Bacillus mobilis and application thereof

Abstract

The invention discloses bacillus mobilis and application thereof, and belongs to the technical field of agriculture and microorganisms. The bacillus mobilis YZ-218 provided by the invention is preserved in the Guangdong Microbial Culture Collection Center, and the preservation number of the bacillus mobilis YZ-218 is GDMCC (China General Microbiological Culture Collection Center) NO: 65400. The invention provides application of the strain in preparation of a growth-promoting microbial agent and application of the strain in preparation of a microbial agent for improving the seed germination rate or / and promoting plant growth. The invention provides a growth-promoting microbial inoculum containing the strain. The invention also discloses a method for improving the seed germination rate by using the strain and a method for promoting plant growth by using the strain. The strain has the growth promoting characteristics of nitrogen fixation, siderophore production, indoleacetic acid secretion and the like, and has a good growth promoting effect on plants.

Description

Technical Field

[0001] The invention belongs to the field of agriculture and microbial technology, and specifically relates to a Bacillus mobilis YZ-218 strain and application thereof. Background Art

[0002] Scutellaria baicalensis is the dried root of Scutellaria baicalensis Georgi, a plant of the Lamiaceae family. It is harvested in spring and autumn and is mainly distributed in northern, northwest and southwest China. Scutellaria baicalensis has the effects of clearing away heat and dampness, purging fire and detoxifying, stopping bleeding, and calming the fetus, and has high medicinal value. Most of China's Scutellaria baicalensis medicinal sources come from the wild. However, due to large-scale harvesting, the wild resources of Scutellaria baicalensis have been severely damaged and the quality of the product has been significantly reduced. Artificial cultivation of Scutellaria baicalensis has problems such as excessive use of fertilizers and pesticides, which makes the yield and quality of Scutellaria baicalensis unguaranteed, affecting the sustainable and healthy development of the Scutellaria baicalensis planting industry.

[0003] The plant rhizosphere is the most active area of ​​soil microorganisms, including archaea, bacteria, viruses, fungi, nematodes and other groups, among which bacteria are one of the most abundant groups. Plant growth promoting rhizobacteria (PGPR) refers to a type of microorganisms that live in the rhizosphere of plants or inside plant tissues. They have multiple growth-promoting properties such as nitrogen fixation, phosphorus solubilization, synthesis of indole-3-acetic acid (IAA) and production of siderophores. They can promote the growth and development of plants and improve the yield and quality of plants. They have become a high-quality alternative source of bacteria for the development of microbial preparations. In the prior art, research on rhizosphere growth promoting bacteria is more focused on the growth-promoting effect of crops, and there are fewer studies related to medicinal plants. There are even fewer reports on the growth-promoting effect of Scutellaria baicalensis.

[0004] Therefore, providing a growth-promoting bacterium that has a good growth-promoting effect on Scutellaria baicalensis and provides support for the high yield and high quality of Scutellaria baicalensis has become an urgent problem to be solved by technical personnel in this field. Summary of the invention

[0005] One of the purposes of the present invention is to provide a strain of Bacillus mobilis YZ-218, which has growth-promoting properties such as nitrogen fixation, siderophore production and indoleacetic acid secretion, and has a good growth-promoting effect on Scutellaria baicalensis.

[0006] The second object of the present invention is to provide the application of Bacillus mobilis YZ-218.

[0007] The third object of the present invention is to provide a bacterial agent comprising the Bacillus mobilis YZ-218.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a strain of Bacillus mobilis YZ-218, which was deposited in Guangdong Provincial Microbiological Culture Collection Center on October 31, 2024, with a deposit number of GDMCC NO: 65400; the deposit address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0010] The invention provides an application of Bacillus mobilis YZ-218, which is an application in preparing a growth-promoting bacterial agent.

[0011] In some embodiments of the present invention, the present invention is used in the preparation of a growth-promoting bacterium that has the functions of nitrogen fixation, siderophore production and IAA secretion.

[0012] The present invention provides the use of Bacillus mobilis YZ-218 in preparing a bacterial agent for improving seed germination rate or / and promoting plant growth;

[0013] Preferably, the seeds are medicinal plant seeds, more preferably Scutellaria baicalensis seeds;

[0014] Preferably, the plant is a medicinal plant; more preferably, it is a Scutellaria baicalensis plant.

[0015] The present invention provides a growth-promoting bacterial agent, which comprises the above-mentioned Bacillus mobilis YZ-218.

