A Bacillus velezensis, a microbial inoculant prepared therefrom, and its application

Abstract

The present invention discloses a Bacillus velezensis, and the preservation number of this Bacillus velezensis is CGMCC No. 24124. The present invention also discloses a microbial inoculant with the above-mentioned Bacillus velezensis as the active component. The present invention further discloses the application of the above-mentioned Bacillus velezensis in the preparation of a microbial inoculant, and the application of the above-mentioned microbial inoculant in the prevention and control of plant diseases. The Bacillus velezensis of the present invention can be used to prepare a microbial inoculant, and has good control effects on various crop diseases such as Sclerotinia sclerotiorum of rape, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, citrus canker, etc., and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological pesticides, and particularly relates to a Bacillus velezensis, a prepared microbial agent and its application. Background Art

[0002] Plant diseases caused by plant pathogens such as Sclerotinia sclerotiorum of rapeseed, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, citrus canker, etc. not only affect the yield of agricultural products, but also seriously affect the quality of products, bringing great harm to agricultural production. For the prevention and control of these diseases, in addition to using biotechnologies and agricultural measures such as cultivating disease-resistant strains and planting management, drug prevention and control is still the main control means.

[0003] With the improvement of people's health needs, problems such as the residues of chemical pesticides, the pressure on the environment, and the resistance of pathogens caused by long-term use have attracted more attention. Since microbial biocontrol agents are not likely to cause problems such as chemical residues and environmental pollution, and have the characteristics of being green and environmentally friendly, they are more easily promoted and applied. However, the biggest difficulties in the application of biocontrol agents at present are: on the one hand, it is necessary to screen more new strains with good disease-resistant activities, and on the other hand, it is how to process the obtained active strains into dosage forms to ensure the stability of the products and make them fully play their efficacy.

[0004] Among many biocontrol agents, Bacillus velezensis is a kind of microorganism with good antibacterial and biocontrol effects. There are many reports in the existing literature on the inhibition of the growth of other bacteria by Bacillus velezensis. However, in actual work, since the taxonomic status usually only classifies strains to species or subspecies, and even for different strains of the same genus, the same species, or even the same small species, there will be some differences in their physiology, and some differences are even sufficient to reach the level of physiological races. Therefore, these different strains also show great differences in their functions. Therefore, the screening, research and development of disease-resistant strains and the research on the application technology of new strains are eternal topics in the field of biological protection. After determining the active strains, the preparation of microbial agents containing the active strains is another important key technology in the field of biocontrol agents. Different from the processing of general pesticide preparations, the processing process of biocontrol agents needs to ensure the survival of the bacterial cells and ensure that a sufficient amount of bacterial cells survive and have biological activity within a certain period of time. Summary of the Invention

[0005] The inventor of this case collected a strain of Bacillus from the suburbs of Shanghai and identified it as Bacillus velezensis. Through research, it was found that this strain has good control effects on various crop diseases such as Sclerotinia sclerotiorum of rapeseed, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, citrus canker, etc., and can be made into a microbial agent for controlling these crop diseases.

[0006] Therefore, the first object of the present invention is to provide a Bacillus velezensis with a preservation number of CGMCC No. 24124.

[0007] The second aspect of the present invention provides a microbial inoculant, which uses Bacillus velezensis as an active component.

[0008] According to the present invention, the dosage forms of the microbial inoculant include: water suspension agent, granule, powder, and microcapsule.

[0009] Furthermore, the weight percentage content of the active component in the water suspension agent, granule, and powder is 5-20%; the weight percentage content of the active component in the microcapsule is 10-30%.

[0010] The third aspect of the present invention provides the application of the Bacillus velezensis in the preparation of a microbial inoculant.

[0011] Furthermore, the dosage forms of the microbial inoculant include: water suspension agent, granule, powder, and microcapsule.

[0012] The fourth aspect of the present invention provides the application of the microbial inoculant in the prevention and control of plant diseases.

[0013] According to the present invention, the plant diseases include Sclerotinia sclerotiorum of rape, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, and citrus canker.

[0014] The Bacillus velezensis of the present invention can be used to prepare a microbial inoculant, and has good control effects on various crop diseases such as Sclerotinia sclerotiorum of rape, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, and citrus canker, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the colony morphology of the Bacillus velezensis of the present invention.

[0016] Figure 2 It is a schematic diagram of the emergence of spores of the Bacillus velezensis of the present invention.

