Bacillus velezensis, microbial inoculum and application of microbial inoculum

Abstract

The invention discloses bacillus velezensis, a microbial inoculum and application of the bacillus velezensis in prevention and treatment of soybean gray speck disease. The bacillus velezensis YD21 has a preservation number of CGMCC (China General Microbiological Culture Collection Center) No.3334 in the General Microbiological Culture Collection Center of the China Committee for Culture Collection of Microorganisms. The bacillus velezensis YD21 provided by the invention is from seeds of wild soybeans LYD120068, can be used for effectively antagonizing 16 plant pathogenic fungi such as soybean gray leaf spot germs, corn black bundle germs, apple core germs, corn gray leaf spot germs and the like, and has an obvious prevention and treatment effect on the soybean gray leaf spot disease, so that the bacillus velezensis YD21 can be used for preventing and treating the soybean gray leaf spot disease, and the bacillus velezensis YD21 can be used for preventing and treating the soybean gray leaf spot disease. The method has a wide application prospect in the development of biological pesticides and biological organic fertilizers.

Description

Technical Field

[0001] The present invention relates to the field of microbial technology, in particular to Bacillus velezensis, a bacterial agent and applications thereof. Background Art

[0002] Wild soybeans, a close relative of cultivated soybeans, possess strong resistance to pests and diseases, stress, and environmental adaptability. They can hybridize with cultivated soybeans to produce offspring, making them a crucial resource for broadening the genetic base of cultivated soybeans, creating superior germplasm, and improving soil and field fertility. Bacillus velezensis, characterized by rapid reproduction, strong stress tolerance, and robust enzyme production, produces a variety of secondary metabolites that antagonize pathogens, promoting growth and exhibiting broad-spectrum antibacterial activity, making it widely used in biological control.

[0003] Microbial fertilizers play an important role in agricultural production, with bacterial strains forming the foundation of their production. Microorganisms can produce active metabolites that promote crop growth; they can also antagonize plant pathogens, enhancing crop disease resistance.

[0004] In summary, the disclosed Bacillus velezensis strain derived from wild soybean seeds with broad-spectrum antibacterial effect has great application potential in the development of new microbial pesticides and fertilizers and the promotion of green and sustainable development research. Summary of the Invention

[0005] In view of this, the present invention discloses Bacillus Velez, a bacterial agent and its application, and provides a bacterium with enzyme production and broad-spectrum antibacterial effect.

[0006] Specifically including: In the first aspect, the present invention provides Bacillus velezensis, which is named Bacillus velezensis YD21. The preservation number of Bacillus velezensis YD21 is CGMCC No. 3334, the preservation time is January 8, 2025, and the preservation address is the General Microbiology Center of China Culture Collection Administration.

[0007] In a second aspect, the present invention further provides a bacterial agent, which is a bacterial suspension, fermentation broth or metabolite thereof of the Bacillus Velezii.

[0008] In combination with the second aspect, the bacterial agent has the activities of protease, cellulase, chitinase, organic acid, pectinase, and amylase.

[0009] The bacterial content of Bacillus velezensis YD21 in the bacterial agent is 1.0×10 8 ~1.0×10 9 cfu / mL.

[0010] In a third aspect, the present invention further provides the use of the bacterial agent in any one or more of (1) to (4),

[0011] 1) Inhibit plant pathogenic fungi;

[0012] 2) Prevent and control plant fungal diseases;

[0013] 3) Improve plant stress resistance;

[0014] 4) Reduce the sensitivity of plants to adversity.

