Bacterial consortium for promoting growth of pasture grass in saline-alkali soil and application thereof

Abstract

The application discloses a kind of bacteria symbiotic of benefiting saline-alkali pasture growth and application thereof, the bacteria symbiotic is the combination of bacterial strain NAU-RHO, NAU-MIC2 and NAU-FLA4 and 4-guanidyl butyric acid.The bacterial strain NAU-MIC2, NAU-FLA4, NAU-RHO are respectively classified and named as Microbacterium laevaniformans, Flavobacterium anhuiense and Rhodococcus oxybenzonivorans research results show that bacteria symbiotic can improve the salt tolerance of bacteria to alfalfa and promote the high yield of alfalfa in saline-alkali soil.

Description

Technical Field

[0001] This invention belongs to the field of microbiology and relates to bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 and their application in promoting the growth of forage grasses in saline-alkali land. Specifically, it relates to a bacterial synbiotic of beneficial growth-promoting bacteria and the application of the bacterial synbiotic in promoting the growth of forage grasses (such as alfalfa). Specifically, it relates to the application of 4-guanidinobutyric acid in combination with bacteria NAU-RHO, NAU-MIC2, and NAU-FLA4 in promoting high yields of forage grasses in saline-alkali land. Background Technology

[0002] my country currently faces a shortage of nearly 50 million tons of high-quality forage grass. However, forage grass cannot compete with grain for land; therefore, breakthroughs in high-yield forage grass cultivation on marginal land are urgently needed. The key to improving the effective utilization of plant nutrients lies in regulating the "rhizosphere community" composed of plant roots and rhizosphere microorganisms. Its core is a mutually beneficial cycle where beneficial microorganisms promote plant growth, and plants provide root exudates to nourish these microorganisms. However, the low nutrient content and high environmental stress of soil in marginal lands lead to a decline in the ecological function of beneficial microorganisms, hindering the mutually beneficial cycle within the rhizosphere community and thus limiting healthy plant growth.

[0003] Currently, establishing rhizosphere growth-promoting measures tailored to plants and strengthening the mutually beneficial relationship between plants and microorganisms in the rhizosphere are key to increasing the yield of plants in marginal land. However, traditional beneficial microbial products often struggle to colonize in the rhizosphere in marginal land due to environmental stress, leading to unstable effects. In marginal soils, it is necessary to combine beneficial bacteria with root exudates that promote their growth and colonization in the rhizosphere to form a "rhizosphere synbiotic," thereby enhancing the mutually beneficial relationship between the beneficial bacteria and plants.

[0004] Therefore, it is necessary to find resources that can promote the growth of alfalfa in saline-alkali soil, provide a suitable environment for forage grass growth in the soil, and enhance its ability to withstand soil salinity stress. The inventors intend to screen resource substances that can effectively improve the growth ability of alfalfa in saline-alkali land, and apply microorganisms in combination with resource substances (synbiotics) into the soil to improve the growth-promoting effect on forage grasses in marginal soils. Summary of the Invention

[0005] To address the technical problem in existing technologies where limited soil nutrients and slow bacterial growth under salt stress hinder bacterial growth promotion in plants, making it difficult for bacteria to proliferate significantly and exert their intended protective effect, the present inventors, through greenhouse pot experiments, discovered that the combined use of three bacterial strains—NAU-RHO, NAU-MIC2, and NAU-FLA4—with 4-guanidinobutyric acid, applied to the soil via root irrigation, significantly increased alfalfa biomass in saline-alkali soils. This demonstrates that the combined use of 4-guanidinobutyric acid with the bacteria NAU-RHO, NAU-MIC2, and NAU-FLA4 can significantly enhance the bacteria's ability to promote salt and alkali tolerance in alfalfa.

[0006] The purpose of this invention is to provide bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4, and their application in promoting the growth of pasture in saline-alkali land.

