A halophytic rhizosphere growth promoting bacterial strain and application thereof

Abstract

The application provides a saline-alkali rhizosphere growth promoting bacterial strain, named Bacillus sp. A015, which is preserved in the China Center for Type Culture Collection, and the preservation number is CCTCC NO: M20242724, and the preservation date is December 4, 2024. The nucleotide sequence of the 16S rRNA of the rhizosphere growth promoting bacterial strain is shown as SEQ ID NO. 1. The application also provides the application of the bacterial strain, which is used for improving the soil environment of saline-alkali soil and promoting crop growth. The bacterial strain has the functions of strong nitrogen fixation, organic phosphorus and inorganic phosphorus dissolution, and difficult soluble potassium decomposition, and can also promote the germination and growth of soybeans, lays an important foundation for the research of saline-alkali soil biological fertilizer, biological improvement agent and bacterial fertilizer, and has great significance for the improvement and utilization of saline-alkali soil, the expansion of the reserve arable land resources of China and the guarantee of national food security and the like.

Description

Technical Field

[0001] This invention belongs to the field of salt-tolerant rhizosphere growth-promoting bacteria technology, specifically relating to a salt-tolerant rhizosphere growth-promoting strain and its application. Background Technology

[0002] Saline-alkali land is characterized by high soil salinity, low soil fertility, nutrient imbalance, low agricultural productivity and efficiency, and difficulty in improvement. Rhizosphere microorganisms, as the "second genome" of plants and raw materials for biological agents to improve saline-alkali land, have great potential for application in enhancing crop resistance to salt-alkali stress and promoting crop growth. Plant growth-promoting rhizobacteria (PGPRs), an important component of microbial fertilizers, can colonize plant roots. They can not only activate nutrients such as phosphorus and potassium in saline-alkali soil, promoting direct absorption and utilization by crops, but also secrete growth-promoting substances such as indoleacetic acid (IAA) to promote crop growth and development, thereby increasing crop yield. Furthermore, the composition and content of root exudates are influenced by PGPRs recruited by the microbial community, and conversely, the rhizosphere microbial community of plants is influenced by root exudates. Therefore, screening rhizosphere growth-promoting bacteria for plants in specific habitats is of great significance for improving the soil environment and increasing the yield of specific crops. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a salt-tolerant rhizosphere growth-promoting strain that addresses the shortcomings of the prior art. This strain has strong nitrogen fixation, organic and inorganic phosphorus dissolution, and potassium solubilization functions, and can promote soybean growth. It lays an important foundation for the research of biological improvement agents and microbial fertilizers for saline-alkali land, and is of great significance for the improvement and utilization of saline-alkali land, the expansion of my country's reserve arable land resources, and the safeguarding of national food security.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a salt-tolerant rhizosphere growth-promoting strain, named Bacillus sp. A015, deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, with accession number CCTCC NO: M20242724 and deposit date of December 4, 2024; the nucleotide sequence of the 16S rRNA of the rhizosphere growth-promoting strain is shown in SEQ ID NO.1.

[0005] The present invention also provides the application of the above-mentioned salt-tolerant rhizosphere growth-promoting strains, which are used to improve the soil environment of saline-alkali land and promote crop growth.

[0006] Preferably, the salt-tolerant rhizosphere growth-promoting strain is used for biological nitrogen fixation, dissolving organic and inorganic phosphorus, and decomposing insoluble potassium; the salt-tolerant rhizosphere growth-promoting strain is used to promote soybean growth.

[0007] Preferably, the salt-tolerant rhizosphere growth-promoting strain is used to improve the germination rate of soybean seeds and increase the length of soybean embryos.

[0008] Compared with the prior art, the present invention has the following advantages:

[0009] The strain Bacillus sp. A015 of this invention has strong nitrogen fixation, dissolution of organic and inorganic phosphorus, and decomposition of insoluble potassium, and can promote soybean growth. It lays an important foundation for the research of biological improvement agents and microbial fertilizers for saline-alkali land, and is of great significance for the improvement and utilization of saline-alkali land, the expansion of my country's reserve arable land resources, and the safeguarding of national food security.

[0010] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0011] Figure 1 This refers to the determination of the nitrogen fixation function of strain A015 in Example 1 of the present invention.