[0017] Figure 3 It is a phylogenetic tree diagram of the Bacillus velezensis of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Depositing matters

[0019] The Bacillus velezensis S297 involved in the present invention was deposited at the China General Microbiological Culture Collection Center (Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing) on December 17, 2021, and the deposit number is CGMCC No. 24124.

[0020] The technical solutions of the present invention will be clearly and completely described below through specific embodiments. It should be understood that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

[0021] The microbial strain S297 of the present invention, which has the functions of preventing and controlling Sclerotinia sclerotiorum of rapeseed, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, citrus canker and other diseases of various crops, is a strain belonging to the genus Bacillus. It was isolated from the soil collected in the suburbs of Shanghai in June 2020, and obtained through purification and mutagenesis. After identification, its taxonomic name is Bacillus velezensis. The strain Bacillus velezensis S297 was deposited at the China General Microbiological Culture Collection Center on December 17, 2021, and the deposit number is CGMCC No. 24124.

[0022] I. The microorganisms used

[0023] The morphological characteristics, cultural characteristics, physiological and biochemical characteristics, the sequence of 16srDNA and the taxonomic results of the strain are as follows:

[0024] 1. Morphological characteristics:

[0025] After culturing Bacillus velezensis S297 on nutrient agar medium at 28°C for about 2 days, the colonies are milky white, the single colonies are round, convex, opaque, the periphery of the circumference is irregular, and the surface of the single colony is smooth ( Figure 1 ). When forming a sheet, wrinkles appear on the surface, no pigment is formed on the culture medium, it is rod-shaped under the microscope, and spores appear under adverse conditions such as poor nutrition ( Figure 2 ).

[0026] 2. Physiological and biochemical characteristics

[0027] The physiological and biochemical characteristics of Bacillus velezensis S297 are shown in Table 1 below.

[0028] Table 1: Physiological and Biochemical Indexes of Strain S297

[0029] Index Result Gram + M-R test - V-P test + Oxidase test - Starch hydrolysis test +

[0030] 3. Molecular Biology Identification

[0031] The above strain was sequenced and verified: The 16S rDNA gene sequence of the strain was amplified using universal primers for general bacteria, and then a phylogenetic tree diagram of the strain was constructed by comparing with the database in GenBank. Figure 3 The phylogenetic tree constructed based on the 16S rDNA sequence is shown.

[0032] Strain S297 has a similarity of more than 99.7% with Bacillus sp. and belongs to the genus Bacillussp. Considering its morphological, physiological, and biochemical characteristics, its appearance is closer to the species Bacillus velezensis. Therefore, it is named Bacillus velezensis.

[0033] II. Method for Microbial Culture and Preparation of Bacterial Cells

[0034] Bacillus velezensis S297 of the present invention can be cultured by common bacterial production methods to obtain corresponding cultures. The preferred culture method is deep liquid culture. For industrial cultivation, a multi-stage culture fermentation method can be used. The bacterial suspension of the above strain is inoculated onto the medium and aerated and stirred.

[0035] There are no special regulations on the nutrient sources in the medium. It is mainly suitable for culturing bacteria and is economical and practical. The medium can contain carbon sources, nitrogen sources, and other nutrient sources commonly used in microbial culture. It is appropriate that the ratio of carbon source to nitrogen source in the medium composition is 2:1 - 5:1. Among them, the carbon source can be starch, dextrin, glucose, etc.; the nitrogen source can be peptone, soybean cake powder, peanut powder, yeast, meat extract, ammonium salts, and other organic or inorganic nitrogen-containing compounds. Some inorganic salts can be appropriately added as other nutrient sources, such as table salt, phosphate, and metal salts such as potassium, calcium, manganese, and iron. When necessary, some animal, plant, and mineral oils can be added as antifoaming agents.

[0036] There are no strict restrictions on the culture conditions such as temperature, pH, and time, which are subject to the production of the strain. For example, the pH range of the culture medium can be 6 - 8, preferably close to neutral; the culture temperature is 25 - 38°C, and the aeration rate is between 1:0.3 and 1:4 (aeration rate: the ratio of the volume of air passing through the culture solution per minute to the volume of the culture solution). The components, pH, culture temperature, aeration conditions, etc. of these culture media can be appropriately adjusted according to the actual situation to obtain the best effect.

[0037] III. Microbial inoculant

[0038] The microbial inoculant of the present invention is a microbial inoculant with good prevention and control effects on various crop diseases such as Sclerotinia sclerotiorum of rape, Sclerotinia sclerotiorum of lettuce, powdery mildew of cucurbits, and citrus canker, with Bacillus velezensis S297 as the main active component.

