Bacillus siamensis and application thereof

Abstract

The present application relates to the technical field of biological control, and discloses bacillus siamensis and application thereof.The bacillus siamensis of the present application is preserved in the China General Microbiological Culture Collection Center, and the preservation number is CGMCC NO.32576.The bacillus siamensis has good prevention effect on pepper blight, and the field prevention effect can reach 71.69+ / -8.00%, and can be used for preventing and treating various plant diseases.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biological control, and particularly relates to a Bacillus siamensis and application thereof. BACKGROUND

[0002] Pepper (Capsicum annuum L.) is one of the largest vegetable industries in China. In production, pepper is harmed by various diseases, among which, pepper blight is the most serious. Pepper blight is a typical soil-borne disease caused by Phytophthora capsici, which can infect roots, stems, leaves and fruits of pepper plants, causing root rot, stem rot and sudden collapse. Due to the wide host range, fast transmission speed and various transmission modes of P. capsici, it is very difficult to control pepper blight.

[0003] For the prevention and control of pepper blight, chemical agents are the most widely used method due to their low price, high efficacy, and no restrictions on time, space, soil type and environmental conditions. Commonly used agents on the market include dimethomorph, azoxystrobin, flumorph, fosetyl-aluminum, chlorothalonil, mancozeb, metalaxyl and metalaxyl-M, etc. However, the mechanism of action of these agents is directed at a single link of pathogen metabolism, and once the action site mutates, it will lead to the development of drug resistance in the pathogen, thereby reducing the efficacy. In addition, the use of a large amount of chemical pesticides will lead to a series of problems such as excessive pesticide residues, soil microbial balance destruction and environmental pollution.

[0004] Biological control is a method of using biocontrol agents or their metabolites to control the occurrence, reproduction or reduce the damage of harmful organisms. The mechanism of action of biocontrol agents mainly includes competition, inhibition, induction of systemic resistance in plants and promotion of plant growth, etc. Therefore, biological control has the advantages of safety, effectiveness, no residue, environmental protection and sustainability, and is an effective measure to ensure the sustainable development of agriculture and food production. At present, there are many reports on the application of pepper blight biocontrol agents to control pepper blight. Wang Rongbo (2022) et al. screened Bacillus subtilis BS193 by plate confrontation method, which had an inhibition rate of 66.70% on P. capsici. In vitro leaf and indoor pot experiments showed good efficacy, and the strain showed good growth-promoting effect on pepper plants, with an increase of 48.16-73.27% in plant height, root length, fresh weight and dry weight, respectively. Zou Xiwei (2022) et al. screened B. velezensis Y4-39 by plate confrontation method, which mainly exerted antibacterial activity by producing antibacterial peptides. Pot experiment showed that the fermentation broth had a control effect of 67.78% on P. capsici, which had the potential to develop bio-fermented fertilizer.

[0005] Screening for efficient pepper Phytophthora biocontrol bacteria is an important strain resource and premise for the development of microbial fungicides. By the end of April 2024, only two microbial pesticides (5 billion CFU / ml Bacillus laterosporus A60 suspension and 100 billion CFU / ml Bacillus subtilis suspension) for effectively preventing and treating pepper Phytophthora have been registered in China. Therefore, the number and effect of pepper Phytophthora biocontrol bacteria cannot meet the production needs of microbial fungicides at present. SUMMARY

[0006] Therefore, the application provides a biocontrol bacterium Bacillus siamensis SD23LJ1314 for preventing and treating pepper Phytophthora, which provides a high-quality strain resource for green prevention and control of pepper Phytophthora and development of microbial fungicides.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The application provides a Bacillus siamensis, which is Bacillus siamensis SD23LJ1314, and the preservation number is CGMCC NO.32576.

[0009] In the application, the 16S rDNA gene sequence of the Bacillus siamensis is shown in SEQ ID NO:1, and the gyrB gene sequence is shown in SEQ ID NO:2.

[0010] In the application, the single colony edge of the Bacillus siamensis is irregular, milky white, the colony surface is wrinkled, the colony is rod-shaped under a microscope, has flagella, is gram-positive, and produces spores.

[0011] The application further includes a culture of the above-mentioned Bacillus siamensis, which is a substance obtained by culturing the above-mentioned Bacillus siamensis in a microbial culture medium.

[0012] As an implementation manner, the microbial culture medium is an LB solid culture medium or an LB liquid culture medium.

[0013] As an implementation manner, the culture includes a bacterial suspension, a fermentation broth and / or a metabolite of the Bacillus siamensis.