[0016] The invention provides a method for improving the germination rate of seeds of Bacillus mobilis YZ-218, comprising the following steps: co-culturing seeds with a bacterial solution of Bacillus mobilis YZ-218; preferably, the seeds are medicinal plant seeds, more preferably scutellaria baicalensis seeds.

[0017] In some embodiments of the present invention, the concentration of the co-cultured Bacillus mobilis YZ-218 bacterial solution is 10 4 ~10 7 CFU / mL, preferably 10 5 CFU / mL.

[0018] The present invention provides a method for promoting plant growth by using Bacillus mobilis YZ-218, comprising the following steps: watering the plant with a bacterial solution of Bacillus mobilis YZ-218 by a root irrigation method;

[0019] Preferably, the plant is a medicinal plant; more preferably, it is a Scutellaria baicalensis plant.

[0020] In some embodiments of the present invention, the concentration of the Bacillus mobilis YZ-218 bacterial solution for irrigation is 10 4 ~10 7 CFU / mL, preferably 10 5 CFU / mL.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The Bacillus mobilis YZ-218 of the invention has the growth-promoting characteristics of nitrogen fixation, iron carrier production and IAA secretion.

[0023] The present invention uses Bacillus mobilis YZ-218 to treat scutellaria seeds, and after treatment, the germination rate of scutellaria seeds can be significantly increased by 17.55-24.55%. In the prior art, the related research on scutellaria seed germination mainly focuses on exploring the influence of different temperatures, controlling water content, adjusting light exposure time or changing storage methods on seed germination. The present invention provides a new idea and technical means for improving the germination rate of scutellaria seeds.

[0024] The Bacillus mobilis YZ-218 of the present invention has a significant growth-promoting effect on the plant height of Scutellaria baicalensis, and the baicalin content is higher than that of the control group and meets the standards of the "Chinese Pharmacopoeia", providing a high-quality bacterial source for the development of biological microbial agents for Scutellaria baicalensis, and providing an important scientific basis and technical support for achieving high yield and high quality of Scutellaria baicalensis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attached Figure 1 This is the phylogenetic tree diagram of Bacillus mobilisYZ-218;

[0026] Attached Figure 2 The results of the effect of Bacillus mobilis YZ-218 on the germination of Scutellaria baicalensis seeds;

[0027] Attached Figure 3 This is a graph showing the effect of Bacillus mobilis YZ-218 on the germination time of Scutellaria baicalensis seeds. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0029] The test culture medium and main reagents used in the examples of the present invention are as follows: LB medium (containing 0.5 g L-tryptophan per liter); Aspergillus nitrogen-fixing medium; inorganic phosphate medium (Pikovaskaia's, PKO; Chrome azurol S solid medium (Chrome azurol S, CAS); KMB liquid medium; CAS detection solution; Salkowski reagent.

[0030] The seeds of Scutellaria baicalensis used for the test were collected from the Medicinal Plant Garden of the College of Traditional Chinese Medicine of Jilin Agricultural University and were identified as Scutellaria baicalensis seeds by Professor Han Mei of the College of Traditional Chinese Medicine of Jilin Agricultural University; the potted Scutellaria baicalensis seedlings were purchased from the transplanted one-year-old Scutellaria baicalensis in Da'an.

[0031] Example 1

[0032] This example discloses the separation and identification of Bacillus mobilis YZ-218 of the present invention.

[0033] 1. Separation

[0034] Collect healthy Acanthopanax rhizosphere soil samples, air-dry and pass through a 20-mesh sieve. Weigh 10 g of the sample and place it in a conical flask containing glass beads and 90 mL of sterile water. Shake thoroughly for 10 to 30 minutes, mix well and let stand for 5 minutes. Under sterile conditions, dilute the sample according to a gradient to 10 -4 200 μL of each dilution was applied to NA medium, and each treatment was repeated 3 times. The plate was inverted and incubated at 30°C in a constant temperature incubator for 24-48 hours. The strains were purified, numbered, and stored at 4°C for later use.