[0039] When preparing a microbial inoculant with Bacillus velezensis S297 as the main active component, various carriers commonly used in known biological pesticides in the technical field, such as solid phase, liquid phase, and emulsifying dispersants, can be used, and it can be formulated into dosage forms such as water suspension agents, granule agents, powder agents, and microcapsule agents. At the same time, some auxiliaries, surfactants, and carriers, such as dispersants, wetting agents, penetrants, spreading agents, adhesives, defoamers, foaming agents, thickeners, stabilizers, and film-forming agents, can generally be appropriately added to various preparations.

[0040] Specifically, the auxiliaries used in the preparation include carboxymethyl cellulose, polyethylene glycol or gelatin, arabic gum, xanthan gum, etc. The surfactants used in the preparation include alcohol sulfonates, alkyl aryl sulfonates, lignin sulfonates, polyethylene glycol ethers, polyethylene glycol alkyl aryl ethers, or polyethylene glycol sorbitan monoalkyl esters. The carriers used in the preparation can be solid carriers such as sawdust, talc, bentonite, clay, kaolin, diatomaceous earth, white carbon black, vermiculite, slaked lime, silica sand, industrial glucose, etc., and liquid carriers such as water, isopropyl alcohol, glycerol, etc.

[0041] The ratio of the active ingredients in various preparations can be appropriately increased or decreased according to different usage purposes. Generally speaking, the range of the active ingredients in water suspension agents, granule agents, and powder agents is usually 5 - 20%, and that in microcapsule agents is 10 - 30%. The content of the active ingredient here is the mass percentage of wet bacteria. Since the content of microbial pesticides also needs to be calculated based on the viable bacteria count in the product, the viable bacteria count needs to be measured separately and marked after preparing the corresponding preparations.

[0042] Specifically, starting from the aforementioned obtained culture, a microbial preparation can be prepared by adding some auxiliaries and selecting some appropriate methods. For example, vacuum thin-film concentration can be used to make the culture into a high-concentration liquid semi-finished product for further preparation of liquid preparation products, or further methods such as ventilation drying and spray drying can be used to obtain a solid semi-finished product, and the obtained solid semi-finished product can be used to prepare the target preparation product after being pulverized.

[0043] IV. Application methods and scope

[0044] In actual use, the microbial inoculant of the present invention can be diluted to an appropriate concentration before use or can be used directly.

[0045] The microbial inoculant of the present invention can be used in combination with other pesticides and fertilizers, but cannot be mixed with bactericidal pesticides.

[0046] The microbial inoculant of the present invention with Bacillus velezensis S297 as the main active component can be used for diseases such as sclerotinia of rapeseed, lettuce, lettuce, cucumber, powdery mildew of cucurbits, citrus canker, etc. Specifically, the inoculant of the present invention can be applied by soil surface treatment or foliar spraying before the onset of diseases at the seedling stage of crops, and the above diseases can be effectively controlled.

[0047] For soil surface treatment, after the land in the planting area is leveled, it is sprayed on the soil surface at a dose of 200 to 400 grams of active ingredient per mu, so that the medicament is evenly distributed in the whole field. For foliar spraying treatment, also at a dose of 200 to 400 grams of active ingredient per mu, it is evenly sprayed on the crop leaves after diluting with water, and the water consumption per mu can be 30 to 50 kilograms.

[0048] Example 1. Preparation of Bacillus velezensis S297 bacterial suspension

[0049] Add 50 mL of a liquid medium containing 0.5% glucose, 0.5% soluble starch, 0.2% sodium chloride, 0.2% peptone, and pH 6.7 - 7.2 into a 250 mL Erlenmeyer flask, cover the bottle mouth tightly with a breathable bottle stopper, sterilize at 121 °C for 25 minutes, and after cooling to room temperature, pick and inoculate the pre-cultured S297 slant seeds on the nutrient agar medium with a sterilized inoculation needle. Then shake the flask on a shaker at 150 - 200 rpm at 28 - 32 °C for 12 - 20 hours to obtain bacterial suspension seeds.

[0050] Add 7 L of a liquid medium containing 1% glucose, 2% soluble starch, 0.5% sodium chloride, 0.5% peptone, 0.5% yeast extract powder, and pH 7.0 into a 10 L fermenter, sterilize with steam at 121 °C for 25 minutes, and after cooling to 35 °C, inoculate the previously cultured bacterial suspension seed, and aerate and stir for 32 - 48 hours to obtain a bacterial suspension containing the target strain.