[0014] Another object of the application is to provide application of the above-mentioned Bacillus siamensis and / or culture thereof in any one of the following:

[0015] 1) Inhibiting plant pathogenic bacteria; the plant pathogenic bacteria are at least one of the following: pepper Phytophthora, Fusarium oxysporum, Fusarium graminearum, Fusarium pseudograminearum, Fusarium pseudocircinatum, Fusarium proliferatum, Fusarium fujikuroi, Ophiostoma novo-ulmi, Colletotrichum siamense, Colletotrichum capsici, Botrytis cinerea and Alternaria solani.

[0016] 2) an inhibitor of the plant pathogenic fungi of 1);

[0017] 3) a plant disease caused by the plant pathogenic fungi of 1);

[0018] 4) an inhibitor of the plant disease of 3).

[0019] As an embodiment, the Fusarium oxysporum includes Fusarium oxysporum f. sp. niveum, Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum f. sp. vasinfectum, Fusarium oxysporum f. sp. cucumeris, Fusarium oxysporum f. sp. phaseoli, Fusarium oxysporum f. sp. fragariae, and Fusarium oxysporum f. sp. conglutinans.

[0020] As an embodiment, the plant disease includes pepper phomopsis blight, crop fusarium wilt, wheat scab, wheat foot rot, corn ear rot, corn stalk rot, rice seedling blight, strawberry root rot, strawberry anthracnose, pepper anthracnose, pepper botrytis blight, and pepper early blight.

[0021] As an embodiment, the method for preventing the plant disease by the Bacillus siamensis includes root soaking treatment with the Bacillus siamensis or its culture before the plant is transplanted, and root irrigation with the Bacillus siamensis or its culture after the plant is planted.

[0022] The application also provides a microbial agent containing the Bacillus siamensis and / or the culture.

[0023] Compared with the prior art, the application has the following advantages and effects:

[0024] The Bacillus siamensis has a good prevention effect on pepper phomopsis blight, and the field prevention effect can reach 71.69±8.00%, which is better than the registered microbial pesticide for preventing and treating pepper phomopsis blight, and is equivalent to the chemical pesticide. The Bacillus siamensis has a broad-spectrum antagonistic effect on plant pathogenic fungi, and can be used for preventing and treating various plant diseases.

[0025] DEPOSIT DESCRIPTION

[0026] The Bacillus siamensis SD23LJ1314 was deposited with the China General Microbiological Culture Collection Center on November 11, 2024, and the deposit number is CGMCC NO. 32576. The address is No. 1, Beichen West Road, Yard 3, Beijing Chaoyang District, Institute of Microbiology, Chinese Academy of Sciences. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A phylogenetic tree of the SD23LJ1314 strain obtained according to the gyrB gene sequence. DETAILED DESCRIPTION

[0028] The present application isolates and purifies a Bacillus siamensis SD23LJ1314 from the rhizosphere soil of robust pepper plants, which has a high control effect on pepper Phytophthora and a wide control spectrum.

[0029] At present, the Bacillus siamensis SD23LJ1314 has been preserved in the China General Microbiological Culture Collection Center, the preservation number is CGMCC NO.32576; the address is No.1, Xibaheyi, Beijing, China Institute of Microbiology, Chinese Academy of Sciences; the preservation date is November 11, 2024, and the classification and naming is Bacillus siamensis.

[0030] The single colony edge of the Bacillus siamensis of the present application is irregular, milky white, the colony surface is wrinkled, and the colony is rod-shaped, flagellated, gram-positive and spore-forming under a microscope.

[0031] The 16S rDNA gene sequence of the Bacillus siamensis of the present application is shown as SEQ ID NO:1, the 16S rDNA is compared with NCBI blast, the result shows that the homology similarity with Bacillus is greater than 99%, which indicates that the SD23LJ1314 strain is Bacillus. The gyrB gene sequence of the Bacillus siamensis of the present application is shown as SEQ ID NO:2, a phylogenetic tree is constructed according to the gyrB gene sequence and the gyrB gene sequence of the model strain with high homology of the test strain sequence downloaded from NCBI, and the SD23LJ1314 strain is identified as Bacillus siamensis.