[0015] Preferably, the plant pathogenic fungi and plant fungal diseases are at least one of the following plant pathogenic fungi and the diseases caused by them:

[0016] 1) Fusarium graminearum;

[0017] 2) Black bunch pathogen (Acremonium strictum);

[0018] 3) Tomato gray mold (Botrytis cinerea Pers.);

[0019] 4) Bipolaris zeicola;

[0020] 5) Pepper wilt pathogen (Fusarium oxysporum f.sp.vasinfectum)

[0021] 6) Pythium aphanidermatum;

[0022] 7) Corn top rot pathogen (Frumentum subglutinans);

[0023] 8) Corn Curvularia lunata;

[0024] 9) Sunflower sclerotinia (Sclerotinia sclerotorium);

[0025] 10) Corn gray leaf spot pathogen (Cercospora zeae-maydis);

[0026] 11) Melon wilt pathogen (Fusarium oxysporum f.sp.melonis);

[0027] 12) Rhizoctonia solani;

[0028] 13) Cucumber scape pathogen (Mycosphaerella melonis)

[0029] 14) Apple core mold (Trichothecium roseum);

[0030] 15) Bipolaris sorghicola;

[0031] 16) Soybean gray leaf spot pathogen (Cercospora sojina).

[0032] Preferably, the adverse environment is one of drought, high temperature, pest and disease invasion or heavy metal pollution.

[0033] The present invention has the following beneficial effects: the Bacillus velezensis YD21CGMCC No. 3334 provided by the present invention is isolated from wild soybean seeds, the strain can antagonize multiple plant pathogenic fungi, and the bacterial agent has protease, cellulase, chitinase, organic acid, pectinase, and amylase activities, has obvious antibacterial effects on 16 tested plant pathogenic fungi, and has broad application prospects in the biological control of plant pathogenic diseases.

[0034] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 1 is a phylogenetic tree of Bacillus velezensis YD21 in the disclosed embodiments of the present invention;

[0038] Figure 2 Growth curve of Bacillus velezensis YD21 in the disclosed embodiments of the present invention;

[0039] Figure 3Qualitative detection of enzyme production capacity of Bacillus velezensis YD21 in the examples disclosed in the present invention; (a protease; b cellulase; c chitinase; d organic acid; e pectinase; f amylase;)

[0040] Figure 4 Detection of antagonism of Bacillus velezensis YD21 against 16 plant pathogenic fungi in the disclosed embodiments of the present invention; a Fusarium graminearum; b Black bunch pathogen of corn; c Botrytis cinerea; d Corn round spot pathogen; e Fusarium wilt pathogen of pepper; f Pythium aphanidermatum; g Corn top rot pathogen; h Curvularia sclerotiorum of corn; i Sunflower sclerotinia; j Gray leaf spot pathogen of corn; k Fusarium wilt pathogen of melon; l Rhizoctonia solani; m Cucumber scape pathogen; n Apple heart mold; o Target leaf spot pathogen of sorghum; p Gray leaf spot pathogen of soybean; (left: CK; right: YD21);

[0041] Figure 5 The effect of the fermentation liquid of strain YD21 on the growth of mycelium of soybean gray leaf spot in the embodiments disclosed in the present invention;

[0042] Figure 6 Schematic diagram of leaf disease classification in the embodiment disclosed in the present invention;

[0043] Figure 7 The present invention discloses the control effect of strain YD21 on soybean gray leaf spot in the examples. DETAILED DESCRIPTION

[0044] The present invention is further explained below with reference to specific embodiments, but is not intended to limit the scope of protection of the present invention.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. The materials and reagents used are all commercially available unless otherwise specified.

[0046] The configuration method of the culture medium used in the following examples is as follows:

[0047] Beef extract peptone solid medium (NA): beef extract 3g, peptone 10g, NaCl 5g, agar 15-20g, distilled water to 1L, sterilize at 121℃ for 30min.

[0048] Beef extract peptone broth (NB): beef extract 3 g, peptone 10 g, NaCl 5 g, distilled water to 1 L, sterilized at 121 °C for 30 min.

[0049] Potato dextrose agar (PDA) medium: 200 g potatoes, 20 g glucose, 18 g agar, dilute to 1 L with distilled water, and sterilize at 121°C for 30 min.

