Method for biosynthesizing nano platinum by using aerospace mutant strain PS04-17 and application of nano platinum

Abstract

The invention discloses a method for biosynthesizing nano platinum by using space mutant bacteria PS04-17 and application of the method. The invention provides a novel application of a space mutant strain PS04-17 strain in biosynthesis of nano platinum particles. Researches show that the PS04-17 strain has a reduction capability on hexachloroplatinic acid; the method for biologically synthesizing nano platinum by reducing hexachloroplatinic acid in a liquid fermentation culture medium by using the PS04-17 strain is simple and convenient, mild in condition, low in cost and environment-friendly. The invention provides more new strain resources with high reduction efficiency on hexachloroplatinic acid, and fills the blank in the field of synthesis of nano platinum by microorganisms. Meanwhile, the PS04-17 synthesized nano platinum can prevent and control various plant pathogens, the bacteriostasis rate of the PS04-17 synthesized nano platinum on colletotrichum litchii and peronophythora litchii can reach 100%, the PS04-17 synthesized nano platinum can also be used for preventing and controlling wheat stem rot, the prevention and control efficiency reaches 78.2%, and a new solution is provided for prevention and control of crop diseases.

Description

Technical Field

[0001] This invention relates to the field of microbial and agricultural disease control technology, and more specifically, to a method for biosynthesizing nano-platinum using aerospace mutant bacteria △PS04-17 and its application. Background Technology

[0002] Platinum is an important precious metal element with excellent catalytic performance, high stability, and good biocompatibility, and is widely used in chemical catalysis, energy conversion, electronic materials, and biomedicine. Platinum can act as a highly efficient catalyst to promote various chemical reactions, such as hydrogenation and oxygen reduction reactions in fuel cells. In the pharmaceutical field, platinum compounds (such as cisplatin) can be used in cancer chemotherapy, exhibiting significant anti-tumor activity. Furthermore, platinum is frequently used to prepare high-precision electrodes and corrosion-resistant materials. Despite its many excellent properties, platinum's scarcity in the Earth's crust, high extraction costs, and uneven resource distribution limit its wider application.

[0003] Hexachloroplatinic acid (HCA) is a common platinum compound and can be used as a precursor for the synthesis of platinum nanomaterials. However, HCA is highly toxic and chemically reactive, and improper handling can easily pollute the environment and potentially harm ecosystems and human health. Nanoplatinum, due to its size and surface effects, exhibits superior catalytic activity and selectivity compared to bulk platinum. Therefore, efficiently and environmentally friendly conversion of HCA into nanoplatinum not only contributes to the recycling of platinum resources but also provides a new pathway for the preparation of functional nanomaterials. Traditional methods for synthesizing nanoplatinum are mostly chemical reduction methods, such as using sodium borohydride and sodium citrate as reducing agents and stabilizers. However, these methods are often costly, use harmful reagents, produce easily aggregated products with wide particle size distributions, and may introduce impurities, affecting the purity and application performance of nanoplatinum.

[0004] In recent years, research on the synthesis of nano-platinum using microbial reduction of platinum ions has gradually attracted attention. For example, Enterococcus faecalis (… Enterococcus faecalis The Z5 strain can convert platinum ions in solution into uniformly distributed nano-platinum particles with a diameter of approximately 5 nm, mainly distributed in the periplasmic space, through bioadsorption and bioreduction in the presence of exogenous electron donors. Other microorganisms such as Shewanella (… Shewanella sp.), Geybacterium ( GeobacterMicrobial strains (e.g.) have also been shown to possess the ability to reduce platinum salts. Biosynthesized platinum nanoparticles exhibit advantages such as good dispersibility, high stability, and strong catalytic activity, and the reaction conditions are mild and environmentally friendly. However, existing microbial strains have low reduction efficiency for hexachloroplatinic acid, and controlling the product synthesis rate and particle size remains a challenge. Currently, there is a shortage of excellent microbial strains that can efficiently reduce hexachloroplatinic acid to platinum nanoparticles, severely restricting the practical application and promotion of biosynthetic platinum nanoparticles. Therefore, screening and developing microbial strains with reduction efficiency for hexachloroplatinic acid is of great significance for achieving green, efficient, and sustainable biosynthesis of platinum nanoparticles. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the problems of low reduction efficiency of hexachloroplatinic acid by existing microbial strains, high cost, large pollution and uneven products of chemical synthesis methods; and lack of efficient, green and sustainable nano-platinum biosynthesis strains. This invention provides a method for biosynthesizing nano-platinum by aerospace mutant strain △PS04-17 and its application.

