Paenibacillus polymyxa strain C2 and application thereof

Abstract

The application discloses a bacillus polymyxa C2 strain and application thereof, and belongs to the technical field of microorganisms. The strain has been preserved in the China General Microbiological Culture Collection Center on December 25, 2022, and the biological preservation number is CGMCC No. 26242. The bacillus polymyxa C2 strain has the functions of producing an iron carrier, decomposing potassium, decomposing phosphorus and degrading cellulose, and has significant antagonistic effects on a plurality of pathogenic fungi causing garlic wilting in a plate confrontation experiment. The bacillus polymyxa C2 strain has a growth-promoting effect on garlic under different soil and cultivation conditions, and has good practical application value.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a strain of polymyxa Bacillus C2 and its applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Garlic (Allium sativum) is a delicious vegetable with both medicinal and culinary uses, and it also has significant economic value, such as export earnings and healthcare benefits. In major garlic-producing areas, continuous cropping has caused severe soil problems, coupled with excessive use of pesticides and fertilizers. This has led to a decline in garlic's resistance to stress, pests, and diseases, resulting in serious problems such as root rot, seedling death, and ultimately a sharp decline in garlic yield and quality. This has also severely impacted the local ecological environment, restricted local economic development, and reduced the brand's value. Therefore, in the face of green and sustainable agricultural development plans, it is essential to shift from pesticide- and fertilizer-dependent continuous cropping to supplementary cropping. Exploring beneficial microorganisms with superior traits and developing new green microbial fertilizers can solve garlic cultivation problems and achieve green and sustainable development.

[0004] *Paenibacillus polymyxa*, belonging to the genus *Paenibacillus*, is a group of spore-forming, Gram-positive bacteria that are beneficial rhizosphere microorganisms with both biocontrol and growth-promoting effects. Current research on the growth-promoting and disease-preventing effects of *Paenibacillus polymyxa* has been conducted, but no *Paenibacillus polymyxa* strains specifically found to simultaneously promote growth and prevent disease in garlic have been identified. Therefore, screening for *Paenibacillus polymyxa* strains that can simultaneously and efficiently inhibit multiple pathogens in garlic and promote garlic growth is of significant value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a strain of Bacillus polymyxa C2 and its applications. Experiments have shown that the Bacillus polymyxa C2 provided by this invention can both inhibit various harmful Fusarium species and promote garlic growth.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a strain of Paenibacillus polymyxa C2, which was deposited on December 25, 2022, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1, Beichen West Road, Chaoyang District, Beijing), with the biological accession number CGMCC No. 26242.

[0008] In a second aspect, the present invention provides a microbial inoculant, characterized in that it contains the aforementioned Paenibacillus polymyxa C2 and its fermentation products.

[0009] Specifically, the microbial agent is a microbial inoculant. The microbial agent is obtained by inoculating *Bacillus polymyxa* C2 into a liquid culture medium and then culturing it. This invention's microbial inoculant contains *Bacillus polymyxa* C2, which can produce siderophores and antagonize various pathogenic fungi, and possesses the ability to degrade cellulose, solubilize potassium, and solubilize phosphorus. Pot and field plot trials have demonstrated that it can significantly promote garlic growth, thus possessing good practical application value.

[0010] A third aspect of the present invention provides the use of the above-mentioned Bacillus polymyxa C2 or microbial inoculant in any one or more of the following a)-d):

[0011] a) It produces iron carriers, degrades cellulose, and degrades potassium and phosphorus;

[0012] b) Antagonistic against Fusarium;

[0013] c) Improve the nutrient environment of the plant rhizosphere soil;

[0014] d) Promote plant growth.

[0015] Specifically, the Fusarium species are *Fusarium oxysporum* OC, 5C, and 6B, *Fusarium verticillioides* 3C, and *Fusarium proliferatum* 9D and 11C. Specifically, the plant is garlic.