[0050] Potato dextrose broth (PDB): 200 g potatoes, 20 g glucose, dilute to 1 L with distilled water, and sterilize at 121°C for 30 min.

[0051] Sodium carboxymethyl cellulose medium: peptone 10 g, KH2PO4 1 g, NaCl 5 g, yeast powder 10 g, sodium carboxymethyl cellulose 10 g, distilled water to 1 L, pH = 7, sterilize at 121 ° C for 30 min.

[0052] Protease assay medium: Add 50 mL of 8% gelatin solution to 1000 mL of GYP agar medium (pH 6.0).

[0053] GYP agar medium: glucose 10 g, yeast extract powder 10 g, peptone 5 g, anhydrous sodium acetate 2 g, magnesium sulfate heptahydrate 0.02 g, MnSO4·4H2O 0.001 g, ferrous sulfate heptahydrate 0.001 g, sodium chloride 0.001 g, agar 15-20 g, distilled water to 1 L, sterilize at 121°C for 30 min.

[0054] Colloidal chitin culture medium: 0.2 g magnesium sulfate heptahydrate, 1 g diammonium hydrogen phosphate, 0.2 g potassium chloride, 10 g colloidal chitin, 18 g agar, dilute to 1 L with distilled water, pH = 7, sterilize at 121°C for 30 min.

[0055] Poria powder culture medium: Poria powder 2g, sodium nitrate 2g, potassium dihydrogen phosphate 1g, potassium chloride 0.5g, magnesium sulfate 0.5g, ferrous sulfate 0.01g, Congo red 0.05g, agar 18g, distilled water to 1L, pH = 7.2, sterilize at 121℃ for 30min.

[0056] Organic acid culture medium: 6.0 g glucose, 1.0 g yeast extract, 1.0 g peptone, 0.2 g MgSO₄·7H₂O, 1.0 g CaCO₃, trace amount of bromocresol purple, 15.0 g agar, distilled water to 1 L, pH 7.2–7.4, sterilize at 121°C for 30 min.

[0057] Pectin culture medium: K2HPO4 2.0g, MgSO4 0.5g, pectin 2.0g, 1.5g / L (NH4)2SO4, 0.01g FeSO4, adjust the pH to 7.2-7.4. Sterilize at 121℃ for 30min.

[0058] Starch culture medium: 5.0 g beef extract, 10.0 g peptone, 5 g NaCl, 2 g soluble starch, 20 g agar powder, distilled water to 1 L, pH 7.2-7.4, sterilize at 121°C for 20 min.

[0059] Hoagland nutrient solution: Take 1.26g Hoagland nutrient solution (powder), add 0.845g calcium nitrate, dilute to 1L with distilled water, and sterilize at 115℃ for 20min.

[0060] Example 1

[0061] The present invention provides the isolation and identification of Bacillus velezensis YD21 strain:

[0062] 1) Isolation and Purification of Bacillus velezensis YD21: Wild soybean seeds were surface sterilized, soaked in 75% ethanol for 2 minutes, rinsed five times with sterile water, soaked in 2.5% sodium hypochlorite for 3 minutes, rinsed five times with sterile water, soaked in 75% ethanol for 30 seconds, rinsed five times with sterile water, and blotted dry with sterile absorbent paper for later use. 100 μL of the final wash water was spread on LB solid medium and incubated at 30°C as a blank control. Surface sterilization was successful if no colonies grew.

[0063] Place the surface sterilized wild soybean seeds in a sterile mortar, add 1 mL of sterile water and grind them. After grinding thoroughly, let them stand for 10 minutes, take the supernatant, and dilute it to 10 -1 ~10 -4 Gradient, take 100 μL of each strain and spread it on LB solid medium, incubate in a constant temperature incubator at 30℃ for 48 hours. Pick a single colony and purify it 3-5 times using the four-zone plate streak method. The purified strain is inoculated on NA slant medium and stored in a refrigerator at 4℃ until use.

