Bacillus velezensis as well as isolated culture method and application thereof

Abstract

The invention discloses bacillus velezensis as well as an isolated culture method and application thereof, and belongs to the technical field of microorganisms. According to the invention, a strain of bacillus velezensis WMCC10514 is obtained by screening from wrapping yeast, and the preservation number is CGMCC (China General Microbiological Culture Collection Center) NO.30177. Experiments prove that the strain provided by the invention has biocontrol potential of degrading vomitoxin and preventing and treating fungal diseases, can utilize various substances such as mannitol, glucose, starch, nitrate, citrate and the like to carry out various vital activities, has relatively good environmental adaptability and antibacterial ability, and can be applied to the field of biocontrol. And a new microbial resource and a new prevention and treatment idea are provided for biodegradation of the mycotoxin.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to a Velezella sp. bacillus and a separation and cultivation method and application thereof. Background Art

[0002] Deoxynivalenol, also known as vomitoxin, is a fungal toxin produced by Fusarium spp. It is widely found in contaminated grains, grain products and feed. Wheat contaminated with vomitoxin can cause fusarium head blight, which greatly reduces its nutritional value and seriously affects the food safety of grains and their products. Excessive intake of vomitoxin can seriously threaten the health of humans or animals, causing adverse effects such as neurotoxicity, cytotoxicity and nephrotoxicity, as well as causing diseases such as liver and spleen bleeding and skin inflammation. In 1998, the International Agency for Research on Cancer (IARC) classified vomitoxin as a Class III carcinogen, and it was identified as one of the most dangerous natural food contaminants by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO). Compared with biological degradation, traditional physical and chemical degradation methods have many shortcomings, and the large-scale use of these methods may lead to secondary pollution. The biological method uses the characteristics of microorganisms to degrade toxins, which is both safe and effective. Therefore, finding microorganisms that can efficiently degrade vomitoxin is of great significance for solving the problem of vomitoxin accumulation.

[0003] As one of the most widely used biocontrol bacteria, Bacillus plays an important role in agricultural production and environmental protection, and can effectively prevent and treat various animal and plant diseases. Among them, Bacillus velezensis can inhibit pathogens by producing secondary metabolites such as bacteriocins, antibacterial proteins, lipopeptides and polyketides, thereby directly or indirectly degrading fungal toxins. Bacillus velezensis FZB42 produces bacillimycin, which can change the morphology of the cytoplasmic membrane, mycelium and conidial cell wall, thereby inhibiting fungal growth. Bacillus velezensis B-11 can produce protease, β-glucanase and siderophore, as well as three lipopeptide antibiotics such as iturin, pancreas and surfactin. The fermentation broth of this bacterium can achieve a control efficiency of 64% against anthracnose of Dendrobium officinale. In addition, Bacillus velezensis can induce systemic resistance in plants, improve plant disease resistance, and produce indole-3-acetic acid to promote plant growth.

[0004] Therefore, screening out new Bacillus Velezii that can degrade vomitoxin can provide new microbial resources and prevention and control ideas for the biodegradation of fungal toxins. Summary of the invention

[0005] The object of the present invention is to provide a strain of Bacillus Velezii that has the ability to degrade vomitoxin. The Bacillus Velezii separated and purified by the present invention is a strain of Bacillus Velezii that has environmental adaptability and antibacterial ability, and has important applications in degrading vomitoxin.

[0006] To achieve the above objectives, in the first aspect, the present invention provides a Bacillus velezensis, whose strain is named Bacillus velezensis WMCC10514, which has been deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration on March 28, 2024, and its deposit number is CGMCC NO.30177.

[0007] The invention analyzes the strain through 16SrRNA sequence, and the strain is identified as Bacillus velezensis, the length of the 16SrRNA sequence is 1493bp, and the strain is named as Bacillus velezensis WMCC10514.

[0008] The 16S rDNA sequence of Bacillus velezensis WMCC10514 of the present invention is shown in SEQ ID NO:1.

[0009] SEQ ID NO:1 The 16S rDNA sequence of Bacillus velezensis WMCC10514 is as follows:

[0010]

[0011] The Bacillus velezensis WMCC10514 of the present invention is a Gram-positive bacterium, and its colony characteristics are as follows: in an LB solid culture medium, the colony is slightly yellow, has a rough and raised surface, an irregular edge, has wrinkles, has a high viscosity, and is opaque; under a 100-fold optical microscope, the strain cells are rod-shaped and have spores.

