Burkholderia SX-J6 and its application in soil improvement in fragile areas

Abstract

This invention belongs to the field of microbial technology, specifically relating to a strain of Burkholderia SX-J6 and its application in soil improvement in vulnerable areas. This invention provides a strain of Burkholderia SX-J6, with accession number CGMCC NO.31723. The Burkholderia SX-J6 provided by this invention exhibits salt and alkali tolerance, can effectively survive in substrates lacking organic carbon sources, possesses carbon fixation capabilities, and can decompose inorganic potassium in the substrate, demonstrating potassium solubilization ability. It also produces high levels of indoleacetic acid. The Burkholderia SX-J6 provided by this invention can be used to improve soils in vulnerable areas, especially in photovoltaic power plant areas.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a strain of Burkholderia SX-J6 and its application in soil improvement in vulnerable areas. Background Technology

[0002] In soils of vulnerable areas, plants have a more urgent need for potassium because potassium helps improve plant resistance, promote root growth, and enhance photosynthetic efficiency. However, the potassium in soils of vulnerable areas is mostly mineral potassium and non-exchangeable potassium, which is not easily utilized by plants directly.

[0003] Soil microorganisms live in the soil and participate in the synthesis and decomposition of soil organic matter, altering soil nutrient conditions through mechanisms such as decomposing organic matter and promoting nutrient cycling. Potassium-solubilizing microorganisms can convert poorly utilized potassium resources into available potassium that plants can absorb by secreting organic acids, enzymes, or other metabolites, thereby increasing the available potassium content in the soil. However, the potassium-solubilizing effect of existing microorganisms is not significant and cannot yet meet practical needs. Summary of the Invention

[0004] The purpose of this invention is to provide a Burkholderia SX-J6 strain and its application in soil improvement in fragile areas. The provided Burkholderia strain is salt-tolerant, has the ability to fix carbon and solubilize potassium, and can also produce high levels of indoleacetic acid, thus improving soil in fragile areas, especially in photovoltaic field areas.

[0005] This invention provides a strain of Burkholderia (… Burkholderia sp.)SX-J6, accession number CGMCCNO.31723.

[0006] The present invention also provides a microbial agent, wherein the active ingredient of the microbial agent includes Burkholderia SX-J6 as described in the above technical solution.

[0007] Preferably, the concentration of Burkholderia SX-J6 in the bacterial agent is 1×10⁻⁶. 6 ~1×10 8 CFU / mL.

[0008] The present invention also provides the application of Burkholderia SX-J6 or the bacterial agent described in the above technical solution in soil improvement in fragile areas and / or in the preparation of indoleacetic acid.

[0009] Preferably, the soil in the vulnerable area includes soil from vulnerable photovoltaic field areas, which improves plant quality.

[0010] Preferably, the soil improvement in the vulnerable area includes increasing the available potassium content in the soil of the vulnerable area.

[0011] This invention also provides a method for preparing indoleacetic acid, comprising the following steps:

[0012] The Burkholderia SX-J6 or the bacterial agent described in the above technical solution is inoculated into a culture medium containing L-tryptophan and fermented to obtain a fermentation broth; the fermentation broth contains indoleacetic acid.

[0013] Preferably, the fermentation culture temperature is 29~39℃, the rotation speed is 170~200rpm, and the time is 36~60h.

[0014] The present invention also provides a method for increasing the available potassium content in soil in vulnerable areas by inoculating the soil in vulnerable areas with Burkholderia SX-J6 or the bacterial agent described in the above technical solution.

[0015] Preferably, the content of mineral potassium in the soil of the vulnerable area is 18626.97~22744.30 μg / g, and the concentration of non-exchangeable potassium is 744.41~1072.48 μg / g. Beneficial effects

[0016] This invention provides a Burkholderia SX-J6 strain, with accession number CGMCC NO.31723. The Burkholderia SX-J6 strain provided by this invention exhibits salt and alkali tolerance, can effectively survive in substrates lacking organic carbon sources, possesses carbon fixation capabilities, and can decompose inorganic potassium in the substrate, demonstrating potassium solubilization ability. It also produces high levels of indoleacetic acid. The Burkholderia SX-J6 strain provided by this invention can be used to improve soils in vulnerable areas, especially in photovoltaic power plant areas.