[0064] 2) Identification of Bacillus velezensis YD21:

[0065] The isolated and purified YD21 strain was placed in NB medium, cultured at 37°C and 160rpm for 12 hours for activation, and then streaked onto NA medium plates to obtain single colonies. The colony PCR method was used, with the total DNA of the YD21 strain as a template and 16SrRNA as a universal primer. The reaction system was: 3μL amplification template; 12.5μL 2×Taq MasterMix; 1μL each of upstream and downstream primers (10μmol / L); 7.5μL sterile water. The reaction conditions were: 94°C pre-denaturation for 10min; 94°C denaturation for 30s, 55°C annealing for 1min, 72°C extension for 1.5min, for a total of 30 cycles; 72°C extension for 10min. The PCR amplification product was sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing, and its sequence is as follows. The sequencing results were uploaded to the NCBI database. After BLAST comparison, it was inferred that the YD21 strain was Bacillus velezensis and named Bacillus velezensis YD21. Its phylogenetic analysis is as follows. Figure 1 shown.

[0066] The gene sequence of the strain Bacillus velezensis YD21 (shown as SEQ ID No. 1) is as follows:

[0067]

[0068] The deposit information of this strain is as follows:

[0069] Bacteria name: Bacillus velezensis

[0070] Latin name: (Bacillus velezensis)

[0071] Strain number: CGMCC No.3334

[0072] Depository: General Microbiology Center of China Culture Collection Administration

[0073] Abbreviation of depository institution: CGMC

[0074] Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing

[0075] Deposit date: January 8, 2025

[0076] Registration number of the CGMCC Collection Center: CGMCC No.3334.

[0077] Example 2:

[0078] This embodiment provides a bacterial agent, the active ingredients of which are Bacillus velezensis YD21CGMCC No. 3334 and its metabolites in Example 1.

[0079] The bacterial agent has active bacterial agents of protease, cellulase, chitinase, organic acid, pectinase and amylase.

[0080] The bacterial agent is a bacterial suspension of Bacillus velezensis YD21, or a fermentation liquid or metabolite obtained by fermentation culture of Bacillus velezensis YD21.

[0081] The bacterial agent is prepared according to the following method:

[0082] 1) The purified cultured Bacillus velezensis YD21 stored at 4°C was inoculated into NB medium and cultured at 30°C and 160 rpm for 24 h for activation.

[0083] 2) The activated strain in step 1) was inoculated into NB medium and cultured at 30°C, 160 rpm, and shaken for 12 h. The OD 600 =1.0 to prepare mother liquor.

[0084] 3) The strain mother solution was transferred to NB medium at a 1% inoculum volume, cultured at 30°C, 160 rpm, and then adjusted to OD600 =1.0, centrifuge at 10000 rpm for 10 min, remove the supernatant, and resuspend the bacteria in an equal volume of sterile water to obtain a bacterial suspension.

[0085] 4) The strain mother solution was transferred to NB medium at a 1% inoculum volume, cultured at 30°C, 160 rpm, and then adjusted to OD 600 =1.0, and the fermentation liquid was obtained.

[0086] Example 3:

[0087] Growth curve determination of Bacillus velezensis YD21

[0088] The fermentation broth of strain YD21 was inoculated into NB medium at 1% inoculum and cultured at 30°C and 160 r / min. Samples were taken at 0h, 1h, 2h, 3h, 4h, 8h, 12h, 16h, 20h, 24h, 28h, 32h, 36h, 40h, 44h, 48h and 60h, and OD 600 The determination was performed with 3 parallel groups set up for each group. 600 The value is the vertical axis, the culture time is the horizontal axis, and the bacterial growth curve is drawn as follows Figure 2 The strain YD21 was in the lag phase from 0 to 2 hours, in the logarithmic phase from 2 to 20 hours, in the stable phase from 20 to 36 hours, reached the maximum biomass at 24 hours, and gradually entered the decline phase after 36 hours.

