Azospirillum sp. Sgz302134 and application thereof

Abstract

The invention discloses azospirillum sp. Sgz302134 and application thereof, the taxonomic name of the azospirillum sp. Sgz302134 is Azospirillum sp., the azospirillum sp. Sgz302134 is preserved in Guangdong Microbial Culture Collection Center on August 11, 2025, and the preservation number of the azospirillum sp. Sgz302134 is GDMCC No: 66829. The azospirillum sp. Sgz302134 disclosed by the invention has an azotobacter function and can be used for reducing nitrogen into nitrogen fertilizer which can be utilized by crops, so that the azospirillum sp. Sgz302134 can be further driven to be applied to rice growth promotion and the like in agricultural production, application of chemical nitrogen fertilizer is reduced, environmental pollution is reduced, and the azospirillum sp. Sgz302134 has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and more specifically, to a nitrogen-fixing spirochete sgz302134 and its applications. Background Technology

[0002] Rice is China's largest food crop, feeding more than half of the world's population. Nitrogen is one of the main limiting factors for rice yield and a primary element that crops absorb from the soil. Soil loses a significant amount of nitrogen every year; if not replenished in time, the nitrogen content in the soil will gradually decrease. Biological nitrogen fixation technology provides a practical and environmentally friendly alternative to traditional chemical fertilizers. This ecological nitrogen fixation method, which can be implemented under normal temperature and pressure, is of great significance for solving soil nitrogen deficiency problems, saving on fertilizer costs, and reducing the ecological problems caused by fertilizer use.

[0003] Azospirillum is a genus of aerobic, Gram-negative bacteria belonging to the family Rhodospirilluceae. They are particularly closely associated with plant roots, establishing beneficial connections with over 113 plant species from 35 different plant families, including important crops such as corn, wheat, rice, and sugarcane. They possess nitrogen-fixing capabilities, converting inert nitrogen from the atmosphere into a bioavailable form. In addition to nitrogen fixation, they promote root development and above-ground growth by secreting plant hormones (such as auxins, cytokinins, and gibberellins), increasing nutrient absorption, enhancing plant resistance, and exhibiting some biocontrol activity by inhibiting the invasion of certain pathogens. Summary of the Invention

[0004] The purpose of this invention is to provide a nitrogen-fixing spirochete, sgz302134, and its applications. In this invention, the inventors discovered and isolated a nitrogen-fixing spirochete, sgz302134, from soil. Multiphasic classification (physiological, biochemical, chemical, and genotypic characteristics) analysis confirmed that this sgz302134 strain is a new species of the genus *Azospirillum*, named *Azospirillum sp. sgz302134*. Furthermore, experiments revealed that this strain possesses excellent nitrogen-fixing properties and enzyme-producing efficiency.

[0005] According to a first aspect of the present invention, a nitrogen-fixing spirochete sgz302134 is provided, taxonomically named Azospirillum sp., and deposited on August 11, 2025 at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No:66829.

[0007] In some embodiments, *Azotrophus sgz302134* was isolated from paddy soil, with the soil sample taken from paddy soil in Jianle County, Sanming City, Fujian Province, China.

[0008] In some embodiments, *Azotrophus sgz302134* is a Gram-negative bacterium.

[0009] In some embodiments, *Azotrophus sgz302134* is rod-shaped, measuring 2.1-2.7 × 0.6-0.8 μm, without flagella, and has round colonies. On R2A medium, the colonies appear as white, smooth, and translucent bodies.

[0010] In some implementations, *Azotrophus sgz302134* was obtained by screening on a modified R2A medium under aerobic conditions.

[0011] In some embodiments, the modified R2A medium is a solid R2A medium supplemented with 6-DMAP at a final concentration of 2.5 μg / mL.

[0012] In some implementations, the growth temperature range of *Azotrophus sgz302134* is 10-45°C.

[0013] In some implementations, the optimal growth temperature range for *Azotrophus sgz302134* is 37 °C.

[0014] In some implementations, the pH adaptation range of *Azotrophus sgz302134* is 5-9.

[0015] In some implementations, the optimal pH for *Azotrophus sgz302134* is 6.5–7.0.

