A complex microbial inoculant containing penicillium oxalicum and a preparation method thereof

Abstract

The present application relates to the technical field of microbial inoculant, in particular to a compound microbial inoculant containing penicillium oxalicum and a preparation method thereof, the compound microbial inoculant containing penicillium oxalicum comprises the following raw materials in parts by weight: penicillium oxalicum solid-state fermentation product 3-5 parts, zeolite powder 20-25 parts, potassium fulvate 5-10 parts, humic acid 10-15 parts, sodium lignosulfonate 8-12 parts, and modified diatomite 30-40 parts. The compound microbial inoculant containing penicillium oxalicum prepared by the present application has excellent soil-borne disease control effect and good stability.

Description

Technical Field

[0001] This invention relates to the field of microbial inoculants, specifically to a compound inoculant containing Penicillium oxalate and its preparation method. Background Technology

[0002] Penicillium oxalate is a widely distributed functional fungus in soil, possessing highly efficient phosphorus-solubilizing capabilities. It can dissolve insoluble phosphates (such as calcium phosphate) in the soil by secreting organic acids such as oxalic acid and citric acid, converting them into available phosphorus that can be absorbed by plants, significantly improving soil phosphorus utilization. Simultaneously, it can secrete extracellular enzymes such as cellulase and protease to degrade soil organic matter, optimize soil microecology, and inhibit soil-borne pathogens such as Ralstonia solanacearum and Fusarium wilt, thus possessing multiple functions including growth promotion, disease prevention, and soil remediation. However, applying Penicillium oxalate alone has problems such as weak colonization, easy loss, and short survival time. After application to the soil, it is easily affected by environmental stresses (such as salinity, drought, low temperature, and high pH), making it difficult to quickly form a dominant microbial community. Its functional performance is unstable and cannot meet the comprehensive improvement needs of complex soil environments.

[0003] Patent CN114424775A discloses a compound microbial agent for controlling nematodes. This powder consists of active ingredients and adjuvants. The active ingredients are: *Paecilomyces lilacinus* powder obtained by fermentation of *Paecilomyces lilacinus* WZ004 and *Paecilomyces oxalate* powder obtained by fermentation of *Paecilomyces oxalate* WZ006; the adjuvants are: kaolin, dispersant NNO, and sodium lignin sulfonate. This compound microbial agent can control soil-borne diseases and promote plant growth. However, the formula lacks growth synergists required for microbial germination and colonization, which may reduce spore survival rate and thus decrease the effectiveness in controlling soil-borne diseases.

[0004] Patent CN11744733A discloses a bio-organic liquid fertilizer and its production method. This bio-organic liquid fertilizer, prepared by effectively combining *Penicillium oxalate* and biogas slurry organic fertilizer containing humic acid, can effectively prevent cucumber wilt, promote cucumber growth, and increase enzyme activity in cucumber-growing soil. However, biogas slurry has a complex composition, typically containing high concentrations of ammonium nitrogen, readily available phosphorus and potassium, and a large number of indigenous microorganisms. In this liquid environment rich in readily available nutrients and not strictly sterilized, *Penicillium oxalate* is highly susceptible to excessive vegetative growth or autolysis, leading to premature cell death or off-odors during storage.

[0005] Therefore, there is an urgent need in the market for a compound microbial agent containing Penicillium oxalate that has excellent control effects on soil-borne diseases and good stability. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain a compound microbial agent containing Penicillium oxalate that has excellent control effect on soil-borne diseases and good stability.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a compound microbial agent containing Penicillium oxalate, comprising the following raw materials in parts by weight: 3-5 parts of Penicillium oxalate solid fermentation product, 20-25 parts of zeolite powder, 5-10 parts of potassium humate, 10-15 parts of humic acid, 8-12 parts of sodium lignosulfonate, and 30-40 parts of modified diatomaceous earth.