[0032] The present application also includes the culture of the above-mentioned Bacillus siamensis, which refers to the substance obtained by culturing Bacillus siamensis in a microbial culture medium, including but not limited to bacterial suspension, fermentation broth and / or metabolites of Bacillus siamensis. The microbial culture medium here refers to a culture medium that can realize the growth and proliferation of Bacillus siamensis, including but not limited to LB solid medium or LB liquid medium, and improved culture medium for better growth or metabolism of Bacillus siamensis on LB medium. The culture medium and culture conditions can be adjusted or improved by the person skilled in the art according to the actual culture situation. As an embodiment, the culture method of the Bacillus siamensis includes inoculating Bacillus siamensis in LB liquid medium, and after 10-12h of shaking culture at 150-180rpm and 30-35℃, transferring to LB liquid medium at a ratio of 1-2%, and then shaking culture at 150-180rpm and 30-35℃ for 48h, to obtain Bacillus siamensis fermentation broth. The content of Bacillus siamensis in the Bacillus siamensis fermentation broth is 1x109 -2 x 10 9 cfu / mL.

[0033] The Bacillus siamensis of the present application and its culture have a function of inhibiting various plant pathogenic fungi, and can be used as a sole or partial active ingredient of a plant pathogenic fungus inhibitor. Preferably, the Bacillus siamensis of the present application and its culture have an inhibitory effect on Phytophthora capsici, Fusarium oxysporum f. sp. niveum, F. oxysporum f. sp. lycopersici, F. oxysporum f. sp. vasinfectum, F. oxysporum f. sp. momordicae, F. oxysporum f. sp. melonis, F. oxysporum f. sp. phaseoli, F. oxysporum f. sp. fragariae, F. oxysporum f. sp. conglutinans, F. graminearum, F. pseudograminearum, F. sporotrichioides, F. proliferatum, F. fujikuroi, Pestalotiopsis, Colletotrichum sisamense, C. capsici, Botrytis cinerea, Alternaria solani, and the like.

[0034] The Paenibacillus thailandensis and culture thereof of the present application can achieve the effect of preventing and treating plant diseases by inhibiting plant pathogenic fungi, and can be used as the sole or partial active ingredient of a plant disease inhibitor. As an embodiment, the plant diseases of the present application include pepper late blight caused by Phytophthora capsici, crop wilt caused by each special form of Fusarium oxysporum, wheat scab caused by Fusarium graminearum, wheat foot rot caused by Pseudofusarium oxysporum, corn ear rot caused by Fusarium verticillioides, corn stalk rot caused by Fusarium proliferatum, rice bakanae disease caused by Fusarium fujikuroi, strawberry root rot caused by Rosellinia necatrix, strawberry anthracnose caused by Colletotrichum gloeosporioides, pepper anthracnose caused by Colletotrichum capsici, pepper gray mold caused by Botrytis cinerea, and pepper early blight caused by Alternaria solani. As an optional embodiment, before the pepper seedlings are transplanted, the seedlings are treated by root soaking in the fermentation broth of the Paenibacillus thailandensis, and after the pepper is planted, the root is irrigated with the bacterial suspension or the diluted fermentation broth of the Paenibacillus thailandensis. Experiments prove that the Paenibacillus thailandensis of the present application can achieve good control effect on pepper late blight, and the field control effect reaches 71.69±8.00%.

[0035] The present application also provides a microbial inoculant containing the Paenibacillus thailandensis and / or culture thereof of the present application. The microbial inoculant of the present application can be produced according to the methods well known to those skilled in the art. The formulation type of the microbial inoculant can be in the form of solution, dispersion, suspension, powder, etc. The use mode can be spraying, spreading, trenching, or irrigation with water.

[0036] In an embodiment, the microbial inoculant of the present application further comprises a different microbial type from the Paenibacillus thailandensis of the present application. The different microorganisms are used in combination, which expands the host spectrum of the microbial inoculant, improves the control effect on plant pathogenic fungi, and delays the generation of drug resistance.

[0037] In an embodiment, the Paenibacillus thailandensis or culture thereof of the present application can be freeze-dried or dissolved in a suitable solvent to prepare a microbial inoculant. The freeze-drying method is a conventional method in the art. The solvent can be water, microbial culture medium, etc.

[0038] The present application is further described below in conjunction with specific examples, but the present application is not limited to the following examples. The plant pathogenic fungi used in the following examples are derived from the plant pathogenic fungi strains preserved in the laboratory, which are known types of plant pathogenic fungi. The experimental methods used in the examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0039] Example 1

[0040] Screening of antagonistic bacteria against Phytophthora capsici

[0041] Select robust pepper plants, collect rhizosphere soil, dry and mix, then take 1 g and add to a triangular flask containing 100 mL of sterilized water and sterilized glass beads, place the flask in a 30°C shaker, shake for 30 min at 180 rpm, then stand at room temperature for 30 min. Take 1 mL of supernatant and add to 9 mL of sterile water for serial dilution, take 100 μL of the diluted liquid and spread on LB solid medium, stand at 30°C for 24 h, select different types of colonies for purification culture.