[0016] In some implementations, the NaCl concentration of *Azotrophus sgz302134* is adapted to a range of 0-0.5% (w / v).

[0017] In some implementations, the optimal NaCl concentration for *Azotrophus sgz302134* is 0% (w / v).

[0018] In some implementations, the inventors have verified that *Azotrophus sgz302134* has motility.

[0019] In some embodiments, the catalase and oxidase tests of *Azospirillum isscasi* sgz302134 were both positive. Furthermore, genomic analysis revealed that strain sgz302134 is most closely related to the type strain *Azospirillum isscasi* C340-1. TThe 16S rRNA gene similarity was 98.24%. The genomic DNA G+C content was 68.4%, and the ANI and dDDH were 87.4% and 27.8% respectively, compared to the most similar type strain. The main fatty acid was C. 16:0 (9.5%), Summed Feature 3 (10.2%), Summed Feature 3 (10.3%), Summed Feature 8 (42.4%), with Q-10 as the main respiratory quinone component. Furthermore, strain sgz302134 exhibits the ability to produce alkaline phosphatase, acid phosphatase, esterase C4, leucine aromatic aminoase, naphthol-AS-BI-phosphatase, and β-glucosidase.

[0020] According to a second aspect of the present invention, a microbial product is provided containing *Azotospira sgz302134*, a strain of the first aspect of the present invention.

[0021] In some embodiments, the content of *Azotrophus sgz302134* or its culture in the above-mentioned microbial products is 0.1% to 100%.

[0022] In some embodiments, the above-mentioned microbial products also contain excipients, including one or more of the following: diluents, absorbents, wetting agents, binders, disintegrants, lubricants, colorants, coating materials, solvents, pH adjusters, antibacterial agents, isotonic adjusters, or chelating agents.

[0023] In some embodiments, the dosage forms of the above-mentioned microbial products include agar inoculants, liquid inoculants, freeze-dried inoculants, solid peat powder, oil-dried inoculants, granular inoculants, and vacuum permeation inoculants.

[0024] In some embodiments, the above-mentioned microbial products include inoculum or fermentation products of Azotobacter sgz302134.

[0025] According to a third aspect of the invention, the application of *Azotrophus sgz302134* in promoting the growth of the taproot of rice is provided.

[0026] According to a fourth aspect of the invention, the application of *Azotrophus sgz302134* in bio-enzyme production is provided.

[0027] In some embodiments, the aforementioned *Azotoxinus sgz302134* is used to prepare alkaline phosphatase, acid phosphatase, esterase C4, leucine aromatic aminoase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase.

[0028] In this invention, the inventors verified through experiments that *Azotrophus sgz302134* has the ability to produce alkaline phosphatase, acid phosphatase, esterase C4, leucine aromatic aminoacidase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase, but does not produce lipolipase (C8), lipolipase (C14), valine aromatic aminoacidase, cystine aromatic aminoacidase, trypsin, chymotrypsin, α-galactosidase, β-galactosidase, β-uronic acid glycoside, α-glucosidase, N-acetyl-glucosidase, α-mannosidase, and β-fucosidase.

[0029] The beneficial effects of the present invention are: (1) A new strain of Azospirillum sp. sgz302134 was discovered and isolated for the first time. This strain is aerobic, Gram-negative, motile; positive for catalase and oxidase; and has white, round colonies. (2) The Azospirillum sp. sgz302134 of the present invention has the function of nitrogen-fixing bacteria, which can reduce nitrogen gas into nitrogen fertilizer that can be used by crops, thereby further driving its application in agricultural production such as rice growth promotion, thereby reducing the application of chemical nitrogen fertilizer and reducing environmental pollution, and has good application prospects. (3) The Azospirillum sp. sgz302134 in this invention has the ability to produce alkaline phosphatase, acid phosphatase, esterase C4, leucine aromatic aminoase, naphthol-AS-BI-phosphohydrolase and β-glucosidase, thus it can be effectively used as an effective candidate strain or parent for bio-enzyme production for the development and utilization of the bio-enzyme industry. Attached Figure Description

[0030] Figure 1 This is a transmission electron microscope image of the cells of the nitrogen-fixing spirochete sgz302134 of the present invention.

