Preparation method of streptomycete agent cooperating with biochar and application of streptomycete agent in prevention and treatment of tomato gray mold

Abstract

The invention provides a preparation method of a streptomycete agent cooperating with biochar and application of the streptomycete agent in prevention and treatment of tomato gray mold, and belongs to the technical field of microbial technology application. The strain used in the invention is streptomyces albidoflavus LNU-CPARS 28, the biochar coconut shell, corn straw and rice straw cooperate with the streptomyces albidoflavus, so that the inhibition effect of the streptomyces albidoflavus on tomato gray mold pathogenic bacteria is remarkably enhanced, and the bacteriostatic effect of the streptomyces albidoflavus is remarkably enhanced by 9.6% (Plt; 0.01) of the substrate. The method is convenient to prepare, simple in production process, low in raw material and equipment cost, green, pollution-free and suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial technology application, and specifically relates to a preparation method of a streptomyces agent synergistic with biochar and application of the agent in preventing and controlling tomato gray mold. Background Art

[0002] Tomato (Solanum lycopersicum) is widely cultivated and rich in nutrients. It is one of the main economic vegetable crops and an important model plant in plant science research. Research on tomatoes is of great significance to agricultural and scientific development. Tomato gray mold is caused by Botrytis cinerea, which seriously harms the leaves, stems, flowers and fruits of tomatoes, causing tomato production to decrease or even fail. Although chemical pesticides can control this disease to a certain extent, their long-term use in large quantities will pose a potential threat to human and natural health. Therefore, finding safe, reliable and environmentally friendly biological control methods has become an important research direction to achieve sustainable agricultural development.

[0003] Biochar is a solid byproduct of thermal cracking of biomass raw materials. It has the characteristics of stable structure, large specific surface area, high content of certain nutrients and organic carbon. In addition to carbon fixation and reducing greenhouse gas emissions, biochar can also be used to improve soil pH, maintain soil moisture, and promote plant growth and health under biotic and abiotic stress conditions. Therefore, biochar is a new material with the potential to inhibit soil-borne plant diseases.

[0004] Streptomyces spp. is the largest genus of actinomycetes. Most Streptomyces produce spores. The genus Streptomyces is characterized by complex secondary metabolism and the ability to produce a variety of secondary metabolites (such as chloramphenicol, neomycin, etc.). These metabolites have antifungal and antibacterial effects to promote growth. Therefore, the genus Streptomyces is a potential genus of beneficial biocontrol bacteria. Summary of the invention

[0005] The purpose of the present invention is to provide a method for using biochar to cooperate with Streptomyces to resist tomato gray mold. The addition of biochar during the cultivation of Streptomyces can effectively improve the inhibition of Streptomyces on the pathogen of tomato gray mold, thereby alleviating soil degradation and improving soil fertility while preventing and controlling tomato diseases and promoting yield increase.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a streptomyces agent that cooperates with biochar comprises the following steps:

[0008] 1) The biochar is air-dried and crushed, and then put into a carbonization furnace for carbonization. After the carbonization is completed, the biochar is cooled to 25°C in a cooler to obtain the biochar. The biochar is ground and sieved through a 180-mesh sieve to obtain biochar powder, which is then sterilized with high-pressure steam at 121°C for 20 minutes for use;

[0009] 2) Add sterilized biochar to the Streptomyces expansion culture medium, and after mixed culture for 4 days, obtain the biochar Streptomyces mixed culture medium.

[0010] Furthermore, in the above preparation method, the biochar is coconut shell, corn stalks or rice stalks.

[0011] Preferably, the biochar is coconut shell.

[0012] Furthermore, in the above-mentioned preparation method, in step 1), the carbonization conditions are: keeping warm at 300-500°C for 2-3h, and the heating rate is 10°C / min.

[0013] Furthermore, in the above-mentioned preparation method, in step 2), the amount of sterilized biochar added is 1%-5% by volume of the mass volume of the Streptomyces expansion culture medium.

[0014] Furthermore, in the above preparation method, in step 2), mixed culture is carried out at 28° C. and a rotation speed of 180 rpm.