[0006] The first objective of this invention is to provide the application of the Cribben-like Bacillus aerospace mutant strain △PS04-17 in the preparation of nano-platinum.

[0007] A second objective of this invention is to provide a method for the biosynthesis of platinum nanoparticles.

[0008] The third objective of this invention is to provide a method for synthesizing nano-platinum using △PS04-17.

[0009] The fourth objective of this invention is to provide an application for the synthesis of nano-platinum using △PS04-17.

[0010] The fifth objective of this invention is to provide a product.

[0011] The sixth objective of this invention is to provide a method for preventing and controlling wheat stem base rot.

[0012] The above-mentioned objective of this invention is achieved through the following technical solution: This invention provides Cribbenoid Bacillus ( Paenibacillus kribbensis The application of the space mutant strain △PS04-17 in the preparation of nano-platinum. The △PS04-17 strain was deposited at the Guangdong Provincial Microbial Culture Collection Center on March 17, 2022, with the accession number: GDMCC NO:62233.

[0013] This invention provides a novel application of the space-mutant strain △PS04-17 in the biosynthesis of platinum nanoparticles. Studies show that strain △PS04-17 possesses the ability to reduce hexachloroplatinic acid (H2PtCl6). The method for synthesizing platinum nanoparticles by reducing hexachloroplatinic acid using strain △PS04-17 in liquid fermentation medium is simple, convenient, and the biosynthetic conditions are mild, requiring no expensive or toxic chemical reducing agents, resulting in low cost and environmental friendliness. The △PS04-17 strain provided by this invention is a novel bacterial resource with high efficiency in reducing hexachloroplatinic acid, filling a gap in the field of microbial synthesis of platinum nanoparticles. Meanwhile, the nano-platinum synthesized by △PS04-17 can control a variety of plant pathogens, showing good inhibitory effects on banana wilt fungus, wheat stem base rot fungus, tomato root rot fungus, tobacco anthracnose fungus, litchi anthracnose fungus, and litchi downy mildew fungus. Among them, the inhibition rate against litchi anthracnose fungus and litchi downy mildew fungus can reach 100%. Moreover, for the first time, biosynthesized nano-platinum was used to control wheat stem base rot, with a control efficiency of 78.2%, showing good control effect and providing a new solution for the control of important diseases.

[0014] This invention provides a method for biosynthesizing nano-platinum. The method involves activating the space mutant bacterium △PS04-17 and inoculating it into a fermentation medium containing platinum salts for fermentation culture. After fermentation, the fermentation broth is centrifuged, the supernatant is discarded, the mixture is washed, purified, and the precipitate is collected, washed, and dried to obtain the final product.

[0015] Preferably, the inoculum amount of the space mutant strain △PS04-17 is 1~5%.

[0016] More preferably, the inoculum amount of the space mutant bacterium △PS04-17 is 1%.

[0017] Preferably, the platinum salt is hexachloroplatinic acid or potassium chloroplatinate.

[0018] Preferably, the concentration of the platinum salt is 1~5 mM.

[0019] More preferably, the concentration of the platinum salt is 1 mM.

[0020] Preferably, the fermentation medium is a modified Czapek medium with the following formula: nitrogen source 1.5~3 g / L, potassium dihydrogen phosphate 1~1.5 g / L, dipotassium hydrogen phosphate 1~2 g / L, potassium chloride 0.5~0.8 g / L, magnesium sulfate 0.5~0.8 g / L, ferrous sulfate 0.01~0.1 g / L, carbon source 30~50 g / L, and pH value 7~7.2.

[0021] More preferably, the carbon source in the fermentation medium is sucrose or glucose, glycerol, etc.; the nitrogen source is sodium nitrate or organic nitrogen sources such as yeast extract, peptone, etc.