[0012] The present invention also provides a method for isolating and culturing the above-mentioned Bacillus Velezii, which comprises the following steps:

[0013] A. Preparation of bacterial suspension: Mix the Baobaoqu and PBS buffer evenly, let it stand, and take the supernatant; dilute the supernatant with PBS buffer to 10 -5 , obtaining a koji fungus suspension;

[0014] B. Screening of strains: The Koji fungus suspension was inoculated into LB solid culture medium containing vomitoxin, and initially screened and cultured to obtain single colonies with different morphologies, and then purified and cultured to obtain single colonies with consistent morphologies. Finally, the purified strain was inoculated into LB liquid culture medium containing vomitoxin, and rescreened and cultured to obtain Bacillus Velezii WMCC10514.

[0015] Among them, in the above-mentioned separation and culture method, in step A, the Baobaoqu and PBS buffer are evenly mixed in a mass volume ratio of 1:5 to 20.

[0016] Among them, in the above-mentioned separation and culture method, in step B, the composition and preparation method of the LB solid culture medium containing vomitoxin are: 5.0g yeast powder, 10.0g peptone, 10.0g sodium chloride, 18.0g agar powder, add water to 1L, use NaOH or HCl to adjust the pH to 7.0-7.2, and sterilize at 121°C for 20min; add vomitoxin before use to make the final concentration of vomitoxin 0.5-3.0ug / ml.

[0017] Among them, in the above-mentioned separation and culture method, in step B, the composition and preparation method of the LB liquid culture medium containing vomitoxin are: 5.0g yeast powder, 10.0g peptone, 10.0g sodium chloride, add water to 1L, use NaOH or HCl to adjust the pH to 7.0-7.2, and sterilize at 121°C for 20min; before use, add vomitoxin to make the final concentration of vomitoxin 0.5-3.0ug / ml.

[0018] Wherein, in the above-mentioned separation and culture method, in step B, the conditions for the initial screening culture are: constant temperature inversion culture at 37±1°C for 12 to 36 hours.

[0019] Wherein, in the above separation and culture method, in step B, the purification culture conditions are: constant temperature inversion culture at 37±1°C for 12 to 36 hours.

[0020] Wherein, in the above separation and culture method, in step B, the purification culture is performed 3 to 5 times.

[0021] Among them, in the above-mentioned separation and culture method, in step B, the conditions for the re-screening culture are: culturing on a constant temperature shaker at 37±1°C, the shaker speed is 100-250rpm / min, and culturing until the bacteria are turbid.

[0022] The present invention also provides a microbial agent capable of degrading mycotoxins, which comprises the aforementioned Bacillus Velezii.

[0023] Among the above-mentioned microbial agents, the bacterial concentration of Bacillus Velezii was OD 600 =0.6~0.7.

[0024] Among them, in the above-mentioned microbial agent, the fungal toxin is vomitoxin.

[0025] The present invention also provides use of the above-mentioned Bacillus Velezii or the above-mentioned microbial agent in preparing a medicine for degrading fungal toxins.

[0026] Wherein, in the above use, the fungal toxin is vomitoxin.

[0027] The present invention also provides a method for degrading vomitoxin using the above-mentioned Bacillus Velezii, which comprises the following steps: preparing Bacillus Velezii WMCC10514 with a bacterial concentration of OD 600 =0.6-0.7 fermentation broth, add 0.5-3.0ug / ml vomitoxin acetonitrile solution thereto, and culture at 37±1°C for 3-5 days.

[0028] The present invention also provides the use of the Bacillus Velezii in preparing koji medicine or producing indole-3-acetic acid.

[0029] Beneficial effects of the present invention:

[0030] The present invention screened and separated a strain of Bacillus Velezii WMCC10514 from Baobaoqu, which can degrade fungal toxins such as vomitoxin to a certain extent. It can utilize mannitol, glucose, starch, nitrate, citrate and other substances to carry out various life activities and has good environmental adaptability. At the same time, GO (Gene Onotology) analysis results show that it also has certain antibacterial properties, providing new microbial resources and prevention and control ideas for the biodegradation of fungal toxins.

[0031] The deposit number of the Bacillus velezensis of the present invention is CGMCC NO.30177. The deposit time is March 28, 2024, and the deposit center is: China General Microbiological Culture Collection Center (CGMCC), the address is No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, zip code 100101. The classification name is Bacillus velezensis WMCC10514. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a graph showing the degradation rate change of Bacillus Velez WMCC10514 under different DON concentration conditions in Example 1 of the present invention.

