Bacillus siamensis fungicide, biological selenium fertilizer and application of bacillus siamensis fungicide and biological selenium fertilizer in ecological restoration

Abstract

The invention discloses a bacillus siamensis fungicide, a biological selenium fertilizer and application of the bacillus siamensis fungicide and the biological selenium fertilizer in ecological restoration, and belongs to the technical field of soil salinization and heavy metal pollution prevention and control. A bacillus siamensis strain is screened from soil, and biological selenium particles which are uniform in particle size and rich in protein and polysaccharide functional groups on the surface are prepared in a culture system containing sodium selenite through biological reduction; then, the prepared biological selenium is independently applied or applied to plant rhizosphere or soil together with living bacillus siamensis to relieve salt-cadmium dual stress, and by adjusting the oxidation-reduction state and rhizosphere micro-ecology in the plant, Cdtoxicity is relieved, and the growth and physiological activity of the plant under salt-cadmium composite stress are improved. The prepared biological selenium is low in toxicity, good in stability, remarkable in synergistic effect with microorganisms, suitable for green remediation and efficient planting of salinized and heavy metal polluted farmlands and good in application prospect.

Description

Technical Field

[0001] This invention relates to the field of soil salinization and heavy metal pollution control technology, specifically to Bacillus sicca inoculants, bio-selenium fertilizers, and their applications in ecological restoration. Background Technology

[0002] Soil salinization and heavy metal pollution are two typical abiotic stresses currently hindering high-quality agricultural development. Salt stress has already affected a large area of ​​arable land globally, significantly inhibiting seed germination, weakening photosynthesis, inducing the accumulation of reactive oxygen species (ROS), leading to membrane lipid peroxidation, apoptosis, and reduced yield. Cadmium (Cd) is a non-essential heavy metal element for plant growth, exhibiting high toxicity to most organisms, 2-20 times more toxic than other heavy metals. Furthermore, due to its strong migration ability, easy absorption by crop roots, and accumulation in fruits, Cd affects the quality of agricultural products and seriously threatens human health. Currently, the remediation of cadmium pollution mainly utilizes sweet soil plants, but these plants are difficult to grow in contaminated saline soils. Therefore, the presence of salt further complicates the bioremediation process of heavy metal-contaminated soils.

[0003] Selenium (Se), as an important micronutrient, plays a crucial role in plant stress resistance and antioxidant activity. Traditional inorganic selenium (such as selenite and selenate) can alleviate abiotic stress at low doses, but it easily induces oxidative stress and membrane lipid peroxidation at concentrations approaching or exceeding critical levels, posing phytotoxicity and environmental risks. In contrast, microbial-mediated biogenic selenium (SeNPs) possess characteristics such as controllable particle size, modifiable surface functional groups, and good biocompatibility, and are considered a safer and more efficient form of selenium source. Currently reported microbial strains capable of producing biogenic selenium mainly include selenium-enriched yeasts, Lactobacillus bulgaricus, and Streptococcus thermophilus, but their biogenic selenium conversion capacity and salt tolerance still need improvement. Therefore, under combined salt and cadmium stress conditions, it is still necessary to explore new biogenic selenium conversion strains. Summary of the Invention

[0004] In view of the above-mentioned prior art, the purpose of this invention is to provide Bacillus sicca inoculants, bio-selenium fertilizer, and their application in ecological restoration.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a strain of Bacillus sicca ( Bacillus siamensis HB2015, this strain was deposited on January 4, 2026 at the China Center for Type Culture Collection (CCTCC, Wuhan University, Wuhan, China), with accession number: CCTCC NO: M 2026001.

[0006] The Bacillus sicca of the present invention ( Bacillus siamensisCompared with existing Bacillus sicca strains, HB2015 has the following characteristics: (1) It has the characteristic of producing a high amount of biological selenium, and the synthesis and conversion efficiency of biological selenium are high; (2) It has high salt tolerance and can withstand a NaCl concentration of 7%, making it suitable for most saline soil environments.

[0007] (3) It has high cadmium resistance and can tolerate cadmium concentrations up to 9 mg / L.