[0022] Preferably, the fermentation conditions are: temperature 25~28℃, time 7~10 days.

[0023] More preferably, the fermentation is static fermentation.

[0024] This invention provides a preferred purification method for nano-platinum: The fermentation broth is centrifuged at 6000 r / min for 20 min, the supernatant is discarded, and the sample is washed three times with sterile water, then three times with 0.9% NaCl solution, and then three times with 0.1 mol / L Tris-HCl. Sterile water is then added to adjust the volume of the precipitated cells to at least half the original sample volume. The sample is then sonicated at 4 ℃ with the following conditions: power 450 W, 5 s sonication intervals followed by a 5 s pause, and a total running time of 40 min. After sonication, the sample is centrifuged at 12000 rpm for 10 min, and the precipitate is washed three times consecutively with 1.5 mol / L Tris / HCl buffer (pH 8.8). The precipitate is collected by centrifugation, resuspended in 4 mL of ultrapure water, and 2 mL of n-octanol is added. The mixture is shaken for 5 min, centrifuged at 3000 rpm for 5 min, and then placed in a 4 ℃ refrigerator for 24 h to allow for clear stratification. After the brown platinum nanoparticles precipitate at the bottom of the centrifuge tube, discard the cells between the two phases to break them up, and wash the precipitate twice with sterile water. Finally, resuspend the platinum nanoparticles in 1 mL of ultrapure water, drop them onto sterile aluminum foil, and allow them to air dry to obtain pure platinum nanoparticles.

[0025] This invention provides a method for synthesizing △PS04-17 nano-platinum, which is prepared by the above method.

[0026] This invention provides the application of △PS04-17 synthesized nanoplatinum in inhibiting plant pathogens or in preventing and controlling plant diseases caused by pathogens.

[0027] This invention also provides the application of △PS04-17 synthesized nanoplatinum in the preparation of products that inhibit plant pathogens or prevent plant diseases caused by plant pathogens.

[0028] Preferably, the plant pathogen is *Fusarium wiltii*, the causal agent of banana wilt (…). Fusarium oxysporum f.sp. cubense ), wheat stem rot fungus ( Fusarium pseudograminearum Tomato root rot pathogen ( Fusarium solani ), tobacco anthrax bacteria ( Colletotrichum nicotianae ), litchi anthracnose fungus ( Colletotrichum siamense ), Phytophthora downy mildew ( Peronophythora litchii One or more of the following.

[0029] Preferably, the plant disease is one or more of the following: banana wilt, wheat stem base rot, tomato root rot, tobacco anthracnose, litchi anthracnose fungus, and litchi downy mildew fungus.

[0030] Preferably, the product is a biocontrol product or a plant pathogen inhibitor.

[0031] This invention provides the application of △PS04-17 synthesized nano-platinum in the prevention and control of wheat stem base rot or in the preparation of products for the prevention and control of wheat stem base rot.

[0032] This invention provides a product containing △PS04-17 to synthesize nano-platinum.

[0033] This invention also provides a method for preventing and controlling wheat stem base rot, which involves treating the plants with nano-platinum synthesized using △PS04-17.

[0034] Preferably, the treatment methods can include seed soaking with nano-platinum, foliar spraying, root irrigation, seed coating, or direct spraying onto the soil.

[0035] The present invention has the following beneficial effects: This invention provides a novel application of the space-mutant strain △PS04-17 in the biosynthesis of platinum nanoparticles. Studies show that strain △PS04-17 possesses the ability to reduce hexachloroplatinic acid (HCA). The method for synthesizing platinum nanoparticles by reducing HCA in liquid fermentation medium using strain △PS04-17 is simple, convenient, and the biosynthetic conditions are mild, requiring no expensive or toxic chemical reducing agents, resulting in low cost and environmental friendliness. Furthermore, strain △PS04-17 demonstrates a novel strain resource with high efficiency in reducing HCA, filling a gap in the field of microbial synthesis of platinum nanoparticles. Simultaneously, the platinum nanoparticles synthesized by △PS04-17 can control various plant pathogens, and for the first time, biosynthesized platinum nanoparticles have been used to control wheat stem rot with high efficacy, providing a new solution for the control of this important disease. Attached Figure Description

[0036] Figure 1 This is a diagram showing the color changes during the cultivation process.