[0033] Figure 2 The morphological diagram of Bacillus Velezii WMCC10514 isolated in Example 2 of the present invention; wherein, (a) is the colony morphology of the strain on LB solid culture medium; (b) is the microscopic morphology of the strain under a 100x optical microscope after Gram staining; (c) is the colony morphology of the strain under a 100x optical microscope after spore staining.

[0034] Figure 3 This is a diagram of the PCR reaction system in Example 2 of the present invention.

[0035] Figure 4 This is a phylogenetic tree diagram of Bacillus velezensis WMCC10514 based on 16SrRNA in Example 2 of the present invention.

[0036] Figure 5 This is the genome circle map of Bacillus velez WMCC10514 in Example 3 of the present invention.

[0037] Figure 6 This is a homologous clustering gene cluster analysis diagram of Bacillus velez WMCC10514 in Example 3 of the present invention.

[0038] Figure 7 This is the GO analysis diagram of Bacillus velezensis WMCC10514 in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the following examples, the preparation and concentration of the vomitoxin working solution: 5 mg of the vomitoxin standard was weighed into a 100 ml volumetric flask and dissolved to the mark with acetonitrile to prepare a vomitoxin working solution with a concentration of 50 ug / ml.

[0041] In the following examples, the composition and preparation method of LB liquid culture medium (containing vomitoxin) are as follows: 5.0 g of yeast powder, 10.0 g of peptone, 10.0 g of sodium chloride, distilled water is added to 1 L, the pH is adjusted to 7.0-7.2 with NaOH or HCl, and sterilized at 121°C for 20 min. Before use, vomitoxin working solution is added to make the final concentration of 1.5 ug / ml or 2.5 ug / ml.

[0042] In the following examples, the composition and preparation method of LB solid medium (containing vomitoxin) are as follows: 5.0 g yeast powder, 10.0 g peptone, 10.0 g sodium chloride, 18.0 g agar powder, distilled water to 1 L, adjusted to pH 7.0-7.2 with NaOH or HCl, sterilized at 121°C for 20 min. Before use, vomitoxin working solution was added to a final concentration of 2.0 ug / ml.

[0043] In the following examples, the composition and preparation method of PBS buffer solution are as follows: 8.0 g sodium chloride, 1.2 g disodium hydrogen phosphate, 0.2 g potassium dihydrogen phosphate, 0.2 g potassium chloride, and distilled water is added to make up to 1 L.

[0044] Example 1: Screening and Isolation of Bacillus Velezii WMCC10514

[0045] (1) Sample collection

[0046] Wuliangye Baobaoqu: Collected from the Wuliangye Qu-making workshop in Yibin, Sichuan Province, China.

[0047] (2) Preparation of bacterial suspension

[0048] Accurately weigh 2.5g of crushed Wuliangye Baobaoqu into a 50ml centrifuge tube, add 25ml of sterile PBS buffer, and vortex for 5min to fully shake the mixture and ensure that the bacteria are fully dissolved in the sterile PBS buffer. After shaking, let the centrifuge tube stand for 5min. After the solution is clarified, take 1ml of the supernatant and dilute it to 10 in 9ml of sterile PBS buffer. -5 , and make a koji fungus suspension.

[0049] (3) Preliminary screening of vomitoxin-degrading strains

[0050] Perform aseptic operation in an ultra-clean workbench and use the plate streak method. Use an inoculation loop to dip the diluted koji suspension and streak it on the LB solid culture medium containing vomitoxin. Place it in a constant temperature incubator at 37±1℃ and culture it upside down for 24 hours. Use an inoculation loop to pick up single colonies with different morphologies grown on the culture medium for pure culture.

[0051] (4) Purification of vomitoxin-degrading strain

[0052] The single colonies with different morphologies obtained in the initial screening were streaked onto a new LB solid culture medium containing vomitoxin, and cultured in an incubator at 37±1°C for 12 to 36 hours. Single colonies were picked out from the culture medium, and the purification was repeated 3 to 4 times. When the morphology of the colonies grown on the plate was consistent, a single colony was picked out with an inoculation loop, stored in 80% glycerol, and stored at 4°C for later use.

