CN110878268A

CN110878268A - Bacillus megaterium for resisting rice sheath blight and application thereof

Info

Publication number: CN110878268A
Application number: CN201911176577.7A
Authority: CN
Inventors: 成一知; 陈亚奎; 卢滇南; 任立伟; 纪智慧; 王伟
Original assignee: Hunan Newworld Science And Technology Co ltd; Tsinghua University
Current assignee: Hunan Newworld Science And Technology Co ltd; Tsinghua University
Priority date: 2019-11-26
Filing date: 2019-11-26
Publication date: 2020-03-13
Anticipated expiration: 2039-11-26
Also published as: CN110878268B

Abstract

The invention discloses a bacillus megaterium for resisting rice sheath blight and application thereof, wherein the preservation number of the bacillus megaterium is as follows: CGMCC NO.17146, the Bacillus megaterium H4 can inhibit the growth of pathogenic bacteria of rice sheath blight, can be effectively applied to the prevention and control of the rice sheath blight, the H4 bacterial strain can replace a pesticide prochloraz to be used for biological prevention and control of the rice sheath blight, and the biological prevention and control process is nontoxic to human and livestock, is environmentally friendly and has no residue and secondary pollution; the strain can be applied to field rice planting, has a good using effect, can effectively prevent and treat rice sheath blight, is convenient and simple to use, can realize industrialization, and is suitable for agricultural large-scale production.

Description

Bacillus megaterium for resisting rice sheath blight and application thereof

Technical Field

The invention relates to the technical field of microorganisms, in particular to a bacillus megaterium for resisting rice sheath blight and application thereof.

Background

Rice is one of the major food crops in the world, and nearly half of the world population eats rice. Besides being edible, the rice can also be used as industrial raw materials for brewing wine and making sugar, and the rice husks and rice straws can be used as feed. The rice sheath blight disease is one of the main diseases in the current rice production, is caused by infection of Rhizoctonia solani (Rhizoctonia solani) and dermataceae (thanatephorusucuurius), mainly occurs under high-temperature and high-humidity conditions, and is seriously harmful to rice areas in south China. The disease can occur from the seedling stage to the ear stage, the ear can not be threshed in serious cases, the number of blighted grains is large, and the grain weight is reduced.

In view of the fact that no immune or high-resistance variety is found in rice sheath blight breeding so far, the prevention and control of rice sheath blight mainly depends on chemical drugs at present, and various problems of secondary pollution, difficult degradation, long-term drug resistance generation, harm to human health and the like exist, so that the biological prevention and control technology of rice sheath blight becomes a research hotspot in recent years. Biocontrol refers to a method of controlling or reducing the extent of harm to a population of harmful animals or plants by an organism or its metabolites. Compared with the traditional treatment method, the biological prevention and control technology has the main advantages of small damage to the environment, high specificity, and difficult point and key point of finding efficient, stable and harmless functional microorganisms. The bacillus is an important biocontrol bacterium, has rich and various physiological characteristics, wide distribution and easy separation culture, and is an important microbial population on the surface and rhizosphere of soil and plants. The bacillus belongs to gram-positive bacteria, can produce spores, has strong stress resistance, can endure various adverse environments, and has wide application value in agriculture, scientific research, industry and medicine. The bacillus has the advantages of simple batch production process, low cost, convenient application, long storage time and the like, and is an ideal biocontrol microorganism. At present, a great number of fungi antagonistic microorganisms with biological prevention and control effects, such as penicillium, trichoderma, pseudomonas, actinomycetes and the like, are used for preventing and controlling various diseases of plants and crops. Although the research on the treatment of the rice sheath blight disease is endless, the biological prevention and control reports are relatively few, and no report exists on the prevention and control of the rice sheath blight disease by using bacillus megaterium.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a bacillus megaterium H4 for resisting rice sheath blight, which has the characteristics of high efficiency, stability and harmlessness and can effectively prevent and control rice sheath blight.

The invention also provides a culture method of the bacillus megaterium H4.

The invention also provides an application of the bacillus megaterium H4, which comprises the following aspects:

the application of the bacillus megaterium H4 in resisting rice sheath blight; or

A product resistant to rice sheath blight disease; or

A strain fermentation liquor for resisting rice sheath blight.