[0037] Figure 2 Scanning electron microscopy image of nano-platinum prepared from fermentation broth of △PS04-17.

[0038] Figure 3 This is a scanning electron microscope image of the prepared platinum nanoparticles.

[0039] Figure 4 This is a site map for measuring the energy spectrum.

[0040] Figure 5 This is an energy spectrum.

[0041] Figure 6This is a graph showing the inhibitory effect of nano-platinum on banana wilt pathogens.

[0042] Figure 7 This is a graph showing the inhibition of wheat stem rot fungus by nano-platinum.

[0043] Figure 8 This is a graph showing the inhibition of tomato root rot fungus by nano-platinum.

[0044] Figure 9 This is a graph showing the inhibitory effect of nano-platinum on tobacco anthrax bacteria.

[0045] Figure 10 The graph shows the inhibition of litchi anthracnose by nano-platinum.

[0046] Figure 11 The graph shows the inhibition of downy mildew fungus on litchi by nano-platinum.

[0047] Figure 12 This is a graph showing the inhibition rate of nano-platinum against plant pathogenic fungi.

[0048] Figure 13 This image shows the growth of potted wheat plants inoculated with and uninoculated with wheat stem rot fungus.

[0049] Figure 14 Figure showing the height of wheat seedlings in pots after inoculation with and without wheat stem rot fungus.

[0050] Figure 15 Figures showing the stem length of potted wheat plants after inoculation with and without wheat stem rot fungus.

[0051] Figure 16 Figures showing the stem thickness of potted wheat plants after inoculation with and without wheat stem rot fungus.

[0052] Figure 17 Root length diagrams of potted wheat plants inoculated with and uninoculated with wheat stem rot fungus.

[0053] Figure 18 Disease index graph for wheat stem base rot in potted plants with and without nanoplatinum application. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0055] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0056] The Cribobacterium species used in the examples ( Paenibacillus kribbensisThe aerospace mutant strain △PS04-17 is a research result of the research group of this invention. Existing research records that it was deposited at the Guangdong Provincial Microbial Culture Collection Center on March 17, 2022, with the accession number: GDMCC NO:62233, the deposit address is No. 100, Xianlie Middle Road, Guangzhou, and the existing Chinese patent publication number is: CN114480222A.

[0057] The culture medium formulation used in the examples is as follows: Modified Czapek liquid culture medium: its components are sodium nitrate 1.5~3 g / L, potassium dihydrogen phosphate 1~1.5 g / L, dipotassium hydrogen phosphate 1~2 g / L, potassium chloride 0.5~0.8 g / L, magnesium sulfate 0.5~0.8 g / L, ferrous sulfate 0.01 g / L, sucrose 30~50 g / L, and pH value 7~7.2.

[0058] Modified Czapek solid medium: Its composition is modified Czapek liquid medium with 17 g / L agar added.

[0059] PDA plates: 200 g potato, 20 g glucose, 1 L distilled water, sterilized at 121 ℃ for 20 min, then poured into plates.

[0060] Example 1: Preparation, purification and identification of nano-platinum 1. Reduction of nano-platinum The △PS04-17 strain was inoculated into solid Czapek's medium and cultured at an incubator to activate it. The activated △PS04-17 was then inoculated into liquid Czapek's medium and cultured with shaking at 28 °C for 2 days to obtain the seed culture solution. A 1×10⁻⁶ solution was prepared. 6 Seed culture at a concentration of cuf / mL was inoculated at a 1% inoculum into liquid Czapek's medium containing 1 mM, 5 mM, and 10 mM hexachloroplatinic acid, respectively, and fermented statically at room temperature (25-28℃) for 7 days. On the seventh day, samples were collected, centrifuged at 6000 r / min for 20 min, and the supernatant was collected for ICP testing. The concentration of platinum in the supernatant was determined, and the conversion rate of hexachloroplatinic acid to nano-platinum was calculated using the following formula: ; Calculations showed that the conversion rates of hexachloroplatinic acid to platinum nanoparticles were 44.8%, 53.76%, and 62.8% at concentrations of 1 mM, 5 mM, and 10 mM, respectively.