[0008] This application involves compounding Penicillium oxalate solid-state fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate, and modified diatomaceous earth to obtain a compound microbial agent containing Penicillium oxalate that exhibits good control efficacy against soil-borne diseases and good stability. Sodium lignosulfonate ensures uniform dispersion of the compound microbial agent in water, while modified diatomaceous earth acts as an inert carrier for Penicillium oxalate, allowing for uniform dispersion after dilution and preventing loss of activity due to precipitation during use. Furthermore, modified diatomaceous earth protects the Penicillium oxalate molecules, reducing their chemical reactions with other substances and thus extending the shelf life of the compound microbial agent.

[0009] In some embodiments, the method for preparing the Penicillium oxalate solid fermentation product includes the following steps: A1. Activation of strain and preparation of seed solution: Penicillium oxalate strain was inoculated into slant culture medium for activation culture, and the activated spores were collected to prepare spore suspension; A2. Preparation and sterilization of solid-state fermentation medium: Mix the solid-state fermentation substrate with the nutrient solution evenly, adjust the initial moisture content to obtain the solid-state fermentation medium, and then sterilize it. A3. Inoculation and solid-state fermentation: The spore suspension prepared in step A1 is inoculated into the sterilized solid-state fermentation medium in step A2 under aseptic conditions, mixed evenly, and placed in a constant temperature incubator for static solid-state fermentation at a temperature of 28℃-35℃ for 5-10 days. A4. Post-processing: After fermentation, the solid fermentation product is collected, dried, crushed and sieved to obtain the solid fermentation product of Penicillium oxalate.

[0010] Preferably, the activation culture conditions are: pH 6.0-7.0, temperature 25-28℃, and culture time 5-7 days.

[0011] In some embodiments, the solid fermentation substrate is one or more of the following: Sophora japonica biomass, wheat bran, rice husk, and straw.

[0012] Preferably, the solid fermentation substrate is obtained by mixing wheat bran and straw powder in a weight ratio of 1.5:1.

[0013] In some embodiments, the nutrient solution contains a nitrogen source and inorganic salts.

[0014] Preferably, the nitrogen source is ammonium sulfate; the inorganic salt is a combination of potassium phosphate and magnesium sulfate.

[0015] Preferably, the amounts of ammonium sulfate, potassium phosphate, and magnesium sulfate added are 1%-2%, 0.2%-0.5%, and 0.05%-0.1% of the dry weight of the solid matrix, respectively.

[0016] In some embodiments, the initial moisture content of the solid fermentation medium is 50wt%-70wt%.

[0017] Preferably, the sterilization conditions are: temperature of 121℃-128℃, pressure of 0.1-0.15MPa, and time of 60-120min.

[0018] In some embodiments, the method for preparing the modified diatomaceous earth includes the following steps: B1. Diatomaceous earth and 3-isocyanate-propyltriethoxysilane are added to an aqueous ethanol solution and reacted at 60-80℃ for 1.5-2.5h. After drying, pretreated diatomaceous earth is obtained. B2. Add the pretreated diatomaceous earth and glucose obtained in step B1 to acetone, react at 60-70℃ for 1-2 hours, and dry to obtain modified diatomaceous earth.

[0019] Preferably, the concentration of the ethanol aqueous solution is 85-93 wt%.

[0020] Preferably, the ratio of diatomaceous earth to ethanol aqueous solution is 1:(8-12) ml.

[0021] This application describes a process where diatomaceous earth is reacted with a silane coupling agent containing isocyanate groups to obtain pretreated diatomaceous earth, which is then reacted with glucose to obtain modified diatomaceous earth. Adding this modified diatomaceous earth to a compound microbial agent enhances its effectiveness in controlling soil-borne diseases. This is likely because: firstly, the modified diatomaceous earth is covered with a layer of glucose organic matter, which significantly improves its compatibility with Penicillium oxalate fermentation products and humic acid; secondly, the modified diatomaceous earth retains its large specific surface area, enabling efficient adsorption of the microbial agent and other active ingredients. Simultaneously, the organic layer on the surface of the modified diatomaceous earth slows down the release of active ingredients, achieving a slow-release effect. During the use of the compound microbial agent, the glucose molecules on the surface act as "bait," rapidly attracting and activating target microorganisms. This facilitates the colonization and germination of Penicillium oxalate on the carrier, allowing functional bacteria to preferentially form a dominant microbial community around the carrier, preventing the bacteria from becoming inactive in the soil due to nutrient deficiency. Furthermore, the carbamate bonds on the surface of modified diatomaceous earth have a certain buffering capacity, which can stabilize the pH value of the entire microenvironment and prevent local over-acidity caused by organic acids produced by Penicillium oxalate metabolism, thereby protecting the structure of humic acid and potassium fulvate from being destroyed.