[0031] Figure 2 This is a phylogenetic tree diagram based on the 16S rRNA gene of the nitrogen-fixing spirochete sgz302134 of the present invention.

[0032] Figure 3 This is a schematic diagram of the total nitrogen content of the nitrogen-fixing spirochete sgz302134 of the present invention.

[0033] Figure 4 This is a comparative graph showing the effects of the nitrogen-fixing spirochete sgz302134 of the present invention on the promotion of rice taproot growth.

[0034] Figure 5 The image shows the effect of the nitrogen-fixing spirochete sgz302134 of the present invention on promoting root growth in rice. Detailed Implementation

[0035] The present invention is further described in detail through specific implementation examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. After reading this invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims. Unless otherwise specified, all raw materials and reagents of the present invention are commercially available.

[0036] Example 1: Isolation and purification of *Azotrophus sgz302134*

[0037] In this embodiment, the paddy soil sample was collected from paddy fields in Sanming City, Fujian Province, China (26.73°N 117.47°E). One gram of fresh paddy soil was thoroughly mixed with 9 mL of sterile water and shaken for 30 minutes to release microbial cells. 200 μL of the centrifuged slurry suspension was spread onto modified R2A medium containing 2.5 μg / mL N6-dimethyladenine (6-DMAP) and 1.5% agar. The medium was incubated aerobically at 30 °C for 2 days.

[0038] The solid R2A medium used has the following composition per liter: 0.5g yeast extract, 0.5g peptone, 0.5g casein hydrolysate, 0.5g glucose, 0.5g soluble starch, 0.3g potassium dihydrogen phosphate, 0.024g anhydrous magnesium sulfate, 0.3g sodium pyruvate, 15.0g agar, 1000mL distilled water, pH 7.0.

[0039] Pick colonies from the plate and purify them using the streak method until a single pure culture is obtained. Repeat this step until pure bacteria are obtained.

[0040] The obtained pure bacteria (Azotocinus sgz302134) had the following morphological characteristics: rod-shaped cells, non-flagellated, and with a size of 0.6~0.8 × 2.1~2.7 μm. Specific morphological characteristics are as follows: Figure 1 As shown.

[0041] Example 2 Identification and Characterization of Azotospirobacter sgz302134

[0042] 2.1 Identification of *Azotrophus sgz302134* and 16S rRNA gene identification

[0043] Genomic DNA was extracted from *Azotrophus sgz302134*, which was isolated and purified in Example 1 above, using a kit. Using the extracted DNA (1 μL) as a template, PCR amplification was performed using universal primers 27F (sequence information: 5'-GAGTTTGATCCTGGCTCAG-3' (SEQ ID NO:1)) and 1492R (sequence information: 5'-ACGGCTACCTTGTTACGACTT-3' (SEQ ID NO:2)) for the bacterial 16S rRNA gene. The PCR reaction program was as follows: 94 °C pre-denaturation for 5 min; 94 °C denaturation for 30 s, 55 °C annealing for 60 s, 72 °C extension for 90 s, for a total of 30 cycles; and a final extension at 72 °C for 10 min to obtain the PCR amplification product. 5 μL of PCR amplification product was spotted onto a 1% agarose gel. Electrophoresis was performed for 15 min at a standard molecular weight of 2000 bp using a 5V / cm voltage, and the electrophoresis results were observed using a gel imaging system. PCR amplification products of strains showing bands were sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing.

[0044] The 16S rRNA gene sequence obtained from sequencing was proofread using Contig Express software to remove extraneous bases at both ends. The obtained valid sequence (SEQ ID NO:3) was submitted to EzBioCloud (https: / / www.ezbiocloud.net / ) for sequence alignment analysis and the 16S rRNA accession number of the strain was obtained from NCBI (https: / / www.ncbi.nlm.nih.gov / ). If the alignment result showed that the 16S rRNA gene similarity was higher than 98.65%, it was preliminarily determined that it belonged to the same taxonomic level as the most closely related strain; otherwise, it was determined to be a potential new taxonomic unit.

