Bacillus spp and application thereof in promoting growth and reducing dosage of chemical fertilizer

Abstract

The invention relates to the technical field of microorganisms, in particular to bacillus ropes and application of the bacillus ropes in promoting growth and reducing the dosage of chemical fertilizers, and the strain B267 is separated from pear rhizosphere soil lacking potassium for a long time by a research group, has good IAA (indoleacetic acid) and potassium-solubilizing capacity, and can be used for producing IAA (indoleacetic acid) and potassium; panel tests find that volatile organic compounds and secretions generated by the B267 can effectively promote development of root systems and overground parts of arabidopsis thaliana, pot tests find that the B267 can significantly improve development forms of root systems of tomato and pyrus betulaefolia seedlings, increase the absorption rate of the root systems to K +, improve seedling biomass, tomato yield and quality, have a good growth promoting effect on plants, and have good application prospects. After the B267 strain is inoculated, chemical potash fertilizer can be replaced to a certain extent, fertilizer investment is reduced, and more theoretical support and technical means can be provided for development of green agriculture.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, in particular to a strain of Bacillus funiculosus and application thereof in promoting growth and reducing the use of chemical fertilizers. Background Art

[0002] Potassium is one of the key mineral elements that are indispensable for plant growth and development. It participates in a variety of physiological and biochemical processes in plants, including photosynthesis, carbohydrate metabolism, protein synthesis, and cell osmotic regulation. Potassium in soil exists mainly in three forms: mineral potassium (potassium bound to mineral crystals), exchangeable potassium (potassium adsorbed on soil colloids), and potassium in the form of potassium. + ) and water-soluble potassium (K dissolved in soil solution + ). However, among these forms of potassium, only water-soluble potassium can be directly absorbed and utilized by plants. Due to factors such as soil pH, texture and organic matter content, a large amount of potassium often exists in a fixed form, resulting in a low utilization rate. This not only limits the absorption of potassium by crops, but may also lead to an imbalance of soil nutrients, thereby affecting crop yield and quality. In the traditional agricultural production model, the long-term excessive use of chemical fertilizers has caused many negative impacts on the ecological environment and seriously threatened the sustainable development of agriculture. At a time when green agriculture has become an inevitable trend in the development of the industry, the use of beneficial microorganisms to maintain healthy plant growth, improve nutrient absorption efficiency, and increase crop yields has become an effective means to replace traditional fertilization methods.

[0003] Traditional fertilization methods often use a single chemical fertilizer for supplementation. This method has the problems of large dosage, high cost, single nutrient, and easy to cause soil compaction and secondary salinization. Long-term use of chemical fertilizers may also destroy the balance of soil microecology, reduce the sustainability of soil fertility, and cause environmental pollution risks. In contrast, Bacillaceae ( Bacillaceae ) show great potential in agriculture. These microorganisms decompose organic matter by secreting extracellular enzymes and releasing soluble potassium ions; at the same time, they can adjust the soil pH and improve the effectiveness of potassium. In addition, Bacillus can promote plant root development, enhance crop resistance to adversity, and inhibit the growth of pathogens through antagonism. Combining these functions with traditional fertilization can not only improve fertilizer utilization, but also achieve the goal of green and sustainable agriculture.

[0004] Bacillus is a new genus that has been separated from Bacillus in recent years and belongs to the Bacillaceae family ( Bacillaceae ), a research team from McMaster University in Canada found through comprehensive phylogenetic analysis that members of the traditional genus Bacillus have significant differences at the genome level and cannot be attributed to a single evolutionary branch. Therefore, it was split into 17 new genera, including Ectobacillus, current research on this genus mainly focuses on fields such as wastewater treatment and bioremediation. However, the research on the role of Bacillus funiculus in potassium solubilization and growth promotion in fruit trees, as well as the related research on its growth-promoting effect on plants, is still relatively scarce. In-depth research is urgently needed to reveal its potential value and provide more theoretical support and technical means for the development of green agriculture. Summary of the Invention

[0005] In view of the above, it is necessary to conduct in-depth research on Bacillus funiculus, develop new strains, mainly study the role of the new strains in potassium solubilization and growth promotion in fruit trees, and conduct in-depth research to reveal its potential value, providing more theoretical support and technical means for the development of green agriculture.