[0015] Furthermore, in the above-mentioned preparation method, in step 2), the preparation method of the Streptomyces expansion culture fluid comprises the following steps:

[0016] 1) Activation of Streptomyces strains: The Streptomyces strains stored in -80°C glycerol were cultured on ISP 3 solid medium at 28°C for 7 days;

[0017] 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces seed solution;

[0018] 3) Streptomyces liquid expansion culture: The Streptomyces seed liquid obtained in step 2) was added to ISP2 liquid culture medium at a volume ratio of 1:10 and cultured at 28° C. for 3 days to obtain Streptomyces expansion culture liquid.

[0019] Furthermore, in the above-mentioned method for preparing the Streptomyces expansion culture medium, the Streptomyces is Streptomyces alboflavus LNU-CPARS28, which is deposited in the General Microbiological Center of China National Microbiological Culture Collection Administration with the number CGMCC No.30893.

[0020] Furthermore, in the above-mentioned method for preparing the Streptomyces expansion culture medium, in step 1), the composition of the ISP3 solid culture medium is: KNO3 0.2g / L, K2HPO4 0.5g / L, MgSO4 0.2g / L, agar 20g / L, and oats 20g / L.

[0021] Furthermore, in the above-mentioned method for preparing the Streptomyces expansion culture medium, in step 2), the composition of the Gauze's Synthetic Medium No.1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl 0.5g / L, MgSO4 . 7H2O0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L.

[0022] Furthermore, in the above-mentioned method for preparing the Streptomyces expansion culture medium, in step 3), the composition of the ISP2 liquid culture medium is: yeast extract powder 4.0 g / L, malt extract powder 10.0 g / L, glucose 4.0 g / L, FeSO4 . 7H2O 0.1g / L, ZnSO4 . 7H2O0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.5.

[0023] Application of the streptomyces agent prepared by any of the preparation methods described above in synergistic biochar in preventing and controlling tomato gray mold.

[0024] The beneficial effects of the present invention are:

[0025] 1. In the experiment of the present invention, Botrytis cinerea was used as the target bacteria, Streptomyces alboflavus LNU-CPARS28 and a mixture of biochar were used as the experimental treatment combination, and the best antibacterial combination was obtained by cultivating, observing and calculating the antibacterial rate: a mixture of coconut shell biochar and Streptomyces.

[0026] 2. The main challenge faced by most biological control agents is that they can significantly control pathogens in vitro, but this effect may be weakened or limited in vivo due to complex and diverse factors (such as temperature, pH value, ultraviolet radiation, etc.). Many studies have shown that the appropriate use of biological control agents has a significant impact on the disease control effect of biological control agents. For example, using potato starch as a carrier can significantly improve the vitality and control effect of Candida sake CPA-1. Biochar is a porous carbonaceous material produced by the pyrolysis of organic matter under oxygen-limited conditions. The present invention uses biochar as a carrier of Streptomyces. Under laboratory conditions, biochar synergizes with Streptomyces to significantly improve the antibacterial ability of Streptomyces, among which coconut shell biochar improves the antibacterial ability of Streptomyces by 9.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 These are the antibacterial effect diagrams of Streptomyces alboflavin LNU-CPARS28 against Botrytis cinerea, among which AC are the confrontation pictures of Streptomyces alboflavin LNU-CPARS28 and Botrytis cinerea (AC are parallel experiments), and D is the picture of Botrytis cinerea cultured alone.

[0028] Figure 2 These are the confrontation pictures of the mixed culture of Streptomyces alboflavin LNU-CPARS28 and three kinds of biochars and Botrytis cinerea. Among them, AC are the confrontation pictures of the mixture of three kinds of biochars and Streptomyces alboflavin LNU-CPARS28 and Botrytis cinerea (○ is a mixture of rice straw biochar and Streptomyces, △ is a mixture of coconut shell biochar and Streptomyces, □ is a mixture of corn straw biochar and Streptomyces, AC are parallel experiments), and D is a picture of Botrytis cinerea cultured alone.

[0029] Figure 3 These are pictures of three types of biochars confronting Streptomyces alboflavinus LNU-CPARS28 (○ is rice straw biochar, △ is coconut shell biochar, and □ is corn straw biochar). A and B are the front and back pictures, respectively.