The invention also provides a method for preventing rice sheath blight.

According to the embodiment of the first aspect of the invention, the bacillus megaterium H4 for resisting rice sheath blight has the deposit number: CGMCC NO. 17146.

The bacillus megaterium H4 for resisting rice sheath blight according to the embodiment of the first aspect of the invention has at least the following beneficial effects: the strain is a plant endophyte, has the characteristics of high efficiency, stability and harmlessness, and has better control effect on rice sheath blight; the prochloraz can replace a pesticide to be used for biological control of rice sheath blight, the operation process is simple, and the biological control process is nontoxic to human and livestock, is eco-friendly and has no residue and secondary pollution; the strain also has the advantages of simple batch production process, low cost, convenient application, long storage time and the like; the strain filtrate has wide bacteriostatic spectrum, has certain inhibiting effect on pathogenic bacteria of various plants, has strong phosphate-solubilizing, potassium-fixing, IAA (indoleacetic acid) synthesizing and growth promoting capabilities, and can further promote the growth of rice.

A culture method according to an embodiment of the second aspect of the present invention comprises the steps of: after the surface of rice is cleaned and disinfected, the rice is placed on an LB solid culture medium for culture (2-3) days at the temperature of 28-35 ℃, and a single colony is obtained by picking.

According to the application of the embodiment of the third aspect of the invention, the bacillus megaterium H4 can be applied to resisting rice sheath blight.

The application of the embodiment of the third aspect of the invention has at least the following beneficial effects: the strain can effectively prevent and treat rice sheath blight, is beneficial to the growth of rice and improves the yield of rice; the biological control has the advantages of no toxicity to human and livestock, environmental protection, no residue and no secondary pollution; the strain also has the advantages of simple batch production process, low cost, convenient application, long storage time and the like, and can be effectively prepared into preparations and fertilizers in various forms for rice production.

According to the fourth aspect embodiment of the invention, the product for resisting rice sheath blight disease comprises the bacillus megaterium H4 or the fermentation liquid thereof.

According to some embodiments of the invention, the product is a fertilizer or a pharmaceutical agent.

According to the fifth aspect of the invention, the culture method of the anti-rice sheath blight strain fermentation broth comprises the following steps: culturing the bacillus megaterium H4 to obtain the strain fermentation liquor.

According to some embodiments of the invention, the above preparation method comprises the steps of: inoculating Bacillus megaterium H4 strain in LB culture medium at 28-35 deg.C, and culturing to obtain OD₆₀₀The value of the strain fermentation liquid reaches (1.0-1.2).

According to a sixth aspect of the present invention, a method for preventing rice sheath blight disease comprises the steps of: the rice seeds are soaked with the seed fermentation broth.

According to some embodiments of the invention, the method comprises the steps of: soaking the rice seeds for 2-4 days by using strain fermentation liquor with the wet weight of (4-6) g/L.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a control of antagonistic experimental colony growth media of H4 with pathogenic bacteria in example 1 of the present invention;

FIG. 2 is a photograph of a pot culture of rice in a pot culture experiment in example 3 of the present invention;

FIG. 3 is a diagram showing the rice seed soaking operation in the early-to-field experiment in example 4 of the present invention;

FIG. 4 is a comparison chart of the late rice field experiment in example 5 of the present invention.

Detailed Description

In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.

The LB liquid culture medium used in the invention: 1000mL of deionized water, 10.0g of peptone, 5.0g of yeast powder and 10.0g of sodium chloride, and sterilizing at 121 ℃ for 15min for later use.

LB solid medium: adding 2% agar into the above culture medium, and sterilizing at 121 deg.C for 15 min.

PDA solid medium: 200g of potato, 20g of glucose, 20g of agar and 1000mL of deionized water.

The first embodiment of the invention is as follows: screening and validation of Bacillus megaterium H4:

1. screening

Taking 5g of rice (the rice is from a rice plant normally planted in Hunan shozhou), washing the rhizome part, taking roots, stems and leaves, respectively soaking the roots, the stems and the leaves in 75% ethanol for 40s, sterilizing the roots, the stems and the leaves for 4min, rinsing the roots, the stems and the leaves in 75% ethanol for 30s again, cleaning the roots, the stems and the leaves with sterile water for 4 times, cutting the roots, the stems and the leaves into 0.5cm small sections, uniformly placing the small sections on an LB solid culture medium, and finally cleaning the small sections with sterile water to form a flat plate as. Then culturing at constant temperature of 30 ℃ for 3d, and obtaining single colony by streak separation and purification.