[0061] 2. Preparation of nano-platinum The △PS04-17 strain was inoculated into solid Czapek's medium and cultured at an incubator to activate it. The activated △PS04-17 was then inoculated into liquid Czapek's medium and cultured with shaking at 28°C for 2 days to obtain a seed culture solution. A 1×10⁻⁶ solution was prepared. 6 The seed culture with a concentration of cuf / mL was inoculated at a rate of 1% into liquid Czapek's medium containing 1 mM hexachloroplatinic acid and allowed to ferment statically at room temperature (25-28°C) for 7 days. The appearance was photographed and recorded on days 0, 1, 3, and 5.

[0062] 3. Purification of nano-platinum The fermented sample was centrifuged at 6000 r / min for 20 min, the supernatant was discarded, and the sample was washed three times with sterile water, then three times with 0.9% NaCl solution, and three times with 0.1 mol / L Tris-HCl. Sterile water was added to adjust the volume of the precipitate cells to at least half the original sample volume. The sample was then sonicated at 4 ℃ with the following settings: power 450 W, 5 s sonication intervals followed by a 5 s pause, and a total running time of 40 min. After sonication, the sample was centrifuged at 12000 rpm for 10 min, and the precipitate was washed three times consecutively with 1.5 mol / L Tris / HCl buffer (pH 8.8). The precipitate was collected by centrifugation, resuspended in 4 mL of ultrapure water, and 2 mL of n-octanol was added. The mixture was shaken for 5 min, centrifuged at 3000 rpm for 5 min, and then placed in a 4 ℃ refrigerator for 24 h to allow for clear phase separation. Once the brown platinum nanoparticles precipitated at the bottom of the centrifuge tube, the cells between the two phases were discarded and the precipitate was washed twice with sterile water. Finally, the platinum nanoparticles were resuspended in 1 mL of ultrapure water, dropped onto sterile aluminum foil, and allowed to dry naturally to obtain pure platinum nanoparticles.

[0063] 4. Identification of nano-platinum The obtained platinum nanoparticles were fixed on the sample stage. One sample was sputter-coated with gold and its morphology was photographed using a scanning electron microscope (SEM). The other sample was observed using an SEM and the elemental composition of the platinum nanoparticles was analyzed by EDS. Simultaneously, a Hitachi SU8010 SEM was used to image and photograph the fermentation broth ΔPS04-17 obtained in a medium containing hexachloroplatinic acid, as well as the purified selenium nanoparticles.

[0064] The color during cultivation on days 0, 1, 3, and 5 is as follows: Figure 1 As shown, the color gradually darkens during the reduction process to form platinum nanoparticles, eventually turning brown, indicating the formation of brown platinum nanoparticles. △Scanning electron micrograph of platinum nanoparticles prepared from PS04-17 fermentation broth is shown below. Figure 2 As shown in the figure, the arrows indicate platinum nanoparticles, showing the formation of spherical platinum nanoparticles on the bacteria; while the scanning electron microscope image of the purified selenium nanoparticles is shown below. Figure 3As shown, the particle size of the platinum nanoparticles was measured to be 30–150 nm. The elemental energy spectrum site diagram and energy spectrum diagram of the nanoparticles are as follows. Figure 4 and Figure 5 As shown in the figure, the energy spectrum positions measured at the point show characteristic peaks of platinum (Pt), indicating that the prepared nanoparticles are platinum nanoparticles.

