Enterobacter asburiae and its application and accumulation method for accumulating nitrite

Abstract

This invention discloses a strain of *Enterobacter argentea*, deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 2022760 and deposit date May 30, 2022. This strain of bacteria is used to achieve the conversion of nitrate to nitrite in nitrate-containing substrates and to achieve a large accumulation of nitrite. The *Enterobacter argentea* strain of this invention can utilize common organic matter (such as readily degradable organic pollutants in common wastewater, glucose, sodium citrate, sucrose, etc., single or mixed organic substances) as a carbon source, thereby utilizing nitrate produced during nitrification in common wastewater as an electron acceptor to achieve a large accumulation of nitrite. This provides sufficient nitrite for anaerobic ammonia oxidation processes for nitrogen removal in water and also enables nitrite recovery. It can be combined with short-cut nitrification / denitrification and anaerobic ammonia oxidation to achieve denitrification of wastewater or water bodies, and can also achieve nitrite accumulation for recovery.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, specifically to a type of Enterobacter auriculi and its application and accumulation method in nitrite accumulation. Background Technology

[0002] With frequent human activities, excessive nitrogen emissions into the environment have led to severe water pollution phenomena such as cyanobacterial blooms and red tides. Biological denitrification is widely used in water and wastewater denitrification due to its high efficiency and environmental friendliness. In most urban wastewater treatment plants, nitrogen removal is achieved through microbial denitrification. However, as a typical heterotrophic bacterium, denitrification often requires organic matter as a carbon source. Yet, with the rapid increase in urban domestic sewage discharge and its trend towards a low C / N ratio, traditional biological denitrification methods face the challenge of insufficient carbon sources. Therefore, new technologies based on carbon reduction and high efficiency, such as "short-cut nitrification-denitrification" and "anaerobic ammonium oxidation," have gained significant attention.

[0003] Anaerobic ammonia oxidation (Anammox) refers to the oxidation of ammonia under anaerobic conditions using CO2 / CO3. 2- As a carbon source, with NO2 - -N is the electron acceptor, which will accept NH4+. + -N is oxidized to N2, producing a small amount of NO3. - -N. Compared to traditional biological nitrogen removal, anaerobic ammonium oxidation (ANAO) reduces energy consumption from aeration and carbon source replenishment, and decreases excess sludge production. Its economic, efficient, and clean advantages make it a highly promising biological nitrogen removal process. However, the mainstream application of ANAO in wastewater treatment plants still faces many challenges. Wastewater often contains only ammonia nitrogen, with relatively low levels of nitrite nitrogen. In common nitrification and denitrification processes, nitrite is an intermediate product, making its accumulation in large quantities extremely difficult. Therefore, simply using ANAO to treat this type of wastewater requires the additional addition of nitrite, increasing treatment costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for short-cut denitrification using Enterobacter aeruginosa to solve the technical problems in current anaerobic ammonia oxidation technology.

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

[0006] A strain of Enterobacter aegyptiacus, deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO:M 2022760, and deposited on May 30, 2022.

[0007] As a preferred embodiment of the present invention, after the Enterobacter aeruginosa is cultured on LB agar medium for 48 hours, the colonies are round, white, raised, with neat and smooth edges, and Gram staining is negative.

[0008] As a preferred embodiment of the present invention, after the Enterobacter aeruginosa is cultured in a denitrified solid medium containing organic carbon source and nitrate for 2 days, the colony diameter (d) is 2.40±0.59 mm.

[0009] In addition, the present invention provides an application of Enterobacter auriculi in the accumulation of nitrite, which is used to achieve the conversion of nitrate to nitrite in a nitrate-containing matrix and to achieve the large-scale accumulation of nitrite.

[0010] In addition, the present invention also provides a method for nitrite accumulation using Enterobacter auriculi, comprising the following steps:

[0011] Step 100, amplification of the bacterial strain: The strain of Enterobacter aegyptiaceae was inoculated into LB liquid medium and cultured at 25-35℃ for 1-2 days. The concentration and growth status of the bacteria were characterized by absorbance at 600 nm.