[0006] To achieve the above object, the present invention has screened out a new strain: Bacillus funiculus Ectobacillus sp. strain B267, and its taxonomic name is: Ectobacillus sp. B267, and its Chinese taxonomic name is: Bacillus funiculus B267, and the preservation number is CCTCC NO: M2025411; this strain is preserved in the China Center for Type Culture Collection, address: No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, and the preservation date is March 10, 2025.

[0007] The present invention also includes a bacterial agent containing the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267.

[0008] The present invention also includes the application of the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267 or the above-mentioned bacterial agent in the preparation of biological organic fertilizer.

[0009] The present invention also includes the application of the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267 or the above-mentioned bacterial agent in promoting plant growth.

[0010] Furthermore, the plant is Arabidopsis thaliana, tomato and / or Pyrus betulifolia.

[0011] The present invention also includes the application of the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267 or the above-mentioned bacterial agent in the production of IAA and / or potassium solubilization.

[0012] The present invention also includes the application of the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267 or the above-mentioned bacterial agent in reducing the dosage of chemical fertilizers.

[0013] The present invention also includes the application of the above-mentioned Bacillus funiculus Ectobacillus sp. strain B267 or the above-mentioned bacterial agent in improving the fruit quality of tomatoes.

[0014] Furthermore, the tomato fruit quality includes: tomato fruit size, fruit yield, fruit vitamin C content, and / or fruit sucrose content.

[0015] The present invention also includes a method for promoting plant growth by applying the Bacillus funiculus Ectobacillus sp. strain B267 or the bacterial agent, and the method is: irrigating the bacterial suspension and / or fermentation broth of Bacillus funiculus Ectobacillus sp. strain B267 to the rhizosphere of plant seedlings.

[0016] Furthermore, the preparation method of the fermentation broth is: inoculating Bacillus funiculus Ectobacillus sp. strain B267 into TSB medium, centrifuging to extract the supernatant after 24 h, performing rotary evaporation on the supernatant, and then diluting it with sterile water to obtain the fermentation broth.

[0017] The present invention has the following beneficial effects: The strain B267 of the present invention is isolated from the rhizosphere soil of long-term potassium-deficient pear by the research group, and has good IAA-producing and potassium-solubilizing abilities. It is found through plate tests that the volatile organic compounds and secretions produced by it can effectively improve the development of Arabidopsis thaliana roots and shoots. Through pot experiments, it is found that B267 can significantly improve the root development morphology of tomato and Pyrus betulifolia seedlings, enhance the absorption rate of K + by roots, increase the seedling biomass, fruit yield and quality, have a good growth-promoting effect on plants, and can replace chemical potassium fertilizers to a certain extent after inoculating with strain B267, reducing fertilizer input, and can provide more theoretical support and technical means for the development of green agriculture. Description of the Drawings

[0018] Figure 1 It is the colony morphology diagram of strain B267.

[0019] Figure 2 It is the phylogenetic tree diagram of strain B267.

[0020] Figure 3 It is the potassium-solubilizing ability result diagram of strain B267.

[0021] Figure 4 It is the result diagram of the effect of strain B267 on the root growth of Arabidopsis thaliana tissue culture seedlings.

[0022] Figure 5 It is the result diagram of the effect of strain B267 on the growth of Arabidopsis thaliana seedlings; in the figure, A is the result of the dry weight of the seedling roots, B is the result of the dry weight of the shoots, and C is the result of the total dry weight.

[0023] Figure 6 It is the morphological result diagram of the effect of strain B267 on the root growth of Arabidopsis thaliana seedlings.

[0024] Figure 7The figure shows the results of the effect of strain B267 on the root system of Arabidopsis thaliana seedlings; in the figure, A is the result of root length, B is the result of root surface area, and C is the result of the number of root tips.

[0025] Figure 8 It is the phenotypic result of the growth of Arabidopsis thaliana seedlings by different concentrations of the secretions of strain B267.

[0026] Figure 9 It is the result of the growth of Arabidopsis thaliana seedlings by different concentrations of the secretions of strain B267; in the figure, A is the result of root dry weight, B is the result of shoot dry weight, and C is the result of total dry weight.

[0027] Figure 10 It is the result of the growth of the root system of Arabidopsis thaliana seedlings by different concentrations of the secretions of strain B267; in the figure, A is the result of root length, B is the result of root surface area, and C is the result of the number of root tips.

[0028] Figure 11 It is the phenotypic result figure of the growth of tomato potted seedlings by strain B267.