[0007] Another object of the present invention is to provide a bacterial synbiotic and its application in promoting the growth of pasture in saline-alkali land.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] In a first aspect, the present invention seeks protection for a bacterial strain, which is any one of bacterial strain NAU-MIC2, bacterial strain NAU-FLA4 and bacterial strain NAU-RHO;

[0010] The bacterial strain NAU-MIC2 was classified as Microbacterium laevaniformans and was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251086 and deposit address: Wuhan University, China.

[0011] The bacterial strain NAU-FLA4 was classified as Flavobacterium anhuiense and was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251087 and deposit address: Wuhan University, China.

[0012] The bacterial strain described is classified as Rhodococcus oxybenzonivorans by NAU-RHO classification. It was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251088 and deposit address: Wuhan University, China.

[0013] Secondly, the present invention seeks protection for a bacterial community that is any combination of two or three of the bacterial strains NAU-MIC2, NAU-FLA4, and NAU-RHO.

[0014] The bacterial strain NAU-MIC2 is classified as Microbacterium laevaniformans, and its accession number at the China Center for Type Culture Collection is CCTCC M 20251086.

[0015] The bacterial strain NAU-FLA4 is classified as Flavobacterium anhuiense, and its accession number at the China Center for Type Culture Collection is CCTCC M 20251087.

[0016] The bacterial strain described is classified as Rhodococcus oxybenzonivorans by NAU-RHO classification, and its accession number at the China Center for Type Culture Collection is CCTCC M 20251088.

[0017] In a specific embodiment of the present invention, the bacterial community is a combination of bacterial strain NAU-MIC2, bacterial strain NAU-FLA4 and bacterial strain NAU-RHO, wherein the ratio of bacterial strain NAU-MIC2, bacterial strain NAU-FLA4 and bacterial strain NAU-RHO in the combination is 1:1:1 (v / v / v).

[0018] Thirdly, the present invention seeks protection for the use of the above-described bacterial strains or bacterial groups in the following (a1) or (a2):

[0019] (a1) Application in promoting the growth of pasture in saline-alkali land;

[0020] (a2) Application in the preparation of microbial preparations for promoting the growth of pasture in saline-alkali land.

[0021] Fourthly, the present invention seeks protection for the use of the aforementioned bacterial strains or the aforementioned bacterial community combined resource substances in the following (b1) or (b2):

[0022] (b1) Application in promoting the growth of pasture in saline-alkali land;

[0023] (b2) Application in the preparation of bacterial synbiotics for promoting the growth of forage grasses in saline-alkali land;

[0024] The resource substance is selected from at least one of vanillic acid, p-coumaric acid, gallic acid, phthalic acid, syringic acid, salicylic acid, cinnamic acid, ferulic acid, coumaric acid, p-hydroxybenzoic acid, S-lactylglutathione, methionine, androstenone, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde, and 5-hydroxyindole-2-carboxylic acid.

[0025] Furthermore, the above application involves combining different resource substances with strains exhibiting different characteristics:

[0026] Choose any one of the following: vanillic acid, p-coumaric acid, gallic acid, phthalic acid, syringic acid, salicylic acid, cinnamic acid, ferulic acid, coumaric acid, p-hydroxybenzoic acid, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde, and 5-hydroxyindole-2-carboxylic acid, and use it in combination with the bacterial strain NAU-RHO.

[0027] Alternatively, any one of S-lactylglutathione, methionine, androstenedione, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde, and 5-hydroxyindole-2-carboxylic acid may be used in combination with bacterial strain NAU-FLA4.

[0028] Alternatively, any one of 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde, and 5-hydroxyindole-2-carboxylic acid may be used in combination with bacterial strain NAU-MIC2.

[0029] Alternatively, any one of 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde, and 5-hydroxyindole-2-carboxylic acid may be used in combination with bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4; preferably, 4-guanidinobutyric acid may be used in combination with bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4.

[0030] In a specific embodiment of the present invention, the root irrigation method is used to apply the microbial community constructed by 4-guanidinobutyric acid and bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 into the soil to promote high yield of saline-alkali pasture (such as alfalfa).

