Acid-resistant nitrogen fixation-activated iron phosphate synthetic flora, complex microbial inoculant and application of acid-resistant nitrogen fixation-activated iron phosphate synthetic flora and complex microbial inoculant

Abstract

The invention relates to the technical field of microorganisms, in particular to an acid-resistant nitrogen fixation-activated iron phosphate synthetic flora and application thereof, and the acid-resistant nitrogen fixation-activated iron phosphate synthetic flora is composed of the following microbial strains: Pseudomonas donghuensis N-13 and Pantoea agglomerans P-23; the preservation number of the pantoea agglomerans P-23 is CGMCC (China General Microbiological Culture Collection Center) No.37622, and the preservation number of the East Lake pseudomonas N-13 is CGMCC No.37624. The method is suitable for synchronous biological enhancement of nitrogen and phosphorus nutrients in an acidic oligotrophic environment.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to an acid-resistant nitrogen-fixing-activated ferric phosphate synthetic microbial community and its applications. Background Technology

[0002] In various acidic environments, including partially acidified black soils, the lack of available nitrogen and phosphorus in the soil is a key factor limiting ecological restoration and agricultural production. Acid stress not only leads to phosphorus fixation by iron and aluminum to form insoluble phosphates (such as ferric phosphate), but also significantly inhibits the activity of nitrogen-fixing microorganisms, resulting in a double deficiency of nutrients. Currently, nutrient improvement in acidic environments mainly relies on applying lime to adjust pH or large-scale application of chemical nitrogen and phosphorus fertilizers. While these methods can produce short-term results, they are costly and prone to causing secondary environmental problems such as soil compaction, salinization, and eutrophication of water bodies. Bioremediation pathways, especially those utilizing functional microorganisms, are green and sustainable remediation approaches and are considered an environmentally friendly and sustainable alternative strategy.

[0003] However, existing functional bacterial agents are mostly suitable for neutral or weakly acidic conditions. For example, CN110257283A discloses a slow-growing rhizobium strain suitable for the Huang-Huai region that is resistant to drug fixation and stress, and its application. However, it only has a single nitrogen-fixing function, and its acid resistance is not clearly defined, making it unsuitable for ferric phosphate activation. CN118126903B discloses a multifunctional Bacillus belyceae that is acid-resistant and produces alkali, its microbial agent, and its application. It focuses on alkali production and acid resistance, has no nitrogen-fixing function, and is a single strain, which cannot simultaneously solve the problem of nitrogen and phosphorus deficiency. As can be seen from the above, the activity and stability drop sharply when the pH is below 5.5, especially the activation efficiency of ferric phosphate is low. Although there are reports of nitrogen-fixing bacteria or phosphate-solubilizing bacteria, there is still no synthetic bacterial group that can stably and synergistically achieve efficient nitrogen fixation and specific activation of ferric phosphate under a wide range of acid gradients (pH 3.0-7.0), making it difficult to cope with the complex problem of nitrogen and phosphorus deficiency in acidic oligotrophic environments. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provide an acid-resistant synthetic microbial community for nitrogen fixation and ferric phosphate activation, a compound microbial agent, and its applications. This synthetic microbial community exhibits significant synergistic effects in acidic culture media with a pH of 3.0-7.0, simultaneously increasing available nitrogen content and efficiently activating ferric phosphate into available phosphorus. Particularly within the pH range of 3.0-6.0, its nitrogen fixation and phosphorus release functions gradually increase with increasing acidity, maintaining stable function even under strong acid (pH 3.0) stress. It is suitable for the simultaneous biofortification of nitrogen and phosphorus nutrients in acidic oligotrophic environments.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A synthetic microbial community of acid-resistant nitrogen-fixing and activated ferric phosphate, comprising the following microbial strains: including *Pseudomonas aeruginosa* (… Pseudomonas donghuensisN-13 and Pantotheca agglomerata ( Pantoea agglomerans P-23; the preservation number of the *Pseudomonas aeruginosa* N-13 is CGMCC No. 37624, and the preservation number of the *Pantotheca cum Caulis* P-23 is CGMCC No. 37622.

[0006] Preferably, the effective viable count ratio of the clustered pantothecin P-23 to the Donghu Pseudomonas N-13 is 1:1.

