Glutamic acid bacillus, microbial inoculant, saline-alkali soil improvement microbial inoculant and application thereof

Abstract

This invention discloses a strain of *Bacillus glutamicum*, a microbial inoculant, a soil conditioner for saline-alkali soil, and their applications. The *Bacillus glutamicum* is named *Bacillus glutamicum* (…). Glutamicibacter arilaitensis The microbial agent or microbial fertilizer contains Bacillus glutamicum QN2307, with the preservation number CCTCC NO:M 20241600. The active ingredient of the microbial agent or microbial fertilizer includes Bacillus glutamicum QN2307. The active ingredient of the saline-alkali soil amendment also includes Bacillus glutamicum QN2307. This bacterium was isolated from saline-alkali soil collected in Dongying City, Shandong Province. It not only has phosphorus-solubilizing properties but also promotes plant growth under salt stress. This bacterium can be used to prepare microbial agents, microbial fertilizers, or saline-alkali soil amendments to improve soil and promote plant growth in saline-alkali areas, showing promising market application prospects.

Description

Technical Field

[0001] This invention relates to the field of microbiology, and more particularly to a strain of Bacillus glutamate, microbial agents, soil conditioner agents for saline-alkali land, and their applications. Background Technology

[0002] Soil salinization affects plant photosynthesis, respiration, and the distribution of assimilates; in severe cases, it can lead to organ withering, death, or even the death of the entire plant. Soil salinization is a significant threat to environmental resources, affecting approximately 1 billion hectares globally. 2 Land is suffering. my country has a vast amount of saline-alkali land, with one of the highest proportions in the world. According to the Third National Land Survey, as of the end of 2019, my country had 7.6667 million hectares of undeveloped saline-alkali land, and an additional 9.2 million hectares of arable land affected by salinity. This demonstrates the abundance of saline-alkali land resources in my country. It is estimated that improving and cultivating 100 million mu (approximately 6.67 million hectares) of saline-alkali land can increase grain, cotton, and oil production by more than 10 billion kilograms, indicating enormous potential for the utilization and development of saline-alkali land in my country. During his inspection tour in Dongying City, Shandong Province, General Secretary Xi Jinping clearly stated that the comprehensive utilization of saline-alkali land is of great strategic significance for ensuring national food security and firmly securing the Chinese people's food supply. In recent decades, my country has gradually attached importance to the transformation of saline-alkali land; however, due to the lack of mature and effective technical measures, the comprehensive utilization efficiency of saline-alkali land is low, resulting in limited economic, ecological, and social benefits.

[0003] Saline-alkali soils occupy a unique ecological niche, inhabited by extremophiles with specific adaptation strategies. These microorganisms interact with plants through various mechanisms and are closely related to the plants' salt tolerance traits. Among them, plant growth-promoting rhizobacteria (PGPRs) colonize the rhizosphere of plants, improving soil structure and physicochemical properties; enhancing plant resistance to biotic stresses such as bacterial and fungal pathogens, as well as abiotic stresses such as salinity, drought, and nutrient deficiency; and promoting plant growth and development. Based on their superior stress-resistance and growth-promoting functions and environmentally friendly characteristics, PGPRs are receiving increasing attention. The development and utilization of salt-tolerant growth-promoting microbial resources will be an important pathway for the green development of saline-alkali land. However, currently, the developed plant growth-promoting microbial resources are extremely limited and cannot meet the application needs of saline-alkali soil improvement.

[0004] Therefore, existing technologies need further improvement. Summary of the Invention

[0005] To address the above problems, this invention provides a strain of Bacillus glutamate, a microbial inoculant, a soil conditioner for saline-alkali land, and their applications. This Bacillus glutamate has salt and alkali tolerance and can promote plant growth under salt stress. It can be used as an active ingredient in the preparation of microbial inoculants, microbial fertilizers, or soil conditioners for saline-alkali land.

[0006] To address the above problems, this application provides the following technical solution: Firstly, this application provides a strain of *Bacillus glutamicum*, which is named *Bacillus glutamicum* (…). Glutamicibacter arilaitensis QN2307, with accession number CCTCC NO: M 20241600.