[0016] Specifically, the improvement of the plant rhizosphere soil nutrient environment is achieved by the above-mentioned Bacillus polymyxa C2 and / or microbial agents being able to produce iron carriers in the soil, possessing the ability to degrade cellulose, solubilize potassium and phosphorus, and also antagonize various Fusarium pathogens, thereby improving the rhizosphere soil nutrient environment and rhizosphere microbial community of garlic.

[0017] In a fourth aspect, the present invention provides a method for promoting garlic growth, the method comprising applying the above-mentioned Bacillus polymyxa C2 and / or microbial agents to garlic to promote garlic growth.

[0018] Specifically, the function is as follows: after garlic cloves are sown, the above-mentioned Bacillus polymyxa C2 and / or microbial agents are applied to the soil around the garlic cloves.

[0019] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0020] This invention reports for the first time a strain of *Bacillus polymyxa* C2 capable of producing siderophores and antagonizing multiple pathogenic fungi, and possessing the ability to degrade cellulose, solubilize potassium, and solubilize phosphorus. In other words, it is a *Bacillus polymyxa* strain that can both inhibit various harmful Fusarium species and promote garlic growth. Pot and field plot trials have demonstrated that it can significantly promote garlic growth, successfully solving the problems of wilt disease, seedling death, increased abundance of harmful Fusarium species in the soil, decreased abundance of beneficial bacteria, and the insignificant effect of adding exogenous beneficial bacteria caused by continuous cropping of garlic. Therefore, it has good practical application value. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a microscopic image of a polymyxin C2 cell from Example 1 of the present invention;

[0023] Figure 2 This is an LB plate colony diagram of Bacillus polymyxa C2 in Example 1 of the present invention;

[0024] Figure 3 This is a phylogenetic tree analysis result of the 16S rDNA of Bacillus polymyxa C2 in Example 1 of the present invention;

[0025] Figure 4 This is a graph showing the siderophore production capacity of Bacillus polymyxa C2 in Example 2 of the present invention;

[0026] Figure 5 This is a graph showing the potassium-solubilizing capacity of Bacillus polymyxa C2 in Example 2 of the present invention;

[0027] Figure 6 This is a graph showing the phosphate solubilization capacity of Bacillus polymyxa C2 in Example 2 of the present invention;

[0028] Figure 7 This is a graph showing the effect of Bacillus polymyxa C2 on the cellulose degradation ability in Example 2 of the present invention;

[0029] Figure 8 This is a diagram illustrating the antagonistic effect of Bacillus polymyxa C2 against multiple pathogenic fungi in Example 3 of the present invention.

[0030] Figure 9 This is a graph showing the plant height data of garlic plants in a pot experiment using original garlic-grown soil and sterilized continuous-crop soil in an incubator during the cultivation of Bacillus polymyxa C2 in Example 4 of the present invention.

[0031] Figure 10 This is a diagram of garlic potted in the original soil during continuous cropping in Embodiment 4 of the present invention;

[0032] Figure 11 This is a diagram of garlic sterilized continuous cropping in pots according to Embodiment 4 of the present invention;

[0033] Figure 12 This is a diagram of garlic root seedlings treated with strain C2 and CK in Example 5 of the present invention.

[0034] Figure 13 This is a potted plant of garlic grown in soil with continuous cropping obstacles after treatment with CK and strain C2 in Example 5 of the present invention;

[0035] Figure 14 This is a statistical graph showing the garlic plant height after treatment with strain C2 and strain CK in Example 5 of the present invention;

[0036] Figure 15 This is a statistical chart showing the thickness of garlic stems after treatment with strain C2 and strain CK in Example 5 of the present invention;

[0037] Figure 16 This is a statistical chart showing the weight of garlic after treatment with strain CK and strain C2 in Example 5 of the present invention;

[0038] Figure 17 This is a statistical graph showing the leaf width and plant height of garlic after treatment with CK and strain C2 in Example 6 of the present invention;

[0039] Figure 18 This is a diagram of garlic treated with strain C2 and CK in Example 6 of the present invention.