[0029] Figure 12 It is the result figure of the growth of tomato seedlings by strain B267; in the figure, A is the result of the dry weight of the seedling root system, B is the result of the dry weight of the shoot, and C is the result of the total dry weight.

[0030] Figure 13 It is the phenotypic result figure of the effect of strain B267 on the tomato root system.

[0031] Figure 14 It is the result of the growth of the tomato root system by strain B267; in the figure, A is the result of root length, B is the result of root surface area, and C is the result of the number of root tips.

[0032] Figure 15 It is the phenotypic result figure of the growth of Pyrus betulifolia Bunge potted seedlings by strain B267.

[0033] Figure 16 It is the result figure of the growth of Pyrus betulifolia Bunge seedlings by strain B267; in the figure, A is the result of the dry weight of the seedling root system, B is the result of the dry weight of the shoot, and C is the result of the total dry weight.

[0034] Figure 17 It is the phenotypic result figure of the effect of strain B267 on the Pyrus betulifolia Bunge root system.

[0035] Figure 18 It is the result of the growth of the Pyrus betulifolia Bunge root system by strain B267; in the figure, A is the result of root length, B is the result of root surface area, and C is the result of the number of root tips.

[0036] Figure 19 It is the result figure of the K + absorption rate of the Pyrus betulifolia Bunge root system by strain B267.

[0037] Figure 20 Phenotypic result graph of strain B267 on the yield of tomato potted plants.

[0038] Figure 21 Result graph of the effect of strain B267 on tomato quality; in the graph, A is the yield per plant, B is the soluble solid content, C is the vitamin C content, D is the fructose content, E is the glucose content, and F is the sucrose content. Biological material preservation information

[0039] The strain information preserved in this application is: Bacillus funiculosus Ectobacillus sp. strain B267, and its taxonomic naming is: Ectobacillus sp. B267, the Chinese taxonomic naming is: Bacillus funiculosus B267, and the preservation number is CCTCC NO: M2025411; this strain is preserved in the China Center for Type Culture Collection, address: No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province, and the preservation date is March 10, 2025. Detailed implementation manners

[0040] All the features disclosed in this specification, or all the steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

[0041] Any feature disclosed in this specification (including any additional claims, abstract) is, unless otherwise stated, only an example of a series of equivalent or similar features. Example 1

[0042] This example is the isolation and identification of Bacillus funiculosus B267.

[0043] 1. Isolation and purification of strain B267: It was screened and isolated from the rhizosphere of long-term potassium-deficient pear trees in Lishui District, Nanjing. Specifically: 1 g of rhizosphere soil was collected and added to a 50 ml Erlenmeyer flask containing glass beads and 9 mL of SM buffer solution. It was shaken at 30 °C and 170 rpm for 30 min to obtain a soil suspension, and then gradually diluted with sterile water into suspensions with concentrations of 10 -5 ~10 -7 . The suspensions were spread on TSA medium and cultured at 30 °C for 48 h, and then single colonies were picked by the streak plate method to purify the strain.

[0044] 2. Identification of strain B267: ① The specific operation of morphological identification is as Figure 1As shown, strain B267 was inoculated on TSA medium and cultured in an incubator at a constant temperature. After 24 hours of culture, circular colonies were observed on the petri dish. The colonies were yellowish-white and opaque with regular edges, which conformed to the morphological characteristics of Bacillus funiculus. Combining with molecular identification, this strain was determined to be Bacillus funiculus. ② After extracting the strain DNA and sequencing, molecular identification was carried out. The DNA sequence of the strain was amplified, and the phylogenetic evolution tree of strain B267 was analyzed and identified based on the DNA sequence (as shown in Figure 2 ), and it was determined that this strain was closely related to Ectobacillus sp. The phylogenetic tree is shown in Figure 2 . Combining with morphological identification, this strain was classified and named as Ectobacillus sp. Example 2

[0045] This example was for the determination of the growth-promoting function of strain B267.