[0089] Example 4:

[0090] Detection of enzyme production characteristics of Bacillus velezensis YD21: The production capacity of protease, chitinase, organic acid, pectinase and amylase was determined by protease assay medium, sodium carboxymethyl cellulose medium, colloidal chitin medium, Poria powder medium, organic acid medium, pectin medium and starch medium. Strain YD21 was spotted onto the above culture medium and cultured at 30°C for 48 hours to observe whether there was a hydrolysis zone; after culture in protease assay medium, saturated ammonium sulfate solution was added to immerse the colony, and after 30 minutes, it was observed whether there was a transparent zone; after culture in sodium carboxymethyl cellulose medium and pectin medium, it was soaked in 1g / L Congo red solution for 1 hour, and then added with 1M NaCl solution and soaked for 30 minutes to observe whether there was a decolorization zone; after culture in starch medium, iodine tincture was added, and after 10 minutes, it was observed whether there was a decolorization zone. The results are as follows Figure 3 The results showed that transparent circles appeared on all six culture media, indicating that the YD21 strain has the activity of producing protease, cellulase, chitinase, organic acid, pectinase and amylase.

[0091] Example 5:

[0092] Determination of the Inhibitory Rate of Bacillus velezensis YD21 against Plant Pathogenic Fungi

[0093] The four-point plate standoff method was used to determine the antibacterial efficiency of strain YD21. Sixteen plant pathogenic fungi were activated on PDA medium at 25°C for 3-4 days. Before the mycelium completely covered the plate, a sterile punch was used to punch out a 5mm-thick cake of mycelium from the edge and inoculated onto the center of the PDA medium. Strain YD21 was then inoculated 1.5cm around the pathogenic fungi in two perpendicular lines, using the center of the plate as the dot. A PDA medium inoculated only with the pathogenic fungus served as a blank control. Each treatment was repeated three times. The plates were incubated at a constant temperature of 25°C. When the mycelium of the blank control group almost covered the plate, the width of the inhibition zone of each group was recorded and the antibacterial efficiency (%) was calculated.

[0094] Inhibition rate = (pathogen diameter of control group - pathogen diameter of treatment group) / pathogen diameter of control group × 100%

[0095] The results are as follows Figure 4 The results are shown in Table 1. Strain YD21 exhibited varying degrees of antifungal activity against 16 plant pathogenic fungi, with inhibition rates exceeding 60% for all strains. Among these, the inhibition rates against apple heart mold and corn black bunch pathogen exceeded 90%, at 93.97% and 91.52%, respectively. The inhibition rate against soybean gray leaf spot was 73.56%.

[0096] Table 1 Detection of the inhibition rate of Bacillus velezensis YD21 against pathogenic fungi

[0097]

[0098]

[0099] Example 6:

[0100] To investigate the inhibitory effect of Bacillus velezensis YD21 fermentation broth on soybean gray leaf spot mycelium:

[0101] Preparation of soybean gray leaf spot fungus cake: Activate soybean gray leaf spot fungus on PDA medium at 25°C for 3-4 days, and use a sterile puncher to punch out soybean gray leaf spot fungus cake with edge mycelia (r=5 mm) before mycelia have not fully grown on the plate.

[0102] Preparation of strain YD21 fermentation broth: strain YD21 stored at 4°C was inoculated into NB medium and cultured at 30°C, 160 r / min for 24 h for activation. The activated strain was inoculated into NB medium and cultured at 30°C, 160 r / min for 12 h, and then the OD was adjusted to 600=1.0 to prepare the mother solution. Transfer the mother solution of the strain to NB medium at a 1% inoculum volume, culture at 30°C, 160 rpm for 24 h, and then adjust the OD to 600 =1.0, and the fermentation liquid was obtained.

