Aerobic iron-reducing fungi promoted by aged iron filings for denitrification and application thereof

Abstract

The present application belongs to the technical field of water pollution treatment, and relates to microbial treatment, in particular to an aged iron filings promoted aerobic iron-reducing fungi for denitrification and application thereof. Aspergillus The aerobic iron-reducing fungi is classified and named as sp. R4, and is preserved in China Center for Type Culture Collection on February 13, 2025, with a preservation number of CCTCC NO: M 2025217. Aquabacter cavernae 1-5 are products obtained by iron filings oxidation in the process of denitrification. The present application provides a new insight for the repair of low carbon-nitrogen ratio water body.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control technology, and relates to microbial treatment, specifically to an aerobic iron-reducing fungus that promotes denitrification of aged iron filings and its application. Background Technology

[0002] Nitrate pollution in water bodies has become one of the major types of pollution in the water treatment field. In recent years, aerobic denitrification, a biological nitrogen removal technology, has received increasing attention from researchers. The intracellular electron transfer mechanism during aerobic denitrification by microorganisms has been extensively studied. However, this biological nitrogen removal technology often faces the problem of insufficient electrons. Biological denitrification is divided into autotrophic denitrification and heterotrophic denitrification based on the type of electron donors utilized by the microorganisms. Heterotrophic denitrification technology, with its added organic carbon source, can cause secondary pollution, while autotrophic denitrification technology suffers from slow start-up and slow denitrification rates. Current research has proposed a heterotrophic-autotrophic synergistic denitrification technology that simultaneously adds organic and inorganic electron donors to treat nitrate wastewater. This technology can reduce the amount of organic matter added while achieving higher denitrification efficiency, resulting in greater economic and environmental benefits. Therefore, the heterotrophic-autotrophic synergistic biological nitrogen removal technology has greater application potential.

[0003] Iron filings are a common inorganic electron donor. The coupling process between iron and nitrogen is very common and complex, involving iron in many biological denitrification processes, such as anaerobic ammonium oxidation, nitrification, denitrification, and ferric ammonium oxidation. The intracellular electron transfer process of nitrate-reducing ferrous oxidizing bacteria has been extensively studied; these microorganisms can couple nitrate reduction and ferrous oxidation processes. However, these bacteria are traditionally believed to exist under anaerobic conditions, and similar microorganisms under aerobic conditions are rarely reported. Furthermore, in this process, most of the reduced iron is ultimately oxidized to ferric iron. It is worth considering whether ferric iron can be utilized by other microorganisms under aerobic conditions to maximize waste resource utilization. The discovery of aerobic iron-reducing microorganisms may enable the effective utilization of ferric iron. Biological iron reduction is traditionally thought to occur under anaerobic and aerobic but acidic conditions. Currently, only a few studies have reported the existence of aerobic iron-reducing bacteria and aerobic iron-reducing actinomycetes under neutral conditions. To our knowledge, aerobic iron-reducing fungi under neutral conditions have not yet been reported. Moreover, it is unknown whether these microorganisms can participate in aerobic denitrification processes. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide an aerobic iron-reducing fungus that promotes denitrification from aged iron filings and its application, thereby solving the technical problem that existing methods for denitrification in water bodies with low carbon-to-nitrogen ratios need further improvement.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an aerobic iron-reducing fungus that promotes denitrification of aged iron filings, wherein the aerobic iron-reducing fungus is classified and named as follows: Aspergillus sp. R4 was deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M 2025217.

[0007] This invention is the first discovery of a unique aerobic iron-reducing fungus— Aspergillus sp. R4. This fungus exhibits remarkable ferric iron reduction and denitrification capabilities under aerobic conditions. Further research revealed that the addition of aged iron filings significantly enhanced its denitrification capacity. This finding provides new ideas and methods for utilizing microorganisms in environmental remediation and resource recovery.

[0008] In a second aspect, the present invention provides a composition for denitrification, comprising the aforementioned aerobic iron-reducing fungi and iron filings.

[0009] Furthermore, the iron is aged iron filings.

[0010] Furthermore, the aged iron filings are products obtained by the oxidation of iron filings during the denitrification process by aerobic denitrifying bacteria.