[0040] Figure 19 This is a statistical chart showing the diameter of garlic bulbs after treatment with strain CK and strain C2 in Example 6 of the present invention;

[0041] Figure 20 This is a statistical chart showing the total fresh weight of garlic after treatment with strain CK and strain C2 in Example 6 of the present invention. Detailed Implementation

[0042] In one specific embodiment of the present invention, a strain of Paenibacillus polymyxa C2 is provided. This strain was deposited at the China General Microbiological Culture Collection Center on December 25, 2022, with the biological accession number CGMCC No. 26242.

[0043] In this invention, by determining the 16S rDNA gene sequence of the strain and by measuring its morphological characteristics and physiological and biochemical indicators, it was finally determined that the strain belongs to Paenibacillus polymyxa.

[0044] In another specific embodiment of the present invention, a microbial inoculant is provided, which contains the above-mentioned Paenibacillus polymyxa C2 and its fermentation products.

[0045] In another specific embodiment of the present invention, the microbial agent is a microbial inoculant.

[0046] In another specific embodiment of the present invention, the microbial agent is obtained by inoculating Bacillus polymyxa C2 into a liquid culture medium and culturing it. Specifically, the liquid culture medium is LB medium. More specifically, the LB medium components are: 0.5% yeast extract, 1% peptone, 1% sodium chloride, 1000 mL distilled water, pH 7.0. More specifically, the culture conditions are: 30-40℃, 10-20 h, rotation speed: 160-200 rpm. Further, the culture conditions are: 37℃, 12 h, rotation speed: 180 rpm.

[0047] In another specific embodiment of the present invention, the microbial agent further includes a carrier. The carrier is a solid carrier or a liquid carrier.

[0048] In another specific embodiment of the present invention, the solid carrier is a mineral material, a biological material, or a polymer compound; the mineral material is at least one selected from clay, talc, kaolin, montmorillonite, white carbon, zeolite, silica, peat moss, and diatomaceous earth; the biological material is at least one selected from various crop straws, pine shells, rice straw, peanut shells, corn flour, soybean flour, starch, peat moss, and animal excrement; the polymer compound is polyvinyl alcohol and / or polyethylene glycol.

[0049] In another specific embodiment of the present invention, the liquid carrier may be an organic solvent, vegetable oil, mineral oil or water; the organic solvent may be decane and / or dodecane.

[0050] In another specific embodiment of the present invention, the dosage form of the microbial agent can be a variety of dosage forms, such as liquid, emulsion, suspension, powder, granules, wettable powder or water-dispersible granules.

[0051] In another specific embodiment of the present invention, the application of the above-mentioned Bacillus polymyxa C2 or microbial agent in any one or more of the following a)-d) is provided:

[0052] a) It produces iron carriers, degrades cellulose, and degrades potassium and phosphorus;

[0053] b) Antagonistic against Fusarium;

[0054] c) Improve the nutrient environment of the plant rhizosphere soil;

[0055] d) Promote plant growth.

[0056] In another specific embodiment of the present invention, the Fusarium is Fusarium oxysporum 0C, 5C and 6B, Fusarium verticillioides 3C, and Fusarium proliferatum 9D and 11C.

[0057] In another specific embodiment of the present invention, the plant is garlic.

[0058] In another specific embodiment of the present invention, a method for promoting garlic growth is provided, the method comprising applying the above-mentioned Bacillus polymyxa C2 and / or microbial agents to garlic to achieve disease prevention and growth promotion of garlic.

[0059] Specifically, the function is as follows: after garlic cloves are sown, the above-mentioned Bacillus polymyxa C2 and / or microbial agents are applied to the soil around the garlic cloves.

[0060] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0061] Example 1: Strain Identification

[0062] A strain obtained from garlic rhizosphere soil that exhibits broad resistance to pathogenic fungi and promotes garlic growth was identified as Paenibacillus polymyxa by 16S rDNA analysis and physiological and biochemical indicators.