[0007] A compound microbial agent comprising the aforementioned synthetic microbial flora.

[0008] Preferably, the OD600 value of the synthetic microbial community in the compound microbial agent is ≥0.5.

[0009] This solution provides the application of the above-mentioned synthetic microbial community or the above-mentioned compound microbial agent for biological nitrogen fixation and phosphorus release by activation of insoluble phosphate under acidic conditions. The acidic conditions include acidic soil or acidic water; the pH range of the acidic conditions is 3.0-7.0; and the insoluble phosphate is iron phosphate or aluminum phosphate.

[0010] The present invention also proposes a method for simultaneously increasing the content of available nitrogen and available phosphorus in an acidic oligotrophic environment, comprising: applying the above-mentioned synthetic microbial community or compound microbial agent to the acidic oligotrophic environment.

[0011] Preferably, the acidic oligotrophic environment is an acidic soil or acidic water body with sparingly soluble phosphate as the sole or main phosphorus source.

[0012] Beneficial effects: The synthetic microbial community provided by this invention exhibits high effective nitrogen accumulation and high effective phosphorus release from ferric phosphate within a pH range of 3.0-6.0. Even under strong acid stress at pH 3.0, it can maintain high functional activity and demonstrates outstanding acid resistance and stability. Furthermore, this synthetic microbial community can work efficiently in systems where ferric phosphate is the sole phosphorus source. It provides an efficient and stable microbial combination resource for the bioremediation of nitrogen- and phosphorus-limited environments such as acidic water bodies and acidified soils, and has broad application prospects.

[0013] Biological Preservation Instructions: Donghu Pseudomonas N-13, Latin name Pseudomonas donghuensis It was deposited on February 2, 2026, at the China General Microbiological Culture Collection Center (CGMCC), Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 37624.

[0014] Pantothecin P-23, Latin name Pantoea agglomeransIt was deposited on February 2, 2026, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 37622. Attached Figure Description

[0015] Figure 1 This is a technical roadmap for strain screening and functional verification of the present invention; Figure 2 For the single-strain functional verification of nitrogen-fixing bacteria and phosphate-solubilizing bacteria, among which Figure 2 (a) in the figure represents the functional verification of a single nitrogen-fixing bacterium. Figure 2 (b) in the figure represents the single-strain functional verification of phosphate-solubilizing bacteria; Figure 3 The effective nitrogen fixation of different single bacteria and synthetic bacterial combinations under different pH conditions, among which Figure 3 In the figure, (a) represents the effective nitrogen fixation of different single bacteria under different pH conditions (3.0, 4.0, 5.0, 6.0, 7.0). Figure 3 (b) represents the effective nitrogen fixation of the synthetic microbial community combination under different pH conditions (3.0, 4.0, 5.0, 6.0, 7.0); Figure 4 The effective phosphorus release of different single bacteria and synthetic bacterial combinations under different pH conditions, among which Figure 4 In the figure, (a) represents the amount of available phosphorus released by different single bacteria under different pH conditions (3.0, 4.0, 5.0, 6.0, 7.0). Figure 4 (b) represents the effective phosphorus release of the synthetic microbial community combination under different pH conditions (3.0, 4.0, 5.0, 6.0, 7.0). Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following will describe this application in detail with reference to the embodiments.

[0017] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0018] This invention provides an acid-resistant nitrogen-fixing-activated ferric phosphate synthetic microbial community, composed of the following microbial strains: including *Pseudomonas aeruginosa* (… Pseudomonas donghuensis N-13 and Pantotheca agglomerata ( Pantoea agglomerans The *Pseudomonas aeruginosa* N-13 has the accession number CGMCC No. 37624, and the *Pantotheca cum Caulis* P-23 has the accession number CGMCC No. 37622. In this invention, the effective viable count of *Pseudomonas aeruginosa* N-13 and *Pantotheca cum Caulis* P-23 is preferably 1:1.