[0011] Furthermore, the aerobic denitrifying bacteria are Aquabacter cavernae 1-5 were deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M 2025216.

[0012] Thirdly, the present invention provides the application of the aerobic iron-reducing fungus or the composition thereof in the remediation of nitrogen-containing water bodies.

[0013] Furthermore, the source of nitrogen includes nitrates.

[0014] Fourthly, the present invention provides a method for remediating nitrogen-containing water bodies using the aforementioned aerobic iron-reducing fungi, comprising the step of adding the aerobic iron-reducing fungi to the nitrogen-containing water body.

[0015] Furthermore, the method also includes the step of adding aged iron filings, which are products obtained by the oxidation of iron filings during the denitrification process by aerobic denitrifying bacteria. The aerobic denitrifying bacteria are... Aquabacter cavernae 1-5 were deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M2025216.

[0016] Furthermore, the aerobic iron-reducing fungi and aged iron filings are added simultaneously or sequentially.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] This invention yields an aerobic iron-reducing fungus that promotes rapid denitrification of aged iron filings. Aspergillus sp. R4 and a strain of iron filings can promote aerobic denitrification bacteria that facilitate nitrogen removal. Aquabacter cavernae 1-5. First, with the addition of iron filings, the aerobic denitrifying bacteria... Aquabacter cavernae The denitrification efficiency of the bacteria increased in steps 1-5. However, as the iron filings were continuously oxidized, the denitrification efficiency of this aerobic denitrifying bacteria was no longer promoted. At this point, the iron filings obtained after the third oxidation step were treated as aged iron filings and added to the aerobic iron-reducing fungi. Aspergillus In the denitrification medium containing sp. R4, this aerobic iron-reducing fungus was found to also perform aerobic denitrification, and at a rate higher than that of aerobic denitrifying bacteria. Aquabacter cavernae 1-5 is faster. Furthermore, the addition of aged iron filings promotes denitrification by this aerobic iron-reducing fungus. Therefore, along with the oxidation of the iron filings, aerobic denitrifying bacteria... Aquabacter cavernae 1-5 and aerobic iron-reducing fungi Aspergillus The denitrification effect of sp. R4 was enhanced. In summary, the combined use of these two bacteria provides a new approach for the remediation of nitrate-polluted waters with low carbon-to-nitrogen ratios and offers new insights into the development of multifunctional aerobic denitrification biological resources. Attached Figure Description

[0019] Figure 1 Phylogenetic tree of aerobic denitrifying bacteria 1-5.

[0020] Figure 2 The effect of iron filings on denitrification by aerobic denitrifying bacteria 1-5 was investigated. Among them, (a) 1-5; (b) 1-5 + iron filings in the first stage; (c) 1-5 + iron filings in the second stage; (d) 1-5 + iron filings in the third stage.

[0021] Figure 3 The effects of iron filings on the growth and carbon removal of aerobic denitrifying bacteria 1-5 were investigated. The results were: (a) 1-5; (b) 1-5 + iron filings from the first stage; (c) 1-5 + iron filings from the second stage; and (d) 1-5 + iron filings from the third stage.

[0022] Figure 4 The aerobic ferric reduction ability of the aerobic ferric reducing fungus R4 to ferric citrate was studied.

[0023] Figure 5 Phylogenetic tree of the aerobic iron-reducing fungus R4.

[0024] Figure 6The effects of aged iron filings on denitrification by aerobic iron-reducing fungi R4 and aerobic denitrifying bacteria 1-5 were investigated. The results were: (a) R4; (b) 1-5; (c) 1-5 + R4; (d) first-stage aged iron filings; (e) second-stage aged iron filings; (f) third-stage aged iron filings; (g) R4 + first-stage aged iron filings; (h) R4 + second-stage aged iron filings; (i) R4 + third-stage aged iron filings; (j) 1-5 + first-stage aged iron filings; (k) 1-5 + second-stage aged iron filings; (l) 1-5 + third-stage aged iron filings; (m) R4 + 1-5 + first-stage aged iron filings; (n) R4 + 1-5 + second-stage aged iron filings; (o) R4 + 1-5 + third-stage aged iron filings.