[0031] Fifthly, the present invention claims protection for a bacterial synbiotic comprising two components, (c1) and (c2):

[0032] (c1) The bacterial strains or bacterial groups mentioned above;

[0033] (c2) is selected from at least one resource material selected from vanillic acid, p-coumaric acid, gallic acid, phthalic acid, syringic acid, salicylic acid, cinnamic acid, ferulic acid, coumaric acid, p-hydroxybenzoic acid, S-lactylglutathione, methionine, androstenone, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde and 5-hydroxyindole-2-carboxylic acid.

[0034] Furthermore, the aforementioned bacterial synbiotics are at least one of the following (1)-(4):

[0035] (1) Contains (c1) bacterial strain NAU-RHO, and (c2) any one of vanillic acid, p-coumaric acid, gallic acid, phthalic acid, syringic acid, salicylic acid, cinnamic acid, ferulic acid, coumaric acid, p-hydroxybenzoic acid, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde and 5-hydroxyindole-2-carboxylic acid;

[0036] (2) Contains (c1) bacterial strain NAU-FLA4, and (c2) any one of S-lactoylglutathione, methionine, androstenone, 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde and 5-hydroxyindole-2-carboxylic acid;

[0037] (3) Contains (c1) bacterial strain NAU-MIC2, and (c2) any one of 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde and 5-hydroxyindole-2-carboxylic acid;

[0038] (4) Contains (c1) bacterial strains NAU-RHO, NAU-MIC2 and NAU-FLA4, and (c2) any one of 4-guanidinobutyric acid, 5-methoxyindole-3-carboxaldehyde and 5-hydroxyindole-2-carboxylic acid; preferably contains (c1) bacterial strains NAU-RHO, NAU-MIC2 and NAU-FLA4, and (c2) 4-guanidinobutyric acid.

[0039] Sixthly, the present invention seeks protection for the application of the above-mentioned bacterial synbiotics in promoting the growth of pasture in saline-alkali land.

[0040] Seventhly, the present invention claims protection for a method for promoting the growth of pasture in saline-alkali land, which involves applying the aforementioned bacterial synbiotic to the pasture using a root irrigation method.

[0041] Furthermore, the above method specifically involves applying a solution of the resource substance in the bacterial synbiotic and the bacterial culture into the soil; applying 0.05–0.15 mmol of the resource substance and a concentration of 1 × 10⁻⁶ mmol / L to each forage seedling. 7 ~1×10 9 The optimal dosage is 5 mL to 15 mL of bacterial suspension with a CFU / mL concentration for each forage seedling; the most preferred dosage is 0.1 mmol of resource substance and 1×10⁻⁶ CFU / mL for each forage seedling. 8 10 mL of bacterial culture for each bacterial strain with CFU / mL.

[0042] Furthermore, the bacterial culture was obtained using the following method: bacterial strains NAU-MIC2, NAU-FLA4, and NAU-RHO were activated using NA solid medium; single colonies of bacterial strains NAU-MIC2, NAU-FLA4, and NAU-RHO were picked and cultured in NA liquid medium (30℃, 170rpm for 2 days); and the obtained fresh bacterial culture was diluted with sterile water to obtain bacterial cultures of bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4, respectively.

[0043] The forage described in the technical solution of this invention is alfalfa, but it is not limited to this.

[0044] In a specific embodiment of the present invention, 5-7 days after transplanting alfalfa seedlings with 2-3 true leaves, the resource substance (4-guanidinobutyric acid) and bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 are applied to the soil via root irrigation. Each alfalfa seedling receives 0.1 mmol of the resource substance and a concentration of 1×10⁻⁶. 8 10 mL of bacterial culture for each bacterial strain with CFU / mL.

[0045] The resource substance is applied in solution form. In a specific embodiment, the concentration of the resource substance solution is 0.1 mol / L, but it is not limited to this. The resource substance solution is prepared by dissolving the resource substance in deionized water or warm water, drawing it up with a sterile syringe, and filtering it through a 0.22 μm filter membrane to obtain the resource substance solution.