[0019] This invention is based on Figure 1 The process involved isolating, cultivating, and validating the functions of the strains. This protocol isolated two strains (Donghu Pseudomonas N-13 and Pantotheca acuminata P-23) that can be cultured individually or in combination. Under room temperature and acidic conditions (pH 3.0-7.0), they efficiently and simultaneously increased the available nitrogen content and activated insoluble iron phosphate in the system. Furthermore, in the combined culture state, they significantly promoted the nutrient conversion efficiency of the system. This has significant application prospects for alleviating the dual deficiency of nitrogen and phosphorus in acidic environments and is of great importance for improving soil fertility, promoting green agricultural production, and ecological restoration.

[0020] This invention provides a compound microbial agent comprising the synthetic microbial community described in the above-mentioned technical solution. In this invention, the OD value of the synthetic microbial community in the compound microbial agent is... 600 The value is preferably ≥0.5; the preparation method of the compound bacterial agent preferably includes the following steps: culturing *Pseudomonas aeruginosa* N-13 and *Pantotheca cumulus* P-23 from the synthetic bacterial group separately to obtain *Pseudomonas aeruginosa* N-13 bacterial suspension and *Pantotheca cumulus* P-23 bacterial suspension; mixing the *Pseudomonas aeruginosa* N-13 bacterial suspension and *Pantotheca cumulus* P-23 bacterial suspension to obtain the compound bacterial agent; the culture medium for culturing the *Pseudomonas aeruginosa* N-13 bacterial suspension and *Pantotheca cumulus* P-23 bacterial suspension preferably includes 1 / 10 LB liquid medium; the volume ratio of the *Pseudomonas aeruginosa* N-13 bacterial suspension and *Pantotheca cumulus* P-23 bacterial suspension is preferably 1:1.

[0021] Based on the above advantages, this invention provides the application of the synthetic microbial community or the compound microbial agent described in the above technical solution in the remediation of nutrient deficiency in acidic environments. The application involves simultaneously increasing the effective nitrogen content and activating insoluble iron phosphate in the environment. In this invention, the pH range of the acidic environment is preferably 3.0-7.0; the insoluble iron phosphate is preferably the main or sole phosphorus source in the environment; and the environment is preferably acidic soil or acidic water.

[0022] Based on the above advantages, this invention provides the application of the synthetic microbial community or the compound microbial agent described in the above technical solution in remediating nitrogen and phosphorus nutrient deficiency in acidic water bodies. The application involves simultaneously increasing the effective nitrogen content in the acidic environment and activating insoluble ferric phosphate. In this invention, the pH range of the acidic environment is preferably 3.0-7.0, more preferably 3.0-6.0; the insoluble ferric phosphate is preferably the main or sole phosphorus source in the environment. This invention does not have special requirements for the application method; methods well known to those skilled in the art can be used.

[0023] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a synthetic microbial community and compound microbial agent of acid-resistant nitrogen-fixing and activated iron phosphate, and their application in degrading complex pollutants, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0024] Example 1: Isolation of potentially functional bacterial strains from soils in the acidified black soil region of Northeast China using conditional screening. (1) Sample collection: In July 2024, the rhizosphere soil of maize in the acidified black soil area of ​​Changchun City, Jilin Province was collected.

[0025] (2) Sample activation: Accurately weigh 200 g of acidified black soil sample into a 500 mL sterile wide-mouth bottle, plant corn seedlings that have been sterilized, and place them in an artificial weather chamber at 28℃ for one week. Pay attention to adding sterile water to keep the moisture content unchanged.

[0026] (3) Isolation of nitrogen-fixing bacteria strains: Accurately weigh 10 g of activated acidified black soil maize rhizosphere soil sample into an Erlenmeyer flask containing 90 mL of sterile physiological saline, place it in a shaker at 28℃ for one hour, remove it and let it stand for two hours, then take 1 mL of the sample and gradually dilute it to 9 mL of sterile physiological saline to a final concentration of 10 mL. -3 10 -4 10 -5 Spread 0.1 mL of each dilution onto Nfb solid agar plates, three plates per dilution. Incubate at 28°C for 5 days. Strains that grow normally and cause discoloration of the medium are considered nitrogen-fixing bacteria. Store the plates at 4°C for later use. The Nfb medium formula is as follows: malic acid 5 g / L, dipotassium hydrogen phosphate 0.5 g / L, magnesium sulfate 0.1 g / L, sodium chloride 0.1 g / L, calcium chloride 20 mg / L, and 0.2% (v / v) bromothymol blue acid-base indicator. Sterilize at 121°C for 20 min.