[0007] This bacterium was isolated from saline-alkali soil collected in Dongying City, Shandong Province. It not only has the function of phosphorus solubilization and phosphorus dissolution, but also promotes plant growth under salt stress. It enriches the resources of salt-tolerant microbial species and lays the foundation for the research and development of soil-improving microbial agents and plant growth promoters in saline-alkali land.

[0008] The bacterium was identified as Bacillus glutamate. On July 18, 2024, the strain was deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 20241600, located at No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0009] Secondly, this application also provides a microbial inoculant or microbial fertilizer, the active ingredient of which includes Bacillus glutamicum as described above.

[0010] The Glutamicinus QN2307 possesses biological characteristics such as phosphorus solubilization, growth promotion, and salt and alkali tolerance. It can be used as an active ingredient in the preparation of microbial agents to reduce the use of chemical fertilizers, increase plant biomass, and improve plant adaptability and growth in high-salt environments.

[0011] It can be directly processed into microbial inoculants for field application. The microbial inoculants can be the fermentation broth or freeze-dried powder of the microorganism.

[0012] In addition, this bacterium can be used to prepare microbial fertilizers. The above-mentioned Bacillus glutamicum QN2307 can be directly fermented in a solid fermentation medium (or liquid medium) to prepare microbial fertilizers of different formulations, or further processed (with carriers, other adjuvants, etc.), or further added with other fertilizers to make compound fertilizers.

[0013] Optionally, in the microbial agent, the Bacillus glutamate can be the bacterial cells, fermentation broth, or fermentation supernatant of the bacterium.

[0014] Optionally, the microbial agent may be in the form of a wettable powder, a water dispersible agent, an aqueous suspension, or a dispersible oil suspension.

[0015] Thirdly, this application also provides the application of the above-mentioned Bacillus glutamate or the above-mentioned microbial agents or microbial fertilizers in promoting plant growth and improving soil.

[0016] Experiments have shown that under normal conditions, strain QN2307 promotes the germination of plant seeds. Among them, strain QN2307 has a significant effect on promoting germination. The germination potential, germination rate, average root length, germination index, and vigor index of wheat seeds treated with its fermentation broth with an OD600 of 1 increased by 27.46%, 76.46%, 105.71%, 50.27%, and 36.91%, respectively, compared with the control group.

[0017] Under normal conditions, this strain promotes the growth of wheat seedlings, increases their biomass, and also increases the chlorophyll content of wheat seedlings; the total chlorophyll and chlorophyll b of seedlings treated with fermentation broth increased by 38.0% and 86.3%, respectively. The indoleacetic acid content of seedlings treated with fermentation broth increased by 67.7%.

[0018] Furthermore, in the aforementioned application, the *Bacillus glutamate* or microbial agent promotes plant growth under high-salt conditions.

[0019] Optionally, the applications include: the application of the glutamate bacillus in promoting plant biomass increase, inducing plants to synthesize large amounts of IAA, and in chlorophyll.

[0020] Strain QN2307 not only promotes plant growth under normal conditions but also enhances their salt tolerance under high-salt conditions. Experiments showed that, compared to the control group, wheat seedlings treated with saline solution using the fermentation broth of this strain exhibited increases in plant height (49.6%), root length (34.0%), fresh weight (51.5%), and dry weight (51.4%), total chlorophyll and chlorophyll b (17.7%), and indoleacetic acid (126%), respectively.

[0021] Optionally, the plants include wheat, cucumber, corn, cotton, etc. Subsequent embodiments will use wheat as an example.

[0022] Fourthly, this application also provides a method for preparing the aforementioned microbial inoculant, which includes the following steps: The aforementioned *Bacillus glutamate* was inoculated into a liquid culture medium and cultured in a shake flask at 28°C and 180 r / min. When the strain reached the logarithmic growth phase, the bacterial solution was diluted to obtain the microbial agent.