[0046] The beneficial effects of this invention are:

[0047] This invention combines 4-guanidinobutyric acid with bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 to enhance the bacteria's ability to tolerate salt and alkali and promote growth. This significantly improves the bacteria's effect on promoting the salt and alkali tolerance of alfalfa and increases the yield of alfalfa in saline-alkali land. Attached Figure Description

[0048] Figure 1 Photographs of single colony plates of three bacterial strains: NAU-RHO, NAU-MIC2, and NAU-FLA4.

[0049] Figure 2 Phylogenetic tree of three strains: NAU-RHO, NAU-MIC2, and NAU-FLA4.

[0050] Figure 3The effects of different resource substances on the biomass (OD600) of bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 were investigated. Water represented the treatment without the resource substance; the others represented the treatments with the corresponding resource substances. The biomass was determined by adding fresh bacterial single colonies to NA medium and culturing at 30°C and 170 rpm for 48 h.

[0051] Figure 4 The results show the effects of three bacteria and resource substances, individually and in combination, on the growth-promoting effects of alfalfa plants in saline-alkali soil.

[0052] Information on the preservation of biological materials:

[0053] The bacterial strain NAU-MIC2, classified as Microbacterium laevaniformans NAU-MIC2, was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251086 and deposit address: Wuhan University, China.

[0054] The bacterial strain NAU-FLA4 was classified and named Flavobacterium anhuiense NAU-FLA4. It was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M20251087 and deposit address: Wuhan University, China.

[0055] The bacterial strain NAU-RHO is classified as Rhodococcus oxybenzonivorans NAU-RHO and was deposited at the China Center for Type Culture Collection (CCTCC) on May 16, 2025, with accession number CCTCC M20251088 and deposit address at Wuhan University, China. Detailed Implementation

[0056] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0057] Experiment Example 1: Isolation, Screening and Identification of Bacteria

[0058] Strain screening: Saline-alkali soil samples were collected from Dongtai City, Jiangsu Province, and approximately 5 g was weighed using a balance. A pre-sterilized conical flask containing 45 ml of sterile water and several sterile glass beads was taken out. The soil sample was poured into the flask, sealed with a sealing film, and placed in a single-layer rotary shaker at 200 rpm for 1 hour. This is 10... -1The dilution solution. On the laminar flow hood, select a test tube containing 4.5 ml of sterile water, and use a sterile pipette tip to transfer 0.5 ml of the suspension from the conical flask into it, and aspirate and blow several times. This is 10. -2 Dilute the solution, then transfer 0.5 ml of the suspension to the next test tube; this makes 10. -3 For diluents, prepare 10 solutions respectively, following this method. -3 10 -4 10 -5 Diluent. Three dilution levels were selected, and bacterial NA medium was used for spread culture. 0.1 ml of diluent was placed on each plate, and the spread should be as uniform as possible. Three replicates were set for each dilution level. The uniformly spread bacterial NA medium plates were placed in an incubator at 30°C. Single bacterial colonies grew within 24 hours. Single colonies were picked and purified a second time, ensuring that each picked colony was a single colony. The bacterial suspension was obtained by shaking in well plates and identified by molecular biology as *Microbacterium laevaniformans*, *Flavobacterium anhuiense*, and *Rhodococcus oxybenzonivorans*, and named NAU-MIC2, NAU-FLA4, and NAU-RHO (e.g., ). Figure 1 and Figure 2 ).

[0059] The bacterial strain NAU-MIC2, classified as Microbacterium laevaniformans, was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251086 and address at Wuhan University, China.

[0060] The bacterial strain NAU-FLA4, classified as Flavobacterium anhuiense, was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251087 and deposit address: Wuhan University, China.

[0061] The bacterial strain NAU-RHO, classified as Rhodococcus oxybenzonivorans, was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251088, at Wuhan University, China.

[0062] Example 2: Investigating the effect of resource materials on bacterial biomass over 48 hours

[0063] Preparation of the mother liquor of resource substances: Accurately weigh each resource substance using a 0.01 g balance, dissolve it in deionized water or warm water, and aspirate it with a sterile syringe. Filter the solution through a 0.22 μm filter membrane into a 50 mL sterile centrifuge tube to obtain a sterile mother liquor of resource substances with a concentration of 1 mM. Store the solution in a -4 ℃ refrigerator for later use.

