Shortia exaltata and use thereof

Abstract

This invention discloses a strain of *Syntrophus vesicatoria* that promotes plant growth and soil nitrogen utilization, and its applications. The strain GHX19 is classified and named *Syntrophus vesicatoria* (…). Brevundimonas bullata The strain GHX19, with accession number CGMCC No. 35707, can grow at pH values ​​between 5.0 and 8.5. It can decompose organic nitrogen into ammonium nitrogen and fix inorganic nitrogen. In particular, under the action of Baimaside or quercetin-3-gentiobiglycoside (Q3Gen), this strain significantly enhances its organic nitrogen mineralization capacity and ammonium fixation capacity, increasing soil ammonium content. Inoculating this strain onto plant roots / rhizosphere improves ammonium uptake and nitrogen use efficiency, promotes plant growth, and increases yield. This invention is of great significance for the development of microbial fertilizers.

Description

Technical Field

[0001] This invention belongs to the field of agricultural microbial technology, specifically relating to a shortwave monocytogenes strain with highly efficient organic nitrogen mineralization capabilities. In particular, it relates to the characteristic that this strain has significantly enhanced mineralization and nitrogen retention capabilities under the action of quercetin and Q3Gen (quercetin-3-gentiobiglycoside), as well as its application in the preparation of microbial fertilizers, soil remediation agents, and plant growth promoters. Background Technology

[0002] Nitrogen is one of the essential macronutrients for plant growth. Soil nitrogen exists primarily in two forms: organic nitrogen and inorganic nitrogen, with approximately 95% existing as organic nitrogen, such as proteins, peptides, amino acids, and chitin. Plants can only directly absorb and utilize inorganic nitrogen (such as ammonium nitrogen and nitrate nitrogen). Organic nitrogen must be converted into inorganic nitrogen through mineralization by soil microorganisms before it can be absorbed and utilized by plants. Therefore, the mineralization efficiency of soil organic nitrogen is a key factor determining soil fertility and agricultural productivity, directly affecting crop yield and quality.

[0003] Currently, agricultural production commonly relies on the extensive application of chemical nitrogen fertilizers to compensate for insufficient available nitrogen in the soil. However, the long-term overuse of chemical fertilizers has led to a series of severe environmental and ecological problems, including but not limited to soil compaction, acidification, salinization, eutrophication of water bodies, and increased greenhouse gas emissions. Furthermore, the utilization rate of chemical fertilizers is generally low, resulting not only in enormous resource waste and economic losses but also hindering the sustainable development of agriculture. Therefore, the development and utilization of functional microorganisms capable of efficiently mineralizing organic nitrogen and transforming it into environmentally friendly and sustainable microbial fertilizers or soil remediation agents has become a research hotspot and important development direction in the field of agricultural microbiology.

[0004] Microorganisms play a central role in soil nitrogen cycling. Plant growth-promoting rhizobacteria (PGPRs) promote plant nitrogen nutrition through multiple mechanisms, including biological nitrogen fixation (converting atmospheric N2 into ammonia), organic nitrogen mineralization (converting organic nitrogen into ammonium nitrogen), and promoting plant nitrogen uptake and utilization. However, most publicly disclosed nitrogen-converting strains focus on single functions, such as nitrogen-fixing bacteria (Azotobacter, Azospirillum, etc.) or saprophytic bacteria with only ammonification capabilities. While a few strains have been reported to possess multiple growth-promoting functions, including nitrogen fixation, phosphorus solubilization, and plant hormone production, strains with bidirectional regulatory capabilities for both organic nitrogen mineralization and inorganic nitrogen assimilation (ammonium fixation) are rarely reported. This limitation of single-function application restricts the universality and stability of microbial fertilizers across different soil types and crop growth stages.