[0023] Fifthly, this application also provides a soil amendment agent for saline-alkali land, the active ingredient of which includes the aforementioned Bacillus glutamate QN2307.

[0024] Experiments have shown that the glutamate bacillus has phosphorus solubilizing ability and can dissolve and solubilize organic and inorganic phosphorus in the soil.

[0025] The present invention has the following beneficial effects: 1. This invention provides a strain of Bacillus glutamate QN2307 isolated from saline-alkali soil. This bacterium not only has excellent salt and alkali tolerance, but also has phosphorus solubilizing and phosphorus-dissolving effects, promoting plant growth. It can be used as a microbial fertilizer or microbial agent and can be widely applied in actual production.

[0026] 2. This glutamate bacillus QN2307 can also improve the salt tolerance of plants and promote plant growth under salt stress. By promoting the increase of plant biomass, inducing plants to synthesize large amounts of IAA and chlorophyll, and improving plant photosynthesis, it can significantly improve plant growth.

[0027] 3. This bacterium enriches the resources of salt-tolerant microbial strains, laying the foundation for the research and development of soil-improving microbial agents and growth promoters for plants in saline-alkali land. Furthermore, its microbial agent preparation method is simple, with high production efficiency and low production cost, making it suitable for large-scale industrial production and easy to promote and use. Attached Figure Description

[0028] Figure 1 To screen for salt-tolerant growth-promoting bacterial strains in wheat; CK was the control, A was QN2301, B was QN2307, and C was QN2322.

[0029] Figure 2 Phosphorus solubilization and phosphorus release analysis of strain QN2307; A represents the ability to solubilize inorganic phosphorus; B represents the ability to solubilize organic phosphorus. Figure 3 The effect of strain QN2307 on salt tolerance and growth promotion in wheat; A: Control (wheat treated with 200mM NaCl), B: Wheat treated with strain QN2307. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the present invention, unless otherwise specified, the equipment and raw materials used can be purchased from the market or are commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0031] Example 1: Isolation and screening of Bacillus glutamicum QN2307 1. Isolation of Bacillus glutamate QN2307 In July 2023, saline-alkali soil was collected in Dongying City, Shandong Province. 10 grams of soil was added to 90 grams of sterile water, shaken thoroughly, and allowed to stand at room temperature. The supernatant was then diluted stepwise and evenly spread onto LB solid medium and incubated at 28°C. Single colonies were picked after 2 days.

[0032] 2. Salt and alkali tolerance screening of Bacillus glutamicum QN2307 The isolated single colonies were inoculated onto LB solid medium containing 2%, 5%, and 7.5% NaCl for salt tolerance screening. Colonies that grew well on the medium containing 7.5% NaCl were selected and inoculated onto LB medium at pH 9.0 for alkali tolerance screening.

[0033] The strains selected from the culture medium were further screened for salt tolerance and growth promotion in wheat liquid culture. Jimai 22 seeds with uniform and plump grains were selected, disinfected with 1% sodium hypochlorite solution for 5 min, and rinsed 4 times with sterile water for 1 min each time. The disinfected wheat seeds were soaked in sterile water for 24 h, and then the seeds with emerging white kernels were transferred to petri dishes containing double-layered filter paper, which was moistened with sterile water. After 24 h, 3 ml of 200 mM and 300 mM NaCl solutions were added to the petri dishes for two treatments, with 3 ml of sterile water added as a control. After 24 h, 1 ml of fermentation filtrate of the salt-tolerant strain was added to each treatment group, and 1 ml of LB liquid medium was added to the control group. The cultures were incubated at 23℃ in a light-dark incubator (16 h light / 8 h dark). After 48 h, 3 ml of 200 mM and 300 mM sodium chloride solutions were added to treatments 1 and 2, respectively, and 3 ml of sterile water was added to the control group for continued incubation. Each treatment was replicated in 3 places, and the observation was carried out for 10 consecutive days. Finally, strain QN2307 was selected as having the best salt tolerance and growth promotion effect. Figure 1 ).