[0017] Biological Preservation

[0018] Burkholderia SX-J6, classified as Burkholderia Burkholderia sp. was deposited on August 23, 2024, at the China General Microbiological Culture Collection Center, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China, with accession number CGMCC NO.31723. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0020] Figure 1 This is a colony morphology diagram of SX-J6;

[0021] Figure 2 Phylogenetic tree of Burkholderia SX-J6;

[0022] Figure 3OD values ​​of Burkholderia SX-J6 under different NaCl concentrations (a) and different pH environments (b) 600 value;

[0023] Figure 4 Quantitative detection results of potassium solubilizing performance of Burkholderia SX-J6;

[0024] Figure 5 Quantitative detection results of IAA production performance of Burkholderia SX-J6;

[0025] Figure 6 Results of photosynthetic index detection in sunflowers treated with Burkholderia SX-J6; where * indicates P <0.05; *** indicates P <0.001;

[0026] Figure 7 The results show the potassium content of sunflower plants treated with Burkholderia SX-J6; where * indicates... P <0.05; *** indicates P <0.001. Detailed Implementation

[0027] This invention provides a strain of Burkholderia (… Burkholderia sp.)SX-J6, accession number CGMCCNO.31723.

[0028] The Burkholderia SX-J6 strain described in this invention is a strain isolated from the fixed inter-plate soil of a centralized large-scale photovoltaic power plant in Daqing, Heilongjiang Province. Its colonies on solid culture media are round or nearly round, relatively raised, uniform in texture, opaque, smooth, moist, and glossy, grayish-white in color, and have neat edges. Figure 1 The nucleotide sequence of the 16S rRNA of Burkholderia SX-J6 described in this invention is shown in SEQ ID NO:1.

[0029] This invention also provides a microbial agent, the active ingredient of which includes Burkholderia SX-J6 as described in the above-mentioned technical solution. As one embodiment, the concentration of Burkholderia SX-J6 in the microbial agent of this invention is 1×10⁻⁶. 6 ~1×10 8 CFU / mL; as another embodiment, the concentration of Burkholderia SX-J6 in the bacterial agent of the present invention is 5 × 10⁻⁶. 6 ~5×10 7 CFU / mL; as another embodiment, the concentration of Burkholderia SX-J6 in the bacterial agent of the present invention is 1×10⁻⁶. 7 CFU / mL.

[0030] The present invention also provides the application of Burkholderia SX-J6 or the bacterial agent described in the above technical solution in soil improvement in fragile areas and / or in the preparation of indoleacetic acid.

[0031] In one embodiment, the soil in the vulnerable area includes soil from a vulnerable photovoltaic field area. In another embodiment, the basic physicochemical properties of the soil in the vulnerable photovoltaic field area described in this invention are: bulk density of 1.35~1.55 g / cm³. 3 The average water content is 33.2%, the pH value is 9.86~10.51, and the cationic components of the soluble salts include Na. + Fe 2+ Ca 2+ Mg 2+ K + Mn 2+ Zn 2+ and Cu 2+ The total salt content was 8108.43 μg / g.

[0032] In one implementation, the soil improvement in the vulnerable area includes increasing the available potassium content in the soil of the vulnerable area to improve plant quality. In another implementation, improving plant quality in this invention includes improving the photosynthetic capacity index of plants in the soil of the vulnerable area.

[0033] The present invention also provides a method for preparing indoleacetic acid, comprising the following steps: inoculating Burkholderia SX-J6 or the bacterial agent described in the above technical solution into a culture medium containing L-tryptophan, and carrying out fermentation culture to obtain a fermentation broth; wherein the fermentation broth contains indoleacetic acid.

[0034] This invention involves inoculating the *Burkholderia SX-J6* strain or the bacterial agent described in the above-mentioned technical solution into a culture medium containing L-tryptophan, and then fermenting it to obtain a fermentation broth. In one embodiment, the fermentation temperature is 29-39°C; in another embodiment, the fermentation temperature is 30-35°C; in yet another embodiment, the fermentation temperature is 35°C. In one embodiment, the fermentation rotation speed is 170-200 rpm; in another embodiment, the fermentation rotation speed is 180-200 rpm; in yet another embodiment, the fermentation rotation speed is 180 rpm. In one embodiment, the fermentation time is 36-60 hours; in another embodiment, the fermentation time is 36-48 hours; in yet another embodiment, the fermentation time is 48 hours.