[0103] Co-culture of soybean gray spot disease fungus cakes and strain YD21 fermentation broth: 3 soybean gray spot disease fungus cakes and 10 mL of strain YD21 fermentation broth were added to 70 mL of PDB medium as the treatment group, and an equal volume of sterile water was added as the control group. The culture was shaken at 120 r / min and 25 ° C for 3d, 5d, and 7d, then the soybean gray spot disease fungus cakes were taken out, filtered and dried. Each group was repeated three times, and the dry weight of the mycelium of the soybean gray spot disease fungus cakes was measured.

[0104] See the results Figure 5 On the 3rd, 5th, and 7th day of culture, the mycelial dry weight of the YD21 fermentation broth-treated group was significantly lower than that of the control group. As the culture time increased, the mycelial dry weight of the control group gradually increased, while that of the treated group did not change significantly. This suggests that the fermentation broth of strain YD21 has a significant inhibitory effect on mycelial growth.

[0105] Example 7:

[0106] Experiment on the control effect of Bacillus velezensis YD21 on soybean gray leaf spot;

[0107] 1) Soybean potted plant test: Using the soybean variety Shennong 12 as the test material, healthy and plump soybean seeds were selected and disinfected by soaking in 75% alcohol for 30 seconds and 2.5% sodium hypochlorite for 20 minutes. After rinsing with sterile water 3-5 times, the seeds were spread flat on a white porcelain plate with moistened filter paper and covered with 4 layers of moistened gauze. The seeds were germinated and cultured at 25°C for 3 days. Uniform seedlings were selected and transplanted into sterilized soil. After the third compound leaf was fully grown, in vitro and in vivo control efficacy tests were conducted.

[0108] 2) Preparation of a spore suspension of C. sojae: C. sojae was inoculated into 70 mL of PDB medium in a 150 mL Erlenmeyer flask equipped with a sterile rotor and cultured at 25°C for 3 days with shaking at 120 rpm. The culture was stirred with a magnetic stirrer and filtered through gauze to prepare a spore suspension.

[0109] 3) Condition investigation standards and calculation methods: Figure 6 Leaf disease grading: Level 0: no lesions; Level 1: lesion area is 1-10%; Level 2: lesion area is 10%-25%; Level 3: lesion area is 25%-50%; Level 4: lesion area is 50%-75%; Level 5: lesion area is 75%-100%.

[0110] Calculation formula: disease index = [Σ(number of diseased leaves at each level × relative level value) / (total number of leaves surveyed × 5)] × 100; control effect (%) = [(disease index of control group - disease index of treatment group) / disease index of control group] × 100.

[0111] 4) In vitro control efficacy test: Randomly take the second to third compound leaves, clean them with sterile water, and place them on a 1% agar medium to keep the leaves moist. Spray the soybean gray spot spore suspension evenly on the leaves, and treat them with the biocontrol bacteria strain YD21 after 24 hours. The bacterial suspension (JT) and fermentation liquid (FJ) of strain YD21 were treated with the original solution and diluted 10 times and 50 times, respectively. Only sterile water was sprayed as the control CK. Different treatment solutions were evenly sprayed on the leaves, and each treatment was repeated 3 times. Seal with plastic wrap, and after 7 days, the disease index and control effect were statistically analyzed according to the above-mentioned disease investigation standards and calculation methods. See the results. Figure 7 Table 2. Leaves sprayed with gray leaf spot spore suspension treated with different concentrations of strain YD21 bacterial suspension and fermentation broth ( Figure 7 ch), and CK( Figure 7 b), both showed some ability to inhibit the onset of soybean gray leaf spot. As shown in Table 2, the control rates of the YD21 bacterial suspension and fermentation broth were 69.51% and 76.82%, respectively. At the same concentration, the fermentation broth treatment had a higher control rate against gray leaf spot than the bacterial suspension. With increasing dilution, the disease index of the bacterial suspension and fermentation broth treatments increased significantly, but was still significantly lower than that of the control.

