corresponding lyophilized phage powders, and the reconstitution method of this invention was followed. Samples were taken at 1 min, 2 min, and 3 min after reconstitution. The phage titer of the samples at different time points was determined using the double-layer plate method, and the activity recovery rate at different sampling times was calculated. Specific results are as follows: Figure 1 As shown.

[0031] Infection efficiency verification: Take the reconstituted phage solution and an equal volume of the target pathogen suspension (concentration 1×10⁻⁶). 8 Mix (CFU / mL) thoroughly and incubate at 37℃ for 1 hour. Use a bacterial suspension of pathogenic bacteria without phage as a blank control. Determine the viable bacteria count after incubation using the plate count method. Infection efficiency is calculated using the following formula: Infection efficiency = (Number of viable bacteria in blank control) / (Number of viable bacteria in blank control) The experimental group viable bacteria count / blank control viable bacteria count × 100% is shown in Table 1.

[0032] Stability test: The reconstitution solvents of each example and comparative example were sealed, refrigerated, and protected from light. After 18 months, samples were taken and reconstituted with the lyophilized phage powder to determine the titer and calculate the titer decay rate. The titer decay rate (%) = (titer after reconstitution) / (titer after reconstitution). (Potency after reconstitution after 18 months of storage) / Initial potency × 100%, specific results are as follows Figure 2 As shown.

[0033] Table 1

[0034] As shown in Table 1, the reconstitution solvent of this invention can efficiently restore the activity of the lyophilized phage powder, with an activity recovery rate of over 91% after reconstitution, which is significantly better than that of the comparative examples. The infection efficiency of Examples 1-5 is between 90.9% and 97.6%, indicating that the lyophilized phage powder of this invention still has good biological activity after reconstitution and can effectively kill the target pathogens.

[0035] Comparative Example 1 lacked skim milk powder as a wall material, which prevented the formation of a glassy protective matrix. As a result, the phage capsid underwent irreversible damage due to ice crystals and dehydration stress during the freeze-drying process. The activity recovery rate decreased from about 92% to 65.4%, and the infection efficiency decreased to 63.2%. This indicates that skim milk powder is the core component for protecting the structural integrity of the phage during the freeze-drying stage.

[0036] Comparative Example 2 lacked glycerol as a low-molecular-weight cryoprotectant. During reconstitution, the osmotic pressure imbalance damaged the capsid structure, resulting in a decrease in activity recovery rate to 72.1% and infection efficiency to 70.5%.

[0037] Comparative Example 3 lacked hydroxypropyl methylcellulose, resulting in a lack of physical buffer barrier during reconstitution. The phage particles suffered increased mechanical damage due to collisions and shear forces, leading to a decrease in both activity recovery rate and infection efficiency.

[0038] like Figure 1As shown, the phages in Examples 2, 4, and 5 exhibited excellent activity recovery rates during reconstitution. After 1 minute of reconstitution, the activity recovery rate of each example reached over 80%; after 2 minutes of reconstitution, the activity recovery rate of Example 2 approached 85%; and after 3 minutes of reconstitution, the activity recovery rate of Example 2 reached the highest, reaching 92.8%. These results demonstrate that the reconstitution solvent of this invention can achieve efficient reconstitution of lyophilized phage powder at room temperature without any special equipment, requiring only 3 minutes. This fully meets the operational needs of rapid on-site disinfection in grassroots scenarios and effectively solves the problems of complex operation, long processing time, and low activity recovery rate of existing reconstitution media.

[0039] like Figure 2 As shown, the potency decay rate of the reconstituted solvents in Examples 1-5 after 18 months of storage is less than 8%, with Example 2 showing the lowest potency decay rate at only 7.1%. This demonstrates that the disinfectant of the present invention has excellent long-term storage stability under normal storage conditions of 25°C in a sealed and light-proof environment.

[0040] Comparative Example 1, lacking skim milk powder as a wall material, could not form a glassy protective matrix, and the phage capsid structure continued to deteriorate during drying and storage, resulting in the highest decay rate.

[0041] Comparative Example 2 lacked glycerol, resulting in severe ice crystal damage at low temperatures. Residual stress during storage further damaged the capsid, leading to a potency decay rate of 17.3%.

[0042] Comparative Example 3 lacked hydroxypropyl methylcellulose, resulting in a potency decay rate of 15.6%. Although this had a relatively small direct impact on long-term storage, the mechanical damage was exacerbated during reconstitution, indirectly affecting the potency determination after storage.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A lyophilized phage powder disinfectant, characterized in that, The disinfectant is composed of a mixture of lyophilized bacteriophage powder and a reconstituter. The resolvent, by mass percentage, comprises 0.2-1% wall material, 0.5-2% low-molecular-weight antifreeze agent, 0.1-0.2% high-molecular-weight film-forming stabilizer, and 96.8-99.2% deionized water; The wall material is skim milk powder; The low-molecular-weight antifreeze agent is glycerol; The polymeric film-forming stabilizer is hydroxypropyl methylcellulose.

2. The disinfectant according to claim 1, characterized in that, The phage lyophilized powder is one of Salmonella phage WHSATYSB-2501 lyophilized powder, Salmonella phage WHSATYSB-2502 lyophilized powder, and Escherichia coli phage lyophilized powder.

3. A method for preparing the lyophilized phage powder disinfectant as described in any one of claims 1 or 2, characterized in that, Includes the following steps: (1) Weigh out the skim milk powder, glycerin and hydroxypropyl methylcellulose by mass percentage, add them to deionized water and stir until all components are completely dissolved to obtain the reconstituted stock solution; (2) The original solution of the reconstituted solvent is sterilized, cooled, and then sealed and stored to obtain the reconstituted solvent; (3) Mix the lyophilized phage powder and the reconstituted solvent to prepare a disinfectant.

4. The method according to claim 3, characterized in that, The sterilization process in step (2) is carried out at a temperature of 120-125°C, a saturated steam pressure of 0.1-0.15 MPa, and a sterilization time of 10-20 min.

5. The method according to claim 3, characterized in that, The temperature for sealing and storing in step (2) is 0~5℃.

6. The method according to claim 3, characterized in that, The mass-volume ratio of the phage lyophilized powder and the reconstituted solvent in step (3) is 1 g: 100 mL.

7. The method according to claim 3, characterized in that, The mixing temperature in step (3) is 25°C and the time is 3 minutes.

8. The application of a phage freeze-dried powder disinfectant as described in any one of claims 1 or 2 in environmental disinfection in grassroots farms and food processing plants.

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