[0051] In order to make the prepared microbial inoculant product have better storage stability and meet the requirements of general microbial inoculant preparations, the bacterial suspension is continuously cultured for 4 - 6 hours in the fermenter without aeration and stirring, so that most of the vegetative strains in the suspension are transformed into spore bodies.

[0052] Example 2. Preparation of a microbial inoculant containing Bacillus velezensis S297

[0053] Add different adjuvants to the spore body bacterial suspension obtained in Example 1, and different dosage forms of microbial inoculants can be obtained by using appropriate methods, as follows:

[0054] 2.1 Preparation of water suspension

[0055] After measuring the bacterial amount of the spore body bacterial suspension obtained in Example 1 by dilution plating, concentrate or add an appropriate amount of distilled water, and add 0.05% xanthan gum, 0.05% coconut oil, and 0.1% wetting agent LS according to the mass ratio, and mix evenly.

[0056] By adjusting the amount of concentrated or added distilled water, microbial water suspensions with different contents of the target strain are obtained.

[0057] 2.2 Preparation of granules

[0058] Take a certain amount of the spore body bacterial suspension obtained in Example 1, add the required amount of light calcium carbonate, 2% wetting agent SXC, 2% dispersant NNO, and 15% sawdust according to the mass percentage, crush and mix them with a pulverizer, then add an appropriate amount of water for extrusion granulation, and dry in an oven at 54 °C for 1 h.

[0059] By adjusting the ratio of the bacterial powder to light calcium carbonate, granules with different contents of the target strain are obtained.

[0060] 2.3 Preparation of powder

[0061] Take a certain amount of the spore body bacterial suspension obtained in Example 1, add the required amount of light calcium carbonate, 1% wetting agent SXC, 1% dispersant NNO, and 1% industrial glucose according to the mass percentage, mix evenly and then spray dry.

[0062] By adjusting the ratio of the amount of bacterial liquid to light calcium carbonate, powders with different contents of the target strain are obtained.

[0063] 2.4. Preparation of Microcapsules

[0064] Take a certain amount of the spore suspension obtained in Example 1, centrifuge to remove most of the water to obtain a paste-like bacterial pulp. Take an appropriate amount of the bacterial pulp according to the required dosage, add about 0.1% of Tween-80, and add an aqueous solution of the microcapsule wall material composed of gelatin and gum arabic (gelatin: gum arabic is 1:1 to 1:2) under stirring. The ratio of the bacterial pulp to the wall material can be appropriately adjusted within the range of 1:2 to 1:5 according to the designed preparation concentration. The wall material is added in the order of first adding the gelatin solution, then adjusting the pH of the system to 3.5 - 4.5, keeping the system temperature at 40°C to 60°C, continuously stirring and adding the aqueous solution of gum arabic, stirring for 20 - 30 minutes and then adding formaldehyde for curing, and continuing to react for 10 - 15 minutes. After washing with water to remove formaldehyde, the required microcapsules can be obtained.

[0065] Example 3. Application of the Microbial Agent Containing the Target Strain in Controlling Plant Pathogens

[0066] 3.1. Control of Sclerotinia rot of Lettuce by Foliar Spray Treatment

[0067] In the same greenhouse where the previous crop was also lettuce and the occurrence of Sclerotinia rot was relatively severe and uniform, set up 5 treatments including the agent treatment (4 different dosage forms) and the clear water control group. Each treatment has 4 replicates, and the area of each plot is 60 square meters, arranged in a randomized block design.

[0068] About 1 month after the lettuce is planted, before the onset of Sclerotinia rot, conduct foliar spray treatment. Dilute the agent products of each dosage form prepared in Example 2 to an aqueous solution of 133.3 billion cfu / L (for example, for a preparation of 10 billion cfu / ml, take 400 g and add 30 kg of water). The amount of the liquid medicine used per mu is 30 kg. Apply the medicine again after 1 week, and apply the medicine continuously for 3 times. Investigate the incidence of Sclerotinia rot in each plot 14 days after the last application of the medicine. Investigate 5 points in each plot, and investigate 10 plants at each point. Record the number of diseased plants and the corresponding disease grades, calculate the disease index and the control effect, and the results are shown in Table 2.