[0064] Preparation of bacterial suspensions: Strains NAU-RHO, NAU-MIC2, and NAU-FLA4 were activated using NA solid medium. Single colonies of NAU-RHO, NAU-MIC2, and NAU-FLA4 were picked and cultured individually on NA liquid medium at 30℃ and 170 rpm for 2 days to obtain single-strain suspensions of NAU-RHO, NAU-MIC2, and NAU-FLA4. Each of the three fresh suspensions was diluted 10-fold with sterile water to obtain 1×10⁻⁶ bacterial suspensions. 8 Individual bacterial suspensions of NAU-RHO, NAU-MIC2, and NAU-FLA4 (CFU / mL) were then added to the rhizosphere of the potted plants in equal proportions (10 ml per bacterium per pot).

[0065] Plate preparation: 96-well plates (200 μL per well) were used. 178 μL of sterile 1 / 20 liquid NA medium was added to each well, along with 20 μL of pre-prepared stock solution of resource material or sterile water. Finally, 2 μL of bacterial culture was added to each well. The plates were incubated at 30°C and 170 rpm on a shaker for 48 hours, and the OD600 biomass was measured.

[0066] Experimental setup and treatment: Experimental group: Added resource materials and bacterial solutions of NAU-RHO, NAU-MIC2, and NAU-FLA4; Control group: Added only bacterial solutions of NAU-RHO, NAU-MIC2, and NAU-FLA4, and replaced the resource materials with an equal volume of water.

[0067] The effects of different resource substances on the biomass of bacteria NAU-RHO, NAU-MIC2, and NAU-FLA4 are shown in the figure. Figure 3 The experimental results showed that, compared with the control group, vanillic acid, cinnamic acid, ferulic acid, p-hydroxybenzoic acid, 4-guanidinobutyric acid, and 5-hydroxyindole-2-carboxylic acid significantly increased the biomass of the NAU-RHO bacterial strain after 48 hours (e.g., Figure 3 (A in the middle)

[0068] Compared with the control group, 4-guanidinobutyric acid significantly increased the biomass of bacterial strain NAU-FLA4 after 48 hours (e.g., Figure 3 (B in the middle)

[0069] Compared with the control group, 4-guanidinobutyric acid significantly increased the biomass of bacterial strain NAU-MIC2 after 48 hours (e.g., Figure 3 (C in the middle).

[0070] In summary, the results show that, compared with the control group, 4-guanidinobutyric acid can significantly promote the increase of bacterial biomass of NAU-RHO, NAU-MIC2, and NAU-FLA4 (P<0.05).

[0071] Example 3: Effects of combined application of resource substances and bacterial growth promoters on alfalfa growth under salt-alkali stress.

[0072] Soil: Saline-alkali soil from Dongtai City, Jiangsu Province (pH: 8.36, EC: 2.69 ms / cm)

[0073] The preparation of bacterial suspensions of NAU-RHO, NAU-MIC2, and NAU-FLA4 is described in Example 2.

[0074] Based on the effect of resource substances on promoting bacterial salt-alkali tolerance, superior resource substances (bacteria NAU-RHO, NAU-MIC2, NAU-FLA4, resource substance: 4-guanidinobutyric acid) were screened, and the effects of the above resource substances and bacteria in combination on the salt-alkali tolerance of alfalfa were further investigated.

[0075] Alfalfa variety: Aurora.