[0012] Step 200, preservation of bacterial strain: Weigh a certain volume of glycerol, sterilize the glycerol by high-pressure steam sterilization for 15-30 minutes, and then cool it to room temperature; take an appropriate amount of the expanded bacterial culture and add it to the glycerol to form a glycerol-bacterial strain mixture with a final glycerol concentration of 10-30%, and store it in cryovials at -18℃ or below for later use;

[0013] Step 300, Dilution of bacterial strain: Dilute the amplified Enterobacter aegyptiacus with physiological saline to prepare the corresponding bacterial suspension;

[0014] Step 400, bacterial inoculation and nitrite generation: Take an appropriate amount of the bacterial suspension described in step 300, inoculate it into a substrate containing nitrate and organic matter, and culture it by shaking or mechanical stirring at 25-35℃.

[0015] Step 500, determination of nitrite accumulation: During step 400, the mixture is periodically taken out from the matrix for nitrate and nitrite determination to obtain the cumulative concentration of nitrite and the nitrite formation rate.

[0016] In addition, the present invention also provides that the substrate is nitrate-containing wastewater, domestic sewage or culture medium.

[0017] In addition, the present invention also provides that the matrix contains organic matter as a carbon source, wherein the organic matter is a carbon source formed by a single or mixed organic pollutant in wastewater, glucose, sodium citrate, or sucrose.

[0018] In addition, the present invention also provides a formula for calculating the formation rate of the nitrite:

[0019] Nitrite formation rate % = (C t -C0) / (C n0 -C nt )×100%;

[0020] Among them, C0 and C t C represents the nitrite content in the substrate at the initial 0 days and after t days of cultivation, respectively; n0 and C n0 The values ​​represent the nitrate content in the substrate at the initial stage and after t days of cultivation, respectively.

[0021] As a preferred embodiment of the present invention, the culture medium consists of: 1.50g KNO3, 7.38g KH2PO4, 2.42g K2HPO4, 0.39g NH4Cl, 0.20g MgCl·7H2O, and distilled water to a final volume of 1000mL.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The Enterobacter aegyptiacus of the present invention has the advantages of strong short-cut denitrification ability, is green and environmentally friendly, and is of great significance for short-cut denitrification-anaerobic ammonia oxidation coupled process. Attached Figure Description

[0024] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0025] Figure 1 This is the bacterial culture colony status of Enterobacter aegyptiacus of the present invention.

[0026] Figure 2 This is a diagram illustrating the effect of nitrite accumulation obtained by the present invention.

[0027] Figure 3 This is a Gram staining result of Enterobacter aegyptiacus according to the present invention.

[0028] Figure 4 This is the NCBI matching result for Enterobacter aegyptiacus of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figures 1-4 As shown, in this invention, the *Enterobacter asburiae* with accession number CCTCC 2022760 was mainly collected from mangrove environment samples. The 16S rDNA gene sequence of *Enterobacter asburiae* is shown in the sequence listing. The depositary institution is the China Center for Type Culture Collection, located at Wuhan University, Wuhan, China, 430072, China. The name of the deposited culture is *Enterobacter asburiae* DNW01, and the deposit date is May 30, 2022.

[0031] The characteristics of Enterobacter aegyptias after 48 hours of culture on the culture medium are as follows:

[0032] H17 colonies are round, milky white, raised, with neat and smooth edges, and are Gram-negative.

[0033] After culturing the *Enterobacter argentea* in a denitrified solid medium containing organic carbon sources and nitrates for 2 days, the colony diameter (d) was 2.40 ± 0.59 mm.

[0034] The present invention also provides an application of Enterobacter auriculi in short-cut denitrification technology, that is, using this strain of bacteria to achieve the conversion of nitrate to nitrite in nitrate-containing substrates and to achieve the accumulation of large amounts of nitrite.

[0035] In a preferred embodiment of the present invention, the carbon source includes glucose, sucrose, and sodium citrate.

[0036] In addition, the present invention also provides a method for nitrite accumulation using Enterobacter auriculi, comprising the following steps:

[0037] Step 100, amplification of the bacterial strain: The strain of Enterobacter aegyptiaceae was inoculated into LB liquid medium and cultured at 25-35℃ for 1-2 days. The concentration and growth status of the bacteria were characterized by absorbance at 600 nm.