[0005] Brevundimonas is a genus of Gram-negative, aerobic rod-shaped bacteria widely distributed in soil, water, and plant rhizospheres. Current research on the function of Brevundimonas bacteria primarily focuses on environmental remediation, such as antibiotic degradation (e.g., cephalexin), resistance to heavy metals, degradation of organic matter, and enzyme production (e.g., lipases). While related species like Brevundimonas diminuta have been reported to possess ammonification capabilities, and some strains (e.g., Brevundimonas sp. TN37) have been shown to have nitrogenase activity, there are no reports on the nitrogen transformation function of the type strain, Brevundimonas bullata, and no publicly available records of this strain simultaneously possessing both organic nitrogen mineralization and inorganic nitrogen fixation functions. This research gap limits the application and development of Brevundimonas bacteria in agricultural microbial fertilizers.

[0006] Furthermore, the metabolic activity of rhizosphere microorganisms is significantly regulated by plant root exudates. Secondary metabolites secreted by plant roots (such as flavonoids and glycosides) can serve as growth substrates or signaling molecules for microorganisms, promoting the colonization and metabolic functions of beneficial microorganisms. Baimaside (quercetin-3-O-sophorobiose) and Q3Gen (quercetin-3-gentiobioside) are flavonoid glycosides widely found in plants, possessing antioxidant and stress-resistance activities, and are also distributed in plant root exudates. However, current technologies have not yet revealed the regulatory role of baimaside or Q3Gen in the nitrogen metabolism of soil microorganisms, particularly their role in promoting organic nitrogen mineralization and nitrogen fixation. Developing microbial fertilizers that can enhance the efficacy of plant-derived natural compounds is of significant application value for improving the stability of microbial fertilizer effects and reducing the amount of exogenous inoculants required.

[0007] In summary, existing microbial fertilizers suffer from several drawbacks, including limited functionality, unstable efficacy, a lack of research on the nitrogen function of *Brevundimonas bullata*, and a lack of technical means to enhance their effectiveness through plant secondary metabolites. Therefore, there is an urgent need to isolate a *Brevundimonas bullata* strain with highly efficient bidirectional nitrogen transformation capabilities and to establish a synergistic enhancement technology between this strain and plant-derived bioactive substances, providing technical support for the development of a new generation of highly efficient and environmentally friendly microbial fertilizers. Summary of the Invention

[0008] The purpose of this invention is to provide a strain of shortwave monocytogenes that has high efficiency in soil nitrogen utilization and whose function can be significantly promoted by ginsenosides and Q3Gen. It can be used to prepare microbial fertilizers, soil remediation agents and plant growth promoters, change soil ammonium content, and promote plant growth and nitrogen absorption.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A strain of Brevundimonas bullata GHX19 has been deposited at the China General Microbiological Culture Collection Center (CGMCC) on August 21, 2025, with accession number CGMCC No. 35707.

[0011] A microbial product comprising the aforementioned *Syntrophus vesicularis* GHX19.

[0012] Preferably, the microbial product is an inoculant, a bacterial suspension, a fermentation product, or a microbial fertilizer.

[0013] More preferably, the concentration of *Bacillus vesicularis* GHX19 in the bacterial suspension is not less than 1 × 10⁻⁶. 8 CFU / mL.

[0014] More preferably, the microbial product further comprises ephedrine and / or Q3Gen, wherein the final concentrations of ephedrine and Q3Gen are 0.1~10 μM, respectively.

[0015] In the aforementioned microbial products, the bacterial suspension is obtained by fermentation culture in TSB liquid medium, and the concentration of the bacterial suspension is not less than 1×10⁻⁶. 8 The concentrations of CFU / mL, specifically ephedrine and Q3Gen, are 0.1-10 μM. In a specific embodiment of the invention, the bacterial suspension is prepared using the following method: *Gastropoda shortwave monoclonalis* GHX19 is activated on solid TSB medium. Solid TSB medium: TSB liquid medium with 20 g / L agar added. The activated strain is fermented in TSB liquid medium: Activated *Gastropoda shortwave monoclonalis* GHX19 is inoculated into TSB liquid medium, cultured at 30°C and 180 r / min with shaking for 24 h, centrifuged at 8000 rpm for 10 min at room temperature, resuspended and washed twice with sterile water, and finally resuspended with sterile water to a bacterial suspension concentration of 1 × 10⁻⁶. 8 CFU / mL.