[0022] In some embodiments, the mass ratio of the diatomaceous earth to 3-isocyanate-propyltriethoxysilane is 1:(0.015-0.018).

[0023] In some embodiments, the mass ratio of the modified diatomaceous earth to glucose in step B2 is (0.04-0.07).

[0024] This application achieves better control effects by selecting a specific ratio of modified diatomaceous earth and glucose in the compound microbial agent. This is likely because when glucose content is excessive, it cannot be consumed by Penicillium oxalate in time, which may promote the reproduction of pathogens. However, by precisely controlling the ratio of modified diatomaceous earth to glucose, this application ensures both effective grafting modification of glucose and diatomaceous earth and avoids the biological risks caused by excessive glucose residue in the modified product, thus achieving a dual optimization of modification efficacy and control effect.

[0025] A second aspect of this invention provides a method for preparing a compound microbial agent containing Penicillium oxalate, comprising the following steps: S1. Add Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth into a mixer and mix at room temperature for 0.5-1.5 hours to obtain a mixture. S2. The mixture obtained in step S1 is added to a pulverizer at a pulverizing temperature of 20-30℃. After pulverizing, it is sieved to obtain a compound bacterial agent containing Penicillium oxalate.

[0026] The third aspect of this application provides the application of a compound microbial agent containing Penicillium oxalate in the prevention and control of soil-borne diseases.

[0027] In some embodiments, the application method of the compound microbial agent is selected from one or more of the following: basal application, hole application, furrow application, root irrigation, fertigation, drip irrigation, and seed dressing.

[0028] In some embodiments, the application rate of the compound microbial agent is as follows: when applied as a base fertilizer, the application rate is 2-8 kg / mu; when applied as a root irrigation, the agent is diluted 300-500 times and then applied to the roots, with a application rate of 500-1500 g / mu; when applied as a fertigation or drip irrigation, the application rate is 1-3 kg / mu / time, and the agent is applied 2-3 times per crop season.

[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention obtains a compound microbial agent containing Penicillium oxalate by compounding Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth. The compound microbial agent has good control effect on soil-borne diseases and good stability.

[0030] (2) The present invention obtains pretreated diatomaceous earth by reacting it with a silane coupling agent containing isocyanate groups, and then reacts it with glucose to obtain modified diatomaceous earth, which has good compatibility with Penicillium oxalate fermentation product and humic acid, and can improve the effect of compound microbial agent in preventing soil-borne diseases.

[0031] (3) The glucose molecules on the modified diatomaceous earth prepared by this invention can quickly attract and activate target microorganisms, which is conducive to the colonization and germination of Penicillium oxalate on the carrier, so that functional bacteria can preferentially form a dominant bacterial community around the carrier, avoiding the inactivation of bacteria in the soil due to nutrient deficiency. The carbamate bonds on its surface have a certain buffering capacity, which can stabilize the pH value of the entire microenvironment, protect the structure of humic acid and potassium fulvate from being destroyed, and further improve the effect of compound bacterial agent in preventing soil-borne diseases. Detailed Implementation

[0032] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0033] In the following examples and comparative examples, except for the Penicillium oxalate solid fermentation product and modified diatomaceous earth, all other polymer monomers and related reagents used were commercially available. The Penicillium oxalate strain had the preservation number CGMCC No. 13763; wheat bran was purchased from Xinchang Pharmaceutical Factory; straw powder was purchased from Shaanxi Jinhe Agricultural Technology Co., Ltd.; the average particle size of zeolite powder was 200 mesh; and the average particle size of diatomaceous earth was 300 mesh.