[0038] Step 200, preservation of bacterial strain: Weigh a certain volume of glycerol, sterilize the glycerol by high-pressure steam sterilization for 15-30 minutes, and then cool it to room temperature; take an appropriate amount of the expanded bacterial culture and add it to the glycerol to form a glycerol-bacterial strain mixture with a final glycerol concentration of 10-30%, and store it in cryovials at -18℃ or below for later use;

[0039] Step 300, Dilution of bacterial strain: Dilute the amplified Enterobacter aegyptiacus with physiological saline to prepare the corresponding bacterial suspension;

[0040] Step 400, bacterial inoculation and nitrite generation: Take an appropriate amount of the bacterial suspension described in step 300, inoculate it into a substrate containing nitrate and organic matter, and culture it by shaking or mechanical stirring at 25-35℃.

[0041] Step 500, determination of nitrite accumulation: During step 400, the mixture is periodically taken out from the matrix for nitrate and nitrite determination to obtain the cumulative concentration of nitrite and the nitrite formation rate.

[0042] In addition, the present invention also provides that the substrate is nitrate-containing wastewater, domestic sewage or culture medium.

[0043] In addition, the present invention also provides that the matrix contains organic matter as a carbon source, wherein the organic matter is a carbon source formed by a single or mixed organic pollutant in wastewater, glucose, sodium citrate, or sucrose.

[0044] In addition, the present invention also provides a formula for calculating the formation rate of the nitrite:

[0045] Nitrite formation rate % = (C t -C0) / (C n0 -C nt )×100%;

[0046] Among them, C0 and C t C represents the nitrite content in the substrate at the initial 0 days and after t days of cultivation, respectively; n0 and C n0 The values ​​represent the nitrate content in the substrate at the initial stage and after t days of cultivation, respectively.

[0047] As a preferred embodiment of the present invention, the culture medium consists of: 1.50g KNO3, 7.38g KH2PO4, 2.42g K2HPO4, 0.39g NH4Cl, 0.20g MgCl·7H2O, and distilled water to a final volume of 1000mL.

[0048] The *Enterobacter argentea* strain obtained by this invention can utilize common organic matter (such as easily degradable organic pollutants in common wastewater, glucose, sodium citrate, sucrose, etc., single or mixed organic substances) as a carbon source, thereby using nitrate produced in the nitrification process of common wastewater as an electron acceptor to achieve a large accumulation of nitrite. This provides sufficient nitrite for the anaerobic ammonia oxidation process for nitrogen removal in water and also enables the recovery and utilization of nitrite.

[0049] This technology can be combined with short-cut nitrification and denitrification as well as anaerobic ammonium oxidation to remove nitrogen from wastewater or water bodies, and can also reduce the accumulation of nitrite for recycling.

[0050] The present invention will now be described in more detail through embodiments, but these are not intended to limit the scope of the invention.

[0051] Example 1: Screening of denitrifying bacteria

[0052] (1) On September 20, 2021, five sampling points were set up in a river in Wuhu City. 50-100g of bottom sediment was collected at each sampling point using a grab bucket, placed in a sterile sealed box, stored in an ice pack, and transported back to the laboratory.

[0053] (2) Prepare a liquid culture medium for screening denitrifying bacteria. The formula is as follows (g / L): 5g sodium citrate, 2g KNO3, 1.0g K2HPO4, 1.0g KH2PO4, 0.2g MgSO4·7H2O. Sterilize in high pressure steam at 121℃ for 30min and cool for later use.

[0054] (3) In a biosafety bench, 10g of sediment sample was transferred to 100mL of sterilized denitrification medium and continuously cultured in a constant temperature shaker at 30℃ and 150r / min. Frequent observation was performed. After 7 days, the culture medium became turbid. 10mL of the enriched mixture was taken and diluted to 100% using a 10-fold gradient plate method. -6 Take 100 μL of each gradient and spread it evenly on a solid medium for screening denitrifying bacteria (the formula is based on liquid medium with 20 g / L agar added). After standing, transfer it to a 30℃ constant temperature incubator for inverted culture.