[0065] Example 2: Determination of the antibacterial effect of △PS04-17 synthesized nano-platinum The antibacterial effect of the ΔPS04-17 synthesized platinum nanoparticles prepared in Example 1 was determined using the mycelial growth rate method. The indicator bacteria (laboratory-preserved plant pathogens: Fusarium wilt of banana) were used. Fusarium oxysporum f.sp. cubense ), wheat stem rot fungus ( Fusarium pseudograminearum Tomato root rot pathogen ( Fusarium solani ) and tobacco anthrax bacteria ( Colletotrichum nicotianae Take a piece of mycelium and place it in the center of a PDA plate containing nano-platinum (concentration of 500 μg / mL) prepared in Example 1. Separately, place an indicator bacterium (a laboratory-preserved plant pathogen: *Litsea cubeba*) in the center. Colletotrichum siamense ), Phytophthora downy mildew ( Peronophythora litchii Mycelial pellets were inoculated into the center of a PDA plate containing 1000 μg / mL of nano-platinum prepared in Example 1. The control group consisted of a PDA plate without nano-platinum. The experiment was performed in triplicate. After inoculation, the plates were placed in a 28°C dark incubator. When the mycelium in the control group nearly covered the plate, the colony diameter was recorded, and the inhibition rate was calculated. The formula for calculating the inhibition rate is as follows: Antibacterial rate = (Control colony diameter - Treated colony diameter) / Control colony diameter × 100%; The results showed that nanoplatin was effective against six plant pathogenic fungi: Fusarium wilt of banana (… Figure 6 ), wheat stem rot fungus ( Figure 7 Tomato root rot pathogen ( Figure 8 ), tobacco anthrax bacteria ( Figure 9 ), litchi anthracnose fungus ( Figure 10 ), Phytophthora downy mildew ( Figure 11 It has a good inhibitory effect, and its antibacterial rate ( ) is statistically shown to be 100%. Figure 12 The results showed that its antibacterial rates were 23.5%, 88.6%, 51.3%, and 52.8%, respectively, and the antibacterial rate against both pathogens of litchi was 100%. This demonstrates that the synthesized nano-platinum of △PS04-17 has broad-spectrum antibacterial activity and can be used for the control of plant diseases, and is effective against *Pseudomonas aeruginosa*, the pathogen causing wheat stem rot. Fusarium pseudograminearum ) and litchi anthracnose fungus ( Colletotrichum siamense), Phytophthora downy mildew ( Peronophythora litchii It has a high inhibitory effect.

[0066] Example 3: Application of nano-platinum in the control of wheat stem base rot The efficacy of the synthetic platinum nanoparticles prepared in Example 1 (△PS04-17) against wheat stem rot (FP) was verified through pot experiments. To eliminate potential interference from existing Fusarium species in the soil, and especially considering the Fusarium-affected nature of the sampling sites, autoclaved soil was used for the experiment. Four groups were set up, with three replicates for each group: ① Sterile water group: After wheat seeds showed signs of sprouting, they were soaked in sterile water for 30 seconds, then dried and soaked in sterile water for 12 hours. ②F.P. group: After wheat seeds showed signs of sprouting, they were soaked in sterile water for 30 seconds, then air-dried and soaked in a 10% FP conidia solution. 5 (pcs / mL) 12 h; ③ Nanoplatinum + FP group: After wheat seeds showed signs of sprouting, they were soaked in nanoplatinum for 30 seconds (concentration 500 μg / mL), then air-dried, and then soaked in a FP conidial solution (concentration 10). 5 (pcs / mL) 12 h; ④ Nanoplatinum group: After wheat seeds showed signs of sprouting, they were soaked in nanoplatin for 30 seconds (concentration 500 μg / mL), then dried and soaked in sterile water for 12 hours; After soaking, transfer the seedlings to sterile soil, maintaining the soil moisture content at 70%-80% daily. Record the seedling status 14 days after inoculation with the pathogen, measuring seedling height, stem length, stem diameter, and root length; and calculate the disease index and control efficiency using the following formulas.

[0067] ; ; The results are as follows Figure 13 ~as Figure 17 As shown, there were no significant differences in seedling height, stem length, stem diameter, and root length between the sterile water group and the nano-platinum group, indicating that nano-platinum does not affect wheat growth. However, significant differences were observed in seedling height, stem length, stem diameter, root length, and disease index between the FP group and the nano-platinum + FP group, indicating that nano-platinum-soaked wheat seeds can effectively mitigate the damage caused by FP, reduce the severity of wheat stem rot, and achieve a control efficiency of 78.2%. Figure 18 The prevention and control effects are significant.