[0034] Preparation Example 1 The preparation method of modified diatomaceous earth-1 includes the following steps: B1. Add 10g of diatomaceous earth and 0.16g of 3-isocyanate-propyltriethoxysilane to 100ml of 90wt% ethanol aqueous solution, react at 70℃ for 2h, and dry at 60℃ for 12h to obtain pretreated diatomaceous earth. B2. Add 10g of the pretreated diatomaceous earth obtained in step B1 and 0.5g of glucose to acetone, react at 65℃ for 1.5h, and dry at 60℃ for 12h to obtain modified diatomaceous earth-1.

[0035] Preparation Example 2 The preparation method of modified diatomaceous earth-2 is the same as that of preparation example 1, except that the amount of 3-isocyanate-propyltriethoxysilane added is 0.22g.

[0036] Preparation Example 3 The preparation method of modified diatomaceous earth-3 is the same as that in preparation example 1, except that the amount of glucose added in step B2 is 1g.

[0037] Preparation Example 4 The preparation method of modified diatomaceous earth-4 includes the following steps: 10g of diatomaceous earth and 0.16g of 3-isocyanate-propyltriethoxysilane are added to 100ml of 90wt% ethanol aqueous solution, reacted at 70℃ for 2h, and dried at 60℃ to obtain modified diatomaceous earth-4.

[0038] Preparation Example 5 The method for preparing Penicillium oxalate solid-state fermentation product includes the following steps: A1. Strain activation and seed culture preparation: *Penicillium oxalate* strain was inoculated onto PDA slant culture medium and activated for 6 days at pH 6.8 and 27℃. After the slant was covered with green spores, the spores were washed away with sterile physiological saline to prepare a 1×10⁻⁶ solution. 7 CFU / mL spore suspension; A2. Preparation and sterilization of solid-state fermentation medium: Wheat bran and straw powder were mixed at a weight ratio of 1.5:1 to obtain a solid-state fermentation substrate. Ammonium sulfate, potassium phosphate, and magnesium sulfate were added to deionized water to prepare a nutrient solution. The solid-state fermentation substrate and nutrient solution were mixed evenly, and the initial moisture content was adjusted to 60 wt% to obtain the solid-state fermentation medium. The medium was sterilized at a temperature of 121℃ and a pressure of 0.11 MPa for 90 min. The added mass of ammonium sulfate, potassium phosphate, and magnesium sulfate were 1.5%, 0.3%, and 0.07% of the dry weight of the solid-state substrate, respectively. A3. Inoculation and solid-state fermentation: The spore suspension prepared in step A1 was aseptically inoculated into the solid-state fermentation medium sterilized in step A2, mixed evenly, and placed in a constant temperature incubator for static solid-state fermentation at a temperature of 30°C for 7 days. A4. Post-processing: After fermentation, collect the solid fermentation product, dry it at 60℃ for 6 hours, pulverize it, and pass it through a 120-mesh sieve to obtain the solid fermentation product of Penicillium oxalate.

[0039] Example 1 A compound microbial agent containing Penicillium oxalate, comprising the following raw materials by weight: 4 parts Penicillium oxalate solid fermentation product, 23 parts zeolite powder, 7 parts potassium humate, 12 parts humic acid, 10 parts sodium lignosulfonate, and 35 parts modified diatomaceous earth-1.

[0040] The preparation method of the compound bacterial agent containing Penicillium oxalate in this embodiment includes the following steps: S1. Add Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth-1 into a mixer and mix at room temperature for 1 hour to obtain a mixture. S2. The mixture obtained in step S1 is added to a pulverizer at a pulverizing temperature of 20-30℃. After pulverizing, it is passed through a 200-mesh sieve to obtain a compound bacterial agent containing Penicillium oxalate.

[0041] Example 2 A compound microbial agent containing Penicillium oxalate, comprising the following raw materials by weight: 3 parts Penicillium oxalate solid fermentation product, 20 parts zeolite powder, 5 parts potassium humate, 10 parts humic acid, 8 parts sodium lignosulfonate, and 30 parts modified diatomaceous earth-1.

[0042] The preparation method of the compound bacterial agent containing Penicillium oxalate in this embodiment includes the following steps: S1. Add Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth-1 into a mixer and mix at room temperature for 0.5 h to obtain a mixture. S2. The mixture obtained in step S1 is added to a pulverizer at a pulverizing temperature of 20°C. After pulverizing, it is passed through a 200-mesh sieve to obtain a compound bacterial agent containing Penicillium oxalate.