[0008] (4) It has nitrogen-fixing and phosphorus-solubilizing properties, which can promote crop growth.

[0009] A second aspect of the present invention provides a microbial agent containing the aforementioned Bacillus sicca (Bacillus sicca). Bacillus siamensis )HB2015.

[0010] Preferably, the bacterial agent contains Bacillus sicca (Bacillus sicca). Bacillus siamensis HB2015 exists in the form of cultured live bacteria, bacterial suspension, or fermentation broth.

[0011] Furthermore, the fermentation broth is prepared by the following method: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured at 30℃ and 150 rpm for 24-36 h with constant temperature shaking.

[0012] A third aspect of the present invention provides the above-mentioned Bacillus sicca ( Bacillus siamensis Application of HB2015 or bacterial agents in the preparation of bio-selenium.

[0013] In a fourth aspect, the present invention provides a bio-selenium fertilizer, wherein bio-selenium fertilizer uses bio-selenium as its active ingredient; The bio-selenium is prepared by the following method: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured with shaking until the logarithmic growth phase. Aseptically filtered sodium selenite solution was added to the culture medium to a final concentration of 10 mmol / L, and the culture was continued at 28 ℃ for 65-75 h until the culture medium turned from light color to red. The fermentation broth was centrifuged to collect the precipitate, which was washed with deionized water. Cells were lysed by sonication and then centrifuged a second time to remove cell debris. The red bio-selenium particles were obtained after washing.

[0014] Furthermore, the bio-selenium fertilizer also includes: Bacillus sicca ( Bacillus siamensis Fermentation broth of HB2015.

[0015] In some preferred embodiments of the present invention, the bio-selenium fertilizer is composed of bio-selenium and Bacillus sicca (…). Bacillus siamensis The fermentation broth of HB2015 was composed of (12.5-25) mg: 25 mL; The Siamese Bacillus ( Bacillus siamensis OD of HB2015 fermentation broth 600 The value is 0.8.

[0016] In a fifth aspect, the present invention provides the above-mentioned Bacillus sicca ( Bacillus siamensis Application of HB2015, microbial agents or bio-selenium fertilizer in improving the ability of plants to resist salt and cadmium stress.

[0017] The beneficial effects of this invention are: This invention isolates a strain of Bacillus sicca capable of producing bioselenium from selenium-rich soil. Bacillus siamensis HB2015, compared with the prior art, the present invention has the following beneficial effects: (1) A new efficient method for preparing bio-selenium from Bacillus sicca was constructed. Bio-selenium particles with basically uniform particle size and rich in protein and polysaccharide functional groups on the surface can be obtained by reducing selenite with Bacillus sicca under normal pressure and low temperature conditions. The process conditions are mild and energy consumption is low, making it suitable for large-scale production.

[0018] (2) The integrated synergistic effect of "microbial agent + biological selenium" has been achieved. The prepared biological selenium and live Bacillus sicca are applied together in the same system to promote growth, activate nutrients and regulate antioxidants, which is significantly better than the application of organic selenium or single microbial agent alone, and has a synergistic effect.

[0019] (3) Significantly improves plant growth and stress resistance under dual salt and cadmium stress conditions. The bio-selenium and its inoculant composition of the present invention can increase crop plant height, root length and biomass, improve photosynthetic characteristics, enhance the activity of antioxidant enzymes such as POD and CAT and reduce MDA content, thereby effectively alleviating the combined stress damage caused by NaCl and Cd²⁺.

[0020] (4) It is conducive to soil environment improvement and green remediation of polluted farmland. This technology not only improves the availability of nutrients such as nitrogen and phosphorus in saline soil and optimizes the structure of rhizosphere microbial community, but also has the potential application value of reducing toxicity and improving plant tolerance in heavy metal pollution scenarios, providing a new technical option for the comprehensive management of saline and heavy metal polluted farmland. Attached Figure Description

[0021] Figure 1 The colony morphology of strain HB2015 on the culture medium.

[0022] Figure 2 Phylogenetic tree of strain HB2015.