[0045] Genome average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) analyses: ANI between bacteria and their model strains was calculated using the ANICalculator on the EzBioCloud website, and dDDH was calculated using the GGDC online calculation software (Genome-to-GenomeDistance Calculator). Average amino acid identity (AAI) analysis was performed using the enveomics online calculation.

[0046] The results showed that *Azospirillum isscasi* sgz302134 was similar to the type strain *Azospirillum isscasi* C340-1. T ,Azospirillum baldaniorum BR 11005 T The 16S rRNA gene similarity was 98.24% and 97.61%, respectively, which is lower than the prokaryotic species definition threshold of 98.65%, suggesting that it may be a potential new species under the genus Azospirillum.

[0047] The phylogenetic tree diagram based on the 16S rRNA gene obtained using the maximum likelihood method is shown below. Figure 2 As shown.

[0048] 2.2 Physiological and biochemical characteristics of *Azotospira sgz302134*

[0049] To further understand the characteristics of *Azotrophus sgz302134*, the relevant physiological and biochemical characteristics of this strain were tested according to standard procedures.

[0050] (1) Temperature gradient test: Incubate on R2A agar plates for 3-7 days at temperatures ranging from 4 to 50°C (i.e., 4°C, 10°C, 15°C, 20°C, 25°C, 30°C, 37°C, 40°C, 45°C and 50°C), with 3 replicates for each temperature, and measure the diameter of the colonies.

[0051] (2) NaCl concentration test: The test was conducted on R2A agar plates for 3-7 days. The NaCl concentration ranged from 0-5% (0, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% and 5%, w / v). Three replicates were set up for each concentration, and the diameter of the colonies was measured.

[0052] (3) pH test: Perform on R2A agar plates for 3-7 days, with pH ranging from 5.0 to 12.0 (incrementing by 0.5 pH units), and set up 3 replicates for each pH value to measure the diameter of the colonies.

[0053] (4) Catalase activity test: In the presence of 3% (v / v) H2O2, the catalase activity was observed by generating bubbles.

[0054] (5) Oxidase activity test: The oxidase activity of *Azotrophus sgz302134* was determined using a 1% (volume fraction) tetramethyl-p-phenylenediamine solution.

[0055] The physiological and biochemical characteristics of *Azotrophus sgz302134* and its closely related strains were compared, and the results are shown in Table 1.

[0056] Table 1. Comparison of phenotypic characteristics between *Azotospira sgz302134* and closely related strains.

[0057]

[0058] Note: "+" indicates positive, and "-" indicates negative.

[0059] (6) The substrate fermentation and utilization of *Azotrophus sgz302134* and its closely related strains were detected using API 20NE reagent strips. The results are shown in Table 2.

[0060] Table 2. Comparison of substrate fermentation and utilization between *Azotospira sgz302134* and closely related strains.

[0061]

[0062] (7) The fermentation of *Azotrophus sgz302134* and its closely related strains was detected using API 50 CH reagent strips. The results are shown in Table 3.

[0063] Table 3. Comparison of fermentation performance between *Azotospirobacter sgz302134* and closely related strains.

[0064]

[0065] (8) Fatty acid detection was performed on Azotospirobacter sgz302134 and its closely related strains. The results are shown in Table 4.

[0066] Table 4. Comparison of fatty acids among closely related strains of *Azotospira sgz302134*.

[0067]

[0068] The results showed that the main fatty acid contained in *Azotrophus sgz302134* after 3 days of culture at 30℃ was C. 16:0 (9.5%), Summed Feature 3 (10.2%), Summed Feature 3 (10.3%), Summed Feature 8 (42.4%). Furthermore, the quinone of *Azotoxinus sgz302134* was found to be ubiquinone Q-10.

[0069] In summary, based on the phylogenetic analysis of the 16S rRNA similarity of *Azospirillum sgz302134*, and a series of identification experiments including physiological and biochemical characteristics, *Azospirillum sgz302134* has many important differences from its closest model strain: 1. Different growth temperature ranges and optimal growth temperatures; 2. Different API 20NE substrate fermentation and utilization; 3. Different API50CH substrate fermentation; 4. Different main fatty acid contents. Considering the low similarity (98.24%) of the 16S rRNA gene sequence of *Azospirillum sgz302134* to the closest strain, and the polymorphic taxonomic results, *Azospirillum sgz302134* represents a new species within the genus *Azospirillum*. Therefore, this strain, sgz302134, is named *Azospirillum sp.*.