[0063] like Figure 1 and 2 As shown, the colony and cell characteristics of the *Bacillus polymyxa* C2 are as follows: After cultivation on LB medium, the colonies are nearly round, flat and dry, with irregular edges, burr-like margins, milky white, and translucent. The cells are rod-shaped, produce spores and polysaccharides, have no irritating odor, and are Gram-positive.

[0064] The physiological and biochemical characteristics of the polymyxin Bacillus C2 are as follows: strain C2 is positive for ONPG; negative for indole production; can utilize mannitol and is positive; can utilize xylose and is positive; can utilize cellobiose and is positive; can utilize arabinose and is positive; can utilize glucose and is positive.

[0065] The 16S rDNA sequence of Paenibacillus polymyxa C2 is as follows:

[0066] GCTATACTGCAGTCGAGCGGGGTTATGTAGAAGCTTGCTTCTAATAA

[0067] CCTAGCGGCGGACGGGTGAGTAACACGTAGGCAACCTGCCCACAAGAC

[0068] AGGGATAACTACCGGAAACGGTAGCTAATACCCGATACATCCTTTTCCTG

[0069] CATGGGAGAAGGAGGAAAGNCGGAGCAATCTGTCACTTGTGGATGGGCC

[0070] TGCGGCGCATTAGCTAGTTGGTGGGGTAANGGCCTACCAAGGCGACGAT

[0071] GCGTAGCCGACCTGAGAGGGTGATCGGCCACACTGGGACTGAGACACG

[0072] GCCCAGACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCGCAATGGGCG

[0073] AAAGCCTGACGGAGCAACGCCGCGTGAGTGATGAAGGTTTTCGGATCGT

[0074] AAAGCTCTGTTGCCAGGGAAGAACGTCTTGTAGAGTAACTGCTACAAGA

[0075] GTGACGGTACCTGAGAAGAAAGCCCCGGCTAACTACGTGCCAGCAGCCG

[0076] CGGTAATACGTAGGGGGCAAGCGTTGTCCGGAATTATTGGGCGTAAAGCG

[0077] CGCGCAGGCGGCTCTTTAAGTCTGGTGTTTAATCCCGAGGCTCAACTTCG

[0078] GGTCGCACTGGAAACTGGAGAGCTTGAGTGCAGAAGAGGAGAGTGGAA

[0079] TTCCACGTGTAGCGGTGAAATGCGTAGAGATGTGGAGGAACACCAGTGG

[0080] CGAAGGCGACTCTCTGGGCTGTAACTGACGCTGAGGCGCGAAAGCGTGG

[0081] GGAGCAAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAAT

[0082] GCTAGGTGTTAGGGGTTTCGATACCCTTGGTGCCGAAGTTAACACATTAA

[0083] GCATTCCGCCTGGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTG

[0084] ACGGGGACCCGCACAAGCAGTGGAGTATGTGGTTTAATTCGAAGCAACG

[0085] CGAAGAACCTTACCAGGTCTTGACATCCCTCTGACCGGTCTAGAGATAGG

[0086] CCTTTCCTTCGGGACAGAGGAGACAGGTGGTGCATGGTTGTCGTCAGCT

[0087] CGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTTATGC

[0088] TTAGTTGCCAGCAGGTCAAGCTGGGCACTCTAAGCAGACTGCCGGTGAC

[0089] AAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGAC

[0090] CTGGGCTACACACGTACTACAATGGCCGGTACAACGGGAAGCGAAGCCG

[0091] CGAGGTGGAGCCAATCCTAGAAAAGCCGGTCTCAGTTCGGATTGTAGGC

[0092] TGCAACTCGCCTACATGAAGTCGGAATTGCTAGTAATCGCGGATCAGCAT

[0093] GCCGCGGTGAATACGTTCCCGGGTCTTGTACACACCGCCCGTCACACCAC

[0094] GAGAGTTTACAACACCCGAAGTCGGTGAGGTAACCGCAAGGAGCCAGC

[0095] CGCCGAAGG (SEQ ID NO.1)