[0023] Figure 3 The results of the salt tolerance test for strain HB2015 are shown.

[0024] Figure 4 This is a scanning electron microscope image of bioselenium prepared according to an embodiment of the present invention.

[0025] Figure 5 The Fourier transform infrared spectrum of the bio-selenium prepared in this embodiment of the invention is shown.

[0026] Figure 6 The effects of biogenic selenium and microorganisms on soybean agronomic traits under salt and cadmium dual stress.

[0027] Figure 7 The effects of biological selenium and microorganisms on chlorophyll content under dual stress of salt and cadmium.

[0028] Figure 8 The effects of biogenic selenium and microorganisms on photosynthetic indices of soybean under dual stress of salt and cadmium. Detailed implementation method: It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] To enable those skilled in the art to more clearly understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments. If specific experimental conditions are not specified in the embodiments, they are generally based on conventional conditions or conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments, unless otherwise specified, can be obtained commercially. Wherein: TY liquid medium: 10 g peptone, 3 g yeast extract, 1 g CaCO3, dissolved in deionized water and brought to a final volume of 1 L; autoclave at 121°C for 20 min. When used as a solid medium, add 1.5% agar.

[0030] Ashby's nitrogen-free medium: CaCO3 5 g, MgSO4 0.2 g, NaCl 0.2 g, CaSO4 0.1 g, KH2PO4 0.2 g, mannitol 10 g, agar 15 g, deionized water 1 L, pH 6.8-7.0; dissolve and bring the volume to 1 L with deionized water; autoclave at 121°C for 20 min. When used as a solid medium, add 1.5% agar.

[0031] Inorganic phosphorus (PKO) medium: 10 g glucose, 0.003 g MnSO4·4H2O, 0.3 g NaCl, 0.3 g MgSO4·7H2O, 0.5 g (NH4)2SO4, 0.3 g KCl, 0.003 g FeSO4·7H2O, 5 g Ca(PO4)2, 15 g agar, 1 L deionized water, pH 7.2; dissolve and bring the volume to 1 L with deionized water; autoclave at 121°C for 20 min. When used as a solid medium, add 1.5% agar.

[0032] Organophosphorus medium: 10 g glucose, 0.5 g (NH4)2SO4, 0.3 g NaCl, 0.3 g KCl, 0.03 g FeSO4·7H2O, 0.03 g MnSO4·4H2O, 0.2 g egg yolk lecithin, 5 g CaCO3, 0.4 g yeast extract. Dissolve in deionized water and bring to a final volume of 1 L, pH 7.0-7.5; autoclave at 121 ℃ for 20 min. When used as a solid medium, add 1.5% agar.

[0033] Potassium-deficient solid culture medium: 5 g sucrose, 2 g Na₂HPO₄, 0.5 g MgSO₄·7H₂O, 1 g (NH₄)₂SO₄, 0.1 g NaCl, 0.5 g yeast extract, 10 g potassium feldspar powder, 15 g agar. Dissolve in 1 L of deionized water, pH 7.2-7.4; bring the volume to 1 L with deionized water; autoclave at 121℃ for 20 min. When used as a solid culture medium, add 1.5% agar.

[0034] ADF medium: Prepare a 0.5 M ACC stock solution, filter and sterilize, add 6 mL of the stock solution to DF medium free of (NH4)2SO4 to obtain a final ACC concentration of 3 mM; dissolve and bring the volume to 1 L with deionized water; autoclave at 121°C for 20 min. When used as a solid medium, add 1.5% agar.