[0012] Figure 2 This refers to the determination of the potassium solubilizing ability of strain A015 in Example 1 of the present invention.

[0013] Figure 3 This refers to the determination of the phosphorus-containing capacity of strain A015 in Example 1 of the present invention.

[0014] Figure 4 This is a determination of the phosphorus-free dissolving ability of strain A015 in Example 1 of the present invention.

[0015] Figure 5 This is the result of the salt tolerance experiment of strain A015 in Example 1 of the present invention.

[0016] Figure 6 This is the result of the alkali resistance test of strain A015 in Example 1 of the present invention.

[0017] Figure 7 This is the colony morphology of strain A015 in Example 1 of the present invention on modified LB medium.

[0018] Figure 8 This is the result of the growth curve measurement of strain A015 in Example 1 of the present invention.

[0019] Figure 9 This is the Gram staining result of strain A015 under an optical microscope in Example 1 of the present invention.

[0020] Figure 10 This is a phylogenetic tree diagram of strain A015 based on 16S rRNA in Example 1 of the present invention.

[0021] Figure 11 This is a diagram of the soybean seed germination rate test using strain A015 in Example 1 of the present invention. Detailed Implementation

[0022] Example 1

[0023] The formulations of the culture media used in this embodiment are as follows:

[0024] Modified LB medium (isolation and purification, salt and alkali tolerance test): tryptone 10.0 g / L, yeast extract 5.0 g / L, NaCl 50.0 g / L (5%), agar 18 g / L, pH 7.0-7.2.

[0025] LB liquid medium: tryptone 10.0 g / L, yeast extract 5.0 g / L, NaCl 10.0 g / L, pH 7.0-7.2.

[0026] Ashby nitrogen-free medium (determination of nitrogen fixation function): mannitol 10.0 g / L, KH2PO4 0.2 g / L, MgSO4·7H2O 0.2 g / L, NaCl 0.2 g / L, CaCO3 5.0 g / L, CaSO4 0.1 g / L, pH 6.8-7.0.

[0027] Monkina Organic Phosphorus Medium (for functional verification of organophosphorus dissolution): MnSO4·H2O 0.03 g / L, FeSO4·7H2O 0.03 g / L, CaCO3 5.0 g / L, glucose 10.0 g / L, (NH4)2SO4 0.5 g / L, lecithin 0.2 g / L, NaCl 0.3 g / L, KCl 0.3 g / L, yeast extract 0.4 g / L, agar 18 g / L, pH 7.0-7.2.

[0028] Inorganic phosphorus medium: glucose 10 g / L, MgCl2·6H2O 5 g / L, MgSO4·7H2O 0.25 g / L, KCl 0.2 g / L, (NH4)2SO4 0.1 g / L, Ca3(PO4)2 5 g / L, pH 6.8-7.0.

[0029] Potassium-solubilizing medium: sucrose 10.0 g / L, yeast extract 0.5 g / L, (NH4)2SO4 1.0 g / L, Na2HPO4 2.0 g / L, MgSO4·7H2O 0.5 g / L, CaCO3 1.0 g / L, potassium feldspar 1.0 g / L, agar 18 g / L, pH 7.0-7.2.

[0030] (I) Isolation and purification of strains

[0031] Soil samples: cotton root soil samples from saline-alkali land in the Tailanhe Irrigation Area of ​​Wensu County, Aksu Prefecture, Xinjiang (80°21′44″-81°10′14″E, 40°41′41″-42°15′13″N).

[0032] Soil suspensions were prepared using saline-alkali soil samples from the Tailan River irrigation area in Wensu County, Aksu Prefecture, Xinjiang, and then diluted to a concentration of 10. -4 The culture was spread onto modified LB medium and cultured. Single colonies were picked and repeatedly streaked to isolate and purify the culture, resulting in strain A015.

[0033] The specific separation and purification method is as follows: Weigh 10g of the soil sample into an Erlenmeyer flask containing 90mL of sterile water, shake at 200r / min for 20min, and then take the soil suspension for 10... -1 10 -2 10 -3 10 -4 10 -5 Gradient dilution, select a suitable dilution gradient (10). -4 Spread the culture evenly onto a modified LB agar plate and incubate at 30°C for 2-3 days. When single colonies appear, purify the culture multiple times on the plate using the streak plate method to obtain a pure culture. Inoculate the culture onto a slant agar plate and incubate at 30°C for 4-5 days. Store the culture in a refrigerator at 4°C for later use.