[0027] (4) Isolation of phosphate-solubilizing bacteria strains: Accurately weigh 10 g of activated acidified black soil maize rhizosphere soil sample into an Erlenmeyer flask containing 90 mL of sterile physiological saline, place it in a shaker at 28℃ for one hour, remove it and let it stand for two hours, then take 1 mL of the sample and gradually dilute it to 9 mL of sterile physiological saline to a final concentration of 10. -3 10 -4 10 -5 Spread 0.1 mL of each diluted NBRIP medium onto modified NBRIP solid agar plates, three plates per dilution. Incubate at 28°C for 5 days. Strains that grow normally and induce the formation of phosphate-solubilizing rings in the medium are considered phosphate-solubilizing bacteria. Store the plates at 4°C for later use. The modified NBRIP medium formula is as follows: glucose 10 g / L, ferric phosphate 5 g / L, magnesium chloride 5 g / L, magnesium sulfate 0.25 g / L, potassium chloride 0.2 g / L, ammonium sulfate 0.1 g / L. Sterilize at 121°C for 20 min.

[0028] (5) Streaking isolation of functional strains: Different morphological colonies of nitrogen-fixing and phosphate-solubilizing bacteria obtained in steps (3) and (4) were streaked to obtain single clones. The streaking was performed on 1 / 10 LB agar plates. After bacterial growth, the plates were stored in glycerol tubes at -80°C. The 1 / 10 LB agar formulation was as follows: 1 g / L tryptone, 0.5 g / L yeast extract, and 1 g / L sodium chloride. The pH of the medium was adjusted to 7.4 with NaOH. After weighing and dissolving the components according to the specified proportions, the medium was autoclaved at 121°C for 20 min. Cultivation on 1 / 10 LB solid medium was the same as on liquid medium, except that 1.5% agar was added.

[0029] (6) Functional assessment of single nitrogen-fixing bacteria: The soil microorganisms to be tested were cultured in sterilized LB liquid medium, centrifuged during the logarithmic growth phase, and the obtained microbial precipitate was washed with sterile physiological saline to remove residual culture medium and resuspended. The OD of the resuspended bacterial solution was measured. 600 The value eventually reached 0.5. 5 mL of resuspended bacterial culture was added to a 25 mL sterile headspace vial containing 10 mL of Nfb liquid medium, and the vial was activated and cultured at 28°C for 24 hours. The headspace vial was flushed with argon to remove air, and then 1% and 10% of the headspace gas were replaced with high-purity oxygen and acetylene, respectively. After culturing at 28°C for 12 hours, the concentration of reduced ethylene gas was analyzed using a gas chromatograph equipped with an FID detector, and this concentration was recorded as the nitrogenase activity of the nitrogen-fixing bacteria. Each treatment was repeated in 5 replicates. The best performing nitrogen-fixing bacteria were *Pseudomonas aeruginosa* (numbered N-13) and *Agrobacterium*. See the appendix for experimental results. Figure 2 (a) in the middle.

[0030] (7) Functional evaluation of single phosphate-solubilizing bacteria: The soil microorganisms to be tested were cultured in sterilized LB liquid medium, centrifuged during the logarithmic growth phase, and the obtained microbial precipitate was washed with sterile physiological saline to remove residual culture medium and resuspended, and the OD of the resuspended bacterial solution was adjusted. 600 The value eventually reached 0.5. 5 mL of resuspended bacterial culture was added to a 25 mL sterile headspace vial containing 10 mL of NBRIP liquid medium with ferric phosphate as the phosphorus source, and the culture was activated at 28°C for 14 days. The available phosphorus content released by the phosphate-solubilizing bacteria was determined by the molybdenum antimony colorimetric method. Each treatment was repeated in 5 replicates. Among the phosphate-solubilizing bacteria, *Panthera phalloides* (numbered P-23) and *Aspergillus* showed the best performance. See the appendix for experimental results. Figure 2 (b) in the middle.