[0112] 5) In vivo control efficacy test: Spray the soybean gray spot spore suspension evenly on the front and back of the leaves until a little drop of liquid is dripping, and then treat with biocontrol bacteria 24 hours later. Spray the biocontrol bacteria strain YD21 bacterial suspension (JT) and fermentation liquid (FJ) evenly on the front and back of the leaves until a little drop of liquid is dripping, and use NB culture medium as the control CK. Spray once every 7 days for a total of three times. Seven days after the third spraying, randomly check 10 leaves of each plant, and calculate the disease index and control effect according to the survey standards and calculation methods. The results are shown in Figure 7 and Table 2. Bacterial suspension of strain YD21 ( Figure 7 j) and fermentation broth treatment ( Figure 7 k), and CK( Figure 7 i) showed a strong ability to inhibit the onset of soybean gray leaf spot. As shown in Table 2, the disease index and control rate of the bacterial suspension and fermentation liquid treatments were significantly lower than those of the control, with control rates of 39.1% and 50.91%, respectively. The disease index of the fermentation liquid treatment was significantly lower than that of the bacterial suspension, and its control rate against gray leaf spot was higher than that of the bacterial suspension.

[0113] The results of in vitro and in vivo control tests showed that both the bacterial suspension and fermentation liquid of strain YD21 had good control effects on soybean gray leaf spot, and the control effect of fermentation liquid treatment was better than that of bacterial suspension.

[0114] Table 2 Test on the efficacy of strain YD21 against soybean gray leaf spot

[0115]

[0116]

[0117] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0118] It should be understood that the present invention is not limited to the above description and that various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. Bacillus Velez, characterized in that The Bacillus velezensis is named Bacillus velezensis YD21, the preservation number of the Bacillus velezensis YD21 is CGMCC No.3334, the preservation time is January 8, 2025, and the preservation address is the General Microbiology Center of the China Culture Collection Administration.

2. A bacterial agent, characterized in that The bacterial agent is one of the bacterial suspension, fermentation broth or metabolites of Bacillus velezensis according to claim 1.

3. The microbial agent according to claim 2, characterized in that The bacterial agent has the activities of protease, cellulase, chitinase, organic acid, pectinase and amylase.

4. The microbial agent according to claim 2, characterized in that The bacterial content of Bacillus velezensis YD21 in the bacterial agent is 1.0×10 8 ~1.0×10 9 cfu / mL.

5. Use of the bacterial agent according to any one of claims 2 to 4 in any one or more of (1) to (4), 1) Inhibit plant pathogenic fungi; 2) Prevent and control plant fungal diseases; 3) Improve plant stress resistance; 4) Reduce the sensitivity of plants to adversity.

6. The use according to claim 5, characterized in that The plant pathogenic fungi and plant fungal diseases are at least one of the following plant pathogenic fungi and the diseases caused by them: 1) Fusarium graminearum; 2) Black bunch pathogen (Acremonium strictum); 3) Tomato gray mold (Botrytis cinerea Pers.); 4) Bipolaris zeicola; 5) Pepper wilt pathogen (Fusarium oxysporum f.sp.vasinfectum) 6) Pythium aphanidermatum; 7) Corn top rot pathogen (Frumentum subglutinans); 8) Corn Curvularia lunata; 9) Sunflower sclerotinia (Sclerotinia sclerotorium); 10) Corn gray leaf spot pathogen (Cercospora zeae-maydis); 11) Melon wilt pathogen (Fusarium oxysporum f.sp.melonis); 12) Rhizoctonia solani; 13) Cucumber scape pathogen (Mycosphaerella melonis) 14) Apple core mold (Trichothecium roseum); 15) Bipolaris sorghicola; 16) Soybean gray leaf spot pathogen (Cercospora sojina).

7. The use according to claim 5, characterized in that The adverse environment is one of drought, high temperature, pest and disease invasion or heavy metal pollution.

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