[0034] (ii) The isolated strains were inoculated into different functional culture media.

[0035] Different isolated strains (J-100-3, A-0-4, A-0-5, A-0-8, A-0-15, J-200-6) were inoculated onto different functional media. Specific assay methods are shown in (1)-(4). A strain A015, possessing nitrogen fixation, organic and inorganic phosphorus solubilization, and potassium solubilization functions, was screened. The organic phosphorus solubilization index of strain A015 was 0.5, and quantitative experiments showed that its lecithin conversion reached 3.77 mg / L; the inorganic phosphorus solubilization index was 1.3, and quantitative experiments showed that its calcium phosphate conversion reached 24.79 mg / L; the potassium solubilization index was 0.9, and its potassium feldspar powder conversion reached 5.16 mg / L. The specific results are shown in Table 1. Figures 1 to 4 As shown.

[0036] Table 1. Results of functional assays for different strains

[0037] J-100-3 Jinghe County - - - D / d = 1.1 A-0-4 Lake Ebi - - D / d = 0.7 - A-0-5 Lake Ebi + - - D / d = 0.8 A-0-8 Lake Ebi - - - D / d = 0.7 A015 Tailan River ++ D / d = 1.3 D / d = 0.5 D / d = 0.9 J-200-6 Jinghe County - - - -

[0038] Note: "+" indicates that the strain has the corresponding function, and the more strains present, the stronger the function; "-" indicates that the strain does not have the corresponding function. "D" represents the diameter of the transparent zone, and "d" represents the diameter of the strain's growth. The larger the D / d ratio, the stronger the corresponding function.

[0039] (1) Determination of nitrogen fixation function:

[0040] The nitrogen-fixing capacity of bacterial isolates was determined using Ashby nitrogen-free medium. Purified strains were inoculated onto Ashby nitrogen-free medium and cultured at 28°C for 7 days. The ability of the bacteria to fix nitrogen was determined by whether they could grow normally on the nitrogen-free Ashby medium, and the degree of nitrogen fixation was judged by the diameter of the colony.

[0041] The results of the nitrogen fixation experiment are as follows Figure 1 As shown, strain A015 grew well on Ashby nitrogen-free medium after being cultured at a constant temperature, indicating that strain A015 has nitrogen-fixing function.

[0042] (2) Determination of the ability to dissolve insoluble potassium:

[0043] Qualitative experiment: The purified strain was inoculated onto potassium-solubilizing medium and cultured at 28℃ for 5-7 days. The diameter of the clear zone (D) and the colony diameter (d) were measured. The potassium-solubilizing clear zone is formed by the secretion of organic acids and other minerals by the strain during growth on the medium to dissolve insoluble potassium minerals. Therefore, the size of the potassium-solubilizing clear zone diameter reflects the strain's ability to release potassium ions. The larger the ratio of the potassium-solubilizing clear zone diameter (D) to the colony diameter (d) of the potassium-solubilizing bacteria, the higher the potassium-solubilizing activity per unit growth area, and the better the potassium-solubilizing effect of the strain.

[0044] Quantitative experiment: The prepared bacterial suspension was inoculated into 50 mL of potassium-solubilizing liquid medium without agar at an inoculation rate of 1% (v / v). After incubation at 30℃ and 180 r / min for 3 days, the culture was centrifuged at 6000 r / min for 20 min. The supernatant was collected and the potassium content in the supernatant was determined by flame spectrophotometer.

[0045] like Figure 2 As shown, the qualitative experimental results indicate that the potassium solubility index of strain A015 is 0.9, and the quantitative experimental results indicate that the conversion capacity of potassium feldspar powder by strain A015 reaches 5.16 mg / L after 3 days of culture.