[0031] Isolation of Pseudomonas aeruginosa ( Pseudomonas donghuensis N-13 and Pantotheca agglomerata ( Pantoea agglomerans P-23 and P-23 are respectively preserved at the China General Microbiological Culture Collection Center (CGMCC); the preservation number of Pseudomonas donghuensis N-13 is CGMCC No. 37624, and the preservation number of Pantotheca cumulus P-23 is CGMCC No. 37622.

[0032] Example 2: Construction of Synthetic Microbial Community and Verification of its Functional Synergy under Acidic Conditions Single clones of *Pseudomonas aeruginosa* N-13, *Agrobacterium*, *Pantothecin* P-23, and *Aspergillus* obtained from screening in Example 1 were selected and inoculated into 100 mL of 1 / 10 LB liquid medium. After shaking culture in a shaker at 28°C, the obtained microbial precipitate was rinsed with sterile physiological saline to remove residual culture medium and resuspended. The OD of the resuspended bacterial solution was adjusted to [value missing]. 600 The value eventually reached around 0.5, which was used as a seed culture for constructing a synthetic microbial community and verifying its functional synergy under acidic conditions.

[0033] Before the culture experiment began, the following experimental designs were made for single bacteria and different 1:1 bacterial community combinations, with a total of 8 treatments and 5 replicates for each treatment: 1) Donghu Pseudomonas N-13 single bacteria (referred to as PD treatment); 2) Agrobacterium single strain (denoted as AT treatment); 3) Clustered Pantotheca P-23 single bacteria (referred to as PA treatment); 4) Aspergillus (referred to as AP treatment); 5) The combination of Pseudomonas aeruginosa N-13 and Pantotheca cumulus P-23 (denoted as PD_PA treatment); 6) The combination of Pseudomonas aeruginosa N-13 and Aspergillus (denoted as PD_AP treatment); 7) Agrobacterium and Pantotheca agglutinosa P-23 combination (denoted as AT_PA treatment); 8) Agrobacterium and Aspergillus combination (denoted as AT_AP treatment).

[0034] Before starting the culture experiment, oligophosphate nutrient liquid culture media with different pH conditions (3.0, 4.0, 5.0, 6.0, 7.0) were prepared. The formulation of the oligophosphate nutrient liquid culture medium was as follows: glucose 10 g / L, ferric phosphate 5 g / L, magnesium chloride 10 g / L, magnesium sulfate 0.25 g / L, potassium chloride 0.2 g / L, and calcium chloride 20 mg / L. The pH of the culture medium was adjusted to 3.0, 4.0, 5.0, 6.0, and 7.0 respectively by adding 0.1 mol / L dilute hydrochloric acid and calcium carbonate. The medium was sterilized at 121℃ for 20 min.

[0035] Finally, 1 mL of the above-treated bacterial solution was added to a 50 mL sterile headspace vial containing 30 mL of oligo-nitrogenous phosphorus nutrient liquid medium, and incubated at 28°C for 14 days. After incubation, the bacterial solution was filtered and centrifuged at 12000 rpm for 2 min. The supernatant was collected, and the available nitrogen content in the liquid was determined by colorimetry to characterize nitrogen fixation capacity. The available phosphorus content was determined by molybdenum-antimony colorimetric method to characterize ferric phosphate activation capacity. The results are shown in […]. Figure 3 , Figure 4 Tables 1 and 2.

[0036] Regarding effective nitrogen accumulation, the PD_PA combination exhibited the highest or near-highest activity under all tested pH conditions. Figure 3 (in Figure 3 In the figure, (a) represents the effective nitrogen accumulation of different single bacteria. Figure 3 (b) shows the effective nitrogen accumulation of the synthetic bacterial community combination (see Table 1). Especially under strong acid stress at pH 3.0, the effective nitrogen accumulation of the PD_PA treatment reached 101.24 ± 0.99 mg / L, 1.85 times that of single-strain PD, and significantly higher than other combinations (such as PD_AP's 90.29 mg / L). As the pH increased to 4.0-6.0, the nitrogen fixation capacity of the PD_PA combination remained leading, reaching a peak of 96.99 mg / L at pH 4.0. Even under neutral conditions at pH 7.0, although its activity decreased somewhat, it still maintained a relative advantage.