[0035] Example 1: Isolation and Identification of Strains 1. Isolation of bacterial strains: Weigh 10 g of soil sample into 90 ml of sterile water, shake at 37℃ and 180 rpm for 30 min, and let stand until the soil completely settles. Collect the soil suspension and centrifuge at 10000 r / min for 10 min. Resuspend the precipitate in 10 mL of sterile water and store at 4℃ for later use. Take 2 mL of the supernatant and add it to TY liquid medium containing 500 μg / mL sodium selenite for screening culture. Shake at 37℃ and 180 rpm for 48 h. Take 1 mL of the solution in a test tube, add 9 mL of sterile water, and prepare 10... -4 10 -5 10 -6 Gradual dilutions were spread onto TY solid medium and incubated at 37°C for 3 days. Strains with different colony morphological characteristics were picked and purified repeatedly until single colonies were obtained. The selected strains were inoculated at a rate of 1% into 150 mL Erlenmeyer flasks containing 50 mL of TY liquid medium and incubated at 37°C for 12 h. Then, 10 mM sodium selenite (Na₂Se₂O₃) filtered through a 0.22 μm membrane was added to the medium, and the flasks were incubated at 28°C for 72 h. The appearance of a red color in the Erlenmeyer flask indicates the production of selenium; the more pronounced the red color, the stronger the strain's ability to convert biogenic selenium.

[0036] The strain HB2015, which showed the most prominent red color, was selected as the target strain for identification.

[0037] 2. Identification of strain HB2015 (1) Morphological identification of strain HB2015: Colony photos of strain HB2015 on TY solid medium are shown below. Figure 1 As shown, the results indicate that the colonies are milky white, with smooth edges, no wrinkles on the surface, and are quite viscous when picked up.

[0038] (2) Molecular biological identification of strain HB2015: The bacterial community of the isolated strain HB2015 was identified using gyrA gene sequence analysis. The determined gyrA gene sequence was compared with sequences in the GenBank database, and multiple sequence homology analysis was performed using MEGA 7.0 software. A phylogenetic tree was then constructed, as shown below. Figure 2 As shown. The strain was confirmed to be Bacillus sicca (…). Bacillus siamensis ).

[0039] Based on the results of morphological and molecular biological identification, strain HB2015 was identified as Bacillus sicca (Bacillus sicca). Bacillus siamensis (and carried out biological preservation of the patented technology, with the preservation information as follows:) Referenced biological material (strain): HB2015; Suggested classification and nomenclature: Bacillus sicca ( Bacillus siamensis ); Accession number: CCTCC NO: M 2026001.

[0040] Example 2: Bacillus sicca ( Bacillus siamensis Performance evaluation of HB2015 1. Evaluation of growth-promoting properties: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated on nitrogen-free (Ashby) medium, inorganic phosphorus (PKO) medium, and potassium-deficient liquid medium, and its growth was observed. The results are shown in Table 1.

[0041] Table 1: Results of growth-promoting indicators of strain HB2015 Note: "-" indicates no relevant ability, "+" indicates that the ability is available. The results showed that strain HB2015 has the ability to fix nitrogen and solubilize phosphorus.

[0042] 2. Salt tolerance test: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured with shaking at 30 ℃ and 150 rpm / min for 24 h. The culture was then diluted with sterile water to an OD value. 600 =0.8, to obtain the inoculum. Take 20 µL of the inoculum and inoculate it onto TY liquid medium with NaCl concentrations of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, respectively. Incubate in a shaking incubator at 30 °C for 3 days and observe the bacterial growth.

[0043] The results are as follows Figure 3 As shown, the results indicate that strain HB2015 has strong salt tolerance, and can tolerate a salt concentration of up to 7%.

[0044] 3. Cadmium resistance test: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured with shaking at 30℃ and 150 rpm for 24 h. The culture was then diluted with sterile water to an OD value. 600 =0.8, used as the inoculum. Add sterile filtered CdCl2 stock solution to TY liquid culture medium to adjust the Cd concentration in the medium. 2+ Final concentrations were set at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 mg / L. After thorough mixing, the solutions were dispensed into sterile Erlenmeyer flasks. 20 μL of the inoculum was then inoculated into different Cd flasks. 2+The culture was incubated in TY liquid medium at a concentration of 30 ℃ and 150 rpm for 3 days, and the turbidity and growth of the bacterial solution were observed. The results are shown in Table 2.

[0045] Table 2: Growth of strain HB2015 on cadmium medium Note: + indicates that the reaction can grow; - indicates that the reaction cannot grow.

[0046] The results showed that strain HB2015 had strong cadmium tolerance, and could tolerate cadmium concentrations up to 9 mg / L.