2. Antagonism experiment

Selecting a bacterial colony of a pathogenic bacterium (rhizoctonia solani) with stronger activity by adopting a three-point plate confronting method, making a bacterial cake by using a puncher with the diameter of 10mm, placing the bacterial cake in the center of a PDA (personal digital assistant) plate, carrying out plate scribing on a bacterial strain (CK is taken as a control group, and H4 is taken as a test group) in a cross-shaped symmetrical direction at a position 20mm away from the bacterial cake of the pathogenic bacterium, culturing for 72 hours at a constant temperature of 30 ℃, observing the formation of a bacteriostatic ring and measuring the size of the bacteriostatic ring, wherein the result is shown in figure 1, and the calculation process and the result are as follows according to the:

the diameter of bacterial colony growth (mm) — the measured diameter-the diameter of the bacterial cake;

hypha growth inhibition (%) (control colony diameter-treated colony diameter) × 100/control colony diameter;

the diameter of the colony growth of the control bacterium (CK) is 70-10 mm-60 mm;

the growth diameter of the treated colony (H4) is 20mm-10 mm;

hypha growth inhibition rate (60-10) × 100/60 ═ 83.3%;

from the above results analysis: h4 has strong antagonism to the growth of pathogenic strains, and the inhibition rate is up to 83.3%.

3. Physiological and biochemical experiment of H4 strain

a: gram stain

Tabletting: a clean glass slide is taken, a drop of physiological saline is added on the glass slide, the aseptic operation of the inoculating loop is noticed, a 24-hour culture is adopted for even smear, and the bacterial mass is noticed to be moderate.

Fixing: the smear was allowed to air dry naturally at room temperature, held by hand with the slide end up with the pellicle facing upwards, and fixed on the flame (2-3) times.

Dyeing: dripping crystal violet for primary dyeing for 2min, and washing with water; washing with iodine solution to remove residual water, covering with iodine solution for about 1min for mordant dyeing, and washing with water.

And (3) decoloring: decolorizing with 95% ethanol.

Counterdyeing: counterstaining with safranine solution for about 2min, washing the excess fuel from the specimen with fine slow flowing water, but not washing the fuel adsorbed by the cells, and air drying.

Microscopic examination: after drying, the cells were stained purple by oil-immersion observation, which was confirmed to be gram-positive.

b: fermentation test of sugar (alcohol)

Adding 1% bromothymol blue into a peptone culture medium taking glucose as a carbon source and an energy source, uniformly mixing, subpackaging a culture solution into test tubes, wherein the height of the culture solution is about 4cm, inverting a Du's small tube in the tube to fill the tube with the culture solution, sterilizing at 115 ℃ for 20min, inoculating a young strain cultured for 10 hours into the culture medium by using a puncture needle, culturing at room temperature for 1d, 3d and 5d, observing, and determining that the color turns yellow and bubbles are generated, wherein the color is positive reaction.

c: liquefaction of gelatin

Taking 4 nutrient gelatin culture media, adopting a puncture inoculation method, wherein 1 strain is inoculated with escherichia coli, 1 strain is inoculated with bacillus subtilis, 1 strain is inoculated with H4, and the 4 th strain is not inoculated as a blank control. After culturing at 37 ℃ for 48H, the gelatin culture medium is gently placed in a refrigerator at 4 ℃ for 30min, and gelatin change is observed, so that extracellular enzyme which indicates that H4 can produce gelatinase can be liquefied. The results of the experiment showed that the gelatin inoculated with H4 did not liquefy, indicating that H4 did not produce the extracellular enzyme gelatinase.

d: starch hydrolysis test

The 24h pure culture was spotted on a starch plate medium and cultured at 30 ℃ for 48 h. And (4) directly dripping iodine solution on the culture surface, and judging whether the iodine solution is blue or not to generate amylase. The results are shown in blue, indicating that H4 produces a starch hydrolyzing enzyme.