[0037] Table 1. Effective nitrogen accumulation in each treatment under different pH conditions (mg / L, mean ± standard error, n=5) ; The PD_PA combination also performed exceptionally well in terms of effective phosphorus release, see [link to relevant documentation]. Figure 4 (in Figure 4In the figure, (a) represents the effective phosphorus release of different single bacteria. Figure 4 (b) shows the effective phosphorus release from the combined microbial community (see Table 2). In a strongly acidic environment of pH 3.0–4.0, its ability to activate ferric phosphate was most significant, with effective phosphorus release reaching 345.04 ± 11.20 mg / L (pH 3.0) and 317.09 ± 4.10 mg / L (pH 4.0), respectively. This value not only far exceeded all single-strain treatments (e.g., 2.99 times that of single-strain PD at pH 3.0), but was also generally higher than or equal to other combinations. Notably, even under stress conditions where ferric phosphate was the sole phosphorus source, the PD_PA combination still efficiently released phosphorus, confirming its highly efficient activation ability for insoluble ferric phosphate.

[0038] Table 2. Effective phosphorus release from each treatment under different pH conditions (mg / L, mean ± standard error, n=5) ; The nutrient activation efficiency of the PD_PA combination is not a simple superposition of the functions of the two single bacteria, but rather produces a stronger synergistic effect. For example, at pH 4.0, the accumulation of available nitrogen and available phosphorus in PD_PA far exceeds the sum of the corresponding indicators of PD and PA single bacteria. This synergy suggests that *Pseudomonas donghuensis* N-13 and *Plasmodium spp.* P-23 may have metabolic complementarity and mutual promotion in the symbiotic system, thus maintaining vigorous physiological activity and nutrient conversion function under acidic oligotrophic stress.

[0039] In summary, the acid-resistant synthetic bacterial communities *Pseudomonas aeruginosa* N-13 and *Pantothecinus flocculationensis* P-23 obtained in this invention exhibit excellent and stable functions in simultaneously increasing available nitrogen content and specifically activating iron phosphate under a wide range of acidic conditions (pH 3.0-7.0). Furthermore, under combined stress conditions of acidic oligotrophic environment, their synergistic efficiency in nitrogen fixation and phosphorus release is significantly enhanced, demonstrating high environmental adaptability. This synthetic bacterial community has strong versatility and can be applied to the remediation of acidic soils, acidic water bodies, and similar nitrogen- and phosphorus-limited ecological environments, showing promising application prospects.

[0040] 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 synthetic bacterial community of acid-resistant nitrogen-fixing and activated ferric phosphate, characterized in that, Composed of the following microbial strains: *Pseudomonas aeruginosa* ( Pseudomonas donghuensis N-13 and Pantotheca agglomerata ( Pantoea agglomerans P-23; the preservation number of the Pantotheca cumulus P-23 is CGMCC No. 37622, ​​and the preservation number of Pseudomonas donghuensis N-13 is CGMCC No. 37624.

2. The synthetic microbial community according to claim 1, characterized in that, The effective viable count ratio of the clustered pantothecin P-23 to the Donghu Pseudomonas N-13 is 1:

1.

3. A compound microbial agent, characterized in that, Includes the synthetic microbial community as described in claim 1 or 2.

4. The compound microbial agent according to claim 3, characterized in that, The OD of the synthetic bacterial community in the compound microbial agent 600 Value ≥ 0.

5.

5. The application of the synthetic microbial community according to claim 1 or 2 or the compound microbial agent according to claim 3 or 4 for biological nitrogen fixation and phosphorus release by activation of insoluble phosphate under acidic conditions, wherein the acidic conditions include acidic soil or acidic water; the pH range of the acidic conditions is 3.0-7.0; and the insoluble phosphate is iron phosphate or aluminum phosphate.

6. A method for simultaneously increasing the content of available nitrogen and available phosphorus in an acidic oligotrophic environment, characterized in that, include: The synthetic microbial community as described in claim 1 or 2, or the compound microbial agent as described in claim 3 or 4, is applied to an acidic, oligotrophic environment.

7. The method according to claim 6, characterized in that, The acidic oligotrophic environment refers to acidic soil or acidic water bodies where insoluble phosphate is the sole or primary phosphorus source; the insoluble phosphate is iron phosphate or aluminum phosphate.

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