[0016] The TSB liquid culture medium formula is as follows: 17 g / L tryptone; 3 g / L soybean peptone; 5 g / L sodium chloride; 2.5 g / L dipotassium hydrogen phosphate; 2.5 g / L glucose; pH: 7.1~7.5; autoclaved at 115℃ for 30 min.

[0017] The following are one or more applications of the aforementioned *Syntrophus vesicularis* GHX19:

[0018] (1) Promotes organic nitrogen mineralization and ammonium assimilation;

[0019] (2) Increase soil ammonium content;

[0020] (3) Promotes ammonium absorption and growth in plants;

[0021] (4) Improve plant nitrogen use efficiency and yield.

[0022] The application of the aforementioned *Syntrophus vesicularis* GHX19 in the preparation of products having any one or more of the following functions:

[0023] (1) Promotes organic nitrogen mineralization and ammonium assimilation;

[0024] (2) Increase soil ammonium content;

[0025] (3) Promotes ammonium absorption and growth in plants;

[0026] (4) Improve plant nitrogen use efficiency and yield.

[0027] Any one or more of the following applications of the aforementioned microbial products:

[0028] (1) Promotes organic nitrogen mineralization and ammonium assimilation;

[0029] (2) Increase soil ammonium content;

[0030] (3) Promotes ammonium absorption and growth in plants;

[0031] (4) Improve plant nitrogen use efficiency and yield.

[0032] A method for increasing soil ammonium nitrogen content, promoting plant growth, improving plant nitrogen use efficiency, or increasing plant yield involves inoculating the soil with the aforementioned *Syntrophus vesicularis* GHX19 or applying the aforementioned microbial product.

[0033] Preferably, the promotion of organic nitrogen mineralization involves decomposing amino acids into ammonium nitrogen; the ammonium assimilation is equivalent to ammonium fixation, which involves assimilating ammonium nitrogen into bacterial organic nitrogen, and the plant is rice.

[0034] Beneficial effects:

[0035] This invention provides a short-wave monoclonal bacterium, GHX19, that promotes soil nitrogen utilization and enhances crop growth. It also reveals for the first time that ephedrine or Q3Gen can significantly enhance its organic nitrogen mineralization and ammonium fixation capabilities, demonstrating strong innovation. This strain can convert organic nitrogen in the soil that is difficult to utilize directly into available nitrogen, thereby reducing dependence on chemical fertilizers. It also possesses ammonium assimilation capabilities, fixing volatile ammonium and thus reducing agricultural non-point source pollution, meeting the development needs of green agriculture. The short-wave monoclonal bacterium GHX19 provided by this invention can be further developed into various microbial preparations, exhibiting stable and significant effects in improving soil fertility and promoting crop growth. Furthermore, ephedrine and Q3Gen, as natural plant root exudates, when used in combination with strain GHX19, can achieve higher agricultural output with lower inputs, showing promising application prospects. Attached Figure Description

[0036] Figure 1 This image shows the colony morphology of the *GUX19* strain, a bacterium of the present invention, on a plate.

[0037] Figure 2 The growth of the strain *Bacillus vesicularis* GUX19, which is the embodiment of this invention, in TSB liquid medium with a pH of 4.0-8.5.

[0038] Figure 3 The effect of the strain *Syntrophus vesicularis* GUX19, used in this invention, on the decomposition of organic nitrogen into ammonium nitrogen.

[0039] Figure 4 This invention aims to verify the ammonium assimilation ability of the strain *Bacillus vesicularis* GUX19.

[0040] Figure 5 The effects of ephedrine and Q3Gen on the expression of the nitrogen transformation genes gdh2 and glnA in the *Bacillus vesicularis* GUX19 strain used in this invention were investigated.

[0041] Figure 6 The effect of the strain *Syntrophus vesicularis* GUX19 on soil ammonium nitrogen content under the influence of ephedrine and Q3Gen was investigated in this invention.

[0042] Figure 7 The effect of the strain *Syntrophus vesicularis* GUX19 on ammonium nitrogen uptake in plant roots under the influence of ephedrine and Q3Gen was investigated in this invention.

[0043] Figure 8 The effects of the strain *Syntrophus vesicularis* GUX19 on plant growth were investigated in this invention.