e: catalase test

The result of directly dropping 3% hydrogen peroxide into the culture solution of the strain shows that a large amount of bubbles are generated, and the reaction is positive, which indicates that H4 contains catalase.

f: oxidase test

Taking a piece of filter paper, dipping H4 bacterial liquid, then dropwise adding a tetramethyl p-phenylenediamine reagent, only wetting the filter paper, wherein the filter paper cannot be excessively wet, the filter paper is positive when the filter paper is red within 10s, the filter paper is delayed to react when the filter paper is red within 10-60 s, and the filter paper is treated as negative when the filter paper is over 60 s. The result showed a red color within 10s, indicating that H4 contains oxidase.

The results of the main physiological and biochemical experiments of the H4 strain are shown in the following Table 1:

table 1: physiological and biochemical experiments of H4 strain

5. Identification of strains

16SrDNA of the strain H4 is subjected to amplification sequencing by using a bacterial universal primer P2F, and the strain H4 is separated to have 99.5% similarity with the Bacillus megaterium by performing sequence comparison through NCBI. The gene sequence SEQ No.1 is shown as follows:

ACATGCAGTCGAGCGAACAGAAAAGGAGCTTGCTCCTTTGACGTTAGCGGCGGAC GGGTGAGTAACACGTGGGCAACCTACCCTATAGTTTGGGATAACTCCGGGAAACCGGGG CTAATACCGAATAATCTCTTTTGCTTCATGGTGAAAGACTGAAAGACGGTTTCGGCTGTC GCTATAGGATGGGCCCGCGGCGCATTAGCTAGTTGGTGAGGTAACGGCTCACCAAGGCG ACGATGCGTAGCCGACCTGAGAGGGTGATCGGCCACACTGGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCACAATGGGCGAAAGCCTGATGGAG CAACGCCGCGTGAGTGAAGAAGGTTTTCGGATCGTAAAACTCTGTTGTAAGGGAAGAA CAAGTACAGTAGTAACTGGCTGTACCTTGACGGTACCTTATTAGAAAGCCACGGCTAACT ACGTGCCAGCAGCCGCGGTAATACGTAGGTGGCAAGCGTTGTCCGGAATTATTGGGCGT AAAGCGCGCGCAGGCGGTCCTTTAAGTCTGATGTGAAAGCCCACGGCTCAACCGTGGA GGGTCATTGGAAACTGGGGGACTTGAGTGCAGAAGAGGAAAGTGGAATTCCAAGTGTA GCGGTGAAATGCGTAGAGATTTGGAGGAACACCAGTGGCGAAGGCGACTTTCTGGTCT GTAACTGACGCTGAGGCGCGAAAGCGTGGGGAGCAAACAGGATTAGATACCCTGGTAG TCCACGCCGTAAACGATGAGTGCTAAGTGTTAGGGGGTTTCCGCCCCTTAGTGCTGCAG CTAACGCATTAAGCACTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAA TTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGA ACCTTACCAGGTCTTGACATCCCGTTGACCACTGTAGAGATATAGTTTCCCCTTCGGGGG CAACGGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAG TCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCATCATTTAGTTGGGCACTCTAAGGT GACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTAT GACCTGGGCTACACACGTGCTACAATGGACGATACAAACGGTTGCCAACTCGCGAGAG GGAGCTAATCCGATAAAGTCGTTCTCAGTTCGGATTGTAGGCTGCAACTCGCCTACATGA AGCCGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTT GTACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGAGGTAACCTTTTGGAGCCAGCCGCCGAA。

according to the identification results of morphological characteristics, molecular biological characteristics and physiological and biochemical characteristics of the strains, the H4 strain is an antagonistic strain Bacillus megaterium (Bacillus megaterium) of ascomycetes and imperfect fungi. The strain is preserved in China general microbiological culture Collection center (CGMCC) in 2019, 1 month and 10 days, and the preservation number is as follows: CGMCC NO. 17146. And (4) storage address: the institute of microbiology, national academy of sciences No. 3, Xilu No.1, Beijing, Chaoyang, Beijing.

The second embodiment of the invention is as follows: preparation of H4 bacterial liquid:

inoculating Bacillus megaterium H4 into LB liquid medium, culturing at 30 deg.C and 170rpm in constant temperature shaking box for 12 hr, and culturing at OD₆₀₀Is (1.0 to 1.2).