[0047] Example 3: Using Bacillus sicca ( Bacillus siamensis HB2015 for the preparation of bio-selenium Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured at 37 ℃ with shaking until the logarithmic growth phase. Sterile filtered sodium selenite solution was added to the culture medium to a final concentration of 10 mmol / L, and the medium was cultured at 28 ℃ for another 72 h, during which the culture medium changed from light color to red. The fermentation broth was centrifuged to collect the precipitate, which was washed with deionized water. Cells were lysed by sonication and then centrifuged again to remove cell debris. After repeated washing, red bio-selenium particles were obtained, which could be dried for later use or prepared into a suspension.

[0048] The morphology of the prepared bio-selenium was observed using a scanning electron microscope, and it appeared as uniform or nearly spherical particles. Figure 4 ); its surface functional groups were analyzed using FTIR ( Figure 5 The results showed that the surface of bio-selenium is rich in characteristic absorption peaks such as hydroxyl, carboxyl and amide groups related to proteins and sugars, which is beneficial to particle stability and biocompatibility.

[0049] The initial concentration of Se in the culture system after the addition of sodium selenite and the concentration of Se after the culture were determined by ICP method. The conversion capacity of strain HB2015 to biogenic selenium was calculated according to the following formula: In the formula, C 0 The initial concentration of Se in the culture system after the addition of sodium selenite; Ct This represents the concentration of Se in the supernatant obtained after centrifugation and filtration following the culture period.

[0050] The ability of strain HB2015 to convert biogenic selenium was measured to be 52.6% ± 0.13.

[0051] Example 4: Application of bio-selenium and Bacillus sicca under dual stress of salt and cadmium. 1. Test method: Each pot contains 2.5 kg of air-dried field soil from the South Campus of Shandong Agricultural University, which has been sieved through a 2 mm sieve. Add 100 mmol / L NaCl solution and 5 mg / kg Cd to the soil in two batches, according to soil weight. 2+ (Added in the form of CdCl2 solution) to simulate the dual stress of salt and cadmium. Simultaneously, based on the target application rate (5 mg / kg or 10 mg / kg), the total amount of SeNPs required per pot was calculated. The bio-selenium prepared in Example 3 was formulated into a bio-selenium nanoparticle (SeNPs) aqueous suspension, which was then sprayed evenly and thoroughly mixed into the soil. After treatment, the soil was left to stand for one week before sowing soybean seeds. The OD of the activated Bacillus sicca HB2015 bacterial suspension in TY liquid medium was uniformly adjusted. 600 The value is 0.8, so add 25 mL of bacterial solution to each pot.

[0052] Configure the following steps: Table 3: Design of a soybean pot experiment on the effects of microorganisms and biogenic selenium on dual salt and cadmium stress. In the table, “Cd+SeNPs 5 treatment” means applying 5 mg / kg of bio-selenium under dual salt and cadmium stress; “Cd+SeNPs 5+J treatment” means applying 5 mg / kg of bio-selenium and 25 mL of Bacillus HB2015 bacterial culture under dual salt and cadmium stress.

[0053] "Cd+SeNPs 10 treatment" indicates the application of 10 mg / kg of bio-selenium under dual salt and cadmium stress; "Cd+SeNPs10+J treatment" indicates the application of 10 mg / kg of bio-selenium and 25 mL of Bacillus sicca HB2015 bacterial culture under dual salt and cadmium stress.

[0054] Thin the seedlings one week after emergence, leaving one healthy seedling per pot. Water the pots daily to 50% ± 10% of the field's water volume, and irrigate with Hogland's nutrient solution every two weeks. Harvest after a 35-day growing period and measure the following indicators: Agronomic traits of soybean plants: plant height, root length, aboveground dry weight, and underground dry weight. Determination of fluorescence parameters, photosynthetic characteristic parameters, and SPAD values ​​in soybean plant leaves: The fluorescence and photosynthetic parameters of soybean plant leaves were measured using a portable photosynthesis meter (Li-6800). Approximately 10 days before harvest, on a sunny day between 9:00 and 11:00 AM, photosynthetic parameters such as net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO2 concentration (Ci), as well as chlorophyll fluorescence parameters, were measured. Simultaneously, a portable chlorophyll meter (SPAD-502) was used to measure the SPAD values ​​of the leaves.