[0070] The characteristics of *Azotrophus sgz302134* can be summarized as follows: *Azotrophus sgz302134* is a Gram-negative, rod-shaped, non-flagellated bacterium. It forms white, translucent, circular colonies on R2A agar plates. Its growth characteristics are aerobic, with the following optimal conditions: 10-45 °C (optimum 37 °C), pH 5-9.5 (optimum pH 6.5-7.0), and 0-0.5% (w / v) NaCl salinity (optimum 0%). In the API ZYM system, alkaline phosphatase, acid phosphatase, esterase C4, leucine aromatic aminoaminase, naphthol-AS-BI-phosphatase, and β-glucosidase were positive, while lipoesterase (C8), lipoesterase (C14), valine aromatic aminoaminase, cystine aromatic aminoaminase, trypsin, chymotrypsin, α-galactosidase, β-galactosidase, β-uronic acid sidase, α-glucosidase, N-acetyl-glucosidase, α-mannosidase, and β-fucosidase were negative. In the API 20NE system, potassium nitrate, urease, aesculin, and nitro-β-D-methylgalactosidase were positive, but others were negative. In the API 50CH system, no acid was produced. The respiratory quinone of strain *Azotocinus sgz302134* was ubiquinone Q-10. The genomic DNA G+C content was 68.4%.

[0071] This strain was deposited on August 11, 2025, at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No:66829 and taxonomic name Azospirillumsp.

[0072] Example 3: Total Nitrogen Experiment of Azotospirobacter sgz302134

[0073] The total nitrogen differential method is a method for determining biological nitrogen fixation, calculated based on the difference in total nitrogen before and after the experiment in the system. Biological nitrogen fixation is obtained by subtracting the input nitrogen from the output nitrogen during the experiment.

[0074] *Azotrophic spirochetes* sgz302134 was grown on LB solid medium for 2 days. After repeated washing with sterile water and centrifugation three times, a bacterial suspension of sgz302134 was obtained and transferred to MFM nitrogen-free liquid medium (which was aerated with high-purity nitrogen for 30 min before sterilization). Immediately after inoculation, 2 mL of the bacterial suspension was collected and stored at -80 °C for later use. The inoculated anaerobic bottles were placed in a shaker and cultured at 200 rpm and 30 °C for 4 days. Then, 2 mL was extracted from each bottle for total nitrogen determination.

[0075] The total nitrogen content was determined using the Hach Total Nitrogen Assay Kit. 1) Add the potassium persulfate reagent powder packet to the bottle containing the hydroxide reagent through a small funnel, and wipe off any powder adhering to the bottle mouth; 2) Add 2 mL of sample to the bottle containing alkaline potassium persulfate, and add 2 mL of ultrapure water to another bottle as a blank control. Tighten the caps and shake vigorously for more than 30 seconds (it is normal for the potassium persulfate not to dissolve completely); 3) After starting the DRB200 digester, set it to 105℃ and heat it. Then place the digestion bottle containing the sample into the digester and set a strict digestion time of 30 minutes. 4) Immediately after heating, remove the digestion flask and allow it to cool naturally to room temperature; 5) Add TN reagent A powder to the digestion flask, remove any residual powder from the flask opening, tighten the cap, shake for 15 seconds, and then let it stand for 3 minutes; 6) Next, add B powder to the digestion tube, tighten the cap, shake for 15 seconds, and then let it stand for 2 minutes; 7) Take 2 mL of the solution from the above digestion flask and add it to the TN reagent C bottle. After capping, slowly invert the bottle to mix the sample and the colorimetric reagent evenly. After 5 minutes, use a Hach UV spectrophotometer DR3900 to determine the total nitrogen concentration. First, adjust the value to 0 mg / mL with a blank control, and then determine the total nitrogen concentration of the sample. The total nitrogen experimental results of *Azotocinobacter sgz302134* are shown below. Figure 3 .