[0053] (5) Rescreening of DON-degrading strains

[0054] The purified and preserved strains were activated (cultured in a constant temperature shaker at 37±1°C and a rotation speed of 180-200rpm / min for 12h), and then inoculated into 30ml LB liquid culture medium containing 1.5ug / ml and 2.5ug / ml vomitoxin, respectively, and cultured in a constant temperature shaker at 37±1°C with a rotation speed of 135rpm / min until the bacteria became turbid. A 30ml LB liquid culture medium containing 1.5ug / ml and 2.5ug / ml vomitoxin that was not inoculated with the strain was set as a blank control. The vomitoxin content in the blank control and the bacterial solution was detected by high performance liquid chromatography, and the initially screened strains were rescreened to screen out and preserve Bacillus Velezii WMCC10514 with the ability to degrade vomitoxin. The test results of the strain's ability to degrade vomitoxin are as follows: Figure 1 As shown in the figure, A indicates that the initial concentration of vomitoxin is 1.5ug / ml, and B indicates that the initial concentration of vomitoxin is 2.5ug / ml. Figure 1 It can be seen from the results that when the concentration of vomitoxin in the LB liquid culture medium is 1.5ug / ml, the degradation rate of vomitoxin by Bacillus Velez WMCC10514 is 31.49%; when the concentration of vomitoxin in the LB liquid culture medium is 2.5ug / ml, the degradation rate of vomitoxin by Bacillus Velez WMCC10514 is 41.51%.

[0055] Example 2: Identification of Bacillus velez WMCC10514

[0056] (1) Morphological identification

[0057] The morphological test of Bacillus Velezii WMCC10514 isolated in Example 1 was performed. Figure 2 shown. Figure 2 (a) is a photo of the colony morphology of Bacillus velez WMCC10514 on LB solid medium. Figure 2 (a) It can be seen that the colony is slightly yellow, with a rough and raised surface, irregular edges, wrinkles, high viscosity, and opaque. Figure 2 (b) is a microscopic morphological photograph of Bacillus velez WMCC10514 under a 100x optical microscope. Figure 2 (b) It can be seen that the cells of this strain are rod-shaped, about 2 μm, and have spores.

[0058] (2) Molecular identification

[0059] The Bacillus Velezii WMCC10514 isolated in Example 1 was subjected to 16sDNA identification. The genomic DNA of the strain was extracted using a bacterial DNA extraction kit, and PCR amplification was performed using specific primers 27F and 1492R of the bacterial 16S rDNA gene.

[0060] The DNA sequence of the specific primer 27F is shown in SEQ ID NO: 2: 5'-AGAGTTTGATCCTGGCTCAG-3'.

[0061] The DNA sequence of the specific primer 1492R is shown in SEQ ID NO: 3: 5'-GGTTACCTTGTTACGACTT-3'. The PCR reaction conditions are shown in Table 1.

[0062] Table 1 PCR reaction conditions

[0063] Components volume 10×Ex Taq Buffer 2.0μl 5u Ex Taq 0.2μl 2.5mM dNTP mixed solution 1.6μl 5p Primer 27F 1μl 5p Primer 1492R 1μl DNA 0.5μl Ultrapure water 13.7μl Total volume 20μl

[0064] PCR reaction system Figure 3 As shown.

[0065] The 16sDNA sequence of the strain is shown in SEQ ID NO: 1. It was compared with the genebank sequence and found to be highly similar to Bacillus velezensis, so the bacterium was determined to be Bacillus velezensis. Bacillus velezensis WMCC10514 was deposited in the General Microbiology Center of the China Microbiological Culture Collection Administration on March 28, 2024, with the deposit number CGMCC NO.30177, and the classification name Bacillus velezensis.

[0066] The BLAST function of the NCBI website was used to perform homology analysis on the measured 16S rDNA sequences to determine the relationship, and the Neighbor-Joining method of MEGA 6.0 software was used to construct a phylogenetic tree. Figure 4 As shown. Figure 4 It can be seen that the strain has the highest similarity with B. velezensis NRRL B-41580 (GCF_001461825.1) and is in the same branch. Combining the bacterial morphological characteristics, physiological and biochemical characteristics and 16S rDNA sequence comparative analysis, the strain was identified as Bacillus velezensis.

[0067] (3) Identification of physiological and biochemical characteristics

[0068] Gram staining and spore staining: Gram staining and spore staining of Bacillus velez WMCC10514 were performed, and its morphology is as follows Figure 2 As shown in (b) and (c). Figure 2 (b) is a photo of the colony morphology of Bacillus velezensis WMCC10514 under a 100x optical microscope after Gram staining. Figure 2 (b) It can be seen that the bacterial morphology of Bacillus velez WMCC10514 is rod-shaped and is a Gram-positive bacterium. Figure 2 (c) is a photo of the colony morphology of Bacillus Velezii WMCC10514 under a 100x optical microscope after spore staining. Figure 2 (c) It can be seen that Bacillus Velez WMCC10514 produces spores and belongs to the Bacillus species.