[0030] Figure 4 This is a schematic diagram of the mixed culture of biochar and Streptomyces alboflavin for controlling Botrytis cinerea, where Botrytis cinerea is in the middle of the plate and the three holes represent the mixed culture of biochar and Streptomyces alboflavin. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0032] The biocontrol streptomyces resistant to tomato gray mold used in the present invention is Streptomyces alboflavus LNU-CPARS28, which is deposited in the General Microbiological Center of China Microbiological Culture Collection Administration and is numbered CGMCC No.30893.

[0033] Example 1 Detection of antibacterial effect of biocontrol Streptomyces LNU-CPARS28

[0034] 1) Activation of Streptomyces strains: The Streptomyces albus LNU-CPARS28 stored in glycerol at -80°C was cultured on ISP 3 solid medium at 28°C for 7 days;

[0035] The composition of ISP3 solid medium is: KNO3 0.2g / L, K2HPO4 0.5g / L, MgSO4 0.2g / L, agar 20g / L, oat 20g / L;

[0036] 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces alboflavin obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces alboflavin seed solution;

[0037] The composition of Gauze's Synthetic Medium No.1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl0.5g / L, MgSO4 . 7H2O 0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L;

[0038] 3) Liquid expansion culture of Streptomyces: the seed liquid of Streptomyces alboflavin obtained in step 2) was added to ISP2 liquid culture medium at a ratio of 1:10 (v / v) and cultured at 28° C. for 3 days to obtain an expansion culture liquid of Streptomyces alboflavin;

[0039] The composition of ISP2 liquid medium is: yeast extract powder 4.0g / L, malt extract powder 10.0g / L, glucose 4.0g / L, FeSO4 . 7H2O0.1g / L, ZnSO4 . 7H2O 0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.5;

[0040] 4) 1 mL of the culture medium of Streptomyces alboflavin obtained in step 3) was taken into a 1.5 mL EP tube and centrifuged at 10,000 rpm for 3 min, the supernatant was discarded, and then the culture medium was resuspended twice with sterile water for later use;

[0041] 5) The biocontrol Streptomyces LNU-CPARS28 was used to conduct an antibacterial experiment on the pathogen Botrytis cinerea: a 7 mm pathogen cake was placed in the center of a potato dextrose solid medium (PDA) plate, and three small holes with a radius of 5 mm were punched in three directions equidistant from the center using a hole puncher. 100 μL of a culture of Streptomyces albus resuspended twice in sterile water was added to the small holes. The plate with only pathogens was used as the control group. All experimental treatments were incubated in a constant temperature incubator at 28°C for 7 days. The experiment was repeated 3 times. After the incubation, the inhibition rate was observed, recorded and calculated.

[0042] 6) Calculation of the inhibition rate: After the incubation, measure and record the diameter of the inhibition zone and calculate it according to formula (1):

[0043]

[0044] The experimental results are as follows Figure 1 And as shown in Table 1.

[0045] Example 2 Detection of antibacterial effect of a mixture of biocontrol Streptomyces LNU-CPARS28 and coconut shell biochar

[0046] 1) Activation of Streptomyces strains: The Streptomyces albus LNU-CPARS28 stored in glycerol at -80°C was cultured on ISP 3 solid medium at 28°C for 7 days;

[0047] The composition of ISP3 solid medium is: KNO3 0.2g / L, K2HPO4 0.5g / L, MgSO4 0.2g / L, agar 20g / L, oat 20g / L;

[0048] 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces alboflavin obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces alboflavin seed solution;

[0049] The composition of Gauze's Synthetic Medium No.1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl0.5g / L, MgSO4 . 7H2O 0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L;

[0050] 3) Liquid expansion culture of Streptomyces: the seed liquid of Streptomyces alboflavin obtained in step 2) was added to ISP2 liquid culture medium at a ratio of 1:10 (v / v) and cultured at 28° C. for 3 days to obtain an expansion culture liquid of Streptomyces alboflavin;