[0035] 2. Identification

[0036] 2.1 Morphological identification

[0037] Refer to the "Microbiology Test Manual" to observe the shape, color, edge, transparency, dryness and wetness of the purified strains, and refer to the "Common Bacteria System Identification Manual" for physiological and biochemical tests. The results are shown in the following table:

[0038] Table 1 Morphological and physiological and biochemical identification results of YZ-218 strain

[0039] Testitems YZ-218 Colony color milky Texture Non-sticky Gram's stain + Transparency opaque Citrate utilization - Starch hydrolysis - Methyl red - VP + Catalase + Glucose breakdown + Sucrose decomposition + 7% NaCl + 10% NaCl - Xylose - Phenylalanine - Lysine decarboxylase -

[0040] Note: In Table 1, “+” indicates positive and “-” indicates negative for each physiological and biochemical test item.

[0041] 2.2 Molecular Biological Identification

[0042] The strain DNA was extracted according to the instructions of Takara Bacterial Genome Extraction Kit (DV810A). The universal primers 27F and 1492R were used to amplify the 16S rDNA gene of the strain. After the PCR product was qualified by gel electrophoresis, it was sent to Sangon Biotechnology for bidirectional sequence sequencing, that is, the sequencing results were entered into the NCBI database for BLAST homology comparison, and then imported into MEGA 11.0 software for developmental tree construction.

[0043] The developmental tree of strain YZ-218 of the present invention is shown in the attached Figure 1 As shown: strain YZ-218 and model strain MCCC 1A05942 are in the same branch, and the sequence similarity is 99.86%. This shows that strain YZ-218 belongs to Bacillus mobilis. The 16S gene sequence of strain YZ-218 of the present invention is shown in SEQ ID NO.1.

[0044] Example 2

[0045] This example discloses the nitrogen fixation, siderophore production, and IAA secretion ability test of strain YZ-218 of the present invention, and compares it with 7 strains of rhizosphere bacteria selected from Acanthopanax senticosus (YZ-38, YZ-121, YZ-128, YZ-141, YZ-151, YZ-159, and YZ-228), 2 strains of rhizosphere bacteria selected from ginseng (SZ-3 and SZ-81), and 2 strains of rhizosphere bacteria selected from Schisandra chinensis (WHY-63 and WHY-185). The isolation method of each strain is the same as that of Example 1.

[0046] 1. Investigation of nitrogenase activity

[0047] The activated strains were inoculated on the solid medium of Ashubei and cultured at 30℃ for 5-7 days. The growth of the strains was observed, and the strains that grew normally and grew well were preliminarily identified as nitrogen-fixing strains. The nitrogenase activity was determined using an ELISA enzyme-linked reaction kit (manufacturer: Shanghai ELISA; batch number: YJ699610), specifically: the strips in the aluminum foil bag were taken out of the refrigerator with the bag, placed at room temperature for 20 minutes, and then the strips were taken out of the aluminum foil bag, and blank wells (blank control without sample and enzyme labeling reagent, the rest of the steps were the same), standard wells, and sample wells to be tested were set up respectively. Accurately add 50μL of the standard sample to the enzyme-labeled plate, add 40μL of sample diluent to each well of the sample well to be tested, and then add 10μL of the sample to be tested (the final dilution of the sample is 5 times). Add the sample to the bottom of the well of the enzyme-labeled plate, try not to touch the well wall, and gently shake to mix. Add 50μL of the standard series solution as above, and repeat each treatment three times. After that, seal the plate with a sealing film and let it stand in a 37℃ incubator for 30 minutes. Aspirate the liquid and tap it on absorbent paper to remove as much water as possible. Add 350μL of washing solution to each well, let it stand for 1 minute, then aspirate the liquid and tap it on absorbent paper to remove as much water as possible. Repeat this 5 times. Add 50μL of enzyme labeling reagent to each well, except for the blank well, repeat the incubation and washing operations, then add 50μL of color developer A and B to each well in turn, and let it stand at 37℃ in the dark for 10 minutes. Add 50μL of stop solution to each well to terminate the reaction. Zero the blank well and immediately measure the OD value of each well at a wavelength of 450nm.