[0069] Analysis of physiological and biochemical characteristics: The physiological and biochemical characteristics of Bacillus velez WMCC10514 were analyzed according to the Bergey's Manual of Bacterial Identification (8th edition) and the HKI003 EasyID Bacillus cereus biochemical identification kit. The results are shown in Table 2 ("+" indicates a positive reaction, and "-" indicates a negative reaction).

[0070] As can be seen from Table 2, Bacillus Velez WMCC10514 can utilize mannitol, glucose, starch, nitrate, citrate and other substances to carry out various life activities.

[0071] Table 2 Physiological and biochemical characteristics of Bacillus velez WMCC10514

[0072]

[0073]

[0074] Example 3: Whole genome sequencing of Bacillus velez WMCC10514

[0075] A single colony of Bacillus Velez WMCC10514 was inoculated into LB liquid medium, cultured at 37°C and 135rpm until the logarithmic phase, and centrifuged at 6000r / min for 5min to collect the bacteria. The genomic DNA of Bacillus Velez WMCC10514 strain was extracted using a DNA extraction kit. The qualified genomic DNA was sent to Shanghai Meiji Biopharmaceutical Technology Co., Ltd. for whole genome sequencing. The results are as follows Figure 5 , Figure 6 and Figure 7 The sequencing results showed that the chromosome size of Bacillus velez WMCC10514 was 4.045043 Mb, the GC content was 46.51%, the number of CDS (Protein-coding sequences) was 3928, and there was no plasmid.

[0076] Figure 5 This is the circle map of the genome of Bacillus velez WMCC10514. The first and fourth circles from the outside to the inside of the circle map are CDS on the positive and negative chains, respectively, and different colors represent different COG functional classifications; the second and third circles are CDS, tRNA, and rRNA on the positive and negative chains, respectively; the fifth circle is the GC content, the outward part indicates that the GC content of this region is higher than the average GC content of the whole genome, and the higher the peak value, the greater the difference with the average GC content, and the inward part indicates that the GC content of this region is lower than the average GC content of the whole genome, and the higher the peak value, the greater the difference with the average GC content; the sixth circle is the GC-Skew value, and the specific algorithm is GC / G+C, which can assist in judging the leading chain and the lagging chain; the innermost circle is the genome size marker.

[0077] Figure 6This is a homologous clustering gene cluster (COG) analysis diagram of Bacillus velez WMCC10514. Among them, A represents RNA processing and modification; B represents chromatin structure and dynamics; C represents energy generation and conversion; D represents cell cycle control, cell division, chromosome segmentation; E represents amino acid transport and metabolism; F represents nucleotide transport and metabolism; G represents carbohydrate transport and metabolism; H represents coenzyme transport and metabolism; I represents lipid transport and metabolism; J represents translation, ribosome structure and biogenesis; K represents transcription; L represents replication, recombination and repair; M represents cell wall / membrane / envelope biogenesis; N represents cell movement; O represents post-translational modification, protein turnover, molecular chaperone; P represents inorganic ion transport and metabolism; Q represents biosynthesis, transport and catabolism of secondary metabolites; R represents only general function prediction; S represents unknown function; T represents signal transduction mechanism; U represents intracellular transport, secretion and vesicle transport; V represents defense mechanism; W represents extracellular structure; X represents mobile group represents phage, transposon; Y represents nuclear structure; Z represents cytoskeleton.

[0078] Figure 7 This is the GO analysis diagram of Bacillus velez WMCC10514. GO annotation includes three aspects: BP (Biological Process): describes the biological process in which the gene product is involved, such as cell growth, metabolism, etc.; CC (Cellular Component): describes the location of the gene product in the cell, such as cell membrane, cell nucleus, etc.; MF (Molecular Function): describes the activity of the gene product at the molecular level, such as catalysis, binding, etc.

[0079] Figure 6 COG (Clusters of Orthologous Groups of proteins) analysis showed that the most abundant genes were those involved in amino acid transport and metabolism, with 307 genes; followed by genes involved in transcription, with 299 genes; the numbers of genes involved in carbohydrate transport and metabolism, general function prediction, translation, and cell wall / membrane / envelope biogenesis were 269, 250, 235, and 206, respectively.