[0044] Figure 9 The effects of the strain *Syntrophus vesicularis* GUX19 on nitrogen use efficiency and yield in plants were investigated in this invention.

[0045] Information on the preservation of biological materials

[0046] GHX19, classified as Brevundimonas bullata, was deposited on August 21, 2025, at the China General Microbiological Culture Collection Center (CGMCC), Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 35707. Detailed Implementation

[0047] Example 1: Isolation and identification of *Syntrophus aeruginosa* GHX19

[0048] Rice roots were collected from paddy fields. Large clods of soil were removed from the root surface. The roots were then placed in sterile water and shaken for 1 hour. The soil suspension was then serially diluted, starting from a dilution gradient of 10. -4 10 -5 10 -6 Take 100 μL of the diluted solution and spread it onto TSB solid medium. Incubate at 30°C until single colonies appear. Pick bacterial colonies with different morphologies and colors onto fresh TSB solid medium and purify them by streaking.

[0049] The purified single colonies were picked and cultured in TSB liquid medium. Total DNA was extracted from the strain using a bacterial DNA extraction kit. The 16S rDNA of the bacteria was amplified using universal primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'). The PCR products were sent to Shanghai Sangon Biotech Co., Ltd. for sequencing. The assembled complete sequence was submitted to NCBI for BLAST alignment, and the strain GHX19 was classified as *Brevundimonas bullata*.

[0050] The strain *Gastromycosis shortwave monocytogenes* GHX19 was deposited on August 21, 2025, at the China General Microbiological Culture Collection Center (CGMCC), accession number CGMCC No. 35707. The deposit address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The colony morphology of strain GHX19 on TSB solid medium is as follows: Figure 1 The colonies are round, with neat edges, raised surfaces, and are white and opaque.

[0051] Example 2: Acid-base adaptation of *Syntrophus aeruginosa* GHX19 growth

[0052] Strawberry strain GHX19 was streaked in solid TSB medium and incubated at 30°C. After single colonies emerged, a single colony was picked and inoculated into 3 ml of liquid TSB medium. The culture was then incubated at 30°C and 180 rpm for 24 h. Next, 100 μL of the bacterial culture was inoculated into 10 ml of liquid TSB medium and incubated at 30°C and 180 rpm until the bacterial OD reached the target growth rate. 600nm =1.0, OD 600 The bacterial culture with a concentration of 1.0 was centrifuged at 8000 rpm for 10 minutes, the supernatant was discarded, and the culture was resuspended in an equal volume of sterile water.

[0053] TSB medium with pH values ​​of 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5 was prepared. 2 μL of bacterial suspension and 198 μL of TSB medium were added to each well plate, with five replicates for each treatment. The well plates were placed in a growth curve analyzer and incubated at 30°C and 180 rpm with shaking. The OD value of the bacterial suspension was measured every 2 hours. 600nm .

[0054] The experimental results are as follows:

[0055] like Figure 2 As shown, strain GHX19 hardly grows at pH 4.5; grows slowly at pH 5.0; and grows normally at pH 5.5-8.5. The suitable soil pH for rice growth is 5.5-8.5, indicating that strain GHX19 can grow normally in soil within this pH range.

[0056] Example 3: Functional characteristics of shortwave monocytogenes GHX19 in producing ammonium nitrogen from organic substrates

[0057] The strain GHX19 was resuspended according to the procedure in Example 2.

[0058] The resuspended bacterial culture was inoculated into culture media with different nitrogen sources. The culture medium formula was as follows: 0.14 g nitrogen per liter (nitrogen sources were ammonium chloride, L-glutamic acid, L-glutamine, L-aspartic acid, and L-asparagine, respectively), 4.5 g sodium citrate, 1 g potassium dihydrogen phosphate, 0.69 g magnesium chloride hexahydrate, 0.05 g ferric chloride hexahydrate, and 0.2 g calcium chloride dihydrate. The pH of the culture medium was adjusted to 7.0, and the medium was autoclaved at 121°C for 15 min. Strain GHX19 was inoculated into the culture medium at a 1% inoculum and cultured in a shaker at 30°C and 180 rpm.