[0025] Figure 7 The effects of aged iron filings on the cell growth and carbon removal of aerobic iron-reducing fungi R4 and aerobic denitrifying bacteria 1-5 were investigated. The results were: (a) R4; (b) 1-5; (c) 1-5 + R4; (d) first-stage aged iron filings; (e) second-stage aged iron filings; (f) third-stage aged iron filings; (g) R4 + first-stage aged iron filings; (h) R4 + second-stage aged iron filings; (i) R4 + third-stage aged iron filings; (j) 1-5 + first-stage aged iron filings; (k) 1-5 + second-stage aged iron filings; (l) 1-5 + third-stage aged iron filings; (m) R4 + 1-5 + first-stage aged iron filings; (n) R4 + 1-5 + second-stage aged iron filings; (o) R4 + 1-5 + third-stage aged iron filings. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified.

[0027] The denitrification solid medium used was a known denitrification solid medium in the prior art. The formulation per 1L consisted of: 0.844g C4H4Na2O4, 0.108g KNO3, 0.1g MgSO4, 1g KH2PO4, 1.5g Na2HPO4·7H2O, 2mL trace elements, and 10g agar powder. The pH of the solution was adjusted to 7.0 with sodium hydroxide. The prepared denitrification solid medium was sterilized at 121℃ for 30 minutes and then poured into sterile petri dishes.

[0028] The denitrification liquid medium used was a known denitrification liquid medium in the prior art. The formulation per 1L consisted of: 0.0844g C4H4Na2O4, 0.036g KNO3, 0.1g MgSO4, 0.2g KH2PO4, 0.25g Na2HPO4·7H2O, and 2mL of trace elements. The pH of the solution was adjusted to 7.0 with sodium hydroxide. The prepared denitrification liquid medium was sterilized at 121℃ for 30 minutes before use.

[0029] The formulas for the above trace elements are as follows: 4.4 mg / L ZnSO4, 144 mg / L EDTA-2Na, 10.2 mg / L MnCl2·4H2O, 11 mg / L CaCl2, 10 mg / L FeSO4·7H2O, 3.2 mg / L CuSO4·5H2O, and 2.2 mg / L (NH4)6Mo7O. 24 • 4H2O, 3.2 mg / L CoCl2·6H2O. After completely dissolving all the above components, bring the volume to a final volume with ultrapure water.

[0030] Iron reduction liquid medium is based on denitrification liquid medium with the addition of 0.3350 g / L of ferric citrate.

[0031] This embodiment describes an aerobic denitrifying bacterium, named... Aquabacter cavernae 1-5 are deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M 2025216, located in Wuhan.

[0032] In this embodiment, the screening and identification method for aerobic denitrifying bacteria specifically includes the following steps:

[0033] Step 1: Isolation and purification of aerobic denitrifying bacteria:

[0034] A mud-water mixture of sediment from a landscape water body in Xi'an was ultrasonically treated for 10 seconds, and then the suspension was serially diluted with sterile water at 10, 10, and 10 times dilutions. 2 10 3 10 4 10 5Take 100 μL of suspension diluted at different gradients and spread it onto denitrification solid medium. Perform three replicates for each dilution gradient. Incubate the plates upside down in a 30°C biochemical incubator for approximately 10 days until distinct bacterial colonies form. Remove the plates with colonies and use a sterile inoculation loop to inoculate different bacteria onto fresh denitrification solid medium and streak them. Return the streaked plates to the incubator for further incubation. Repeat the streak separation process until clearly morphologically uniform single bacterial colonies are observed. Inoculate the selected single bacteria into liquid medium with and without iron filings for further screening to identify aerobic denitrification bacteria that promote nitrogen removal when iron filings are added.

[0035] Step 2, Molecular biological identification of aerobic denitrifying bacteria:

[0036] DNA from the test strain was extracted using the Ezup column-based bacterial genomic DNA extraction kit, followed by DNA electrophoresis and PCR amplification. The primers used for PCR amplification were 27F and 1492R, their sequences shown in SEQ ID NO.2 and SEQ ID NO.3, respectively. The 25 μL PCR reaction system consisted of: 10×PCR Buffer, 10 mM each of dNTPs, 5 U / μL TaqPlus DNA Polymerase, 12.5 μL 50 mM MgSO4, 1 μL 10 µM primer F, 1 μL 10 µM primer R, 1 μL DNA template, and 9.5 μL ddH2O. The PCR program was: 95℃, 5 min; 94℃, 30 s; 57℃, 30 s; 72℃, 90 s; 30 cycles, followed by 72℃, 10 min. The 16S rDNA nucleotide sequence was then obtained by electrophoresis and sequencing, as shown in SEQ ID NO.1.