[0096] Example 2: Experiments on the production of siderophores, potassium solubilization, phosphorus solubilization, and cellulose degradation by Bacillus polymyxa C2

[0097] The siderophore-producing, potassium-solubilizing, phosphorus-solubilizing, and cellulose-degrading abilities of Bacillus polymyxa C2 were tested, and the results are as follows: Figure 4 , 5 As shown in Figures 6 and 7, it is demonstrated that Bacillus polymyxa C2 possesses the ability to produce iron carriers, solubilize potassium and phosphorus, and degrade cellulose.

[0098] Example 3: Experiment on the antagonism of multiple pathogenic fungi by Bacillus polymyxa C2

[0099] A plate confrontation experiment was conducted to determine that *Bacillus polymyxa* C2 exhibits antagonistic effects against pathogenic fungi isolated in situ from rotten and withered parts of garlic. Figure 8 As shown in Table 1, the specific pathogenic Fusarium species are Fusarium oxysporum OC, 5C and 6B, Fusarium verticillatum 3C, and Fusarium lamellae 9D and 11C. The inhibition rates compared with the blank control are shown in Table 1 below.

[0100] Table 1

[0101]

[0102]

[0103] As shown in Table 1, strain C2 has a broad-spectrum antagonistic effect against pathogenic fungi.

[0104] Example 4: Pot experiment of Bacillus polymyxa C2 in a light incubator using garlic-grown soil.

[0105] 1. Preparation of bacterial suspension

[0106] The activated strain C2 was cultured in liquid LB medium at 28°C and shaken at 150 rpm until OD was reached. 600 The value was 1.5. Bacterial cells were collected from 100 mL of liquid culture medium by centrifugation at 4000 rpm for 10 min. The supernatant was discarded, and the strain was resuspended in 50 mL of sterile water for later use.

[0107] 2. Garlic clove treatment

[0108] Select plump and healthy garlic cloves (weighing 4.8–5.3g), sun-dry them for 2 days, remove the outer skin (without damaging the cloves), treat them with 75% alcohol for 5 minutes, then treat them with 10% sodium hypochlorite for 3 minutes, and wash them three times with deionized water.

[0109] 3. Potted soil treatment

[0110] Garlic soil collected from fields where garlic has been grown for over 15 years was crushed, mixed, dried in a cool place, and the garlic roots and small stones were removed before being sieved for later use.

[0111] Sterile soil sterilization treatment: 121℃, 40min, repeat twice for moist heat sterilization.

[0112] 4. Planting methods

[0113] The microbial inoculant was strain C2. Before planting, the pots (7cm×7cm×8cm) were autoclaved at 121℃ for 40 minutes. Two garlic cloves were sown in each pot, and 50mL of the bacterial suspension was applied to the soil around the garlic cloves. Seven days after germination, one plant was retained per pot. Garlic cloves not inoculated with the strain served as a control. All potted garlic were grown in a growth chamber for 4 weeks under long-day conditions (day / night: 14h / 10h, 22℃ / 24℃). Each treatment was replicated three times. Finally, three garlic seedlings were sampled to measure agronomic traits such as plant height.

[0114] 5. Results and Analysis

[0115] A pot experiment was conducted in an incubator using garlic-continuously-cropped soil to cultivate strain C2. Two treatments were applied to the garlic-continuously-cropped soil to explore the direct and indirect growth-promoting effects of strain C2 on garlic. Plant height was measured after 25 days to determine the growth-promoting phenotype. Figure 9 , 10 As shown in Figure 11, after treatment with strain C2, the height of garlic plants in the original soil increased by 38.9%, and the height of garlic plants in the sterilized soil increased by 9.5%. Whether in the original soil or the sterilized soil from continuous cropping, strain C2 increased the height of garlic plants. Strain C2 can directly promote plant growth by secreting various mineral-dissolving enzymes, and can also indirectly promote plant growth by recruiting other beneficial microorganisms through secretions such as polysaccharides and siderophores, thus corroborating the results of the above examples.