[0055] Nitrogen, phosphorus and potassium content determination in plants: After the plant samples were digested with H2O2-H2SO4, the nitrogen content was determined by the Kjeldahl method, the phosphorus content was determined by the molybdenum antimony absorbance spectrophotometric method, and the potassium and sodium content was determined by the flame atomic absorption spectrophotometric method.

[0056] Determination of chlorophyll a, chlorophyll b, and carotenoids: Weigh veinless leaf leaves and place them in a mortar. Add a small amount of silica, calcium carbonate, and 95% ethanol, and grind until the tissue turns white. After centrifugation and volume adjustment, measure the background value with 95% ethanol. After zeroing, measure the absorbance of the solution at wavelengths of 649 nm and 665 nm.

[0057] 2. Test Results: The results are shown in Table 4 and Figures 6 - 8 As shown.

[0058] Table 4: Effects of biogenic selenium and microorganisms on the potassium-sodium ratio in soybean leaves under dual salt and cadmium stress The results showed that compared with the control and the double stress treatment of salt and cadmium, bio-selenium had no obvious toxicity to soybeans at the same or higher application rates, but instead significantly promoted plant growth. The combined treatment of bio-selenium and Bacillus sicca can synergistically improve plant height, root length, biomass, and enhance photosynthetic and fluorescence parameters such as Pn, Gs, Tr, and Fv / Fm.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A strain of Bacillus sicca ( Bacillus siamensis HB2015, its accession number is: CCTCC NO: M2026001.

2. A microbial agent, characterized in that, The bacterial agent contains a strain of Bacillus sihamnium as described in claim 1. Bacillus siamensis )HB2015.

3. The microbial agent according to claim 2, characterized in that, The bacterial agent contains one strain of Bacillus sicca ( Bacillus siamensis HB2015 exists in the form of cultured live bacteria, bacterial suspension, or fermentation broth.

4. The microbial agent according to claim 3, characterized in that, The fermentation broth was prepared by the following method: Bacillus sihamensis ( Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured at 30℃ and 150rpm for 24-36 h with constant temperature shaking.

5. The Bacillus sicca of claim 1 ( Bacillus siamensis The use of the bacterial agent as described in HB2015 or any one of claims 2-4 in the preparation of bio-selenium.

6. A bio-selenium fertilizer, characterized in that, The bio-selenium fertilizer uses bio-selenium as its active ingredient; The bio-selenium is prepared by the following method: The Siamese Bacillus (as described in claim 1) Bacillus siamensis HB2015 was inoculated into TY liquid medium and cultured with shaking until the logarithmic growth phase. Aseptically filtered sodium selenite solution was added to the culture medium to make a final concentration of 10 mmol / L. The culture was continued at 28 ℃ for 65-75 h until the culture medium changed from light color to red. The fermentation broth was centrifuged to collect the precipitate and washed with deionized water. Cell debris was removed by lysing cells with ultrasound followed by a second centrifugation. Washing yields red bio-selenium particles.

7. The bio-selenium fertilizer according to claim 6, characterized in that, The bio-selenium fertilizer also includes: Bacillus sicca ( Bacillus siamensis Fermentation broth of HB2015.

8. The bio-selenium fertilizer according to claim 7, characterized in that, The bio-selenium fertilizer is composed of bio-selenium and Bacillus thuringiensis (Bacillus subtilis). Bacillus siamensis The fermentation broth of HB2015 was composed of (12.5-25) mg: 25 mL; The Siamese Bacillus ( Bacillus siamensis OD of HB2015 fermentation broth 600 The value is 0.

8.

9. The Bacillus sicca of claim 1 ( Bacillus siamensis HB2015, the application of the microbial agent according to any one of claims 2-4 or the bio-selenium fertilizer according to any one of claims 6-8 in improving the ability of plants to resist salt and cadmium stress.

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