The third embodiment of the invention is as follows: pot experiment:

the method comprises the steps of selecting rice seeds normally planted in Hunan, using 5g/L (wet weight) of bacterial liquid to replace pesticide sterilization to soak the rice seeds, transferring the rice seeds into soil in a later period, keeping soil humidity and temperature normal cultivation in the process, as shown in figure 2, growing the rice seeds to a blank group with the germination rate of about 20 centimeters and the germination rate of 90 percent, causing rice bakanae disease to cause the rice survival rate to be about 78 percent, the germination rate of an experimental group to be 91 percent and the survival rate to be 89 percent, and preventing rice sheath blight from occurring in the whole process.

The fourth embodiment of the invention is as follows: early rice field test:

the early season rice is ordinary rice, and the test field is Hunan province city.

Seed soaking and seedling raising: in the control group, rice seeds are soaked in cold water solution 3000 times of prochloraz pesticide for 3 days, the seeds are fished out and washed once by cold water after soaking, then are scalded for 15 minutes by water at 35 ℃, and then are fished out and placed in a bag to be kept at 20 ℃ for germination acceleration. The test group directly uses H4 wet weight 5g/L bacterial liquid to replace prochloraz water solution to soak rice seeds for 3 days, the subsequent operation is completely consistent, and no other steps are added. The specific seed soaking process is shown in FIG. 3.

Early rice is ordinary rice, seedling culture and field growth are carried out according to local operations in Hunan in the later stage, other operations are not added in the whole process, and diseased seedlings are not generated from seedling culture to final harvest. The experimental group does not have the rice sheath blight phenomenon, and the bacterial strain is proved to be capable of replacing pesticide prochloraz and being effectively applied to the field planting of early rice.

The fifth embodiment of the invention is as follows: late rice field test:

the late rice is Huyou 9803 hybrid rice, and the test field is Shannan province, Tanzhou, China.

Seed soaking and seedling raising: the contrast group adopts 3000 times of cold water solution of prochloraz pesticide to soak rice seeds for 6 hours, after soaking, the seeds are fished out and placed for two hours, then the seeds are soaked in the cold water for 6 hours, and the seeds are circularly soaked for three days without soaking at night. Finally, the seeds are fished out and put in a bag to be kept at 20 ℃ for accelerating germination. The test group directly uses H4 wet weight 5g/L bacterial liquid to replace prochloraz water solution to soak rice seeds for 3 days, the subsequent operation is completely consistent, and no other steps are added. The operation of the specific seed soaking implementation is shown in fig. 3.

The regional rice sheath blight disease appears in the control group, specifically shown in (a) and (b) in fig. 4, wherein (a) in fig. 4 is the control group, and (b) in fig. 4 is the experimental group, and the rice sheath blight phenomenon does not appear in the experimental group, so that the bacterial strain can replace the pesticide prochloraz and can be effectively applied to field planting of late rice.

Through pot simulation verification and field early and late rice implementation verification, the strain can reduce the incidence rate of rice sheath blight. No extra step is added in the field implementation process, the seeds are directly soaked in 5g/L (wet weight) H4 solution in the breeding stage, other operations are not needed, and the local rice planting habit is not changed.

In conclusion, the bacillus megaterium H4 for resisting rice sheath blight has a good prevention and treatment effect on rice sheath blight; the bacterial strain H4 provided by the invention can replace a pesticide prochloraz to be used for biological control of rice sheath blight, the operation process is simple, only 5g/L (wet weight) of the bacterial strain is needed to soak seeds, and the biological control process is nontoxic to people and livestock, is environment-friendly and has no residue and secondary pollution; the strain can be applied to field rice planting, has a good using effect, can effectively prevent and treat rice sheath blight, is convenient and simple to use, can realize industrialization, and is suitable for agricultural large-scale production.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.