[0035] In one implementation method, the inoculation dose is 5.0 × 10⁻⁶. 6 CFU / mL ~5.0×107 CFU / mL; as another embodiment, the inoculation amount is 1.0 × 10⁻⁶. 7 CFU / mL. In one embodiment, the L-tryptophan concentration in the culture medium containing L-tryptophan is 0.06~0.15 wt.%; in another embodiment, the L-tryptophan concentration in the culture medium containing L-tryptophan is 0.1 wt.%.

[0036] In one embodiment, after obtaining the fermentation broth, the present invention performs solid-liquid separation on the fermentation broth and collects the liquid portion. In one embodiment, the solid-liquid separation includes centrifugation. In one embodiment, the centrifugation speed is 6000-8000 rpm; in another embodiment, the centrifugation speed is 7000 rpm. In one embodiment, the centrifugation time is 8-15 minutes; in another embodiment, the centrifugation time is 10 minutes.

[0037] The present invention also provides a method for increasing the available potassium content in soil in vulnerable areas by inoculating the soil in vulnerable areas with Burkholderia SX-J6 or the bacterial agent described in the above technical solution.

[0038] As one implementation method, the basic physicochemical properties of the soil in the vulnerable area are: bulk density ≥ 1.35 g / cm³. 3 The average water content is 33.2%, the pH value is 9.86~10.51, and the cationic components of the soluble salts include Na. + Fe 2+ Ca 2+ Mg 2+ K + Mn 2 + Zn 2+ and Cu 2+ The total salt content was 8108.43 μg / g. In one embodiment, the potassium content in the soil of the vulnerable area was 9012.97~12490.30 μg / g, and the concentration of non-exchangeable potassium was 744.41~1072.48 μg / g. In one embodiment, the inoculum size was 5.0 × 10⁻⁶. 6 CFU / mL ~5.0×10 7 CFU / mL; as another embodiment, the inoculation amount is 1.0 × 10⁻⁶. 7 CFU / mL.

[0039] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a Burkholderia SX-J6 strain provided by the present invention and its application in soil improvement in vulnerable areas, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0040] Solid culture medium without organic carbon source: Na₂HPO₄ 0.5 g / L, KH₂PO₄ 0.5 g / L, MgSO₄ 0.3 g / L, CaCl₂ 0.2 g / L, NaHCO₃ 0.5 g / L, NH₄Cl 0.5 g / L, NaNO₃ 0.25 g / L, NaCl 0.4 g / L, trace element solution 2 mL / L, and agar 20 g / L, pH 7.0; wherein the trace element solution consists of: FeCl₂ 0.3 g / L, FeSO₄·7H₂O 0.3 g / L, MnSO₄·H₂O 0.15 g / L, ZnSO₄·7H₂O 0.25 g / L, and CoCl₂ 0.2 g / L, diluted to 1 L and sterilized through a 0.22 μm filter membrane;

[0041] LB solid medium: 10g tryptone, 5g yeast extract, 10g sodium chloride (NaCl), 15g agar powder, bring the volume to 1000mL with deionized water, set the natural pH to 7, stir well, sterilize at 121℃ for half an hour, and cool to room temperature after sterilization.

[0042] LB liquid medium: 10g tryptone, 5g yeast extract, 10g sodium chloride (NaCl), bring the volume to 1000mL with deionized water, natural pH 7, stir well, sterilize at 121℃ for half an hour, and cool to room temperature after sterilization.

[0043] Potassium-solubilizing liquid culture medium: 5g glucose, 0.5g yeast powder, 0.5g ammonium sulfate, 0.3g magnesium sulfate, 2g disodium hydrogen phosphate, 0.03g ferrous sulfate, 0.03g manganese sulfate, and 2g of the inorganic potassium source obtained in Example 3. Dilute to 1000mL with distilled water, stir well, and heat to promote dissolution. Adjust the pH to 7.0-7.2, sterilize at 121℃ for 15min, and set aside.