[0048] 2. Investigation of iron carrier activity

[0049] Using the CAS colorimetric method, the strain was inoculated onto CAS solid culture medium and cultured at 30°C for 5 to 7 days to observe whether an orange-yellow bacterial ring was produced around the strain. The strain that could grow normally and produce an orange-yellow bacterial ring around the strain was preliminarily determined to be a strain with the ability to produce iron carriers; 1% of the bacterial liquid was inoculated into KMB liquid culture medium for culture at 30°C and 150r / min for 48h, and then the bacterial suspension was centrifuged at 10000r / min for 10min to obtain the bacterial fermentation supernatant. Equal amounts of the fermentation supernatant were taken and mixed with CAS detection solution respectively. After standing for 1h, the absorbance value (As) was measured at a wavelength of 630nm using a spectrophotometer, and double distilled water was taken as a control to adjust to zero. Another equal amount of CAS detection solution was taken and mixed with the uninoculated KMB liquid culture medium supernatant. The absorbance value measured in the same way as above was the reference value (Ar). The siderophore activity was calculated according to the formula: Su (%) = (Ar-As) / As × 100%, where Su is the siderophore activity; Ar is the absorbance value after the control reaction; and As is the absorbance value after the bacterial solution reaction.

[0050] 3. Investigation of IAA secretion characteristics

[0051] The Salkowski colorimetric method was used. The purified strain was inoculated into LB liquid medium with a mass concentration of 100 mg / L L-tryptophan. After culturing for 7 days at 28°C and setting a shaker at 180 r / min, the bacterial fermentation broth was centrifuged at 4000 rpm for 10 min, and 50 μL of the bacterial suspension was dropped onto a white ceramic plate. An equal amount of Salkowski colorimetric solution was added simultaneously. The white ceramic plate was stored at room temperature and protected from light for 30 min and then observed. If the color turned red, it indicated that the bacteria had the ability to produce IAA. 10 mL of the bacterial suspension of the strain in the qualitative test was placed in a centrifuge tube and centrifuged at 10000 r / min for 5 min. 5 mL of the supernatant was added to an equal volume of Salkowski colorimetric solution. After standing at room temperature and protected from light for 30 min, the absorbance value of each culture solution (wavelength 530 nm) was measured. After the measurement, the standard curve was compared to calculate the IAA concentration.

[0052] Preparation of IAA standard curve: Prepare a series of IAA standard solutions with concentrations of 0, 5, 10, 20, 30, and 40 μg / mL. The rest of the treatment is the same as above, and the standard curve is drawn with IAA concentration as the horizontal axis (X) and absorbance as the vertical axis (Y).

[0053] The linear equation of the standard curve is y = 0.0189x + 0.0092R 2 =0.9992

[0054] 4. Results

[0055] The results are shown in Table 2.

[0056] Table 2 Results of investigation on growth-promoting properties of strains

[0057]

[0058]

[0059] In Table 2, “-” for each growth-promoting ability determination item indicates a negative reaction.

[0060] As shown in Table 2, strains YZ-141 and YZ-218 have good nitrogenase activity; their nitrogenase activities are 229.29 IU / L and 145.65 IU / L, respectively;

[0061] Strains YZ-3, YZ-63, YZ-81, YZ-121, YZ-141, YZ-159, YZ-185, YZ-218, and YZ-228 all have siderophore activity, ranging from 2.47% to 63.49%;

[0062] Strains YZ-121, YZ-128, YZ-151, YZ-159, and YZ-218 can secrete IAA, and the amount of IAA secretion by the strains is 8.03 to 26.70 mg / L.

[0063] All 12 rhizospheric bacteria had no ability to dissolve phosphorus and potassium.

[0064] Through screening of growth-promoting properties based on three indicators, it was found that strain YZ-218 has multiple growth-promoting properties and can simultaneously fix nitrogen, produce siderophores and secrete IAA. Its nitrogenase activity is 145.65 IU / L; the siderophore synthesis rate is 14.36%; and the IAA concentration of the fermentation broth is 8.22 mg / L.

[0065] Example 3

[0066] This example investigates the effect of the strain YZ-218 of the present invention on the germination of Scutellaria baicalensis seeds.

[0067] 1. Pre-seed treatment

[0068] Select Scutellaria baicalensis seeds with full grains, uniform size and no diseases or insect pests. Soak them in distilled water for 10 hours, disinfect them with 10% sodium hypochlorite for 10 minutes, rinse them with sterile water 5 to 6 times, disinfect them with 75% alcohol for 1 minute, rinse them with sterile water 5 to 6 times, and place the seeds on a moist sterilized culture dish with two layers of filter paper and one layer of gauze, with 50 seeds in each dish.

[0069] 2. Preparation of fermentation broth

[0070] The strain YZ-218 was inoculated into LB medium for activation, and the concentration of the bacterial solution was adjusted to 10 with sterile water. 8 , 10 7 , 10 6 , 10 5 , 10 4 CFU / mL, for future use.