[0046] 1. Qualitative determination of the IAA-producing function of the strain: Strain B267 was added to TSB medium containing L-tryptophan at an inoculation amount of 1%. After shaking at 30 °C and 170 rpm for 48 h, the supernatant was obtained by centrifugation at 10,000 rpm for 5 min. 100 μL of the supernatant was mixed with an equal volume of Salkowski colorimetric solution, and 100 μL of the uninoculated medium was mixed with an equal volume of Salkowski colorimetric solution as a blank control. The reaction was carried out for 30 min under light-shielded conditions. The red color of the solution indicated that the strain had the ability to produce IAA. -1 2. Determination of the potassium-solubilizing ability of the strain: 10 μL of the activated B267 bacterial suspension was added to the silicate solid medium with potassium feldspar replacing the potassium source, and this was repeated three times. The culture was carried out in an incubator at 28 °C for 5 d, and the presence of halos or transparent circles on the medium was observed. The ability of the strain to dissolve insoluble potassium was judged according to the ratio of the halo or transparent circle (D) to the colony diameter (d). At the same time, strain B267 was added to the silicate liquid medium with potassium feldspar replacing the potassium source at an inoculation amount of 1%, with three replicates each. The culture was carried out on a shaker at 28 °C for 2 d, and the potassium ion content in the supernatant was measured on a flame spectrophotometer.

[0047] The results of the above growth-promoting characteristic determinations are shown in Table 1 and

[0048] as shown. Figure 3 as shown.

[0049]

[0050] As can be seen from Table 1 and Figure 3 , strain B267 has the ability to produce IAA and significantly dissolve insoluble potassium. Example 3

[0051] This example is a study on the growth-promoting effect of strain B267 on Arabidopsis thaliana.

[0052] (1) Arabidopsis thaliana seedling raising: Arabidopsis thaliana seeds were placed in sterile water and soaked for 24 h, then soaked in 75% alcohol for 30 s, rinsed with sterile water 3 - 5 times, then added 2% sodium hypochlorite and soaked for 5 min, and finally rinsed clean with sterile water. The disinfected seeds were spread out on a medium with only agar and placed in a constant temperature incubator at 28 °C for germination for 3 - 5 days. The germinated seeds were selected for transplantation.

[0053] (2) Exploration of the growth-promoting effect of B267 VOC (volatile organic compounds): The prepared B267 bacterial suspension (final concentration 10 7 CFU / g soil) was inoculated on one side of a partitioned plate, and 3 Arabidopsis thaliana seedlings were transplanted on the other side. No inoculation was used as a control treatment. There were 12 replicates for each treatment. After culturing for 20 d, samples were collected to measure the phenotypic traits of Arabidopsis thaliana.

[0054] (3) Exploration of the growth-promoting effect of B267 secretions: B267 was inoculated in TSB medium. After 24 h, it was centrifuged at 5000 g to extract the supernatant. The supernatant was rotary evaporated in units of 1 ml and diluted serially at 10 2 、10 3 and 10 4 in the medium. At the same time, 5 Arabidopsis thaliana seedlings were transplanted into the medium. No addition of fermentation broth was used as a control treatment. There were 12 replicates for each treatment. After culturing for 20 d, samples were collected to measure the phenotypic traits of Arabidopsis thaliana.

[0055] Test results: 1. As Figure 4 shown, the VOC of B267 can significantly promote the growth of Arabidopsis thaliana seedlings. As Figure 5 shown, compared with the control group, the root dry weight, shoot dry weight and total dry weight of Arabidopsis thaliana seedlings treated with inoculated strain B267 increased significantly by 508.00%, 323.49% and 337.06% respectively.

[0056] 2. As Figure 6 shown, the VOC of strain B267 can improve the root morphology of Arabidopsis thaliana. As Figure 7 shown, compared with the control group, the root length, root surface area and root tip number of Arabidopsis thaliana seedlings treated with inoculated strain B267 increased by 142.15%, 182.29% and 56.78% respectively.

[0057] 3. As Figure 8 shown, the secretions of strain B267 at different concentrations can significantly promote the growth and root morphology of Arabidopsis thaliana seedlings; as Figure 9 and Figure 10As shown, compared with the control, the dry weights of the roots, shoots, and total dry weights of Arabidopsis thaliana seedlings treated with the secretions of strain B267 at different concentrations were significantly increased, and the root length, root surface area, and number of root tips were also significantly increased; when diluted 10 2 , 10 3 , and 10 4 , there was no significant difference in the effect of the secretions on the dry weight of the roots of Arabidopsis thaliana seedlings. The secretions diluted 10 2 significantly increased the dry weight of the shoots of Arabidopsis thaliana seedlings compared to other concentrations, while the secretions diluted 10 2 and 10 3 significantly increased the total dry weight of Arabidopsis thaliana seedlings compared to other concentrations. Example 4

[0058] This example is a study on the growth-promoting effect of strain B267 on Pyrus betulifolia seedlings and tomato seedlings.