[0069] Disease grading standard: Grade 0, the plant grows normally; Grade 1, 1 - 2 lower leaves of the plant become soft and brown, and the upper and middle leaves are normal; Grade 2, 5 - 10 lower leaves become soft and brown, and at the same time the disease spreads to the stem, and the plant does not wilt; Grade 3, the upper leaves of the plant have wilted, the lower leaves are brown and withered, and most of the stem is diseased; Grade 4, the plant is dead or lodging.

[0070] From the analysis of the disease susceptibility of lettuce after applying the medicine, after applying the Bacillus velezensis agent, the disease symptoms are significantly reduced. Even if there are symptoms, they mostly only appear on a few old lower leaves, and almost no symptoms on the stem are found.

[0071] The analysis results of the test results show that the use of Bacillus velezensis bactericide can effectively prevent and control the damage of Sclerotinia sclerotiorum on lettuce. 14 days after application, the average control effect of the bactericide treatment was 88.97%.

[0072] Table 2: Field efficacy of bactericide foliar spray treatment against Sclerotinia sclerotiorum on lettuce

[0073] Treatment Average disease index % Average control efficacy % Water control 52.12 / Water suspension agent 7.00 86.57 Granule 5.50 89.45 Powder 5.00 90.41 Microcapsule agent 5.50 89.45

[0074] 3.2 Control of Sclerotinia sclerotiorum on lettuce by soil treatment plus foliar spray treatment

[0075] The experimental design and procedures were basically the same as those in Experiment 3.1 above. After the plot was leveled, the bactericide products of each dosage form prepared in Example 2 were diluted to an aqueous solution of 2666 billion cfu / L (for example, for a 20 billion cfu / ml preparation, take 600 g and add 45 kg of water). First, spray the surface soil by spraying method, with a liquid volume of 45 kg per mu. The blank control group sprayed the same amount of clear water. After 2 days, the lettuce was planted.

[0076] Approximately 1 week after planting, when the lettuce seedlings were fully survived, the foliar spray treatment method was used again. Take any dosage form of the bactericide product and dilute it to an aqueous solution of 1333 billion cfu / L (for example, for a 20 billion cfu / ml preparation, take 200 g and add 30 kg of water) and spray it on the lettuce leaves, with a liquid volume of 30 kg per mu. The blank control group sprayed the same amount of clear water. Spray again after an interval of 7 - 10 days. After 2 weeks, calculate the disease index and control effect according to the disease incidence, and the results are shown in Table 3.

[0077] Disease grading standard: Grade 0, the plants grow normally; Grade 1, the lower 1 - 2 leaves of the plants become soft and brown, and the upper and middle leaves are normal; Grade 2, the lower 3 - 4 leaves become soft and brown, and at the same time the disease spreads to the stem, and the plants do not wilt; Grade 3, the central leaves of the plants have wilted, the lower leaves are brown and withered, and the stem is severely diseased; Grade 4, the plants are dead or lodged.

[0078] Table 3: Field efficacy of bactericide soil treatment plus foliar spray treatment against Sclerotinia sclerotiorum on lettuce

[0079] Treatment Average disease index % Average control efficacy % Water control 41.26 / Water suspension agent 8.50 79.58 Granule 7.50 81.98 Powder 5.50 86.79 Microcapsule agent 9.00 78.38

[0080] The analysis results of the test results show that the use of Bacillus velezensis bactericide can effectively prevent and control the damage of Sclerotinia sclerotiorum on lettuce. 2 weeks after application, the average control effect of first soil treatment and then foliar spray treatment was 81.68%.

[0081] 3.3 Inhibitory effect of indoor soil treatment on citrus canker

[0082] The soil collected from the field was passed through a 60-mesh sieve and spread evenly at the bottom of a triangular flask with a thickness of about 2 cm. After covering the bottle mouth with a breathable stopper, it was sterilized in an autoclave at 121 °C for 30 minutes. After cooling and standing for 1 day, it was sterilized again for 30 minutes to ensure that all the bacteria in the soil were killed. After the soil was cooled after two sterilizations, 5 mL of the suspension of Xanthomonas citri subsp. citri that had been previously cultured and counted (about 10 7 cfu / mL) was added. After the soil shake flask inoculated with the pathogen was cultured on a shaker at 35 °C for 24 hours, 5 mL of the aqueous solution diluted with each dosage form prepared in Example 2 was added to make it contain 10 billion cfu / mL for treatment. At the same time, a treatment with 5 mL of clear water was set as a control. After the treated shake flasks were continuously cultured on the shaker for 2 days, the dilution plate method was used to determine the number of pathogens in the soil.

[0083] The results showed that in the soil treated with the microbial inoculant, the number of pathogens decreased from 1.6 million per gram of soil to 100,000 per gram of soil.