[0046] (3) Organic phosphorus dissolution experiment:

[0047] Qualitative determination method for organophosphate degrading bacteria: The purified strain was inoculated onto Monkina organophosphate medium and cultured in a constant temperature incubator at 28℃ for 5-7 days. The diameter of the phosphate-solubilizing zone (D) and the colony diameter (d) were measured. Since strains with phosphate-solubilizing function can convert lecithin in the culture medium into choline, glycerol, and other substances during cultivation, and choline is further decomposed into amines, organic acids, carbon dioxide, etc., ultimately forming a clear zone. Therefore, the larger the ratio of the phosphate-solubilizing zone diameter (D) to the colony diameter (d) of organophosphate-degrading bacteria, the better the organophosphate degradation effect.

[0048] Quantitative experiment on dissolved organophosphorus: The bacterial suspension was inoculated into 50 mL of organophosphorus liquid culture medium at an inoculation rate of 1% (v / v) and cultured at 30℃ and 180 r / min for 3 days. After centrifugation at 10000 r / min for 15 min, the supernatant was collected and the available phosphorus content in the supernatant was determined by molybdenum blue colorimetric method.

[0049] like Figure 3 As shown, the qualitative experimental results indicate that the organic phosphorus solubility index of strain A015 is 0.5; according to the quantitative experimental results, the conversion of lecithin after 3 days of culture is 3.77 mg / L.

[0050] (4) Experiment on dissolving inorganic phosphorus:

[0051] Qualitative determination method for inorganic phosphorus degradation: The purified strain was inoculated onto an inorganic phosphorus medium and cultured in a constant temperature incubator at 28℃ for 5-7 days. The diameter of the phosphate-solubilizing zone (D) and the colony diameter (d) were measured. Phosphate-solubilizing bacteria can convert insoluble Ca3(PO4)2 in the medium into a soluble state through secretion, acidification, and chelation, allowing phosphate in the medium to be released and diffused, thus forming a clear zone. Therefore, the larger the ratio of the phosphate-solubilizing zone diameter (D) to the colony diameter (d) of inorganic phosphorus-degrading bacteria, the better the inorganic phosphorus degradation effect.

[0052] Quantitative experiment on dissolved inorganic phosphorus: The bacterial suspension was inoculated into 50 mL of inorganic phosphorus liquid culture medium at an inoculation rate of 1% (v / v) and cultured at 30℃ and 180 r / min for 3 days. After centrifugation at 10000 r / min for 15 min, the supernatant was collected and the available phosphorus content in the supernatant was determined by molybdenum blue colorimetric method.

[0053] like Figure 4 As shown, the qualitative experimental results indicate that the inorganic phosphorus solubility index of strain A015 is 1.3; the quantitative experimental results indicate that the conversion capacity of calcium phosphate by A015 after 3 days of culture is 24.79 mg / L.

[0054] (III) Salt and Alkali Tolerance Test:

[0055] 1. Preparation of bacterial suspension

[0056] Under aseptic conditions, purified single colonies were picked and inoculated into 250 mL Erlenmeyer flasks containing 100 mL of liquid LB medium. The flasks were incubated at 180 rpm and 30 °C with shaking for 2 days until the late logarithmic growth phase. The colonies were then centrifuged at 8000 rpm for 10 min, the supernatant was discarded, and the bacterial cells were collected. The OD value was adjusted to 0.5% with sterile water. 600 =Approximately 0.5 for backup.

[0057] 2. Salt tolerance test

[0058] LB liquid culture media with pH=7.0 and NaCl concentrations of 0%, 3%, 5%, 10%, 15%, and 20% were prepared. The prepared bacterial suspensions were inoculated into LB liquid culture media with different NaCl concentration gradients at an inoculation rate of 1%. The shaking conditions were set at 30℃ and 180 r / min. The OD values ​​were measured after 7 days. 600 The value was used to determine the salt tolerance of the strain.

[0059] 3. Alkali resistance test

[0060] Based on the results of the salt tolerance test, the alkali tolerance of the strain was further determined. The bacterial suspension was inoculated at a rate of 1% into LB liquid medium with a NaCl concentration of 5% and different pH gradients (pH = 3, 5, 6, 8, 10, 11, 12, 13). The shaking conditions were set at 30℃ and 180 r / min. The OD value was measured after 7 days. 600 The value was used to determine the acid and alkali tolerance of the strain.

[0061] Salt and alkali tolerance experiments showed that strain A015 could tolerate an alkaline environment of 20% (w / v) NaCl concentration and pH=10, and grew best in a medium with 5% (w / v) NaCl and pH 8. Specific results are as follows... Figure 5 , Figure 6 As shown.