[0044] Solid culture medium containing L-tryptophan: 10g tryptone, 5g yeast extract, 10g sodium chloride (NaCl), 15g agar powder, bring the volume to 1000mL with deionized water, set the natural pH to 7, stir well, sterilize at 121℃ for half an hour, cool to room temperature after sterilization, and then add 0.1% L-tryptophan solution to the culture medium, set the natural pH to 7.

[0045] Liquid culture medium containing L-tryptophan: 10g tryptone, 5g yeast extract, 10g sodium chloride (NaCl), bring the volume to 1000mL with deionized water, stir well, sterilize at 121℃ for half an hour, cool to room temperature after sterilization, and then add 0.1wt.% L-tryptophan solution to the culture medium at natural pH. Example

[0046] Isolation and identification of strains

[0047] 1. Soil samples were collected from the top 0-20 cm of the fixed-panel soil layer in a centralized large-scale photovoltaic power plant area in Daqing City, Heilongjiang Province. 10.0 g of the collected soil was added to 100 mL of sterile water and shaken on a shaker (180 rpm, 30 min) to prepare a soil suspension. The soil suspension was then diluted 10-fold to 10⁻⁶. -5 Take 0.2 mL of the soil dilution and spread it onto a solid culture medium without organic carbon source. Incubate upside down at 30°C for 4 days.

[0048] 2. Select colonies with good morphology and growth rate from solid culture media without organic carbon sources, and purify them multiple times on fresh LB solid medium using the streak plate method until pure culture. A target strain, designated SX-J6, was obtained through screening. The colonies were round or nearly round, pale yellow, smooth, moist, glossy, with regular edges, and varied in size. Figure 1 ).

[0049]

[0050] 4. Using the NCBI database, BLAST analysis was performed based on the 16S rRNA gene sequence of strain SX-J6, and a phylogenetic tree was constructed. The results showed that strain SX-J6 is related to... Burkholderia paludis MSh1 The 16S rRNA gene sequence (accession number NR_178850.1) and Burkholderia contaminans J2956 The 16S rRNA gene sequence (accession number NR_104978.1) showed 100.00% homology with [other sequences]. Burkholderia lata 383 The 16S rRNA gene sequence (accession number NR_102890.1) showed 99.86% homology with [other sequences]. Burkholderia arboris R-24201 The 16S rRNA gene sequence of accession number NR_042634.1 has 99.78% homology with [other genes]. Burkholderia aenigmatica LMG 13014 The 16S rRNA gene sequence (accession number NR_174230.1) showed 99.64% homology. Strain SX-J6 and... Burkholderia paludis and Burkholderia contaminans Having the closest phylogenetic relationship ( Figure 2 ), combined with its cell morphology and colony characteristics ( Figure 1 The strain was identified as belonging to the genus Burkholderia (…). Burkholderia sp.), named Burkholderia ( Burkholderia sp.)SX-J6, and biologically preserved. Example

[0051] Study on salt and alkali tolerance of Burkholderia SX-J6

[0052] 1. Pick Burkholderia SX-J6 isolated in Example 1 and inoculate it into 10 mL of fermentation medium (tryptone 10 g / L, yeast extract 5 g / L, sodium chloride 10 g / L) and culture at 35 °C with shaking at 180 rpm for 48 h to obtain SX-J6 seed culture.

[0053] 2. Effect of NaCl concentration on Burkholderia SX-J6

[0054] SX-J6 seed culture was inoculated at a volume ratio of 2% into 10 mL of LB liquid medium (pH 7.0) with different NaCl concentrations (0 wt.%, 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, 14 wt.%, 16 wt.%, and 18 wt.%). The culture was incubated at 35°C and 170 rpm for 4 days. The bacterial culture at the end of the incubation period was then analyzed using a spectrophotometer for OD500. 600Values ​​were determined, and preliminary data processing was performed using Microsoft Excel Office 2016 software. Graphs were then generated using R language (R v4.1.2). The results are as follows: Figure 3 As shown in Figure a.

[0055] according to Figure 3 As shown in Figure a, Burkholderia SX-J6 exhibited good activity when NaCl concentrations of 6 wt.% or lower were added to LB liquid medium. While further increasing the NaCl concentration to 12 wt.% decreased the activity, it still retained some activity. Burkholderia SX-J6 demonstrates strong salt tolerance.