[0055] (3) After culturing for 3-7 days, a large number of colonies were observed to grow on the plate culture medium. Colonies were picked up with a sterile inoculation loop, and the morphological characteristics of each colony were observed. Then, a single colony was picked up with a sterile inoculation loop and added to a sterilized denitrifying bacteria screening liquid culture medium and cultured for 2 days. After centrifuging to remove bacteria, the concentration of nitrate in each supernatant was measured.

[0056] (4) Take 100 μL from the bacterial mixture with relatively low nitrate concentration and spread it evenly on a solid culture medium plate for screening denitrifying bacteria. After standing, transfer it to a 30℃ constant temperature incubator for inverted culture. After the colonies grow, observe the morphological characteristics of each colony. Use a sterile inoculation loop to pick a single colony and transfer it to a sterile liquid culture medium for culture. Then select bacteria from the liquid culture medium with relatively low nitrate concentration. Repeat this process of purification and separation using solid-liquid culture medium to finally obtain a strain with good denitrification effect and purity.

[0057] (5) Take 2 mL of the obtained bacterial mixture and add it to 100 mL of LB liquid medium. Culture continuously for 2 days in a constant temperature shaker at 30℃ and 150 r / min. Pour in 35 mL of sterilized glycerol to make glycerol tubes and store them at -18℃.

[0058] (6) After being frozen for more than 15 days, a glycerol cryopreservation tube was taken and denitrification liquid culture medium was added. It was found that the strain of bacteria grew well and the nitrate concentration decreased significantly. This proved that a strain of bacteria with denitrification ability was obtained and was recorded as DNW01.

[0059] Example 2: Molecular biological identification of strain DNW01

[0060] (1) Inoculate strain H17 into 100 mL of LB liquid culture medium and incubate at 30 °C with shaking at 150 rpm for 48 h. Take 150 μL of bacterial culture and extract genomic DNA using Ezup column bacterial genomic DNA extraction kit SK8255 (Shanghai Sangon Biotech), Ezup column fungal genomic DNA extraction kit SK8259 (Shanghai Sangon Biotech), and Ezup column yeast genomic DNA extraction kit (Shanghai Sangon Biotech).

[0061] (2) Using DNA as a template, PCR amplification of 16S rDNA was performed using universal primers for bacteria. The primer sequences were as follows: upstream primer 27F: 5'-AGAGTTTGATCCTGGCTCAG-3', downstream primer 1492R: 5'-TACGGCTACCTTGTTACGACTT-3'; for fungi, ITS1: 5'-TCCGTAGGTGAACCTGCGG-3', ITS4: 5'-TCCTCCGCTTATTGATATGC-3'; for yeast, NL1: 5'-GTAGTCATATGCTTGTCTC-3', NL4: 5'-GCATCACAGACCTGTTATTGCCTC-3'.

[0062] The PCR reaction system consisted of 25 μL of: 0.5 μL template DNA (genomic DNA 20-50 ng / μL), 0.5 μL each of forward and reverse primers (10 μmol / L), and 10× Buffer (with Mg). 2+ Add 2.5 μL of dNTPs (2.5 mM each) and 1.0 μL of double-distilled water to a final volume of 25 μL.

[0063] The PCR amplification conditions were as follows: 94℃ pre-denaturation for 4 min; 94℃ denaturation for 45 s, 55℃ annealing for 45 s, 72℃ extension for 1.0 min, 30 cycles; 72℃ extension for 10 min.

[0064] The PCR products were detected by 1% agarose gel electrophoresis, and the qualified PCR products were sent to Sangon Biotech (Shanghai) Co., Ltd. for gene sequencing.

[0065] (2) Sequencing results of strain DNW01 were analyzed using BLAST in the NCBI database. A phylogenetic tree was constructed using MEGA 7.0 software with a neighbor-joining method (e.g., ...). Figure 3 (As shown). 16S rDNA sequencing results showed that strain H17 was most closely related to Enterobacter asburiae strain CAV1043, with 100% similarity. Colony morphology and Gram staining results were also consistent with it.