[0043] Example 3 A compound microbial agent containing Penicillium oxalate, comprising the following raw materials by weight: 5 parts of Penicillium oxalate solid fermentation product, 25 parts of zeolite powder, 10 parts of potassium humate, 15 parts of humic acid, 12 parts of sodium lignosulfonate, and 40 parts of modified diatomaceous earth-1.

[0044] The preparation method of the compound bacterial agent containing Penicillium oxalate in this embodiment includes the following steps: S1. Add Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth-1 into a mixer and mix at room temperature for 1.5 h to obtain a mixture. S2. The mixture obtained in step S1 is added to a pulverizer at a pulverizing temperature of 30°C. After pulverizing, it is passed through a 200-mesh sieve to obtain a compound bacterial agent containing Penicillium oxalate.

[0045] Example 4 A compound bacterial agent containing Penicillium oxalate and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified diatomaceous earth-1 is replaced with modified diatomaceous earth-2 in equal amounts.

[0046] Example 5 A compound bacterial agent containing Penicillium oxalate and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified diatomaceous earth-1 is replaced with modified diatomaceous earth-3 in equal amounts.

[0047] Example 6 A compound bacterial agent containing Penicillium oxalate and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified diatomaceous earth-1 is replaced with modified diatomaceous earth-4 in equal amounts.

[0048] Comparative Example 1 A compound bacterial agent containing Penicillium oxalate and its preparation method are described. The specific implementation method is the same as in Example 1, except that the modified diatomaceous earth-1 is replaced with an equal amount of diatomaceous earth.

[0049] Performance testing The performance of the compound bacterial agents containing Penicillium oxalate obtained in the above embodiments and comparative examples was tested: (1) Antibacterial performance against Fusarium solani: Fusarium solani was isolated and screened from the roots of eggplant infected with root rot. Eight Fusarium solani colony edge blocks were taken using a sterile punch with a diameter of 4 mm and inoculated into the center of a 9 cm diameter PDA plate, which were numbered 1-8. Medium 1-8 were used as test mediums. 1 g of the compound bacterial agent prepared in each example and comparative example was added to the upper, lower, left, and right sides of the central bacterial block in medium 1-8, 1 cm away from the edge of the petri dish. Medium 1 was used as the control medium and was not treated in any way. Medium 1-7 were cultured under natural light at 25℃. When Fusarium solani in medium 8 (the control medium) grew to the edge, the radius of Fusarium solani colonies in mediums 1-7 (the test mediums) was measured, and the inhibition rate was calculated. The calculation formula and results are as follows: Inhibition rate = (Radius of Fusarium solani colonies in the control medium - Radius of Fusarium solani colonies in the test medium) / Radius of Fusarium solani colonies in the control medium × 100%.

[0050] (2) Antibacterial performance against Fusarium solani: Based on the above tests, Fusarium solani isolated from eggplant roots infected with root rot was replaced with Fusarium solani isolated from ginger roots infected with root rot. The above test methods were then used to conduct the experiment, and the antibacterial rate was calculated. The calculation formula and results are as follows: Antibacterial rate = (radius of Fusarium solani colony in control culture medium - radius of Fusarium solani colony in test culture medium) / radius of Fusarium solani colony in control culture medium × 100%.

[0051] The test results are shown in Table 1: Table 1

[0052] As shown in Table 1, the high inhibition rate of the compound microbial agents containing Penicillium oxalate in Examples 1-3 of this invention indicates that the compound microbial agents in Examples 1-3 have a good control effect on soil-borne diseases. A comparison between Example 4 and Example 1 shows that changing the ratio of 3-isocyanate-propyltriethoxysilane to diatomaceous earth may cause silane self-polymerization, leading to pore blockage and a decrease in specific surface area of ​​the diatomaceous earth. Simultaneously, the residual isocyanate groups may have biotoxicity to Penicillium oxalate, thus reducing the control effect of the microbial agent. A comparison between Example 5 and Example 1 shows that changing the ratio of modified diatomaceous earth to glucose may prevent Penicillium oxalate from consuming excess glucose in time, potentially promoting pathogen reproduction and reducing the control effect of the compound microbial agent. A comparison between Example 6 and Example 1 shows that using only 3-isocyanate-propyltriethoxysilane to modify diatomaceous earth reduces the control effect of the compound microbial agent. A comparison between Comparative Example 1 and Example 1 shows that the control effect of the compound microbial agent is poor when using unmodified diatomaceous earth.