[0080] Figure 7In the results of GO (Gene Onotology) analysis, it was shown that Bacillus Velez WMCC10514 contained genes related to environmental cold and heat response (GO:0009409), indicating that Bacillus Velez WMCC10514 had certain stress resistance properties. In addition, Bacillus Velez WMCC10514 also contained genes related to iron-sulfur cluster components (GO:0016226) and cell lysis (GO:0019835), indicating that Bacillus Velez WMCC10514 had certain antibacterial properties.

[0081] These results indicate that Bacillus Velezii WMCC10514 has the biocontrol potential to degrade vomitoxin and control fungal diseases, providing new control ideas and Bacillus Velezii strain resources for fungal toxin infection in grain.

Claims

1. Bacillus Velez, characterized in that: The strain of Bacillus velezensis is named Bacillus velezensis WMCC10514, which is deposited in the General Microbiological Center of China National Microbiological Culture Collection Committee, and its deposit number is CGMCC NO.30177.

2. The method for isolating and culturing Bacillus Velezii according to claim 1, wherein: The following steps are involved: A. Preparation of bacterial suspension: Mix the Baobaoqu and PBS buffer evenly, let it stand, and take the supernatant; dilute the supernatant with PBS buffer to 10 -5 , obtaining a koji fungus suspension; B. Screening of strains: The Koji fungus suspension was inoculated into LB solid culture medium containing vomitoxin, and initially screened and cultured to obtain single colonies with different morphologies, and then purified and cultured to obtain single colonies with consistent morphologies. Finally, the purified strain was inoculated into LB liquid culture medium containing vomitoxin, and rescreened and cultured to obtain Bacillus Velezii WMCC10514.

3. The method for isolating and culturing Bacillus Velezii according to claim 2, wherein: In step A, the Baobaoqu and PBS buffer are mixed evenly at a mass volume ratio of 1:5-20.

4. The method for isolating and culturing Bacillus Velezii according to claim 2, wherein: At least one of the following is met: In step B, the composition and preparation method of the LB solid culture medium containing vomitoxin are as follows: 5.0 g of yeast powder, 10.0 g of peptone, 10.0 g of sodium chloride, 18.0 g of agar powder, add water to 1 L, adjust the pH to 7.0-7.2 with NaOH or HCl, and sterilize at 121° C. for 20 min; add vomitoxin before use to make the final concentration of vomitoxin 0.5-3.0 ug / ml; In step B, the composition and preparation method of the LB liquid culture medium containing vomitoxin are as follows: 5.0 g of yeast powder, 10.0 g of peptone, 10.0 g of sodium chloride, add water to 1 L, adjust the pH to 7.0-7.2 with NaOH or HCl, and sterilize at 121° C. for 20 min; before use, add vomitoxin to make the final concentration of vomitoxin 0.5-3.0 ug / ml; In step B, the conditions for the primary screening culture are: constant temperature inversion culture at 37±1°C for 12 to 36 hours; In step B, the purification culture conditions are: constant temperature inversion culture at 37±1°C for 12 to 36 hours; In step B, the purification culture is performed 3 to 5 times; In step B, the conditions for the rescreening culture are: culturing in a constant temperature shaker at 37±1°C, with a shaker speed of 100-250 rpm / min, and culturing until the bacteria become turbid.

5. A microbial agent capable of degrading mycotoxins, characterized in that: The microbial agent comprises the Bacillus Velezii described in claim 1.

6. The microbial agent according to claim 5, characterized in that: At least one of the following is met: In the microbial agent, the concentration of the Bacillus Velezii described in claim 1 is OD 600 =0.6~0.7; The fungal toxin is vomitoxin.

7. Use of the Bacillus Velezii according to claim 1 or the microbial agent according to claims 5 to 6 in the preparation of a medicament for degrading mycotoxins.

8. The use according to claim 7, characterized in that: The fungal toxin is vomitoxin.

9. The method for degrading vomitoxin using the Bacillus Velezii according to claim 1, characterized in that: The following steps are involved: The concentration of Bacillus Velezii WMCC10514 was OD 600 =0.6-0.7 fermentation broth, add 0.5-3.0ug / ml vomitoxin acetonitrile solution thereto, and culture at 37±1°C for 3-5 days.

10. Use of the Bacillus Velezii according to claim 1 in preparing koji medicine or producing indole-3-acetic acid.

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