[0037]

[0038] SEQ ID NO. 2: AGAGTTTGATCMTGGCTCAG.

[0039] SEQ ID NO. 3: GGTTACCTTGTTACGACTT.

[0040] The sequences obtained above were compared with known sequences in NCBI, and a phylogenetic tree was constructed. The results are as follows: Figure 1 As shown, analysis suggests that the tested strain is *Aquaporinus cavitaria* (…). Aquabacter cavernae ), and named it Aquabacter cavernae 1-5, denoted as 1-5.

[0041] Example 2:

[0042] This embodiment describes the addition of iron filings to the aerobic denitrifying bacteria of Example 1. Aquabacter cavernae The denitrification effects of 1-5 are detailed below:

[0043] Take 1 mL of solution with a concentration of 3.428 × 10⁻⁶. 7 Seed culture of aerobic denitrifying bacteria with a concentration of cells / mL was inoculated into 199 mL of fresh denitrification liquid medium. Treatment groups were set up with and without 5 g / L iron filings, with three replicates for each treatment group. The cultures were incubated in the dark at 30°C and 140 rpm for 108 h. Samples were taken to determine the cell count, dissolved organic carbon (DOC), total nitrogen (TN), and ammonia nitrogen (NH4). + -N, nitrate nitrogen NO3 - -N and nitrite nitrogen NO2 - The concentration of -N. After the first stage reaction, iron filings were removed and added to fresh denitrification liquid culture medium, and new aerobic denitrifying bacteria were introduced simultaneously. The second stage reaction was carried out under the same conditions. Similarly, the three-stage reaction was carried out. The results are as follows. Figure 2 and Figure 3 As shown.

[0044] Depend on Figure 2 It can be seen that, compared with only adding aerobic denitrifying bacteria... Aquabacter cavernae Compared to the control group, strain 1-5 showed higher denitrification efficiency in both the first and second stages of the iron filings treatment, indicating that iron filings promoted aerobic denitrification in strain 1-5. However, in the third stage with added iron filings, the denitrification efficiency of strain 1-5 decreased, suggesting that as the reaction progressed, the iron filings were continuously oxidized, leading to a cessation of denitrification promotion in strain 1-5. Therefore, zero-valent iron and ferrous iron play a dominant role in the denitrification enhancement process of strain 1-5.

[0045] Depend on Figure 3It was observed that although high nitrogen removal efficiency was observed in both the first and second stages of the iron filings treatment group, the cell number of aerobic denitrifying bacteria 1-5 was lower in the first stage than in the control group without iron filings. However, iron filings in the second stage promoted the growth and carbon removal of strain 1-5. This indicates that excessive iron filings can also cause some toxicity to strain 1-5, possibly attributed to the free radicals generated by the reaction of reduced iron with oxygen. This also suggests that the cells surviving in the first stage have stronger denitrification performance.

[0046] Example 3:

[0047] This embodiment describes an aerobic iron-reducing fungus, named... Aspergillus sp. R4 is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 2025217 in Wuhan.

[0048] In this embodiment, the screening and identification method for the aerobic iron-reducing fungus specifically includes the following steps:

[0049] Step 1, Isolation and purification of fungi:

[0050] A sludge-water mixture of activated sludge from a wastewater treatment plant in Xi'an was ultrasonically treated for 10 seconds, and then the suspension was serially diluted with sterile water at 10, 10, and 10 times dilutions. 2 10 3 10 4 10 5 Take 100 μL of the diluted suspension and spread it onto denitrification solid medium. Perform three replicates for each dilution gradient. Incubate the plates upside down in a 30°C biochemical incubator for approximately 5 days, until distinct fungal colonies form. Using a sterile inoculation loop, inoculate the colonies onto fresh denitrification solid medium and streak the plates. Return the streaked plates to the incubator for further incubation. Repeat the streak isolation process until clearly visible, uniformly morphologically uniform fungal colonies with spores are observed.