[0071] 3. Seed test treatment

[0072] The culture dish was watered with 10% 8 , 10 7 , 10 6 , 10 5 , 10 4 2mL of bacterial solution with a CFU / mL concentration was added every 3 days, and the sterile LB medium was used as a control. The culture was placed in a dark incubator (temperature 25°C) for cultivation, and each treatment was repeated 3 times. The lost water was replenished by weighing every day to keep the concentration of the treatment solution constant. The germination standard was when the embryo broke through the seed coat and exceeded 1 / 2 of the seed length itself. The test period was 14 days.

[0073] 4. Determination of seed germination index

[0074] The germination rate (GR), germination potential (GP) and germination index (GI) were calculated according to the following formulas.

[0075] GR = (n / N) × 100%, where n is the final number of normally germinated seeds, and N is the total number of seeds tested;

[0076] GP = (germination rate of seeds in the treatment group / germination rate of seeds in the control group) × 100%;

[0077] GI = ∑(Gt / Dt), where: Gt is the number of germinations on the tth day, and Dt is the corresponding number of germination days.

[0078] 5. Results

[0079] 5.1 Effects of strain YZ-218 on germination rate, germination potential and germination index of Scutellaria baicalensis seeds

[0080] like Figure 2 The results showed that the growth-promoting effect of strain YZ-218 on the germination of Scutellaria baicalensis seeds was different at different concentrations. The germination rate of Scutellaria baicalensis seeds showed a trend of first increasing and then decreasing with the increase of bacterial solution concentration, and 10 8 CFU / mL concentration, the germination rate of the bacterial solution treatment group was lower than that of the CK treatment group, indicating that high concentration bacterial solution treatment had an inhibitory effect on the germination of Scutellaria baicalensis seeds. 5 CFU / mL concentration had the best effect on promoting the germination of Scutellaria baicalensis seeds, and the germination rate was significantly increased by 24.55% compared with CK.

[0081] 5.2 Effect of strain YZ-218 on germination time of Scutellaria baicalensis seeds

[0082] like Figure 3 As shown in the figure, the first 7 days of germination is the peak period of germination of Scutellaria baicalensis seeds, and then it tends to be stable. 4 ~10 5 For seeds treated with CFU / mL concentration, the germination start date can be advanced by 1 day compared with the control.

[0083] Example 4

[0084] This example investigates the effect of the strain YZ-218 of the present invention on the growth of Scutellaria baicalensis plants.

[0085] 1. Experimental Design

[0086] An outdoor pot experiment was conducted, with one Scutellaria baicalensis plant in each pot and 12 replicates for each treatment. After planting and seedling determination, the bacterial solution was irrigated with the root method. The bacterial solution concentration was the optimal concentration of each strain screened in the Scutellaria baicalensis seed germination experiment (10 5CFU / mL), 50mL of bacterial solution was poured into each pot, and the control group was poured with sterile LB medium. The day of pouring bacterial solution was regarded as the first day of the experiment, and the bacterial solution was replenished on the 30th day after the start of the experiment, and samples were taken during the harvest period (the experimental period was 75 days in total). No fertilizer was applied during the experiment, and water was added every 7 days. Soil background values: available phosphorus 4.06mg / kg; available potassium 20.41mg / kg; alkaline nitrogen 29.17mg / kg; organic matter 0.83g / kg; pH 8.20.

[0087] 2. Determination of potted plant indicators

[0088] Growth index determination: measure the plant height (length from base to leaf tip), taproot length, taproot diameter, and fresh weight of above-ground and underground parts.

[0089] Place in an oven at 105°C for 15 minutes and then dry at 60°C to constant weight. Count the dry weights of the aboveground and underground parts, and calculate the root-to-shoot ratio (root-to-shoot ratio = underground part dry weight / aerial part dry weight).

[0090] The dried Scutellaria baicalensis root was crushed and passed through a 60-mesh sieve, and the baicalin content was determined according to the method under the Scutellaria baicalensis content determination item in the Pharmacopoeia of the People's Republic of China (2020 edition, Volume 1).

[0091] 3. Results

[0092] 3.1 Effects of strain YZ-218 on morphological parameters of Scutellaria baicalensis

[0093] Strain YZ-218 significantly promoted the growth characteristics of Scutellaria baicalensis, as shown in Table 3. Independent sample variance test showed that YZ-218 significantly promoted plant height, with an increase of 15.83% over CK. The stem diameter and aboveground fresh weight of the treatment group were higher than those of CK, but the difference was not significant.