[0042] Pepper Phytophthora was used as the target bacteria and inoculated in the middle of the PDA plate, 2 cm away from the pathogenic bacteria, 3 test bacteria were inoculated in each dish. The plate inoculated with pepper Phytophthora only was used as a blank control to indicate the growth of pepper Phytophthora. Cultured at 25°C, when the pepper Phytophthora in the blank control plate grew to cover the entire culture dish, the control growth amount (colony radius d1), the treatment growth amount (inhibition growth radius d2 after inoculation of bacteria) and the distance d3 from the growth edge of pepper Phytophthora to the growth edge of the test bacteria (i.e. the inhibition zone) were measured, the inhibition rate was calculated, and the strain with antagonistic effect was screened.

[0043] Inhibition rate (%) = (d1-d2) / d1x100.

[0044] Among the 11458 strains of pepper rhizosphere and endophytic bacteria isolated by plate confrontation, 190 strains with antagonistic effect on pepper Phytophthora were obtained.

[0045] Example 2

[0046] Screening of strains with high antagonistic effect on pepper Phytophthora

[0047] Preparation of antagonistic bacteria fermentation broth: the antagonistic bacteria of Example 1 were inoculated in a test tube containing 5 mL of LB liquid medium, and cultured at 180 rpm and 30°C for 12 h, then transferred to 200 mL of LB liquid medium at a ratio of 1%, and cultured at 180 rpm and 30°C for 48 h, to obtain the antagonistic bacteria fermentation broth. Detection showed that the content of antagonistic bacteria in the antagonistic bacteria fermentation broth was 1x10 9 -2x10 9 cfu / mL.

[0048] Pepper seeds were sown in a hole tray filled with vermiculite for seedling, and after the pepper seedlings grew to 4 leaves and 1 heart, they were transplanted into flowerpots filled with nutrient soil. When the height of the pepper seedlings reached about 20 cm and the number of leaves was about 15, the pathogenic bacteria were inoculated and the antagonistic bacteria fermentation broth was irrigated. The operation was as follows: one day before inoculation of pathogenic bacteria, the seedlings were irrigated with 40 mL of 10-fold diluted antagonistic bacteria fermentation broth, and the next day the seedlings were inoculated with Phytophthora spore suspension (concentration of 5x10 4The seedlings were inoculated with 3 mL of the antagonistic bacteria fermentation liquid, and 3-5 days later, the seedlings were again irrigated with the diluted antagonistic bacteria fermentation liquid. Three replicates were set for each treatment, with 45 seedlings in each replicate. After 15 days, the control effect was investigated.

[0049] Disease investigation criteria:

[0050] Dead seedlings: stem base with lesions, lower leaves falling off, upper part of the plant wilting, and whole plant dead.

[0051] Healthy: no symptoms.

[0052] Dead seedling rate (%) = (number of dead seedlings / total number of seedlings investigated) x 100

[0053] Control effect (%) = [(control dead seedling rate - treatment dead seedling rate) / control dead seedling rate] x 100

[0054] In a pot experiment under greenhouse conditions, the preliminary screening and rescreening of the disease control effect of the antagonistic bacterial strain on pepper bacterial wilt were carried out. From 190 antagonistic bacterial strains, the strain SD23LJ1314 with better disease control effect on pepper bacterial wilt was obtained, with a control effect of 78.53%.

[0055] Table 2 Evaluation of the disease control effect of the biocontrol bacteria SD23LJ1314 on pepper bacterial wilt in the laboratory

[0056]

[0057]

[0058] Example 3

[0059] Classification status identification of the SD23LJ1314 strain

[0060] The genome of the SD23LJ1314 strain was extracted by the improved CTAB method, and the DNA of the SD23LJ1314 strain was amplified by using 16s rDNA and gyrB gene sequence primers. The PCR products were detected by 1% agarose gel electrophoresis, and were sequenced by Shanghai Sunred Bioengineering Co., Ltd. The sequencing results were subjected to homology analysis and multiple sequence alignment in the GenBank database of NCBI, and a phylogenetic tree was constructed by using MEGA software according to the alignment results.