[0059] After culturing the bacterial culture for 24 h, the fermentation broth was centrifuged at 12000g for 10 min at 4℃, and the supernatant was retained. The ammonium nitrogen concentration was determined using a continuous flow analyzer. Each treatment was performed in triplicate.

[0060] The experimental results are as follows:

[0061] like Figure 3 As shown, after inoculating culture media with glutamic acid, glutamine, aspartic acid, and asparagine as the sole nitrogen sources, respectively, the concentration of ammonium nitrogen in the fermentation broth significantly increased, indicating that strain GHX19 has the ability to mineralize amino acids into ammonium. Figure 4 As shown, when strain GHX19 was inoculated into a culture medium with ammonium chloride as the sole nitrogen source, the concentration of ammonium nitrogen in the fermentation broth decreased significantly, indicating that strain GHX19 has ammonium assimilation ability.

[0062] Example 4: Functional characteristics of shortwave monocytogenes GHX19 and its biostimulants ginsenoside and Q3Gen in enhancing soil nitrogen use

[0063] The strain GHX19 was resuspended according to the procedure in Example 2.

[0064] To assess the impact of Pseudomonas GHX19 and its potential biostimulants on soil nitrogen use, an in vitro soil culture system was established. First, GHX19 strain was inoculated at a 1% inoculum into a system containing 100 g of sterile soil and 100 ml of sterile water, and incubated at 30°C for 3 days to allow for initial colonization.

[0065] The tested compounds were derived from previous metabolomics analysis of rice root exudates, from which a pair of flavonoid compounds that are isomers were identified: Baimaside (quercetin-3-O-sophoradiosyl glycoside, CAS: 18609-17-1) and Q3Gen (quercetin-3-gentiobiose glycoside, CAS: 7431-83-6).

[0066] After colonization, the above-mentioned compound was added to the system at final concentrations of 0.01, 0.1, 1, and 10 μM (DMSO was used as a control), and the mixture was incubated for another 6 hours. Soil samples were collected after incubation for the following analyses:

[0067] Functional gene expression: Total RNA was extracted from the soil, and the expression levels of the organic nitrogen mineralization gene gdh2 and the ammonium assimilation gene glnA in strain GHX19 were determined by RT-qPCR to characterize their mineralization and immobilization capabilities, respectively.

[0068] Soil ammonium nitrogen concentration: The content of ammonium nitrogen in rhizosphere soil is measured to visually reflect the net transformation results.

[0069] Each treatment had 6 biological replicates.

[0070] The specific measurement method is as follows:

[0071] In RT-qPCR experiments, RNA (OMEGA) was extracted using a soil RNA extraction kit, and cDNA was obtained by reverse transcription using a HiScript IV All-in-One Ultra RT SuperMix (Vazyme) kit. After quantitative amplification of the gene using a SYBR Green I (Vazyme) kit, gene expression was detected using QuantStudio 6 Flex Real-Time PCR (Applied Biosystems, MA, USA). The microbial ropB gene was used as an internal control. CT values ​​were calculated based on the internal control gene and the gene to be tested. This represents the relative gene expression level. Soil ammonium nitrogen content: potassium chloride extraction-indophenol blue colorimetric method.

[0072] The experimental results are as follows:

[0073] Result 1: As Figure 5 As shown, compared with the control group (DMSO), the exogenous addition of 0.1–10 μM of ephedrine or Q3Gen to the culture system significantly upregulated the relative expression levels of the organic nitrogen mineralization gene gdh2 and the ammonium assimilation gene glnA in *Bacillus shortwave diplossum* GHX19. These results indicate that even at low concentrations, these two compounds can effectively activate the expression of nitrogen transformation genes in GHX19, thereby predicting enhanced organic nitrogen decomposition and ammonium retention capabilities at the transcriptional level.

[0074] Result 2: As Figure 6 As shown, compared with the uninoculated control (CK), GHX19 inoculation significantly increased the concentration of ammonium nitrogen in the soil. Furthermore, adding 0.1 μM of ephedrine or Q3Gen to the GHX19 inoculation further significantly increased the soil ammonium nitrogen content. These results confirm that ephedrine and Q3Gen can further enhance the nitrogen transformation function of GHX19 in the soil, and both have a clear synergistic effect on the strain's function.