[0062] (iv) Morphological and physiological-biochemical identification of strains

[0063] Morphological identification method: When the strain is clearly visible and growing well on the culture medium, observe the morphological characteristics of the strain on the culture medium, such as colony color, shape, and transparency, referring to Bergey's Manual of Bacteriological Identification. Take a small amount of the strain and streak it on modified LB medium. Pick a purified single colony for Gram staining.

[0064] Growth curve determination: A single colony of A015 was picked and placed in a 500 mL Erlenmeyer flask containing 350 mL of LB liquid medium. The flask was then incubated on a shaker at 30 °C and 180 rpm for 2 days. The cells were then centrifuged at 10,000 rpm at 4 °C for 10 min. The collected cells were then diluted with sterile water to prepare an OD curve. 600=0.5g of bacterial suspension, then transferred to 350mL LB liquid medium at a 5% inoculation rate. Sampling was performed at time points of 0, 12, 24, 36, 48, 72, 96, and 120 hours, and the absorbance at 600nm using a UV spectrophotometer reflected the cell concentration. Figure 8 As shown.

[0065] Catalase test: Use a sterilized inoculation loop to pick up an appropriate amount of activated bacterial cells and spread them on a glass slide. Add 2-3 drops of 3% hydrogen peroxide solution to perform the catalase test. Observe whether bubbles are produced. If bubbles are produced, it proves that the catalase reaction is positive; otherwise, it is negative.

[0066] The above experimental results show that the colony morphology of the target strain A015 in the modified LB solid medium is as follows: Figure 7 As shown, the strain is pale yellow, opaque, with nearly circular edges, flat, and a rough, wrinkled surface. Figure 8 The growth curve shows that strain A015 reaches the late logarithmic growth phase at approximately 48 hours of growth. Microscopic observation of its cell morphology is as follows... Figure 9 As shown, the Gram staining result is red, indicating a Gram-negative strain. The catalase reaction result is positive.

[0067] (v) Molecular identification of strains

[0068] Molecular identification method: Pick a single colony with a sterile inoculation loop and add 200 μL of 5% (w / v) BT-chelex 100resin (prepared in distilled water and sterilized at 121℃ for 30 min). Boil in a water bath for 15 min, then quickly freeze at -20℃ and thaw at room temperature. Thaw at 4℃ and 6000 rpm. -1 Centrifuge for 3 min, and collect 2 μL of the supernatant as template DNA for later use. The template DNA was amplified using universal primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3) and 1492R (5'-GGTTACCTTGTTACGACT T-3') for the bacterial 16S rRNA gene.

[0069] The total volume of the PCR reaction was 25 μL, including 2.0 μL of DNA template, 0.5 μL each of forward and reverse primers, 9.5 μL of ddH2O, and 12.5 μL of Green tapMix enzyme. The PCR reaction program was as follows: 95℃, 5 min pre-denaturation; 94℃, 1 min denaturation, 55℃, 1 min annealing, 72℃, 1.5 min extension, 35 cycles; 72℃, 10 min extension, and storage at 4℃. After detection by 1.0% agarose gel electrophoresis, the PCR products were sent to Shanghai Sangon Biotech Co., Ltd. for sequencing. The sequencing results were compared and analyzed in the bacterial and archaea 16S rRNA gene database EZBioCloud (https: / / www.ezbiocloud.net / ), and a phylogenetic tree was constructed using Mega11.0 software.

[0070] Sequencing revealed that the 16S rRNA gene fragment of strain A015 was 1440 bp. Homology comparison analysis using the EZBioCloud database (https: / / www.ezbiocloud.net / ) indicated that this strain belongs to the genus Bacillus and is related to Bacillus zhangzhouensis DW5-4. T (JOTP01000061) showed a similarity of 99.17%. Based on the homology comparison results, a phylogenetic tree was constructed using MEGA 11.0, and the results are as follows. Figure 10 As shown.

[0071] (vi) Growth promotion test of the strain

[0072] Preparation of bacterial suspension: After activating the test strain, inoculate it into a 250 mL Erlenmeyer flask containing 150 mL of LB liquid medium and incubate at 30 °C with shaking at 180 rpm for 72 h; centrifuge at 8000 rpm for 10 min, discard the supernatant, collect the bacterial cells, wash the bacterial cells twice with sterile water, and resuspend them in sterile water. Adjust the OD of the bacterial suspension. 600 =0.5, reserved.