[0116] Example 5: Growth-promoting effect of Bacillus polymyxa C2 on garlic in continuously cropped soil under natural open conditions.

[0117] 1. Preparation of bacterial suspension

[0118] The activated strain C2 was inoculated into 30 mL of liquid LB medium and cultured at 28 °C with shaking for 6–8 h to prepare a seed culture. A 3% seed culture inoculum was then inoculated into 150 mL of liquid LB medium for fermentation. Cells were collected from 100 mL of liquid medium by centrifugation at 4000 rpm for 10 min. The supernatant was discarded, and the OD value of the strain was calculated. 600 Dilute with sterile water to 0.1–0.2, and then process the diluted suspension of the strain according to the experimental procedure.

[0119] 2. Garlic clove treatment

[0120] Select plump and healthy garlic cloves (weighing 4.8–5.3g), sun-dry them for 2 days, remove the outer skin (without damaging the cloves), treat them with 75% alcohol for 5 minutes, then treat them with 10% sodium hypochlorite for 3 minutes, and wash them three times with deionized water.

[0121] 3. Potted soil treatment

[0122] Soil containing continuous cropping obstacles was collected from fields where garlic has been grown for over 15 years. After being broken up and mixed, the soil was dried in a cool place, garlic roots and small stones were removed, and the mixture was sieved for later use.

[0123] 4. Planting methods

[0124] The microbial inoculant was strain C2. Before planting, the pots (9cm×9cm×8cm) were autoclaved at 121℃ for 40 minutes. Two garlic cloves were sown in each pot, and 70mL of the bacterial suspension was applied to the soil around the garlic cloves. Garlic cloves not inoculated with the strain served as control plants. All potted garlic plants were grown under natural open conditions for 4 weeks. Each treatment was replicated three times. Finally, three garlic seedlings were sampled for measuring agronomic traits such as plant height.

[0125] 5. Results and Analysis

[0126] After initial incubator experiments, further experiments were conducted under natural open conditions to promote the growth of garlic using strain C2 in continuously cropped soil with growth barriers. The effects of strain C2 on garlic growth were explored, and plant height was measured after 25 days to determine the growth-promoting phenotype. Figure 12 , 13As shown in Figures 14, 15, and 16, under natural conditions with further expanded environmental disturbance, after treatment with strain C2, the total root length of garlic increased by 21%, plant height by 17.5%, stem diameter by 1.6%, whole plant fresh weight by 13.1%, above-ground dry weight by 35.8%, and above-ground fresh weight by 6.4%, thus promoting garlic plant height, stem diameter, dry weight, and fresh weight.

[0127] Example 6: Growth-promoting plot experiment of Bacillus polymyxa C2 on garlic in non-obstructive soil under natural open conditions.

[0128] 1. Experimental design for field trials

[0129] The field trial was conducted at the Field Experiment Station of Shandong Agricultural University, Panhe Campus. This example used purple-skinned garlic from Jinxiang, Shandong Province. Garlic was planted in a 3*15m plot, with six plots (two treatments: microbial inoculum strain C2 and control CK, with each treatment replicated three times) randomly assigned to the plot. Within each plot, 24 garlic cloves were sown in 6 rows and 4 columns, with a 20cm spacing between rows and between rows. Garlic plants were harvested at maturity to measure biomass, nutrient content, and garlic yield. No fertilizer was applied during the garlic's growth period. Except for inoculation with microbial inoculum strain C2, field irrigation management and pest control followed local practices.