[0051] Step 2, Analysis of the aerobic iron reducing capacity of fungi:

[0052] Different morphologies of fungi were inoculated into fresh aerobic denitrification liquid medium. After a large number of mycelia grew, the fungi were preserved with glycerol at a 1:1 ratio and stored at -20°C. 0.5 mL of the preserved bacterial culture was taken and inoculated into 100 mL of fresh aerobic denitrification liquid medium for activation. Subsequently, 20 μL of the activated bacterial culture was inoculated into 10 mL of liquid denitrification medium supplemented with ferric citrate. The control group contained only liquid medium and no bacterial culture. Sterile air was added to each treatment group daily to ensure an aerobic environment was maintained. Each treatment group was divided into three replicates, and ferrous iron was measured under aerobic conditions. Results are as follows: Figure 4 As shown.

[0053] Depend on Figure 4 It can be seen that, with or without addition Aspergillus Compared to the control group of sp. R4, in addition Aspergillus Higher ferrous concentrations were detected in the sp. R4 treatment group, indicating that... Aspergillus sp. R4 can reduce ferric iron under aerobic conditions.

[0054] Step 3, Molecular biological identification of aerobic iron-reducing fungi:

[0055] DNA from the test strain was extracted using the Ezup column-based fungal genomic DNA extraction kit, followed by DNA electrophoresis and PCR amplification. The primers used for PCR amplification were ITS1 and ITS4-R, whose sequences are shown in SEQ ID NO. 5 and SEQ ID NO. 6, respectively. The 25 μL PCR reaction system consisted of: 10×PCR Buffer, 10 mM each of dNTPs, 5 U / μL Taq Plus DNA Polymerase, 12.5 μL 50 mM MgSO4, 1 μL 10 µM primer F, 1 μL 10 µM primer R, 1 μL DNA template, and 9.5 μL ddH2O. The PCR program was: 95℃, 5 min; 94℃, 30 s; 57℃, 30 s; 72℃, 90 s; 30 cycles, followed by 72℃, 10 min. The ITS nucleotide sequence was then obtained by electrophoresis and sequencing, as shown in SEQ ID NO. 4.

[0056] SEQ ID NO.4:

[0057] SEQ ID NO.5:TCCGTAGGTGAACCTGCGG.

[0058] SEQ ID NO.6:TCCTCCGCTTATTGATATGC.

[0059] The sequences obtained above were compared with known sequences in NCBI, and a phylogenetic tree was constructed. The results are as follows: Figure 5 As shown. Analysis suggests that the tested strain belongs to the genus Aspergillus ( ). Aspergillus sp.), named it Aspergillus sp.R4, denoted as R4.

[0060] Example 4:

[0061] This embodiment demonstrates the denitrification effect of adding the aerobic iron-reducing fungus R4 from Example 3 to aged iron filings. Details are as follows:

[0062] First, the fungal spores were rinsed with sterile phosphate buffer, while scraping them off with a sterile spreader and repeatedly rinsing the petri dish. The suspension containing the spores was then passed through three layers of lens paper. The filtrate was centrifuged and washed at least three times to prepare the aerobic iron-reducing fungus. Aspergillus The concentration of sp. R4 spore suspension was determined by dilution and spread plating method. Simultaneously, the spore suspension was diluted with sterile phosphate buffer to control its concentration at 3.428 × 10⁻⁶. 7 The concentration is cells / mL, which is consistent with the concentration of aerobic denitrifying bacteria solution.

[0063] In the formal experiment, seven treatment groups were set up, including: ① 1-5; ② R4; ③ 1-5 + R4; ④ aged iron filings; ⑤ aged iron filings + 1-5; ⑥ aged iron filings + R4; ⑦ aged iron filings + 1-5 + R4. Each treatment group was set up in triplicate. The aged iron filings were obtained from the iron filings after the third stage of the reaction in Example 2, and the denitrification liquid culture medium in each treatment group was 199 mL. In treatment groups ② and ⑥, 1 mL of fungus R4 was inoculated; in treatment groups ① and ⑤, 1 mL of bacteria 1-5 was inoculated; and in treatment groups ③ and ⑦, 0.5 mL of R4 and 0.5 mL of 1-5 were inoculated simultaneously. All treatment groups were cultured at 30°C and 140 rpm for 108 h. Samples were taken to determine the cell count, dissolved organic carbon (DOC), total nitrogen (TN), and ammonia nitrogen (NH4). + -N, nitrate nitrogen NO3 - -N and nitrite nitrogen NO2 - -N concentration. After the first stage reaction, aged iron filings were removed and added to fresh denitrification liquid culture medium, along with fresh R4 and 1-5, and the second stage reaction was carried out under the same conditions. Similarly, three stages were performed. The results are as follows. Figure 6 and Figure 7 As shown.