[0073] Seed germination experiment: Plump soybean seeds of the Heinong 87 variety with uniform size were selected and surface-sterilized (immersed in 70% alcohol for 10 minutes, then rinsed three times with sterile water). Two treatments were included: CK (blank control group) and A015 (inoculated with A015 bacterial suspension), with three replicates per treatment and 20 seeds per replicate. Two layers of sterilized filter paper were placed in each sterile petri dish. The sterilized and air-dried soybean seeds were spread evenly on the filter paper. 5 mL of sterile water was added to each petri dish for the CK (control group), and 5 mL of the prepared bacterial suspension was added to each petri dish for the A015 treatment group. The seeds were incubated at 28℃ in the dark for 3 days. Sterile water was added as needed to keep the filter paper moist during the incubation period. Germination rate and sprout length were then calculated. Specific results are shown in Table 2. Figure 11 As shown.

[0074] Table 2 Effects of different treatments on soybean seed germination

[0075] CK 70.0％ 1.60±0.36 A015 95.0％ 2.93±0.40

[0076] Seed germination test results showed that, compared with CK, the germination rate of seeds inoculated with A015 increased by 26.3%, and the plumule length increased by 45.4%, demonstrating a significant growth-promoting effect.

[0077] The salt-tolerant rhizosphere growth-promoting strain A015 obtained by screening in this invention is named Bacillus sp. A015, and is deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, with accession number CCTCC NO: M20242724 and deposit date of December 4, 2024; its 16S rRNA nucleotide sequence is shown in SEQ ID NO.1.

[0078] The salt-tolerant rhizosphere growth-promoting strain A015 of this invention can be used for nitrogen fixation, dissolution of organic and inorganic phosphorus, and decomposition of insoluble potassium. These functions play an important role in improving crop yield and quality in saline-alkali land, reducing fertilizer use, improving the soil environment, and promoting the sustainable use and development of agricultural soils.

[0079] The strain A015 of this invention possesses strong nitrogen-fixing, phosphorus-solubilizing, insoluble potassium-decomposing, and seed-germination-promoting functions. It exhibits a lecithin solubility of 3.77 mg / L, an insoluble calcium phosphate solubility of 24.79 mg / L, and a potassium feldspar conversion rate of 5.16 mg / L. Furthermore, it can grow normally in a saline-alkali environment of 5% NaCl and pH=8, increasing the germination rate of soybean seeds by 26.3%. The strain's multiple growth-promoting functions help plants decompose and utilize insoluble silicate inorganic minerals such as phosphorus and potassium feldspar in the soil, converting them into soluble nutrients, increasing the content of available nutrients in the soil, improving fertilizer utilization, and contributing to the cultivation and utilization of soil ecological fertility, thus maintaining agricultural ecological balance. The discovery of salt-tolerant and high-growth-promoting strain resources lays an important foundation for research on biological agents and fertilizers for saline-alkali land improvement, and is of great significance for the improvement and utilization of saline-alkali land, expanding my country's reserve arable land resources, and ensuring national food security.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A salt-tolerant rhizosphere growth-promoting bacterial strain, characterized in that, The salt-tolerant rhizosphere growth-promoting strain was named Bacillus sp.A015, deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M20242724, on December 4, 2024; the nucleotide sequence of the 16S rRNA of the rhizosphere growth-promoting strain is shown in SEQ ID NO.

1.

2. The application of a salt-tolerant rhizosphere growth-promoting strain as described in claim 1, characterized in that, The salt-tolerant rhizosphere growth-promoting strains are used to improve the soil environment of saline-alkali land and promote crop growth.

3. The application according to claim 2, characterized in that, The salt-tolerant rhizosphere growth-promoting strains are used for biological nitrogen fixation, dissolving organic and inorganic phosphorus, and decomposing insoluble potassium; the salt-tolerant rhizosphere growth-promoting strains are used to promote soybean growth.

4. According to claim 3, the salt-tolerant rhizosphere growth-promoting strain is used to improve the germination rate of soybean seeds and increase the length of soybean embryos.

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