[0084] 3.4 Control effect of field foliar spray treatment on citrus canker

[0085] In the experiment, 3-year-old Wogan trees with severe disease incidence in the previous year were selected as the objects. Two treatments, namely microbial inoculant treatment and clear water control, were set, with 3 replicates for each treatment, a total of 6 plots, and the plots were randomly arranged. There were 3 trees in each plot, and the untreated plants were separated between each treatment and plot. Using the method of foliar spray treatment, the inoculants of each dosage form prepared in Example 2 were selected and diluted to an aqueous solution of 125 billion / L for spray treatment. The liquid spraying amount per plant was sufficient to wet evenly (according to the conventional water consumption).

[0086] The first spraying was carried out when the autumn shoots grew 1 - 2 cm, and then spraying was carried out every 10 days for a total of 3 times. Before spraying, the sporadic early autumn shoots were removed. Two weeks after the last spraying, 20 autumn shoot leaves were taken from each tree in 5 directions of east, west, south, north, and middle for efficacy investigation.

[0087] The grading standard for leaf disease incidence was: grade 0, no disease spots; grade 1: 1 - 3 disease spots; grade 2, 4 - 6 disease spots; grade 3, 7 - 9 disease spots; grade 4, more than 10 disease spots. The disease index and control effect were calculated, and the results are shown in Table 4.

[0088] The results showed that when the incidence of canker in the control group was extremely severe, the average control effect of the inoculant treatment could still reach 72.34%.

[0089] Table 4: Field efficacy of foliar spray treatment with inoculant against citrus canker

[0090] Treatment Disease index % Control efficacy % Water control 100.00 Water suspension agent 30.00 70.00 Granule 28.75 71.25 Powder 24.58 75.42 Microcapsule agent 27.32 72.68

[0091] 3.5 Control effect of field foliar spray treatment on powdery mildew of cucurbits

[0092] In the cucumber field, plots were set up according to the ridges. A total of 5 treatments were set up in the field plot experiment, including the treatment with the microbial agent (4 different dosage forms) and the water control. Each treatment was replicated 4 times, with each plot being 25 square meters, and the plots were randomly arranged. To ensure uniform incidence of powdery mildew in the field, when the cucumber seedlings in the field grew to 6 true leaves, the conidial suspension of powdery mildew pathogen was artificially sprayed on the cucumber seedlings. On the second day after inoculating the pathogen, the microbial agents of each dosage form prepared in Example 2 were selected and diluted to an aqueous solution of 125 billion / L and sprayed on the cucumber plants. Spraying was carried out again after one week, and the investigation was conducted 10 days later. During the investigation, 10 plants were examined in each plot, and the upper 4 leaves of each plant were investigated. The number of disease spots on each leaf was counted, and then compared with the blank control to calculate the control effect. The results are shown in Table 5.

[0093] Table 5: Control effect of foliar treatment with microbial agent on cucumber powdery mildew

[0094] Treatment Average number of disease spots per plot / piece Average control efficacy / % Water suspension agent 89 96.83 Granule 28 99.00 Powder 15 99.47 Microcapsule agent 10 99.64 Blank control 2806 /

[0095] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A Bacillus velezensis ( Bacillus velezensis ), characterized in that The Bacillus velezensis Bacillus velezensis ) has a deposit number of CGMCC No. 24124.

2. A microbial inoculant, characterized in that, The microbial inoculant uses the Bacillus velezensis ([[]] Bacillus velezensis [[]]) described in claim 1 as the active component.

3. The microbial inoculant according to claim 2, characterized in that, The dosage forms of the microbial inoculant include: water suspension, granule, powder, and microcapsule.

4. The microbial inoculant according to claim 3, wherein The weight percentage content of the active ingredient in the water suspension and granule is 5-20%.

5. The microbial inoculant according to claim 3, characterized in that, The weight percentage content of the active ingredient in the microcapsule is 10-30%.

6. Use of the Bacillus velezensis as claimed in claim 1 ( Bacillus velezensis ), characterized in that For preparing the microbial inoculant.

7. The application according to claim 6, wherein The dosage forms of the microbial inoculant include: water suspension, granule, powder, and microcapsule.

8. Use of the microbial inoculum according to any one of claims 2 to 5, characterized in that, For controlling plant diseases, and the plant diseases are selected from: lettuce sclerotinia rot, lettuce sclerotinia rot, citrus canker, and cucumber powdery mildew.

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