[0076] After surface sterilization, alfalfa seeds were placed on sterile plates lined with filter paper moistened with sterile deionized water and germinated at 4℃ for 2 days. Seedlings with uniform growth were transplanted into 4-well seedling trays containing 100 g of Dongtai saline-alkali soil. Seven days after transplanting, bacteria and resource substances were evenly applied to the roots of the alfalfa using a root irrigation method. 1 mL of a 0.1 mol / L resource substance solution was added to each pot (ensuring a total of 0.1 mmol of resource substance per pot), along with 10 mL of a 10% concentration solution. 8CFU / mL of NAU-RHO, NAU-MIC2, and NAU-FLA4 bacterial suspensions were used in the experiment. The treatments were: 1) Bacterial NAU-RHO, NAU-MIC2, and NAU-FLA4 + resource substance group: resource substance and bacterial NAU-RHO, NAU-MIC2, and NAU-FLA4 suspensions were added; 2) Bacterial NAU-RHO, NAU-MIC2, and NAU-FLA4 group: only three bacterial suspensions were added, and the resource substance was replaced with an equal volume of water; 3) Single bacterial suspension group: only a single bacterial suspension was added, and the resource substance and the other two bacterial suspensions were replaced with an equal volume of water; 4) Resource suspension group: only resource substance was added, and the three bacterial suspensions were replaced with an equal volume of water; 5) Control group: an equal volume of water replaced the resource substance and bacterial suspensions. After approximately 60 days of growth, the growth-promoting effect of bacterial prebiotics on alfalfa under salt-alkali stress was observed.

[0077] In this embodiment, different treatment combinations affect the growth of alfalfa seedlings as follows: Figure 4 As shown.

[0078] The results showed that the plant height and fresh weight of alfalfa plants increased significantly compared with the control group (CK) after the addition of a single substance, indicating that a single bacterial solution or resource substance can promote the growth of alfalfa under salt-alkali stress.

[0079] In this embodiment, the plant height and fresh weight of alfalfa plants significantly increased compared to the control group (CK) after the addition of a single substance or bacterial solution, indicating that bacterial solution and resource substances can promote the growth of alfalfa under salt-alkali stress. The combined use of three bacterial strains, NAU-RHO, NAU-MIC2, and NAU-FLA4, with 4-guanidinobutyric acid showed significantly better growth-promoting effects on alfalfa under salt-alkali stress than the combined application of bacteria NAU-RHO, NAU-MIC2, and NAU-FLA4. This indicates that the combined use of the three bacterial strains NAU-RHO, NAU-MIC2, and NAU-FLA4 with 4-guanidinobutyric acid can better improve the salt-alkali tolerance and growth-promoting ability of alfalfa under salt-alkali stress, alleviate salt damage, increase biomass, and thus promote alfalfa growth.

Claims

1. A bacterial synbiotic, characterized in that, It contains the following two components: (c1) and (c2): (c1) Any one of the bacterial strains NAU-MIC2, NAU-FLA4 and NAU-RHO, or a combination of the bacterial strains NAU-MIC2, NAU-FLA4 and NAU-RHO; (c2) 4-Guidinobutyric acid; The bacterial strain NAU-MIC2 is classified and named Levomicrobacterium (L-microbacterium) Microbacterium laevaniformans The sample was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251086 and address: Wuhan University, China. The bacterial strain NAU-FLA4 is classified and named Flavobacterium anhuiense It was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251087, and the deposit address is Wuhan University, China. The bacterial strain described is classified and named NAU-RHO. Rhodococcus oxybenzonivorans It was deposited at the China Center for Type Culture Collection on May 16, 2025, with accession number CCTCC M 20251088, and the deposit address is Wuhan University, China.

2. The use of the bacterial synbiotic according to claim 1 in either (a1) or (a2): (a1) Application in promoting the growth of pasture in saline-alkali land; (a2) Application in the preparation of microbial preparations for promoting the growth of pasture in saline-alkali land.

3. A method for promoting the growth of pasture grasses in saline-alkali land, characterized in that: The bacterial synbiotic described in claim 1 is applied to forage grass using the root irrigation method.

4. The method according to claim 3, characterized in that, The solution of 4-guanidinobutyric acid from the bacterial synbiotic and the bacterial culture of the bacterial strain were applied to the soil; each forage seedling was treated with 0.05–0.15 mmol of 4-guanidinobutyric acid and a solution of 1 × 10⁻⁶ mmol / L. 7 ~1×10 9 5 mL to 15 mL of bacterial culture for each bacterial strain with CFU / mL.

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