[0094] Table 3 Morphological indexes of Scutellaria baicalensis under strain YZ-218 treatment

[0095] deal with Plant height(cm) Stem diameter (mm) Fresh weight above ground (g) YZ-218 86.59±6.18* 5.63±0.26 33.18±3.22 CK 74.75±10.28 5.56±0.83 32.20±4.08

[0096] In Table 3, "*" indicates significant difference, p < 0.05.

[0097] 3.2 Effect of strain YZ-218 on yield indexes of Scutellaria baicalensis

[0098] The results are shown in Table 4. Inoculation of strain YZ-218 is beneficial to the accumulation of Scutellaria baicalensis biomass. The root weight, root dry weight and root diameter of the treated Scutellaria baicalensis were higher than those of the CK treatment group. The root-crown ratio and stem reduction rate of the YZ-218 treatment group were higher than those of the CK group, indicating that strain YZ-218 promoted the growth of the underground part of Scutellaria baicalensis.

[0099] Table 4 Yield index of Scutellaria baicalensis radix under strain YZ-218 treatment

[0100] deal with Root weight (g) Root dry weight (g) Root diameter(mm) Root-to-shoot ratio (%) Dry rate (%) YZ-218 12.89±1.66 4.48±0.08 9.31±0.84 38.86％ 34.75％ CK 12.47±0.98 4.19±0.05 8.93±0.84 38.75％ 33.60％

[0101] 3.3 Effect of strain YZ-218 on yield indicators of Scutellaria baicalensis

[0102] The results are shown in Table 5. The YZ-218 strain treatment can increase the baicalin content. Compared with the uninoculated (CK) Scutellaria baicalensis, the baicalin content of the treated group increased by 6.67%. The Chinese Pharmacopoeia stipulates that the main quality control component in Scutellaria baicalensis is baicalin content not less than 9%, and the baicalin content of each group meets the pharmacopoeia standard.

[0103] Table 5 Effect of strain YZ-218 on the quality of Scutellaria baicalensis

[0104] deal with Baicalin(%) YZ-218 14.55±0.14* CK 13.64±0.37

[0105] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solution of the present invention, but not to limit it, and certainly not to limit the patent scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention without any substantial meaning, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention; in addition, the direct or indirect application of the technical solution of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A strain of Bacillus mobilis YZ-218, characterized in that: It is deposited in Guangdong Microbiological Culture Collection Center with the accession number GDMCC NO:65400.

2. The use of a strain of Bacillus mobilis YZ-218 according to claim 1, characterized in that: Application in the preparation of growth-promoting bacteria.

3. The use according to claim 2, characterized in that: Application in the preparation of growth-promoting bacteria with the functions of nitrogen fixation, siderophore production and IAA secretion.

4. The use of a strain of Bacillus mobilis YZ-218 according to claim 1, characterized in that: Application in the preparation of a bacterial agent for improving seed germination rate and / or promoting plant growth; Preferably, the seeds are medicinal plant seeds, more preferably Scutellaria baicalensis seeds; Preferably, the plant is a medicinal plant; more preferably, it is a Scutellaria baicalensis plant.

5. A growth-promoting bacterial agent, characterized in that: It comprises the Bacillus mobilis YZ-218 described in claim 1.

6. A method for improving seed germination rate using the Bacillus mobilis YZ-218 of claim 1, characterized in that: The method comprises the following steps: co-culturing seeds with a bacterial solution of Bacillus mobilis YZ-218; preferably, the seeds are medicinal plant seeds, more preferably Scutellaria baicalensis seeds.

7. The method according to claim 7, characterized in that: The concentration of Bacillus mobilis YZ-218 bacterial solution is 10 4 ~10 7 CFU / mL, preferably 10 5 CFU / mL.

8. A method for promoting plant growth using the Bacillus mobilis YZ-218 of claim 1, characterized in that: The method comprises the following steps: watering the plant with a bacterial solution of Bacillus mobilis YZ-218 by a root irrigation method; Preferably, the plant is a medicinal plant; More preferably, it is a Scutellaria baicalensis plant.

9. The method according to claim 8, characterized in that The concentration of Bacillus mobilis YZ-218 bacterial solution is 10 4 ~10 7 CFU / mL, preferably 10 5 CFU / mL.

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