[0034] Example 2: Identification of Bacillus glutamate QN2307 1. Physiological and biochemical identification Physiological and biochemical identification was performed in accordance with the "Manual of Systematic Identification of Common Bacteria" and the "Bergey's Manual of Bacterial Identification".

[0035] 2. Molecular biological identification Using a small amount of QN2307 bacterial culture as a template, the 16S DNA of QN2307 was amplified using 27F / 1492R primers. The primer sequences are as follows: 27F: TACGGYTACCTTGTTACGACTT 1492R:AGAGTTTGATCMTGGCTCAG.

[0036] The sequencing results of the 16S rDNA of QN2307 are shown in SEQ ID NO:1 in the sequence listing. BLAST alignment analysis showed that QN2307 is related to *Bacillus glutamicum*. Glutamicibacter arilaitensis With a sequence identity of up to 99.79%, QN2307 was identified as a novel strain of *Bacillus glutamicum*. G. arilaitensis .

[0037] Example 3: Analysis of the phosphorus and potassium solubilizing ability of Bacillus glutamicum QN2307 1. Identification of the strain's phosphorus solubility and phosphorus absorption capacity (1) Experimental methods The selected strains were activated, and single colonies were picked and inoculated into LB liquid culture. The culture was then incubated at 28°C and 180 r / min. 10 μL of the bacterial culture was then transferred to organic and inorganic phosphorus agar plates and incubated at 28°C for 5 days. The appearance of a clear zone was observed, and the diameter of the clear zone was recorded as a ratio to the colony diameter. The ratio of the clear zone diameter to the colony diameter was used to preliminarily determine the strain's phosphorus solubility.

[0038] (2) Experimental results and analysis After 5 days of cultivation, strain QN2307 showed significant effects in phosphate solubilization and phosphorus removal (see...). Figure 2 ) 2. Identification of the strain's potassium solubilization ability (1) Experimental methods The strain was cultured using the method described above. 10 μL of bacterial culture was inoculated onto a silicate medium plate and incubated at 28°C. The formation of a clear zone was observed daily, and the diameter of the clear zone and the diameter of the colony were recorded. The ratio of the diameter of the clear zone to the diameter of the colony was used to preliminarily determine the potassium-solubilizing ability of the strain. (2) Experimental results After inoculating the bacterial culture onto silicate medium plates and conducting multiple experiments, no significant potassium-solubilizing ability was observed.

[0039] 3. Identification of the strain's ability to produce IAA (1) Experimental method: The selected bacterial culture was added to LB liquid medium at a ratio of 1:50 and cultured in a shaker at 28℃ and 180 r / min. The bacterial fermentation broth was extracted after 12h, 24h, 36h, and 48h of culture and filtered using a 0.22μm bacterial filter. Using LB liquid medium as a control solution, 10μL each of the bacterial fermentation filtrate and liquid LB medium were injected into a liquid chromatograph, and the production of IAA by the bacterial fermentation broth was determined at 276nm using a UV absorbance detector.

[0040] (2) Experimental results and analysis The fermentation filtrate of QN2307, cultured on a constant-temperature shaker at 28℃ and 180 rpm for 12 h, 24 h, 36 h, and 48 h, was analyzed using liquid chromatography (HPLC), with LB liquid medium as a control. The results showed that the IAA content in the fermentation filtrate of strain QN2307 was too low to indicate that the strain could produce IAA.

[0041] Experimental Study: Effect of Bacillus glutamate QN2307 on Seed Germination Promotion 1. Experimental Methods The QN2307 strain was incubated in LB liquid medium at 28°C until OD200 was reached. 600 The values ​​were 0.2, 0.5, and 1.0. Wheat seeds were surface-sterilized according to the method described in Experiment 2, and then soaked in the prepared bacterial solution for 12 hours, with LB liquid medium soaking as a control. The soaked wheat seeds were evenly placed in Petri dishes lined with sterile double-layered filter paper (the filter paper was moistened with sterile water), with 15 wheat seeds in each dish. Each group had 3 replicates, and the dishes were incubated at 25℃ for 4 days. Germination potential, germination rate, root length, germination index, and vigor index of the wheat seeds were calculated using the following formulas.