[0075] Example 5: Effects of GUX19 on ammonium nitrogen uptake in plant roots

[0076] The strain GHX19 was resuspended according to the procedure in Example 2.

[0077] Nipponbare rice seeds of similar size and plumpness were selected for the experiment. Surface disinfection was performed using ethanol and sodium hypochlorite. After disinfection, the seeds were germinated on 1 / 2 MS medium. One-week-old rice seedlings were then transferred to a 0.5 mM N nutrient solution for hydroponics, prepared according to international rice nutrient solution formulations.

[0078] The rice nutrient solution formula was as follows: 1 mM (NH4)2SO4, 0.5 mM KNO3, 0.3 mM KH2PO4, 0.25 mM K2SO4, 1 mM CaCl2, 1 mM MgSO4, 0.5 mM Na2SiO3, 9 μM MnCl2, 0.39 μM Na2MoO4, 20 μM H3BO3, 0.32 μM CuSO4, 20 μM Fe-EDTA, and 0.77 μM ZnSO4 (pH 5.5). The light intensity was 16,000 lux, the humidity was 70%, and the day / night (10h / 14h) temperatures were 30℃ and 24℃, respectively. The nutrient solution was changed every two days to maintain a sterile environment and ensure an adequate supply of nutrients for the rice growth.

[0079] Rice seedlings (Nipponbare) were subjected to nitrogen deficiency treatment for 3 days, and then the nitrogen source in the nutrient solution was replaced with organic nitrogen (L-glutamic acid, L-aspartic acid, L-leucine, L-phenylalanine, and L-valine, 0.1 mM each). The roots were then treated with a GHX19 bacterial suspension for 24 hours, with the addition of 0.1 μM ephedrine or Q3Gen. The control group received an equal volume of sterile water. The total bacterial count in the roots was approximately 10. 7 CFU / plant. After soaking the roots, rinse the roots with 0.1 mM CaSO4 for 1 min, then transfer the rice seedlings into a container containing 1 L of nutrient solution (0.25 mM CaSO4). 15 The root cells were treated in a culture chamber with NH4)2SO4 as the sole nitrogen source for 5 min, followed by rinsing with 0.1 mM CaSO4 for 1 min to remove residual nitrogen from the root surface. 15 N. Rice roots were collected and dried in a 70℃ oven to constant weight. After weighing and pulverizing, the content of N was determined by isotope mass spectrometry using a MAT253-Flash 2000HT-MS (Thermo Fisher Scientific). 15 N abundance.

[0080] The experimental results are as follows:

[0081] like Figure 7 As shown, compared with the blank control (CK), inoculation with strain GHX19 significantly enhanced the ammonium uptake rate, indicating that GHX19 itself has the ability to promote ammonium uptake in rice. Furthermore, in addition to GHX19 inoculation, exogenous addition of ephedrine or Q3Gen further significantly increased the root ammonium uptake rate. These results indicate that ephedrine and Q3Gen can enhance the physiological function of GHX19 in promoting host nitrogen uptake.

[0082] Example 6: Effects of GUX19 on plant growth

[0083] Huang Huazhan (HHZ) was selected as the experimental material, and its surface was disinfected using anhydrous ethanol and sodium hypochlorite. Rice seeds were raised in seedling trays, and before transplanting to pots, the roots were treated with sterile water or GHX19 bacterial suspension for 24 hours, with a total bacterial count of approximately 10⁻⁶. 7 CFU / plant. Potted plants were kept at a water level approximately 2 cm below the soil surface. Plant samples were collected during the peak tillering stage of rice to determine plant biomass and tiller number. Each indicator was tested with 6 biological replicates.

[0084] The experimental results are as follows:

[0085] like Figure 8 As shown, compared with the uninoculated strain, the aboveground dry weight, root dry weight and tiller number of plants inoculated with GHX19 were significantly increased, indicating that strain GHX19 can promote plant growth.