[0051] The composition of ISP2 liquid medium is: yeast extract powder 4.0g / L, malt extract powder 10.0g / L, glucose 4.0g / L, FeSO4 . 7H2O0.1g / L, ZnSO4 . 7H2O 0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.5;

[0052] 4) After air-drying and crushing, the coconut shell biochar was placed in a carbonization furnace and slowly heated to 450°C at a rate of 10°C / min, and kept warm for 2 hours. After the carbonization was completed, it was cooled to 25°C in a cooler to obtain the coconut shell biochar. The coconut shell biochar was ground and sieved through a 180-mesh sieve to obtain the coconut shell biochar powder, which was then sterilized with high-pressure steam at 121°C for 20 minutes for later use;

[0053] 5) Add the sterilized coconut shell biochar to the expanded culture medium of Streptomyces alboflavin at a ratio of 5% (w / v), and culture the mixture at 28° C. and 180 rpm for 4 days to obtain a coconut shell biochar-Streptomyces alboflavin mixed culture medium.

[0054] 6) 1 mL of the coconut shell biochar Streptomyces alboflavin culture medium obtained in step 5) was taken into a 1.5 mL EP tube and centrifuged at 10,000 rpm for 3 min, the supernatant was discarded, and then the culture medium was resuspended twice with sterile water for later use;

[0055] 7) The antibacterial experiment of the mixture of biocontrol Streptomyces LNU-CPARS28 and coconut shell biochar against the pathogen Botrytis cinerea was carried out: a 7mm pathogen cake was placed in the center of a potato dextrose solid medium (PDA) plate, and three small holes with a radius of 5mm were punched in three directions equidistant from the center with a hole puncher, and 100μL of a mixed culture of coconut shell biochar and Streptomyces albus resuspended twice in sterile water was added to the small holes. The plate with only pathogens was used as the control group. All experimental treatments were incubated in a constant temperature incubator at 28℃ for 7d. The experiment was repeated 3 times. After the incubation, the inhibition rate was observed, recorded and calculated.

[0056] 8) Calculation of the inhibition rate: After the incubation, measure and record the diameter of the inhibition zone and calculate it according to formula (1).

[0057] The experimental results are as follows Figure 2 And as shown in Table 1.

[0058] Example 3 Detection of antibacterial effect of a mixture of biocontrol Streptomyces LNU-CPARS28 and rice straw biochar

[0059] 1) Activation of Streptomyces strains: The Streptomyces albus LNU-CPARS28 stored in glycerol at -80°C was cultured on ISP 3 solid medium at 28°C for 7 days;

[0060] The composition of ISP3 solid medium is: KNO3 0.2g / L, K2HPO4 0.5g / L, MgSO4 0.2g / L, agar 20g / L, oat 20g / L;

[0061] 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces alboflavin obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces alboflavin seed solution;

[0062] The composition of Gauze's Synthetic Medium No.1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl0.5g / L, MgSO4 . 7H2O 0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L;

[0063] 3) Liquid expansion culture of Streptomyces: the seed liquid of Streptomyces alboflavin obtained in step 2) was added to ISP2 liquid culture medium at a ratio of 1:10 (v / v) and cultured at 28° C. for 3 days to obtain an expansion culture liquid of Streptomyces alboflavin;

[0064] The composition of ISP2 liquid medium is: yeast extract powder 4.0g / L, malt extract powder 10.0g / L, glucose 4.0g / L, FeSO4 . 7H2O0.1g / L, ZnSO4 . 7H2O 0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.5;

[0065] 4) After air-drying and crushing, the rice straw biochar was placed in a carbonization furnace and slowly heated to 450°C at a rate of 10°C / min, and kept warm for 2 hours. After the carbonization was completed, it was cooled to 25°C in a cooler to obtain the rice straw biochar. After grinding, the rice straw biochar was sieved through a 180-mesh sieve to obtain rice straw biochar powder, which was then sterilized with high-pressure steam at 121°C for 20 minutes for use;

[0066] 5) Add sterilized rice straw biochar to the expanded culture medium of Streptomyces alboflavin at a ratio of 5% (w / v), and culture the mixture at 28° C. and 180 rpm for 4 days to obtain a rice straw biochar Streptomyces alboflavin mixed culture medium.