[0056] 3. Effect of pH on Burkholderia SX-J6

[0057] SX-J6 seed culture was inoculated at a volume ratio of 2% into 10 mL of LB liquid medium at different pH values ​​(2.8, 3.4, 4.2, 5.0, 5.8, 6.6, 7.4, 8.2, 9.0, and 10.0). The culture was incubated at 35℃ and 170 rpm for 4 days. The bacterial culture at the end of the incubation period was then analyzed using a spectrophotometer for OD500 analysis. 600 Values ​​were determined, and preliminary data processing was performed using Microsoft Excel Office 2016 software. Graphs were then generated using R language (R v4.1.2). The results are as follows: Figure 3 As shown in b.

[0058] according to Figure 3 As shown in b, Burkholderia SX-J6 activity was good in LB liquid medium at pH ≥ 5.0, and the activity was best at pH 7.0 (initial LB medium). OD 600 =1.542. At pH 7.4 ≤ pH ≤ 10.0, the activity decreases slightly with increasing alkalinity, but still maintains a high level of activity. However, its activity is poor at pH < 5.0. Burkholderia SX-J6 exhibits strong alkali resistance. Example

[0059] Detection of potassium-solubilizing capacity of Burkholderia SX-J6

[0060] 1. Preparation of Inorganic Potassium Sources

[0061] Select potassium feldspar powder, pass it through a 180-mesh sieve, soak it in deionized water overnight, and then wash it thoroughly with deionized water 3 to 5 times to remove soluble potassium. Air dry it for later use.

[0062] 2. Potassium solubilization performance test

[0063] (1) Burkholderia SX-J6 isolated in Example 1 was picked and inoculated into 10 mL of LB liquid medium. It was cultured at 35 °C and 170 rpm for 4 days to obtain 5.0 × 10⁻⁶ cells / year. 8 ~8.0×10 8 CFU / mL SX-J6 seed solution.

[0064] (2) The SX-J6 seed culture was inoculated into 10 mL of potassium-solubilizing liquid medium at a volume ratio of 2% and cultured at 35℃ and 170 r / min for 4 days. After the culture was completed, the supernatant was taken and centrifuged at 4000 rpm for 10 min to remove the bacterial cells and insoluble impurities. Then, it was mixed with sodium tetraphenylborate (NaTPB) solution and allowed to stand for a period of time. A white precipitate was found to be formed, indicating that Burkholderia SX-J6 can decompose potassium in inorganic potassium sources.

[0065] 3. Potassium solubilization capacity test

[0066] (1) Configuration of standard curve

[0067] A 0.05 mol / L NaTPB aqueous solution was prepared using sodium tetraphenylborate (NaTPB). Potassium chloride standard solutions of 0 mg / L, 10 mg / L, 20 mg / L, 50 mg / L, and 100 mg / L were prepared using potassium chloride. 5 mL of the potassium standard solution was added to a colorimetric tube, and NaTPB aqueous solution was added in an equal volume ratio. The tube was gently shaken to mix thoroughly. After standing for 10–15 minutes, a white precipitate was completely formed. The absorbance of the reaction solution was measured at 620 nm. The absorbance was directly proportional to the concentration of potassium ions in the solution. A standard curve meeting the accuracy requirements was plotted, with the equation y = 0.0083x + 0.0126. The goodness of fit of the standard curve R0 was [value missing]. 2 =0.999 ( Figure 4 ).

[0068] (2) 2% (v / v) of SX-J6 seed culture was inoculated into 10 mL of potassium-solubilizing liquid medium and cultured at 35℃ and 170 r / min for 4 days. After the culture was completed, the supernatant was collected and centrifuged at 4000 rpm for 10 min to remove bacterial cells and insoluble impurities. 5 mL of Burkholderia SX-J6 culture supernatant was added to a colorimetric tube, and NaTPB aqueous solution was added in an equal volume ratio. The tube was gently shaken to mix the solution thoroughly. After standing for 10-15 min, a white precipitate was formed. The absorbance of the reaction solution was measured at 620 nm. The result was used to quantitatively analyze the potassium content in the Burkholderia SX-J6 culture supernatant. Two replicates were performed. The results showed that the OD of the reaction product of Burkholderia SX-J6 culture supernatant and NaTPB aqueous solution was... 620The values ​​were 0.651 and 0.687, respectively, and the quantitative analysis showed that the potassium content was 76.92 mg / L and 81.25 mg / L, respectively. Figure 4 The raw data in this embodiment was initially processed using Microsoft Excel Office 2016 software. The experimental results were plotted using R language (R v4.1.2). Example