[0042] Germination potential (%) = (Number of seeds germinated in 48 hours / Total number of seeds tested) x 100% Germination rate (%) = (Number of seeds germinated in 96 hours / Total number of seeds tested) x 100% Germination Index (GI) = ∑(Gt / Dt), where Gt represents the germination rate at time td, and Dt represents the number of days since germination. Vitality index (VI) = S x GI, where GI represents the germination index and S represents the average root length.

[0043] 2. Experimental Results and Analysis The results are shown in Table 1. From these results, it can be seen that the OD of strain QN2307... 600 A concentration exceeding 0.5 significantly promotes wheat seed germination and increases its vigor index. The fermentation broth of strain QN2307 showed the most significant germination-promoting effect at an OD600 of 1, with germination potential, germination rate, average root length, germination index, and vigor index increasing by 27.46%, 76.46%, 105.71%, 50.27%, and 36.91% respectively compared to the control group.

[0044] Table 1 Effects of strain QN2307 on wheat seed germination

[0045] Example: Growth-promoting effect of Bacillus glutamate QN2307 on potted wheat seedlings under non-salt stress conditions. 1. Pot Experiment Design Soak a suitable amount of wheat seeds of uniform size and plumpness in clean water for 8-10 hours. After soaking, place them in a beaker containing 75% alcohol for surface sterilization, then rinse three times with sterile water. Spread the cleaned seeds evenly on absorbent paper, cover with more absorbent paper, and gently drip water to moisten the paper. Place the seeds in a 25℃ constant temperature incubator for germination treatment. After a period of time, select seeds with roughly the same degree of germination for planting. Plant 20 wheat seeds per pot, with three replicates per treatment group, and cultivate in a glass greenhouse.

[0046] The pot experiment consisted of two treatment groups: ① no inoculum treatment, ② inoculum treatment. Treatments were administered every 2-3 days depending on soil conditions. Wheat seedling growth was observed regularly. After 22 days of growth, plant height, root length, fresh weight, dry weight, chlorophyll content, and indoleacetic acid (IAA) content were measured.

[0047] 2. Effects of bacterial strain fermentation broth on wheat seedling biomass (1) Test method After cultivating according to the aforementioned plan, wash the soil around the roots of the wheat seedlings with tap water and dry them with absorbent paper. Separate the above-ground parts and roots, measure the height of the wheat plants and the length of the roots using a ruler, and weigh the fresh and dry weight of the wheat using an electronic scale.

[0048] (2) Experimental results and analysis After applying the fermentation broth of Bacillus glutamicum QN2307, the growth of wheat seedlings improved. Compared with water treatment alone, treatment with water plus fermentation broth from strain T7 resulted in increased plant height, root length, fresh weight, and dry weight, with increases of 21.5%, 14.6%, 24.7%, and 62.9%, respectively. Based on these results, it can be concluded that applying fermentation broth from strain QN2307 can promote wheat growth.

[0049] Table 2. Effects of bacterial fermentation broth on wheat seedling biomass.

[0050] 2. Effects of bacterial fermentation broth on chlorophyll in wheat seedlings (1) Test method Weigh 0.5 g of wheat leaves and place them in a mortar. Add a small amount of quartz sand and 2 mL of 95% ethanol and grind until the tissue turns white. Then pour the ground leaf juice into a 25 mL test tube, add 95% ethanol to make up to 10 mL, and let it stand in the dark for about 30 min. Each treatment was performed in triplicate. Using 95% ethanol as a control, the absorbance was measured at wavelengths of 663 and 645 nm using a spectrophotometer. Calculate the chlorophyll a, chlorophyll b, and total chlorophyll content using the following formulas.