[0064] Depend on Figure 6 It was found that in the system with added aged iron filings, compared with aerobic denitrifying bacteria 1-5, aerobic iron-reducing fungus R4 exhibited faster aerobic denitrification performance, achieving relatively high nitrate and total nitrogen removal rates within 12 hours. Furthermore, the denitrification rate of the reaction system with both 1-5 and R4 added was not significantly different from that of the system with only R4 added, indicating that aerobic iron-reducing fungus R4 was dominant in the co-culture system. Compared with the system without added aged iron filings, the presence of aged iron filings promoted denitrification by aerobic iron-reducing fungus R4, and a lower nitrite concentration was detected. Therefore, the increased denitrification efficiency may be attributed to both the biological process and the chemical reaction between ferrous iron and nitrite.

[0065] Depend on Figure 7It can be seen that, compared with aerobic denitrifying bacteria 1-5, aerobic iron-reducing fungus R4 can rapidly utilize dissolved organic carbon to maintain cell growth. Figure 6 The results were similar; the co-culture system showed little difference compared to the system with only R4 added. However, the total number of bacterial cells 1-5 was higher than that of fungal R4 after the reaction, indicating that, for individual cells, the aerobic iron-reducing fungus R4 had stronger denitrification performance than the aerobic denitrifying bacteria 1-5.

[0066] The results from Examples 1 to 4 show that, along with the oxidation of iron filings, aerobic denitrifying bacteria... Aquabacter cavernae 1-5 and aerobic iron-reducing fungi Aspergillus The denitrification effect of sp. R4 was enhanced, indicating that the use of these two bacteria can improve the denitrification capacity of water bodies. This study provides a new approach for the development of denitrifying agents and the treatment of water bodies with low carbon-to-nitrogen ratios.

[0067] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. An aerobic iron-reducing fungus that promotes denitrification of aged iron filings, characterized in that, The aerobic iron-reducing fungi are classified and named as follows: Aspergillus sp. R4 was deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M 2025217.

2. A composition for denitrification, characterized in that, Includes the aerobic iron-reducing fungi and iron filings as described in claim 1.

3. The composition for denitrification according to claim 2, characterized in that, The iron in question is aged iron filings.

4. The composition for denitrification according to claim 3, characterized in that, The aged iron filings are products obtained by the oxidation of iron filings during the denitrification process by aerobic denitrifying bacteria.

5. The composition for denitrification according to claim 4, characterized in that, The aerobic denitrifying bacteria are Aquabacter cavernae 1-5 were deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M 2025216.

6. The application of the aerobic iron-reducing fungus of claim 1 or the composition of any one of claims 2 to 5 in the remediation of nitrogen-containing water bodies, characterized in that, The nitrogen in the nitrogen-containing water body is derived from nitrates.

7. A method for remediating nitrogen-containing water bodies using the aerobic iron-reducing fungi described in claim 1, characterized in that, The method includes the step of adding the aerobic iron-reducing fungus to a nitrogen-containing water body, wherein the nitrogen in the nitrogen-containing water body is derived from nitrate.

8. The method according to claim 7, characterized in that, The process also includes adding aged iron filings, which are products obtained by the oxidation of iron filings during the denitrification process by aerobic denitrifying bacteria. The aerobic denitrifying bacteria are... Aquabacter cavernae 1-5 were deposited at the China Center for Type Culture Collection on February 13, 2025, with accession number CCTCC NO: M 2025216.

9. The method according to claim 8, characterized in that, The aerobic iron-reducing fungi and aged iron filings are added simultaneously or sequentially.

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