[0076] Depend on Figure 3 It was found that the total nitrogen concentration on day 4 increased by 3.1 mg / L compared to day 0. This indicates that under the nitrogen-fixing conditions of this embodiment, *Azotrophic spirochete* sgz302134 converts N2 into biological nitrogen. Based on the biological nitrogen-fixing effect of *Azotrophic spirochete* sgz302134, this bacterium can be used to prepare microbial fertilizer, thereby promoting rice yield or other agricultural production activities. This could further drive its application in agricultural production, thereby reducing the application of chemical nitrogen fertilizers and lowering environmental pollution, showing promising application prospects.

[0077] Example 4: Effect of Nitrogen-fixing Spirochete sgz302134 on the promotion of rice taproot growth

[0078] To evaluate the growth-promoting effect of *Azotrophus sgz302134* on rice, uniformly sized, whole-grain japonica rice seeds were selected. *Azotrophus sgz302134* was grown in LB liquid medium for one day. 30 mL of the culture medium was centrifuged, the supernatant was removed, and the culture was resuspended in 30 mL of sterile water and centrifuged again. This process was repeated three times to obtain a *sgz302134* suspension. The sterilized japonica rice seeds were then placed in a container containing 5 mL of the *sgz302134* suspension (2 × 10⁻⁶). 6 The solution was added to a 30 mL flask (CFU / mL) and shaken at 100 rpm for 24 hours. Sterile water was used as a control.

[0079] Treated japonica rice seeds were evenly placed on moist filter paper in petri dishes and cultured for one week in a constant temperature and light incubator at 25-27°C. The taproot length of the rice seedlings was then measured. The effects of *Azotrophus sgz302134* and sterile water on promoting taproot growth in rice were compared; the results are shown below. Figure 4 , Figure 5 .

[0080] Depend on Figure 4 , Figure 5 It can be seen that the taproot length of rice treated with *Azotrophus sgz302134* was significantly better than that of the control group, indicating that *Azotrophus sgz302134* has nitrogen-fixing function and can reduce nitrogen gas into nitrogen fertilizer that crops can use. It has a significant growth-promoting effect on the taproot growth of rice, and can therefore be used for rice growth promotion and other applications, reducing the application of chemical nitrogen fertilizer and reducing environmental pollution, showing good application prospects.

[0081] The above descriptions are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A nitrogen-fixing spirochete sgz302134, characterized in that, The taxonomic name of the nitrogen-fixing spirochete sgz302134 is Azospirillum sp., which was deposited at the Guangdong Provincial Center for Microbial Culture Collection on August 11, 2025, with accession number GDMCC No:66829.

2. The *Azotoxinus* sgz302134 according to claim 1, characterized in that, The sgz302134 is a Gram-negative bacterium.

3. The *Azotoxinus* sgz302134 according to claim 1, characterized in that, The sgz302134 is rod-shaped, with a size of 2.1-2.7×0.6-0.8μm, without flagella, and the colony shape is round. On R2A medium, the colony appears as a white, smooth, and translucent body.

4. A microbial product, characterized in that, The microbial product contains *Azotospira sgz302134* as described in any one of claims 1 to 3.

5. The microbial product according to claim 4, characterized in that, The content of *Azotobacter sgz302134* or its culture in the microbial product is 0.1% to 100%.

6. The microbial product according to claim 4, characterized in that, The microbial product also contains excipients, which include one or more of the following: diluents, absorbents, wetting agents, binders, disintegrants, lubricants, colorants, coating materials, solvents, pH adjusters, antibacterial agents, isotonic adjusters, or chelating agents.

7. The microbial product according to claim 4, characterized in that, The dosage form of the microbial product is one of the following: agar inoculum, liquid inoculum, freeze-dried inoculum powder, solid peat powder, oil-dried inoculum, granular inoculum, or vacuum permeation inoculum.

8. The microbial product according to claim 4, characterized in that, The microbial products include microbial agents or microbial fermentation products.

9. The application of the nitrogen-fixing spirochete sgz302134 according to any one of claims 1 to 3 in promoting the growth of the taproot of rice.

10. The use of the nitrogen-fixing spirochete sgz302134 according to any one of claims 1 to 3 in the production of bio-enzymes.

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