[0053] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A compound bacterial agent containing Penicillium oxalate, characterized in that, By weight, it includes the following raw materials: 3-5 parts of Penicillium oxalate solid fermentation product, 20-25 parts of zeolite powder, 5-10 parts of potassium humate, 10-15 parts of humic acid, 8-12 parts of sodium lignosulfonate, and 30-40 parts of modified diatomaceous earth.

2. The compound bacterial agent containing Penicillium oxalate according to claim 1, characterized in that, The method for preparing the Penicillium oxalate solid fermentation product includes the following steps: A1. Activation of strain and preparation of seed solution: Penicillium oxalate strain was inoculated on slant culture medium for activation culture, and the activated spores were collected to prepare spore suspension; A2. Preparation and sterilization of solid-state fermentation medium: Mix the solid-state fermentation substrate with the nutrient solution evenly, adjust the initial moisture content to obtain the solid-state fermentation medium, and then sterilize it. A3. Inoculation and solid-state fermentation: The spore suspension prepared in step A1 is inoculated into the sterilized solid-state fermentation medium in step A2 under aseptic conditions, mixed evenly, and placed in a constant temperature incubator for static solid-state fermentation at a temperature of 28℃-35℃ for 5-10 days. A4. Post-processing: After fermentation, the solid fermentation product is collected, dried, crushed and sieved to obtain the solid fermentation product of Penicillium oxalate.

3. The compound bacterial agent containing Penicillium oxalate according to claim 2, characterized in that, The solid fermentation substrate is one or more of the following: Sophora japonica biomass, wheat bran, rice husk, and straw.

4. The compound bacterial agent containing Penicillium oxalate according to claim 2, characterized in that, The nutrient solution contains a nitrogen source and inorganic salts.

5. The compound bacterial agent containing Penicillium oxalate according to claim 2, characterized in that, The initial moisture content of the solid fermentation medium is 50wt%-70wt%.

6. The compound bacterial agent containing Penicillium oxalate according to claim 1, characterized in that, The method for preparing the modified diatomaceous earth includes the following steps: B1. Diatomaceous earth and 3-isocyanate-propyltriethoxysilane are added to an aqueous ethanol solution and reacted at 60-80℃ for 1.5-2.5h. After drying, pretreated diatomaceous earth is obtained. B2. Add the pretreated diatomaceous earth and glucose obtained in step B1 to acetone, react at 60-70℃ for 1-2 hours, and dry to obtain modified diatomaceous earth.

7. The compound bacterial agent containing Penicillium oxalate according to claim 6, characterized in that, The mass ratio of the diatomaceous earth to 3-isocyanate-propyltriethoxysilane is 1:(0.015-0.018).

8. The compound bacterial agent containing Penicillium oxalate according to claim 6, characterized in that, The mass ratio of modified diatomaceous earth to glucose in step B2 is 1:(0.04-0.07).

9. A method for preparing a compound bacterial agent containing Penicillium oxalate according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Add Penicillium oxalate solid fermentation product, zeolite powder, potassium humate, humic acid, sodium lignosulfonate and modified diatomaceous earth into a mixer and mix at room temperature for 0.5-1.5 hours to obtain a mixture. S2. The mixture obtained in step S1 is added to a pulverizer at a pulverizing temperature of 20-30℃. After pulverizing, it is sieved to obtain a compound bacterial agent containing Penicillium oxalate.

10. The application of a compound microbial agent containing Penicillium oxalate as described in any one of claims 1-8 or a compound microbial agent containing Penicillium oxalate obtained by the preparation method described in claim 9 in the prevention and control of soil-borne diseases.

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