[0130] 2. Results and Analysis

[0131] A growth-promoting effect of strain C2 on garlic was explored in a plot experiment conducted under natural open conditions in non-obstructive soil. Plant height, fresh weight, and dry weight were measured after 45 days. Figure 17 , 18 As shown in Figures 19 and 20, under natural conditions with further expanded environmental disturbance, after treatment with strain C2, leaf width increased by 19.9%, plant height increased by 14.5%, bulb diameter increased by 24.5%, and total fresh weight increased by 39.7%, thus promoting garlic plant height, stem diameter, dry weight, and fresh weight.

[0132] In summary, the polymyxa C2 strain obtained by screening in this invention has the functions of producing siderophores, solubilizing potassium and phosphorus, and degrading cellulose. At the same time, the strain screened in this invention has a significant antagonistic effect on a variety of pathogenic fungi that cause garlic wilting in plate confrontation experiments, and has disease prevention and growth promotion effects on garlic under different soil and culture conditions.

[0133] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A strain of Polymyxin Bacillus ( Paenibacillus polymyxa Applications of C2 in the following a)-c): a) producing siderophore, degrading cellulose, solubilizing potassium, and solubilizing phosphorus; b) improving the soil nutrient environment of the plant rhizosphere; c) promoting plant growth in continuous cropping barrier soil; the plant is garlic; after garlic cloves are sown, the Paenibacillus polymyxa C2 is applied to the soil around the garlic cloves, which increases the plant height, stem diameter, dry weight, and fresh weight of garlic; The Paenibacillus polymyxa C2 has been deposited with the China General Microbiological Culture Collection Center on December 25, 2022, and has a biological accession number of CGMCC No. 26242.

2. A microbial inoculant for use in a) - c) below: a) producing siderophore, degrading cellulose, solubilizing potassium, and solubilizing phosphorus; b) improving the soil nutrient environment of the plant rhizosphere; c) promoting plant growth in continuous cropping barrier soil; the plant is garlic; after garlic cloves are sown, the microbial inoculant is applied to the soil around the garlic cloves, which increases the plant height, stem diameter, dry weight, and fresh weight of garlic; The microbial agent contains Bacillus polymyxa (Bacillus polymyxa) Paenibacillus polymyxa ) C2 and a fermentation product thereof; The Paenibacillus polymyxa C2 has been deposited with the China General Microbiological Culture Collection Center on December 25, 2022, and has a biological accession number of CGMCC No. 26242.

3. Use according to claim 2, wherein the compound is ###0002### The microbial inoculant is a microbial inoculant.

4. The use according to claim 2, wherein The microbial inoculant is obtained by inoculating the Paenibacillus polymyxa C2 in a liquid culture medium.

5. The use according to claim 4, wherein the compound is ###00002### The liquid culture medium is LB medium.

6. The use according to claim 5, wherein the compound is ###0002### The components of the LB medium are: yeast extract 0.5%, peptone 1%, sodium chloride 1%, distilled water 1000 mL, pH 7.

0.

7. The use according to claim 4, wherein the compound is ###00003### or a pharmaceutically acceptable salt thereof. The culture conditions are: 30-40 ℃, 10-20 h of culture, rotation speed: 160-200 rpm.

8. Use according to claim 7, wherein the compound is ###0002### The culture conditions are: 37℃, 12h of culture, rotation speed 180 rpm.

9. The use according to claim 2, wherein The microbial inoculant further comprises a carrier.

10. Use according to claim 9, wherein the compound is ###0002### The carrier is a solid carrier or a liquid carrier.

11. Use according to claim 9, wherein the compound is ###0002### The dosage form of the microbial inoculant is liquid, powder, or granules.

12. The use according to claim 11, wherein the compound is ###0002### The dosage form of the microbial inoculant is emulsion, suspension, wettable powder, or water dispersible granules.

13. A strain of Polymyxin Bacillus ( Paenibacillus polymyxa C2, this strain was deposited at the China General Microbiological Culture Collection Center on December 25, 2022, with the biological accession number CGMCC No. 26242.

14. A microbial inoculant, characterized in that, containing the Paenibacillus polymyxa (P Paenibacillus polymyxa ) C2 and fermentation products thereof.

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