[0066] Therefore, it can be determined that the strain obtained through screening is Enterobacter asburiae, and it has been deposited by the China Center for Type Culture Collection (CCTCC) for patent preservation, with accession number CCTCC M2022760.

[0067] Example 3: Determination of the growth curve of Enterobacter alginate DNW01

[0068] In a biosafety bench, a one-loop inoculation loop was used to pick up the bacterial strain and inoculate it into 100 mL of sterile LB medium. The culture was continuously incubated at 30°C and 150 rpm for 24 h using a constant-temperature shaker. Then, a 10% inoculation volume was added to 100 mL of LB medium, and the culture was continuously incubated under the same conditions. Samples were taken aseptically every 4 h, and the optical density (OD) of the bacterial solution at 600 nm was measured using a visible spectrophotometer. A growth curve was plotted with incubation time on the x-axis and OD600 on the y-axis, revealing that the bacteria entered the exponential growth phase after 8–24 h.

[0069] Example 4: Application of Enterobacter alginate DNW01 in nitrite accumulation using glucose as a carbon source

[0070] Glycerol tubes containing DNW01 bacterial suspension were inoculated into LB medium and activated for 24 h. The activated bacterial suspension was then added to a denitrification medium with glucose as the carbon source. The denitrification medium consisted of: glucose (4 g), NH4Cl (0.29 g), KNO3 (1.085 g), Na2HPO4·12H2O (5.87 g), KH2PO4 (1.22 g), MgSO4·7H2O (0.05 g), trace elements (0.05 mL), and distilled water to a final volume of 1000 mL. 100 mL of the prepared medium was autoclaved, cooled, and then inoculated with the activated bacterial suspension at a rate of 0.5% (V / V). The culture was then continuously incubated at 30℃ and 150 rpm for 12 and 16 h. After incubation, the culture was centrifuged at 10000 rpm for 5 min, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 150 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 133 and 141 mg / L, respectively, and the nitrite formation rates were 86% and 90%, respectively.

[0071] Example 5: Application of Enterobacter auriculi DNW01 in nitrite accumulation using sodium citrate as a carbon source

[0072] Glycerol tubes containing DNW01 bacterial suspension were inoculated into LB medium and activated for 24 h. The activated bacterial suspension was then added to denitrification medium with glucose as the carbon source. The denitrification medium consisted of: sodium citrate (3.30 g), NH4Cl (0.29 g), KNO3 (1.085 g), Na2HPO4·12H2O (5.87 g), KH2PO4 (1.22 g), MgSO4·7H2O (0.05 g), trace elements (0.05 mL), and distilled water to a final volume of 1000 mL. 100 mL of the prepared medium was autoclaved, cooled, and inoculated with the activated bacterial suspension at a rate of 0.5% (V / V). The culture was then continuously incubated at 30℃ and 150 rpm for 12 and 16 h. After incubation, the culture was centrifuged at 10000 rpm for 5 min, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 150 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 97 and 124 mg / L, respectively, and the nitrite formation rates were 62% and 81%, respectively.

[0073] Example 6: Application of Enterobacter auriculi DNW01 in nitrite accumulation using sucrose as a carbon source

[0074] Glycerol tubes containing DNW01 bacterial suspension were inoculated into LB medium and activated for 24 h. The activated bacterial suspension was then added to a denitrification medium with glucose as the carbon source. The denitrification medium consisted of: sucrose (2.17 g), NH4Cl (0.29 g), KNO3 (1.085 g), Na2HPO4·12H2O (5.87 g), KH2PO4 (1.22 g), MgSO4·7H2O (0.05 g), trace elements (0.05 mL), and distilled water to a final volume of 1000 mL. 100 mL of the prepared medium was autoclaved, cooled, and then inoculated with the activated bacterial suspension at a rate of 0.5% (V / V). The culture was then continuously incubated at 30℃ and 150 rpm for 12 and 16 h. After incubation, the culture was centrifuged at 10000 rpm for 5 min, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 150 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 121 and 135 mg / L, respectively, and the nitrite formation rates were 82% and 90%, respectively.