[0086] Example 7: Field verification of the effect of GUX19 on rice performance

[0087] Using the rice variety Huanghuazhan (HHZ) as the experimental subject, two treatments were set up: one with bacterial inoculation and one without.

[0088] Rice seeds are raised in a nursery. Before transplanting the seedlings to the field, the roots are first treated with a GHX19 bacterial suspension for 24 hours, resulting in a total bacterial count of approximately 10. 7 CFU / plant was used to transplant the rice seedlings into the plot. Field water management followed standard practices. Cross-flow was avoided between treatments. Rice yield was recorded at maturity, and nitrogen use efficiency (NUE) was calculated: NUE = Yield / Nitrogen application rate.

[0089] The experimental results are as follows:

[0090] like Figure 9 As shown, compared with the untreated group, application of GHX19 bacterial suspension improved nitrogen use efficiency and significantly increased yield in rice. Based on these trait-enhancing effects, it can be concluded that GHX19 has a certain growth-promoting and yield-increasing effect on rice.

[0091] In summary, inoculation of plant rhizosphere with strain GHX19 increases soil ammonium content, promotes ammonium uptake by plant roots, and reduces soil nitrogen loss. This effect is significantly enhanced by the exogenous addition of ephedrine or rutin. Simultaneously, strain GHX19 promotes plant growth-related traits and also significantly improves yield.

[0092] The embodiments described above are merely preferred examples of the present invention and are not intended to limit the scope of the present invention in any other way. Any modifications and improvements made by those skilled in the art to the embodiments of the present invention without departing from the design of the present invention shall still fall within the protection scope defined by the claims of the present invention.

Claims

1. A strain of *Syntrophus aeruginosa* ( Brevundimonas bullata GHX19, characterized in that, It is deposited at the China General Microbiological Culture Collection Center (CGMCC) on August 21, 2025, with accession number CGMCC No. 35707.

2. A microbial product, characterized in that, It contains the vesicular shortwave monoclonal bacteria GHX19 as described in claim 1.

3. The microbial product according to claim 2, characterized in that, The microbial products are inoculants, inoculant suspensions, fermentation products, or microbial fertilizers.

4. The microbial product according to claim 3, characterized in that, The concentration of *Syntropha vesicularis* GHX19 in the bacterial suspension is not less than 1 × 10⁻⁶. 8 CFU / mL.

5. The microbial product according to any one of claims 2-4, characterized in that, The microbial product further contains ephedrine and / or quercetin-3-gentiobiglycoside, wherein the final concentrations of ephedrine and quercetin-3-gentiobiglycoside are 0.1~10 μM, respectively.

6. Any one or more of the following applications of the *Syntrophus vesicularis* GHX19 as described in claim 1: (1) Promotes organic nitrogen mineralization and ammonium assimilation; (2) Increase soil ammonium content; (3) Promotes ammonium absorption and growth in plants; (4) Improve plant nitrogen use efficiency and yield.

7. The use of the *Syntrophus vesicularis* GHX19 according to claim 1 in the preparation of products having any one or more of the following functions: (1) Promotes organic nitrogen mineralization and ammonium assimilation; (2) Increase soil ammonium content; (3) Promotes ammonium absorption and growth in plants; (4) Improve plant nitrogen use efficiency and yield.

8. Any one or more of the following applications of the microbial product according to claim 2: (1) Promotes organic nitrogen mineralization and ammonium assimilation; (2) Increase soil ammonium content; (3) Promotes ammonium absorption and growth in plants; (4) Improve plant nitrogen use efficiency and yield.

9. A method for increasing soil ammonium nitrogen content, promoting plant growth, improving plant nitrogen use efficiency, or increasing plant yield, characterized in that, Inoculate the soil with the vesicular shortwave monoclonal bacteria GHX19 as described in claim 1 or apply the microbial product as described in any one of claims 2-5.

10. The method according to claim 9, characterized in that, The promotion of organic nitrogen mineralization is the decomposition of amino acids into ammonium nitrogen; the ammonium assimilation is equivalent to ammonium fixation, which is the assimilation of ammonium nitrogen into bacterial organic nitrogen, and the plant is rice.

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