[0069] Burkholderia SX-J6 IAA production function detection

[0070] 1. Configuration of the standard curve

[0071] Accurately weigh 10 mg of IAA standard, dissolve it in a small amount of ethanol, and then dilute to 100 mL with distilled water (the concentration at this point is 0.1 g / L) to prepare the IAA stock solution (mother liquor). Pipette 0, 2.5, 5, 7.5, and 10 mL of the mother liquor to 25 mL volumetric flasks to prepare standard solutions of 0, 10, 20, 30, and 40 mg / L, respectively. Mix an appropriate amount of the IAA standard solution with an equal volume of Salkowski colorimetric solution, shake well, and incubate at room temperature in the dark for 30 min. Measure the absorbance (OD) at a wavelength of 530 nm. 530 A standard curve for IAA was plotted with the concentration of the IAA standard solution on the x-axis and the corresponding absorbance on the y-axis, meeting the accuracy requirements. The results showed that the equation y = 0.031x + 0.024 was suitable, and the goodness of fit R of the standard curve was satisfactory. 2 =0.998 ( Figure 5 ).

[0072] 2. Pick 1 ml of Burkholderia SX-J6 isolated in Example 1 and inoculate it with a solution of concentration 1.0 × 10⁻⁶. 8 CFU / mL of SX-J6 seed culture was incubated in 10 mL of L-tryptophan-containing liquid medium at 35°C and 180 rpm for 48 h using a constant temperature shaker. The fermentation broth was then collected, with uninoculated L-tryptophan-containing liquid medium used as a control. The fermentation broth was centrifuged at 7000 rpm for 10 min, and the supernatant was retained. 2 mL of the supernatant was pipetted and an equal volume of Salkowski colorimetric solution was added. The mixture was thoroughly mixed onto a white ceramic plate and incubated at room temperature in the dark for 30 min. If the mixture turned pink, it indicated that the strain had the ability to produce IAA, and the redder the color, the greater the production intensity. Conversely, if the added strain solution and the blank control did not show a significant red color change, but the standard IAA concentration solution turned red, it indicated that the strain did not have the ability to produce IAA. The results showed that the supernatant of Burkholderia SX-J6 fermentation reacted with Salkowski colorimetric solution to turn red, indicating that it has the ability to produce IAA.

[0073] After standing, its absorbance value (OD) at a wavelength of 530 nm was measured. 530 Substituting the values ​​into the standard curve, the IAA production of Burkholderia SX-J6 was quantitatively analyzed, with four replicates. The results showed that the absorbance values ​​of the Burkholderia SX-J6 fermentation supernatant at 600 nm were 1.403, 1.551, 1.774, and 1.884, respectively; the absorbance values ​​of the Burkholderia SX-J6 fermentation supernatant and the Salkowski colorimetric mixture at 530 nm were 0.177, 0.193, 0.235, and 0.284, respectively, corresponding to IAA production amounts of 4.94, 5.45, 6.81, and 8.39 mg / L, respectively. Figure 5 The raw data in this embodiment was initially processed using Microsoft Excel Office 2016 software. The experimental results were plotted using R language (R v4.1.2). Example

[0074] Effects of Burkholderia SX-J6 on photosynthetic capacity indices of sunflower

[0075] 1. Burkholderia SX-J6 isolated in Example 1 was picked and inoculated into 10 mL of fermentation medium (10 g / L tryptone, 5 g / L yeast extract, 10 g / L sodium chloride), and cultured at 35°C with shaking at 180 rpm for 48 h to obtain SX-J6 seed culture. The concentration of the SX-J6 seed culture was diluted to 1.0 × 10⁻⁶ using RO water. 6 1.0×10 7 1.0×10 8 Burkholderia SX-J6 bacterial suspensions at three concentration gradients of CFU / mL.