[0068] In summary, this invention provides a novel application of the space-mutant strain △PS04-17 in the biosynthesis of platinum nanoparticles. Studies show that strain △PS04-17 possesses the ability to reduce hexachloroplatinic acid (HPA). The method for synthesizing platinum nanoparticles by reducing HPA in liquid fermentation medium using strain △PS04-17 is simple, convenient, and the biosynthetic conditions are mild, requiring no expensive or toxic chemical reducing agents, resulting in low cost and environmental friendliness. Furthermore, this invention demonstrates that strain △PS04-17 is a novel strain resource with high efficiency in reducing HPA, filling a gap in the field of microbial synthesis of platinum nanoparticles. Meanwhile, the nano-platinum synthesized by △PS04-17 can control a variety of plant pathogens, showing good inhibitory effects on banana wilt fungus, wheat stem base rot fungus, tomato root rot fungus, tobacco anthracnose fungus, litchi anthracnose fungus, and litchi downy mildew fungus. Among them, the inhibition rate against litchi anthracnose fungus and litchi downy mildew fungus can reach 100%. Moreover, for the first time, biosynthesized nano-platinum was used to control wheat stem base rot, with a control efficiency of 78.2% and good control effect, providing a new solution for the control of important diseases in agricultural production.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. Cribbenoid Bacillus ( Paenibacillus kribbensis The application of the space-malignant mutant bacterium △PS04-17 in the preparation of nano-platinum is characterized by, The △PS04-17 strain was deposited at the Guangdong Provincial Center for Microbial Culture Collection on March 17, 2022, with accession number GDMCC NO:62233.

2. A method for biosynthesizing platinum nanoparticles, characterized in that, The space-bred mutant strain △PS04-17 was activated and inoculated into a fermentation medium containing platinum salts for fermentation culture. After fermentation, the fermentation broth was centrifuged, the supernatant was discarded, and the mixture was washed and purified. The precipitate was collected, washed, and dried to obtain nano-platinum. The space-bred mutant strain △PS04-17 was deposited at the Guangdong Provincial Center for Microbial Culture Collection on March 17, 2022, with the accession number: GDMCC NO:62233.

3. The method according to claim 2, characterized in that, The inoculation amount of the space mutant strain △PS04-17 is 1~5%.

4. The method according to claim 3, characterized in that, The platinum salt is hexachloroplatinic acid or potassium chloroplatinate; the concentration of the platinum salt is 1~5mM.

5. The method according to claim 3, characterized in that, The fermentation medium used is a modified Czapek medium with the following formula: nitrogen source 1.5~3 g / L, potassium dihydrogen phosphate 1~1.5 g / L, dipotassium hydrogen phosphate 1~2 g / L, potassium chloride 0.5~0.8 g / L, magnesium sulfate 0.5~0.8 g / L, ferrous sulfate 0.01~0.1 g / L, carbon source 30~50 g / L, and pH value 7~7.

2.

6. A method for synthesizing △PS04-17 nanoplatinum, prepared by the method described in any one of claims 2 to 5.

7. The application of the nano-platinum according to claim 6 in inhibiting plant pathogens or in preventing and controlling plant diseases caused by pathogens, characterized in that, The plant pathogen is *Fusarium wilt* (a fungus that causes banana wilt). Fusarium oxysporum f. sp. cubense ), wheat stem rot fungus ( Fusarium pseudograminearum Tomato root rot pathogen ( Fusarium solani ), tobacco anthrax bacteria ( Colletotrichum nicotianae ), litchi anthracnose fungus ( Colletotrichum siamense ), Phytophthora downy mildew ( Peronophythora litchii One or more of the following.

8. The application of the nano-platinum according to claim 6 in the preparation of products that inhibit plant pathogens or prevent plant diseases caused by plant pathogens, characterized in that, The plant pathogen is *Fusarium wilt* (a fungus that causes banana wilt). Fusarium oxysporum f. sp. cubense ), wheat stem rot fungus ( Fusarium pseudograminearum Tomato root rot pathogen ( Fusarium solani ), tobacco anthrax bacteria ( Colletotrichum nicotianae ), litchi anthracnose fungus ( Colletotrichum siamense ), Phytophthora downy mildew ( Peronophythora litchii One or more of the following.

9. A product characterized in that, Contains the nano-platinum as described in claim 6.

10. A method for preventing and controlling wheat stem base rot, characterized in that, The plants were treated with the nano-platinum described in claim 6.

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