[0067] 6) 1 mL of the rice straw biochar Streptomyces alboflavinus culture medium obtained in step 5) was taken into a 1.5 mL EP tube and centrifuged at 10,000 rpm for 3 min, the supernatant was discarded, and then the culture medium was resuspended twice with sterile water for later use;

[0068] 7) The antibacterial experiment of the mixture of biocontrol Streptomyces LNU-CPARS28 and rice straw biochar against the pathogen Botrytis cinerea was carried out: a 7 mm pathogen cake was placed in the center of a potato dextrose solid medium (PDA) plate, and three small holes with a radius of 5 mm were punched in three directions equidistant from the center with a hole puncher, and 100 μL of a mixed culture of rice straw biochar and Streptomyces albus resuspended twice in sterile water was added to the small holes. The plate with only pathogens was used as the control group. All experimental treatments were incubated in a constant temperature incubator at 28°C for 7 days. The experiment was repeated 3 times. After the incubation, the inhibition rate was observed, recorded and calculated.

[0069] 8) Calculation of the inhibition rate: After the incubation, measure and record the diameter of the inhibition zone and calculate it according to formula (1).

[0070] The experimental results are as follows Figure 2 And as shown in Table 1.

[0071] Example 4 Detection of antibacterial effect of a mixture of biocontrol Streptomyces LNU-CPARS28 and corn straw biochar

[0072] 1) Activation of Streptomyces strains: The Streptomyces albus LNU-CPARS28 stored in glycerol at -80°C was cultured on ISP 3 solid medium at 28°C for 7 days;

[0073] The composition of ISP3 solid medium is: KNO3 0.2g / L, K2HPO4 0.5g / L, MgSO4 0.2g / L, agar 20g / L, oat 20g / L;

[0074] 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces alboflavin obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces alboflavin seed solution;

[0075] The composition of Gauze's Synthetic Medium No.1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl0.5g / L, MgSO4 . 7H2O 0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L;

[0076] 3) Liquid expansion culture of Streptomyces: the seed liquid of Streptomyces alboflavin obtained in step 2) was added to ISP2 liquid culture medium at a ratio of 1:10 (v / v) and cultured at 28° C. for 3 days to obtain an expansion culture liquid of Streptomyces alboflavin;

[0077] The composition of ISP2 liquid medium is: yeast extract powder 4.0g / L, malt extract powder 10.0g / L, glucose 4.0g / L, FeSO4 . 7H2O0.1g / L, ZnSO4 . 7H2O 0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.5;

[0078] 4) After air-drying and crushing, the corn straw biochar was placed in a carbonization furnace and slowly heated to 450°C at a rate of 10°C / min, and kept warm for 2 hours. After carbonization, it was cooled to 25°C in a cooler to obtain corn straw biochar. After grinding, the corn straw biochar was sieved through a 180-mesh sieve to obtain corn straw biochar powder, which was then sterilized with high-pressure steam at 121°C for 20 minutes for later use;

[0079] 5) Sterilized corn straw biochar was added to the expanded culture medium of Streptomyces alboflavin at a ratio of 5% (w / v), and mixed culture was carried out at 28° C. and 180 rpm for 4 days to obtain a corn straw biochar Streptomyces alboflavin mixed culture medium.

[0080] 6) 1 mL of the corn straw biochar Streptomyces alboflavinus culture medium obtained in step 5) was taken into a 1.5 mL EP tube and centrifuged at 10,000 rpm for 3 min, the supernatant was discarded, and then the culture medium was resuspended twice with sterile water for later use;

[0081] 7) The antibacterial experiment of the mixture of biocontrol Streptomyces LNU-CPARS28 and corn straw biochar against the pathogen Botrytis cinerea was carried out: a 7 mm pathogen cake was placed in the center of a potato dextrose solid medium (PDA) plate, and three small holes with a radius of 5 mm were punched in three directions equidistant from the center with a hole puncher. 100 μL of a mixed culture of corn straw biochar and Streptomyces albus resuspended twice in sterile water was added to the small holes. The plate with only pathogens was used as the control group. All experimental treatments were incubated in a constant temperature incubator at 28°C for 7 days. The experiment was repeated 3 times. After the incubation, the inhibition rate was observed, recorded and calculated.