[0076] 2. Preparation of Inorganic Potassium Sources

[0077] Select potassium feldspar powder, pass it through a 180-mesh sieve, soak it in deionized water overnight, and then wash it thoroughly with deionized water 3 to 5 times to remove soluble potassium. Air dry it for later use.

[0078] 3. Preparation of cultivation substrate

[0079] Peat moss and vermiculite were mixed in a volume ratio of 2:1 to obtain a soil substrate; the mass ratio of peat moss to vermiculite was 1.05:0.45. Potassium feldspar powder, prepared in step 2, was added at 0.2% of the soil substrate mass. After mixing thoroughly, the mixture was sterilized at 121℃ under high temperature and pressure for 2 hours, and then air-dried in a separate, clean environment at room temperature to obtain the cultivation substrate.

[0080] 4. Sunflower seed treatment

[0081] Select plump, mold-free, uniformly sized, insect-free, and undamaged sunflower seeds (Black Three-Stripe Sunflower, registration number GPD Sunflower (2018) 620617). Rinse the surface with sterile water to remove dust, then wipe with 75% v / v ethanol for 16-20 seconds. After that, soak in 0.1 wt.% potassium permanganate solution for 10 minutes, and finally rinse with sterile water 5-8 times. Take 100 mL of the sterile water from the last rinse and spread it on peptone solid medium. Incubate upside down at a constant temperature for 48 hours. Observe whether colonies form on the surface of the medium to verify the thoroughness of sunflower surface disinfection.

[0082] 5. Fill 0.4L flowerpots with the cultivation substrate, with peat moss and vermiculite weighing 1.05kg / pot and 0.45kg / pot respectively. Sow sunflower seeds at a depth of 0.5cm and place them in a plant incubator. Set the plant incubator to 30℃ during the day, 15000Lux light for 12h, and 80% relative humidity; and 25℃ and 75% relative humidity for 12h in the dark.

[0083] After the seeds germinated, four treatment groups were randomly assigned to each group, with three replicates in each group, and the following treatments were performed:

[0084] CK (RO water): Use 50mL of RO water to water the roots of sunflower plants, and add the same amount of RO water again 10 days and 20 days after the first addition of RO water;

[0085] Low concentration J6 bacterial culture: using 50 mL of 1.0 × 10⁻⁶ bacterial solution. 6 Sunflower plants were irrigated with a CFU / mL Burkholderia SX-J6 suspension, and the same concentration of Burkholderia SX-J6 suspension was added again 10 and 20 days after the first addition.

[0086] Medium concentration J6 bacterial culture: using 50 mL of 1.0 × 10⁻⁶ microbial solution. 7 Sunflower plants were irrigated with a CFU / mL Burkholderia SX-J6 suspension, and the same concentration of Burkholderia SX-J6 suspension was added again 10 and 20 days after the first addition.

[0087] High-concentration J6 bacterial culture: using 50 mL of 1.0 × 10⁻⁶ bacterial solution. 8 Sunflower plants were irrigated with a CFU / mL Burkholderia SX-J6 suspension, and the same concentration of Burkholderia SX-J6 suspension was added again 10 and 20 days after the first addition.

[0088] Three days after the last addition of bacterial solution, the chlorophyll content of sunflowers in each treatment group was measured. Statistical tests were used to determine whether there were significant differences in the relative chlorophyll content among the different experimental groups. After data analysis, plotting was performed using R language (Rv4.1.2). The results are shown below. Figure 6 As shown.

[0089] according to Figure 6 It can be seen that the CK group and the low concentration J6 bacterial solution (1.0×10⁻⁶) showed better results. 6 CFU / mL), medium concentration J6 bacterial culture (1.0×10⁻⁶ CFU / mL), 7 CFU / mL) and high concentration J6 bacterial solution (1.0×10⁻⁶ CFU / mL) 8 The relative chlorophyll contents of sunflower leaves under the four treatments (CFU / mL) were 25.60, 27.27, 28.24, and 29.38, respectively. There was no significant difference in the relative chlorophyll content between the control group and the low-concentration J6 bacterial solution treatment; however, the relative chlorophyll content in the control group was significantly lower than that in the medium and high concentrations of J6 bacterial solution. The addition of Burkholderia SX-J6 bacterial solution increased the chlorophyll content of sunflower leaves, indicating that Burkholderia SX-J6 promotes the utilization of inorganic potassium and enhances plant photosynthetic capacity.