[0051] Ca (chlorophyll a) = 13.95 * OD663 - 6.88 * OD645 Cb (chlorophyll b) = 24.96 * OD645 - 7.32 * OD663 CT (Total Chlorophyll) = 17.64 * OD645 + 6.63 * OD663 (2) Experimental results and analysis The results are shown in Table 3. It can be seen that the chlorophyll content of wheat seedlings treated with the fermentation broth of the strain was significantly increased. The chlorophyll a content remained roughly the same, while the chlorophyll b and total chlorophyll contents increased significantly. Compared with water alone, the total chlorophyll and chlorophyll b content increased by 38.0% and 86.3%, respectively, with the addition of water and fermentation broth.

[0052] Table 3 Effects of fermentation broth of the strain on chlorophyll in wheat seedlings

[0053] 3. Effects of bacterial strain fermentation broth on indoleacetic acid (IAA) in wheat seedlings (1) Test method Take 1 mL of indoleacetic acid (IAA) standard solutions of 0.5, 1, 5, 10, and 20 μg / mL respectively, and add 2 mL of indoleacetic acid reagent B (8.1% FeCl3) to each solution. Incubate in a 30℃ constant temperature water bath for 30 min. Zero the instrument with 1 mL of water + 2 mL of indoleacetic acid reagent B and measure the absorbance A of each solution. Use Excel to fit the regression equation: M = k*A + b, where M represents the amount of IAA in the reaction solution (μg) and A is the corresponding absorbance value.

[0054] Collect 0.2g of fresh wheat leaves treated with different methods, add 4 mL of 0.1M NaOH solution and grind. Heat in a 95℃ water bath for 15 min, then add 2.5 mL of NaOH solution and dilute to 10 mL with methanol. Let stand for 30 min, then centrifuge at 8000 rpm for 30 min and collect the supernatant. Take two test tubes: test tube 1: 1 mL supernatant + 2 mL indoleacetic acid reagent B; test tube 2: 1 mL 35% methanol (containing 0.26% NaOH) + 2 mL indoleacetic acid reagent B. Incubate both test tubes in a 30℃ water bath for 30 min. Zero the chamber using the reaction solution from test tube 2 and measure the absorbance of the reaction solution from test tube 1 at a wavelength of 530 nm. Calculate the corresponding IAA content based on the absorbance and the standard curve.

[0055] (2) Test results and analysis The results are shown in Table 4 below. These results indicate that the IAA content in wheat seedlings treated with the fermentation broth of strain T7 was significantly increased. Compared to treatment with only water, the IAA content in wheat seedlings treated with water plus the fermentation broth of strain T7 increased by 67.7%.

[0056] Table 4. Effects of QN2307 strain fermentation broth on auxin levels in wheat seedlings under salt stress.

[0057] Example 6: Growth-promoting effect of Bacillus glutamicum QN2307 on potted wheat seedlings under salt stress. The germination and planting of wheat seedlings were carried out according to the method in Example 5, and the following three aspects were tested.

[0058] 1. Effects of bacterial fermentation broth on wheat seedling biomass under salt stress (1) Test method The QN2307 strain was inoculated into LB liquid medium and cultured at 28°C with shaking at 180 r / min until OD reached. 600 =1.0. The pot experiment consisted of two treatments: ① 200mM NaCl, ② 200mM NaCl + QN2307 bacterial solution, with three replicates per treatment. For the first treatment, wheat seedlings in each treatment were watered with 50ml of NaCl. Three days later, ① seedlings were watered with 50ml of water, and ② seedlings were watered with 50ml of QN2307 bacterial solution. Thereafter, depending on soil conditions, 50ml of NaCl was applied every 3-4 days. Wheat seedling growth was observed regularly, and after 3 weeks, biomass measurements including plant height, root length, fresh weight, and dry weight were taken.

[0059] (2) Test results and analysis The results show that strain QN2307 can significantly promote wheat growth under salt stress (see...). Figure 3 (Table 5). After wheat seedlings were treated with fermentation broth from strain QN2307, their plant height, root length, fresh weight, and dry weight increased. Compared with the treatment with saline only, the wheat seedlings in the saline treatment group and the QN2307 fermentation broth treatment group showed increases of 49.6%, 34.0%, 51.5%, and 51.4% in plant height, root length, fresh weight, and dry weight, respectively.