[0059] (1) Tomato and Pyrus betulifolia seeding: The seeds were placed in sterile water and soaked for 24 h, then soaked in 75% alcohol for 30 s, rinsed with sterile water 3 - 5 times, then soaked in 2% sodium hypochlorite for 20 min, and finally washed clean with sterile water. The disinfected seeds were spread out on a culture medium padded with filter paper moistened with sterile water and placed in a constant temperature incubator at 28°C for germination for 3 - 5 days. The germinated seeds were selected and sown into the sterilized substrate for seeding. When the seedlings in the substrate of the base seedlings grew to 2 - 3 true leaves, the healthy and consistent seedlings were selected and transplanted into sterilized substrate flower pots.

[0060] (2) Inoculation: The prepared B267 bacterial suspension (final concentration of 10 7 CFU / g soil) was inoculated into the rhizosphere of the seedlings, and non-inoculation was used as the control treatment. There were 12 replicates for each treatment. After culturing for 60 d, the phenotypic traits of tomatoes and Pyrus betulifolia were measured after sampling.

[0061] (3) K + flux measurement: Select plants with consistent growth and good condition within the group. Use filter paper strips and resin blocks to fix the intact roots at the bottom of the culture dish, exposing the root tip part. Add the test solution (0.05 mM KCl, 0.2 mM MES, pH 5.8) to the culture dish to submerge the roots, and let it stand for 30 minutes, then load the sample for detection. Locate the root measurement site to be detected under the microscope (a point on the root surface 1200 μm from the root tip vertex, belonging to the elongation zone). Place the K + flux microsensor 5 μm away from the measurement site to be detected without contacting the sample, and start detection. Record the data for 5 minutes for each sample, and detect 6 biological replicates for each group. Directly read and output the K + flux data through the imFluxes V3.0 software. The flux unit is pico mol • cm -2 • s -1 . The positive and negative values of the flux only represent K+ Transport direction, a negative value indicates K + flows from outside the root cells into the root cells; a positive value indicates the opposite.

[0062] Test results: 1. As Figure 11 shown, B267 can significantly promote the growth of tomato seedlings; as Figure 12 shown, compared with the control, although the root dry weight of tomato seedlings treated with B267 did not reach a significant difference, the shoot dry weight and total dry weight increased significantly by 13.61% and 12.80% respectively.

[0063] 2. As Figure 13 shown, inoculation with B267 can significantly improve the root morphology of tomatoes. As Figure 14 shown, compared with the control group, the root length, root surface area and root tip number of tomatoes increased by 13.21%, 20.71% and 37.17% respectively.

[0064] 3. As Figure 15 shown, inoculation with B267 can significantly promote the growth of Pyrus betulifolia seedlings. As Figure 16 shown, compared with the control group, the root dry weight, shoot dry weight and total dry weight of Pyrus betulifolia seedlings treated with B267 increased significantly by 65.32%, 54.61% and 56.64% respectively.

[0065] 4. As Figure 17 shown, inoculation with B267 can improve the root morphology of Pyrus betulifolia. As Figure 18 shown, compared with the control group, the root length, root surface area and root tip number of Pyrus betulifolia treated with B267 increased by 49.11%, 65.23% and 116.01% respectively.

[0066] 5. As Figure 19 shown, inoculation with B267 can significantly increase the K + absorption rate of Pyrus betulifolia roots by 2806.41%. Example 5

[0067] This example is a study on the effects of strain B267 on the yield and fruit quality of tomato plants.

[0068] (1) Tomato seedling raising: Soak MicroTom tomato seeds in sterile water for 24 h, then soak them in 75% alcohol for 30 s, wash them with sterile water 3 - 5 times, add 2% sodium hypochlorite and soak for 20 min, and finally wash them clean with sterile water. Spread the disinfected seeds evenly on the culture medium padded with filter paper moistened with sterile water, place them in a constant temperature incubator at 28 °C for germination for 3 - 5 days, select the germinated seeds and sow them into the sterilized substrate for seedling raising. When the seedlings in the substrate reach 2 - 3 true leaves, select the healthy and consistent seedlings and transplant them into the sterilized substrate flowerpots.