[0090] Three days after the last addition of bacterial solution to each treatment group, three replicate sunflower plants from each treatment group were harvested, and the sunflower plant samples were placed at 105°C. o Dry in an oven at 75°C for 2 hours; then adjust the oven temperature to 75°C. o C. Continue drying for 24 hours until the sample reaches constant weight. Take 10-15g of each of the three replicate dried samples from each treatment group, and determine the total potassium content in the sunflower plants using the "nitric acid-perchloric acid digestion-atomic absorption spectrometry". Statistical tests were used to determine whether there were significant differences in the total potassium content of sunflowers among different experimental groups. After data analysis, plotting was performed using R language (R v4.1.2). The results are shown below. Figure 7 As shown.

[0091] according to Figure 7 It can be seen that the CK group and the low concentration J6 bacterial solution (1.0×10⁻⁶) showed better results. 6 CFU / mL), medium concentration J6 bacterial culture (1.0×10⁻⁶ CFU / mL), 7 CFU / mL) and high concentration J6 bacterial solution (1.0×10⁻⁶ CFU / mL) 8The total potassium content of sunflowers under the four treatments (CFU / mL) was 29.45, 34.51, 32.60, and 32.54 g / kg, respectively. The potassium content of sunflowers in the control group was significantly lower than that in the medium-concentration J6 bacterial solution, medium-concentration J6 bacterial solution, and high-concentration J6 bacterial solution treatments. The addition of Burkholderia SX-J6 bacterial solution increased the total potassium content of sunflowers, indicating that Burkholderia SX-J6 can promote the utilization of inorganic potassium by sunflowers and enhance the plant's potassium absorption capacity.

[0092] As can be seen from the above, the Burkholderia SX-J6 strain provided by this invention is salt-alkali tolerant, can survive effectively in a matrix without organic carbon sources, has carbon fixation ability, and can decompose inorganic potassium in the matrix, has potassium solubilization ability, and can also produce high levels of indoleacetic acid, which can improve soil in fragile areas, especially in fragile photovoltaic field areas.

[0093] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A strain of Burkholderia ( Burkholderia sp.)SX-J6, accession number CGMCC NO.31723.

2. A microbial agent, characterized in that, The active ingredient of the bacterial agent includes Burkholderia SX-J6 as described in claim 1.

3. The microbial agent according to claim 2, characterized in that, The concentration of Burkholderia SX-J6 in the bacterial agent is 1×10⁻⁶. 6 ~1×10 8 CFU / mL.

4. The application of Burkholderia SX-J6 as described in claim 1 or the inoculant as described in claim 2 or 3 in the improvement of soil in vulnerable areas.

5. The application according to claim 4, characterized in that, The soil in the vulnerable area includes the soil in the vulnerable photovoltaic field area.

6. The application according to claim 4 or 5, characterized in that, The soil improvement in the vulnerable areas includes increasing the available potassium content in the soil and improving plant quality.

7. The use of Burkholderia SX-J6 of claim 1 or the inoculum of claim 2 or 3 in the preparation of indoleacetic acid.

8. A method for preparing indoleacetic acid, characterized in that, Includes the following steps: Burkholderia SX-J6 as described in claim 1 or the inoculum as described in claim 2 or 3 is inoculated into a culture medium containing L-tryptophan and fermented to obtain a fermentation broth; the fermentation broth contains indoleacetic acid.

9. The preparation method according to claim 8, characterized in that, The fermentation culture was carried out at a temperature of 29-39℃, a rotation speed of 170-200 rpm, and a time of 36-60 h.

10. A method for increasing the available potassium content in soils of vulnerable areas, characterized in that, Inoculate the soil in the vulnerable area with Burkholderia SX-J6 as described in claim 1 or the inoculum as described in claim 2 or 3.

11. The method according to claim 10, characterized in that, The mineral potassium content in the soil of the vulnerable area ranges from 18626.97 to 22744.30 μg / g, and the concentration of non-exchangeable potassium ranges from 744.41 to 1072.48 μg / g.

Images