Sequence listing

<110> New nine-square science and technology Co., Ltd, Hunan

Qinghua university

<120> bacillus megaterium for resisting rice sheath blight and application thereof

<160>1

<170>SIPOSequenceListing 1.0

<210>1

<211>1426

<212>DNA

<213> Bacillus megaterium (Bacillus megaterium)

<400>1

acatgcagtc gagcgaacag aaaaggagct tgctcctttg acgttagcgg cggacgggtg 60

agtaacacgt gggcaaccta ccctatagtt tgggataact ccgggaaacc ggggctaata 120

ccgaataatc tcttttgctt catggtgaaa gactgaaaga cggtttcggc tgtcgctata 180

ggatgggccc gcggcgcatt agctagttgg tgaggtaacg gctcaccaag gcgacgatgc 240

gtagccgacc tgagagggtg atcggccaca ctgggactga gacacggccc agactcctac 300

gggaggcagc agtagggaat cttccacaat gggcgaaagc ctgatggagc aacgccgcgt 360

gagtgaagaa ggttttcgga tcgtaaaact ctgttgtaag ggaagaacaa gtacagtagt 420

aactggctgt accttgacgg taccttatta gaaagccacg gctaactacg tgccagcagc 480

cgcggtaata cgtaggtggc aagcgttgtc cggaattatt gggcgtaaag cgcgcgcagg 540

cggtccttta agtctgatgt gaaagcccac ggctcaaccg tggagggtca ttggaaactg 600

ggggacttga gtgcagaaga ggaaagtgga attccaagtg tagcggtgaa atgcgtagag 660

atttggagga acaccagtgg cgaaggcgac tttctggtct gtaactgacg ctgaggcgcg 720

aaagcgtggg gagcaaacag gattagatac cctggtagtc cacgccgtaa acgatgagtg 780

ctaagtgtta gggggtttcc gccccttagt gctgcagcta acgcattaag cactccgcct 840

ggggagtacg gtcgcaagac tgaaactcaa aggaattgac gggggcccgc acaagcggtg 900

gagcatgtgg tttaattcga agcaacgcga agaaccttac caggtcttga catcccgttg 960

accactgtag agatatagtt tccccttcgg gggcaacggt gacaggtggt gcatggttgt 1020

cgtcagctcg tgtcgtgaga tgttgggtta agtcccgcaa cgagcgcaac ccttgatctt 1080

agttgccatc atttagttgg gcactctaag gtgactgccg gtgacaaacc ggaggaaggt 1140

ggggatgacg tcaaatcatc atgcccctta tgacctgggc tacacacgtg ctacaatgga 1200

cgatacaaac ggttgccaac tcgcgagagg gagctaatcc gataaagtcg ttctcagttc 1260

ggattgtagg ctgcaactcg cctacatgaa gccggaatcg ctagtaatcg cggatcagca 1320

tgccgcggtg aatacgttcc cgggccttgt acacaccgcc cgtcacacca cgagagtttg 1380

taacacccga agtcggtgag gtaacctttt ggagccagcc gccgaa 1426

Claims

1. A strain of bacillus megaterium H4 for resisting rice sheath blight is characterized in that the preservation number is as follows: CGMCC NO. 17146.

2. The method for culturing Bacillus megaterium H4 according to claim 1, comprising the steps of: after the surface of rice is cleaned and disinfected, the rice is placed on an LB solid culture medium for culture (2-3) days at the temperature of 28-35 ℃, and a single colony is obtained by picking.

3. The use of Bacillus megaterium H4 of claim 1 for combating Rhizoctonia solani.

4. A product against rice sheath blight disease, comprising bacillus megaterium H4 or a fermentation broth thereof according to claim 1.

5. The product of claim 4, wherein the product is a fertilizer or a pharmaceutical agent.

6. A method for culturing a strain fermentation liquid resisting rice sheath blight is characterized by comprising the following steps: culturing the Bacillus megaterium H4 of claim 1 to obtain the fermentation broth.

7. The culture method according to claim 6, comprising the steps of: inoculating Bacillus megaterium H4 strain in LB culture medium at 28-35 deg.C, and culturing to obtain OD₆₀₀The value of the strain fermentation liquid reaches (1.0-1.2).

8. A fermentation broth of a strain prepared by the process according to claim 6 or 7.

9. A method for preventing rice sheath blight disease, comprising the steps of: soaking rice seeds with the seed culture broth of claim 8.

10. The method according to claim 9, wherein the strain fermentation broth has a strain wet weight of (4-6) g/L; the soaking time is 2-4 days.