[0069] (2) Inoculation: When the tomato plants enter the flowering stage, inoculate the prepared B267 bacterial suspension (final concentration: 10 7 CFU / g soil) into the rhizosphere. Use non-inoculation as the control treatment. There are 12 replicates for each treatment. During this period, mark the flowers every 2 days, for a total of 3 times. After culturing for 45 days, collect the samples to calculate the yield and measure the tomato fruit traits.

[0070] (3) Determination of tomato fruit quality indicators: For the soluble solid content, uniformly select 10 color-changing fruits from the second flower marking for juicing, and use the refractometer method for determination; for the contents of three soluble sugars (fructose, glucose, and sucrose), take 1 g of fresh fruit sample, add 50 mL of water, vortex and mix evenly for 10 min, ultrasonicate for 30 min, then centrifuge at 9000 r / min for 10 min, transfer the supernatant. After the aforementioned supernatant is roughly filtered through qualitative fast filter paper, dilute it, and pass it through a 0.22 μm aqueous syringe filter to obtain the sample to be measured, and use an ion chromatography combined instrument for quantitative analysis of soluble sugars; for the vitamin C content, use the 2,6-dichlorophenolindophenol titration method for determination. Weigh 10 g of fresh sample, place it in a mortar, add about 5 ml of 2% oxalic acid solution and grind it, transfer it to a 100 ml volumetric flask, make up the volume with 2% oxalic acid, use a high-speed and low-temperature centrifuge for centrifugation, and take 10 ml of the supernatant after centrifugation into a triangular flask, and titrate it with the calibrated 2,6-dichlorophenolindophenol solution until it turns pink and does not fade within 30 s.

[0071] Test results: 1. As Figure 20 shown, after inoculation with the B267 bacterial suspension, the tomato fruits are significantly larger than those in the CK control group without inoculation of the bacterial suspension, indicating that the B267 bacterial suspension can significantly increase the tomato fruit yield.

[0072] 2. As Figure 21 shown, compared with the control, although there are no significant changes in the soluble solids, fructose, and glucose contents of the tomato fruits after inoculation with the B267 bacterial suspension, on the basis of a 12.79% increase in yield, the Vc and sucrose contents increase significantly.

[0073] In summary, the Bacillus funiculus B267 self-screened by the applicant of the present invention has good IAA production and potassium-solubilizing abilities. It is found in the plate test that the volatile organic compounds and secretions produced by it can effectively improve the development of Arabidopsis thaliana roots and shoots. Through the pot experiment, it is found that B267 can significantly improve the root development morphology of tomato and Pyrus betulifolia seedlings, enhance the absorption rate of roots to K + and increase the seedling biomass, yield, and quality, and has a good growth-promoting effect on plants. After inoculating with the B267 strain, it can replace chemical potassium fertilizers to a certain extent and reduce fertilizer input. It shows that the strain of this application can be promoted and utilized as a biological organic fertilizer material.

[0074] The embodiments described above merely represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. Bacillus mycoides Ectobacillus sp. strain B267, with the deposit number of CCTCC NO: M2025411.

2. A microbial agent containing Bacillus mycoides Ectobacillus sp. strain B267.

3. Use of Bacillus mycoides Ectobacillus sp. strain B267 or the microbial agent according to claim 2 in the preparation of biological organic fertilizer.

4. Application of Bacillus mycoides sp. strain B267 as claimed in claim 1 or the microbial agent as claimed in claim 2 in promoting plant growth. Ectobacillus ​ 5. The application according to claim 4, characterized in that The plants are Arabidopsis thaliana, tomato and / or Pyrus betulifolia Bunge.

6. Application of Bacillus mycoides Ectobacillus sp. strain B267 or the microbial agent according to claim 2 in the production of IAA and / or potassium solubilization.

7. Application of Bacillus mycoides Ectobacillus sp. strain B267 or the microbial agent according to claim 2 in reducing the amount of chemical fertilizers used.

8. Use of Bacillus mycoides Ectobacillus sp. strain B267 or the microbial agent according to claim 2 in improving the quality of tomato fruits.

9. The application according to claim 8, characterized in that, The tomato fruit quality includes: tomato fruit size, fruit yield, fruit vitamin C content and / or fruit sucrose content.

10. Method for promoting plant growth by using Bacillus mycoides Ectobacillus sp. strain B267 or the microbial inoculum as described in claim 2, characterized in that The method is as follows: Pour the bacterial suspension and / or fermentation broth of Bacillus subtilis Ectobacillus sp. strain B267 onto the rhizosphere of plant seedlings.

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