[0061] The universal primer for 16S rDNA sequence is:

[0062] 27F: 5'-AGAGTTTGATCCTGGCTCAG-3',

[0063] 1492R: 5'-CTACGGCTACCTTGTTACGA-3'.

[0064] PCR reaction system: 10 x Easy Tap Mix 25 μL, 27-F 1 μL, 1492-R 1 μL, DNA 1 μL, ddH2O 22 μL.

[0065] PCR instrument amplification program: 94℃ 5min, 94℃ 45s, 58℃ 45s, 72℃ 1min, 35 cycles, 72℃ 10min, 4℃ ∞.

[0066] The universal primers of the gyrB gene are:

[0067] gyrB-F: 5'-TTGRCGGHRGYGGHTATAAAGT-3',

[0068] gyrB-R: 5'-TCCDCCSTCAGARTCWCCCTC-3'.

[0069] PCR reaction system: 10 x Easy Tap Mix 25 μL, gyrB-F 1 μL, gyrB-R 1 μL, DNA 1 μL, ddH2O 22 μL.

[0070] PCR instrument amplification program: 94℃ 5min, 95℃ 30s, 58℃ 45s, 72℃ 1min, 35 cycles, 72℃ 5min, 4℃ ∞.

[0071] The 16S rDNA universal primers 27F / 1492R were used to amplify the SD23LJ1314 strain, and the size was 1445bp. The NCBI blast comparison result showed that the homology similarity with Bacillus was greater than 99%, and the SD23LJ1314 strain was Bacillus. The universal primers gyrB-F and gyrB-R were used for PCR amplification, and the size was 1000bp. The gyrB gene sequence of the model strain with high sequence homology with the test strain was downloaded on NCBI, a phylogenetic tree was constructed, and the SD23LJ1314 strain was identified as Bacillus siamensis (Bacillus siamensis). Figure 1

[0072] Example 4

[0073] Field evaluation of SD23LJ1314 strain

[0074] The biocontrol bacteria SD24LJXF1314 was carried out field plot evaluation. The microbial inoculant Bacillus subtilis 100 billion CFU / ml suspension and the chemical pesticide thiabendazole+cymoxanil were used as controls, and the field evaluation was completed in the disease nursery.

[0075] The preparation method of the fermentation liquid of SD23LJ1314 was the same as that of Example 2, and the bacterial content of SD23LJ1314 in the fermentation liquid was 1 x 10​9 cfu / mL. The experiment was designed with 4 treatments: biocontrol bacteria SD23LJ1314 root irrigation, commercial bacterial agent root irrigation, chemical agent root irrigation, and blank control, with 3 replicates per treatment, and plots were randomly distributed.

[0076] Before transplanting, the seedlings were immersed in the SD23LJ1314 fermentation liquid for 30 minutes. On the first day after planting, the seedlings were irrigated with 1-fold diluted SD23LJ1314 fermentation liquid (100 mL per plant), and on the 3rd to 5th day after planting, the seedlings were irrigated again (100 mL per plant). The process was repeated for 3 times. As a biocontrol bacteria control, 100 billion CFU / mL of Bacillus subtilis suspension was diluted five times for root irrigation treatment. As a chemical control, 25% thiophanate-methyl + cymoxanil wettable powder was diluted 2000 times for root irrigation treatment. The treatment methods were the same as those of SD23LJ1314. Each treatment had 3 replicates, with 60 plants per replicate. Disease investigation was conducted after 15 days.

[0077] Disease investigation criteria:

[0078] Dead seedlings: stem base with lesions, lower leaf abscission, upper plant wilting, and whole plant dead.

[0079] Healthy: no symptoms.

[0080] Dead seedling rate (%) = (number of dead seedlings / total number of seedlings surveyed) x 100

[0081] Control effect (%) = [(control dead seedling rate - treatment dead seedling rate) / control dead seedling rate] x 100

[0082] The results showed that the field control effect of SD24LJXF1314 was 71.69%; the field control effects of 100 billion CFU / mL of Bacillus subtilis suspension and chemical pesticide thiophanate-methyl + cymoxanil were 49.05% and 77.36%, respectively (Table 3).

[0083] Table 3 Evaluation of biocontrol bacteria on pepper blight control effect in field test

[0084]

[0085]

[0086] Example 5

[0087] Determination of the inhibition spectrum of SD23LJ1314 strain

[0088] The inhibition spectrum of biocontrol strain SD23LJ1314 was determined by plate confrontation method.