[0082] 8) Calculation of the inhibition rate: After the incubation, measure and record the diameter of the inhibition zone and calculate it according to formula (1).

[0083] The experimental results are as follows Figure 2 And as shown in Table 1.

[0084] Table 1 Antibacterial rate of each experimental treatment group

[0085]

[0086] The present invention obtained the results of the experiments of Examples 1-4: the inhibitory effect of biochar and Streptomyces on the pathogen Botrytis cinerea was significantly enhanced (P<0.01), wherein coconut shell biochar increased the inhibitory effect of Streptomyces by 9.6%. The experiment also showed that biochar itself had no inhibitory effect on the pathogen (Botrytis cinerea) ( Figure 3 ).

Claims

1. A method for preparing a streptomyces agent that cooperates with biochar, characterized in that: The steps include: 1) The biochar is air-dried and crushed, and then put into a carbonization furnace for carbonization. After the carbonization is completed, the biochar is cooled to 25°C in a cooler to obtain the biochar. The biochar is ground and sieved through a 180-mesh sieve to obtain biochar powder, which is then sterilized with high-pressure steam at 121°C for 20 minutes for use; 2) Add sterilized biochar to the Streptomyces expansion culture medium, and culture at 28° C. and 180 rpm for 4 days to obtain a biochar Streptomyces mixed culture medium.

2. The preparation method according to claim 1, characterized in that: The biochar is coconut shell, corn stalks or rice stalks.

3. The preparation method according to claim 1, characterized in that: In step 1), the carbonization conditions are: keeping warm at 300-500°C for 2-3h, and heating rate is 10°C / min.

4. The preparation method according to claim 1, characterized in that: In step 2), the amount of sterilized biochar added is 1%-5% by volume of the Streptomyces expansion culture solution.

5. The preparation method according to claim 1, characterized in that: In step 2), the method for preparing the Streptomyces expansion culture fluid comprises the following steps: 1) Activation of Streptomyces strains: The Streptomyces strains stored in -80°C glycerol were cultured on ISP 3 solid medium at 28°C for 7 days; 2) Preparation of Streptomyces seed solution: inoculate the Streptomyces obtained in step 1) into Gauze's Synthetic Medium No. 1 liquid culture medium and culture at 180 rpm and 28° C. for 3 days to obtain a Streptomyces seed solution; 3) Streptomyces liquid expansion culture: The Streptomyces seed liquid obtained in step 2) was added to ISP2 liquid culture medium at a volume ratio of 1:10 and cultured at 28° C. for 3 days to obtain Streptomyces expansion culture liquid.

6. The preparation method according to claim 5, characterized in that: The streptomyces is Streptomyces alboflavus LNU-CPARS28, which is deposited in the General Microbiological Center of China National Microbiological Culture Collection Administration and is numbered CGMCC No.30893.

7. The preparation method according to claim 5, characterized in that: In step 1), the composition of the ISP3 solid culture medium is: KNO3 0.2 g / L, K2HPO4 0.5 g / L, MgSO4 0.2 g / L, agar 20 g / L, and oats 20 g / L.

8. The preparation method according to claim 5, characterized in that: In step 2), the composition of the Gauze's Synthetic Medium No. 1 liquid culture medium is: KNO3 1g / L, K2HPO4 0.5g / L, NaCl 0.5g / L, MgSO4 . 7H2O0.5g / L, FeSO4 . 7H2O 0.01g / L, soluble starch 20g / L.

9. The preparation method according to claim 5, characterized in that: In step 3), the composition of the ISP2 liquid culture medium is: yeast extract powder 4.0 g / L, malt extract powder 10.0 g / L, glucose 4.0 g / L, FeSO4 . 7H2O 0.1g / L, ZnSO4 . 7H2O0.1g / L, MnCl2 . 4H2O 0.1g / L, pH range adjusted to 7.0-7.

5.

10. Use of the streptomyces agent prepared by the preparation method according to any one of claims 1 to 9 in synergistic biochar in preventing and controlling tomato gray mold.

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