[0075] Example 7: Application of Enterobacter auriculi DNW01 in nitrite accumulation using domestic sewage as a carbon source

[0076] To further verify the denitrification and nitrite accumulation effects of this bacterial strain, domestic sewage from a university septic tank was used as the carbon source for this case study. Glycerol tubes containing DNW01 bacterial suspension were inoculated into LB medium and activated for 24 hours. To increase the nitrate content in the sewage, 0.23 g of KNO3 was added to 1 L of sewage, resulting in a final nitrate concentration of 40 mg / L. The activated bacterial suspension was then inoculated at a rate of 0.1% (V / V), and continuously cultured at 30℃ and 150 rpm for 12 and 16 hours. After cultivation, the culture was centrifuged at 10000 rpm for 5 minutes, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 40 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 33 and 37 mg / L, respectively, and the nitrite formation rates were 82.5% and 92.5%, respectively.

[0077] Example 8: Application of Enterobacter auriculi DNW01 in nitrite accumulation using domestic sewage as a carbon source

[0078] To further verify the denitrification and nitrite accumulation effects of this bacterial strain, domestic sewage from a university septic tank was used as the carbon source for this case study. Glycerol tubes containing DNW01 bacterial suspension were inoculated into LB medium and activated for 24 hours. To increase the nitrate content in the sewage, 0.50 g of KNO3 was added to 1 L of sewage, resulting in a final nitrate concentration of 70 mg / L. The activated bacterial suspension was then inoculated at a rate of 0.1% (V / V), and continuously cultured at 30℃ and 150 rpm for 12 and 16 hours. After cultivation, the culture was centrifuged at 10000 rpm for 5 minutes, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 40 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 33 and 37 mg / L, respectively, and the nitrite formation rates were 84% and 89%, respectively.

[0079] Example 9: Application of Enterobacter auriculi DNW01 in nitrite accumulation using domestic sewage as a carbon source

[0080] To further verify the denitrification and nitrite accumulation effects of this bacterial strain, a case study was conducted using effluent from the secondary sedimentation tank of a wastewater treatment plant. Glycerol tubes containing DNW01 bacterial culture were inoculated into LB medium and activated for 24 hours. To increase the nitrate and organic carbon source content in domestic wastewater, 0.50 g of KNO3 was added to 1 L of domestic wastewater, resulting in a final nitrate concentration of 82 mg / L; 0.6 g of glucose was added as a supplementary carbon source. The activated bacterial culture was then inoculated at a rate of 0.2% (V / V), and continuously cultured at 30℃ and 150 rpm for 12 and 16 hours. After cultivation, the culture was centrifuged at 10000 rpm for 5 minutes, and the supernatant was collected to determine the NO3 content. - -N and NO2 - The content of -N. Examples show that in denitrification media with an initial concentration of 40 mg / L, the NO2 content at 12 and 16 h... - The -N concentrations were 69 and 77 mg / L, respectively, and the nitrite formation rates were 84% and 94%, respectively.

[0081] In summary, the Enterobacter DNW01 strain can utilize various carbon sources, including those found in domestic wastewater, for growth. It also possesses the advantages of a strong ability to convert nitrates into nitrites with a nitrite formation rate exceeding 80%. This bacterium is of great significance for coupling with processes such as anaerobic ammonia oxidation for denitrification and nitrite recovery.

[0082] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A strain of Enterobacter asburiae, characterized in that, The Enterobacter aegyptiacus is deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 2022760 and deposit date of May 30, 2022.

2. The Enterobacter aegyptiacus strain according to claim 1, characterized in that: After culturing the *Enterobacter aegyptiacus* in a denitrified solid medium containing organic carbon sources and nitrates for 2 days, the colony diameter d was 2.40 ± 0.59 mm.

3. The application of *Enterobacter argentea* as described in claim 1 in the accumulation of nitrite, characterized in that, The Enterobacter aegyptiaceae enables the conversion of nitrate to nitrite in a nitrate-containing matrix and achieves the accumulation of nitrite.

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