[0060] Table 5. Effects of QN2307 strain fermentation broth on wheat seedling biomass under salt stress.

[0061] 2. Glutamic acid bacteria QN2307 induces chlorophyll production in wheat under salt stress. (1) Test method Collect 0.5g of fresh wheat leaves from different treatments and place them in a mortar. Add a small amount of quartz sand and 2mL of 95% ethanol and grind until the tissue turns white. Then pour the ground leaf juice into a 25mL test tube, add 95% ethanol to make up to 10mL, and let it stand in the dark for 30min. Each treatment was repeated in triplicate, with 95% ethanol as a control. Measure the absorbance at wavelengths of 663 and 645 nm using a spectrophotometer. Calculate the chlorophyll a, chlorophyll b, and total chlorophyll content using the following formulas. Ca (chlorophyll a) = 13.95 * OD663 - 6.88 * OD645 Cb (chlorophyll b) = 24.96 * OD645 - 7.32 * OD663 CT (Total Chlorophyll) = 17.64 * OD645 + 6.63 * OD663 (2) Test results and analysis The results are shown in Table 6. It can be seen that QN2307 induces a large amount of chlorophyll production in wheat under salt stress. Among them, compared with the control group that was only treated with saline, the total chlorophyll and chlorophyll b of wheat treated with saline and fermentation broth of strain QN2307 increased by 17.7% and 38.4%, respectively.

[0062] Table 6. Effects of QN2307 strain fermentation broth on chlorophyll content in wheat seedlings under salt stress.

[0063] 3. The effect of Bacillus glutamate QN2307 on inducing auxin production in wheat under salt stress. (1) Test method The testing method is the same as the auxin content measurement method in the aforementioned embodiments.

[0064] (2) Test results and analysis The results are shown in Table 7. It can be seen that QN2307 significantly induces the production of wheat auxin under salt stress. Compared with salt water alone, wheat seedlings treated with salt water plus fermentation broth from strain QN2307 showed a 126% increase in IAA content.

[0065] Table 7. Effects of QN2307 strain fermentation broth on auxin levels in wheat seedlings under salt stress.

[0066] Although QN2307 of this invention cannot produce IAA, it can induce plants to synthesize large amounts of IAA under salt stress, thereby promoting plant growth. Simultaneously, QN2307 can also induce plants to synthesize large amounts of chlorophyll, thereby promoting plant photosynthesis. Experimental results also show that under salt stress, treatment with QN2307 fermentation broth significantly increased the biomass of wheat seedlings, demonstrating that QN2307 promotes plant growth.

[0067] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solutions and concepts of this invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A strain of Bacillus glutamicum Glutamicibacter arilaitensis Its characteristics are, It was named Bacillus glutamate QN2307, and its accession number is CCTCC NO: M 20241600.

2. A microbial inoculant or microbial fertilizer, characterized in that, The active ingredient includes Bacillus glutamicum as described in claim 1.

3. The microbial inoculant or microbial fertilizer according to claim 2, characterized in that, The microbial agent is formulated as a wettable powder, a water dispersible agent, an aqueous suspension, or a dispersible oil suspension.

4. The application of the Bacillus glutamate as described in claim 1 or the microbial agent or microbial fertilizer as described in claim 2 in promoting wheat growth and improving soil.

5. The application according to claim 4, characterized in that, The glutamate bacillus, microbial inoculants, or microbial fertilizers promote wheat growth under high-salt conditions.

6. The application according to claim 4, characterized in that, The applications include: promoting wheat biomass and inducing wheat to synthesize large amounts of IAA, chlorophyll b, and total chlorophyll.

7. A method for preparing a microbial inoculant as described in claim 2, characterized in that, Includes the following steps: The *Glutamicinus glutamate* strain described in claim 1 was inoculated into a liquid culture medium and cultured in a shake flask at 28°C and 180 r / min. When the strain reached the logarithmic growth phase, the bacterial solution was diluted to obtain the microbial agent.

8. A soil conditioner for saline-alkali land, characterized in that, The active ingredient includes Bacillus glutamicum as described in claim 1.

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