[0089] The specific method is as follows: Use a punch (Φ=6mm) to create a fungal disc by punching holes along the edge of the newly activated pathogen colony. Transfer this disc to the center of a new PDA plate. Then, spot-inoculate the newly activated SD23LJ1314 strain 2cm to the left and right of the fungal disc. Use a plate inoculated only with the pathogen as a blank control to indicate the growth of the pathogen. Incubate at 25℃. When the blank control is about to completely cover the entire petri dish, measure the control growth (colony radius d1), the treatment growth (inhibition radius d2 after bacterial inoculation), and the distance d3 from the edge of the pathogen growth to the edge of the test bacteria (i.e., the inhibition zone). Calculate the inhibition rate.

[0090] Antibacterial rate (%) = (d1-d2) / d1×100.

[0091] The results showed that the biocontrol bacterium SD23LJ1314 was effective against Fusarium oxysporum watermelon-specific strain.

[0092] Fusarium oxysporum f.sp.niveum, Fusarium oxysporum f.sp.lycopersici, Fusarium oxysporum f.sp.vasinfectum, Fusarium oxysporum f.sp.bitter ...

[0093] *F. oxysporum* f. sp. melononis, *F. oxysporum* f. sp. phaseoli, *F. oxysporum* f. sp. fragariae, *F. oxysporum* f. sp. conglutinans, *F. graminearum*, *F. pseudograminearum*, *F. verticillata*.

[0094] *Fusarium sporotrichioides*, *F. proliferatum*, *F. fujikuroi*, *Pestalotiopsis*, *Colletotrichumsis amense*, *C. capsici*, *Botrytis cinerea*, and *Alternaria solani* all showed good antibacterial activity, with inhibition rates ranging from 61.19% to 81.73%.

[0095] Table 4 Inhibition of different pathogenic bacteria by biocontrol bacteria SD23LJ1314

[0096]

[0097]

[0098] The above examples are the best mode of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. Bacillus siamensis, characterized in that, The said Bacillus siamensis is Bacillus siamensis SD23LJ1314, with the preservation number of CGMCC NO. 32576.

2. The Bacillus siamensis according to claim 1, characterized in that, The 16S rDNA gene sequence of the said Bacillus siamensis is shown as SEQ ID NO: 1, gyrB The gene sequence is shown as SEQ ID NO:

2.

3. The culture of Bacillus siamensis according to claim 1 or 2, characterized in that, The culture is selected from the group consisting of a bacterial suspension or a fermentation broth of Bacillus siamensis.

4. The culture of claim 3, wherein, The culture medium for culturing the Bacillus siamensis is LB solid medium or LB liquid medium.

5. Use of the Bacillus siamensis of claim 1 or 2 and / or the culture of any one of claims 3 to 4 in any one of the following: 1) inhibiting a plant pathogenic fungus; the plant pathogenic fungus is at least one of Phytophthora capsici, Fusarium oxysporum, Fusarium graminearum, Fusarium pseudograminearum, Fusarium pseudocircinatum, Fusarium proliferatum, Fusarium fujikuroi, Pestalotiopsis versicolor, Glomerella siamensis, Colletotrichum capsici, Botrytis cinerea and Alternaria solani; 2) preparing an inhibitor of the plant pathogenic fungus of 1); 3) controlling a plant disease caused by the plant pathogenic fungus of 1); 4) preparing an inhibitor of the plant disease of 3).

6. Use according to claim 5, characterized in that, The Fusarium oxysporum includes Fusarium oxysporum f. watermelon, Fusarium oxysporum f. tomato, Fusarium oxysporum f. cotton, Fusarium oxysporum f. momordica, Fusarium oxysporum f. melonis, Fusarium oxysporum f. phaseoli, Fusarium oxysporum f. fragariae and Fusarium oxysporum f. conglutinans.

7. Use according to claim 5, characterized in that, The plant disease includes pepper blight, crop wilt, wheat scab, wheat foot rot, corn ear rot, corn stalk rot, rice seedling blight, strawberry root rot, strawberry anthracnose, pepper anthracnose, pepper botrytis blight and pepper early blight.

8. Use according to claim 5, characterized in that, The method for controlling a plant disease by the Bacillus siamensis includes root soaking treatment with the Bacillus siamensis or the culture of claim 3 or 4 before transplanting a plant and root irrigation with the Bacillus siamensis or the culture of claim 3 or 4 after planting.

9. A microbial inoculant, characterized in that, The Bacillus siamensis of any one of claims 1 to 2 and / or the culture of any one of claims 3 to 4.

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