A strain of Priesteria gigantea DF3-2 and its bacterial agent and its application in treating nitrogen-containing wastewater

Abstract

The present invention relates to a strain of Priesteria gigantea DF3-2 and a bacterial agent thereof and an application thereof in treating nitrogen-containing sewage, belonging to the technical field of microorganisms. Priestia megaterium )DF3‑2 is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.32449 and the deposit date October 31, 2024. The address of the deposit institution is: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The present invention also provides an application of Priococcus giganteus DF3‑2 in the treatment of nitrogen-containing wastewater. The Priococcus giganteus DF3‑2 provided by the present invention can treat nitrogen-containing wastewater by denitrification and still maintain high activity in a low temperature environment. The range of options for treating nitrogen-containing wastewater is expanded while reducing energy consumption. Priococcus giganteus DF3‑2 has a high tolerance to higher concentrations of nitrate nitrogen.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, and in particular to a strain of Priesteria gigantea DF3-2 and a bacterial agent thereof and application thereof in treating nitrogen-containing sewage. Background Art

[0002] During industrial production, many industries will produce a large amount of nitrogen-containing wastewater. For example, the chemical industry will discharge wastewater containing high concentrations of ammonia nitrogen and nitrate nitrogen during the production of synthetic ammonia, nitric acid, urea and other products; the pharmaceutical industry will also produce nitrogen-containing wastewater during drug synthesis and fermentation. If the nitrogen in industrial wastewater is discharged directly without effective treatment, it will lead to eutrophication of water bodies. In eutrophic water bodies, algae and other plankton will multiply in large numbers, consume dissolved oxygen in the water, cause aquatic organisms to die due to lack of oxygen, and destroy the water ecological balance. Some nitrogen-containing compounds in industrial wastewater may be toxic. For example, nitrate nitrogen may be converted into nitrosamines in the human body, which has a carcinogenic risk. In addition, some nitrogen-containing substances in industrial wastewater may cause damage to the human nervous system, liver, kidneys and other organs.

[0003] Traditional industrial wastewater denitrification technologies include physical and chemical methods, including air stripping, chemical precipitation, and ion exchange. Biological treatment methods include traditional biological denitrification processes and biofilm methods. As people pay more and more attention to environmental protection, the discharge standards of industrial wastewater in various countries are becoming more and more stringent. In particular, the emission limits of nitrogen are constantly decreasing, which requires industrial enterprises to adopt more efficient denitrification technologies to meet environmental protection requirements. While pursuing economic benefits, industrial enterprises are also paying more and more attention to sustainable development. The use of efficient denitrification technology can not only reduce the pollution of wastewater to the environment, but also reduce treatment costs.

[0004] Under low temperature conditions, low-temperature denitrifying bacteria have strong shock resistance and can adapt to situations with large fluctuations in water quality. For example, when the nitrogen load in industrial wastewater suddenly increases or other water quality parameters change, the low-temperature denitrification system can operate relatively stably and maintain a certain denitrification efficiency. Low-temperature denitrification can reduce greenhouse gas emissions, has low energy consumption and low pollution, and because it does not require the addition of a large amount of chemical agents, the pollution to the environment is relatively small, which is of great significance for the treatment of water sources such as industrial wastewater.

[0005] There is no related report on the use of Priesteria gigantea in low-temperature denitrification treatment of sewage in the prior art. Summary of the invention

[0006] In view of the problem that Priesteria gigantea has not been found to be applicable in the existing biological treatment of nitrogen-containing sewage, the present invention provides a Priesteria gigantea DF3-2 and its bacterial agent and application in treating nitrogen-containing sewage to solve the above problem.

[0007] In a first aspect, the present invention provides a strain of Priesteria gigantea DF3-2, wherein the Priesteria gigantea ( Priestia megaterium )DF3-2 is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.32449, the deposit date is October 31, 2024, and the address of the deposit institution is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0008] In a second aspect, the present invention provides a bacterial agent containing Prioccidioides giganteus DF3-2, wherein the bacterial agent is a solid bacterial agent or a liquid bacterial agent.

[0009] A method for preparing the above-mentioned liquid bacterial agent comprises the following steps: preparing a denitrification culture medium, the ingredients of which are as follows: 1 g / L glucose, 1.2 g / L sodium nitrate, 1 g / L potassium dihydrogen phosphate, 0.5 g / L ferrous sulfate, 0.2 g / L calcium chloride, 1 g / L magnesium sulfate, 10 ml / L trace element solution (trace element solution: 50 g / L EDTA, 2.2 g / L ZnSO4, 5 g / L MnSO4·4H2O, 1.1 g / L Na2MoO4, 1.5 g / L CuSO4·5H2O, 1.6 g / L CoCl2·6H2O, pH=6.0), pH=7.0; then inoculating the activated Priesteria gigantea DF3-2 into the denitrification culture medium, and fermenting at 30±1°C for 24 hours to obtain a liquid bacterial agent containing Priesteria gigantea DF3-2.

[0010] A method for preparing the above-mentioned solid bacterial agent comprises the following steps: taking a liquid bacterial agent and freeze-drying it to obtain a solid bacterial agent containing Prioccidioides giganteus DF3-2.

[0011] In a third aspect, the present invention provides a use of Priesteria gigantea DF3-2 in treating nitrogen-containing wastewater, wherein the Priesteria gigantea DF3-2 degrades nitrate nitrogen in the wastewater by denitrification.

[0012] Furthermore, the denitrification temperature is ≤35° C., preferably 30° C. In the actual denitrification process, when the temperature drops to 10° C., the denitrification effect of Priesteria gigantea DF3-2 is still effective.

[0013] Furthermore, during denitrification, the carbon-nitrogen ratio in the nitrogen-containing wastewater is controlled to be 5-11, with the preferred carbon-nitrogen ratio being 5.

[0014] Furthermore, when the carbon-nitrogen ratio is less than 5, a carbon source is added to increase the carbon-nitrogen ratio; the carbon source is selected from glucose, sodium acetate, methanol or molasses; preferably glucose.

[0015] The beneficial effects of the present invention are:

[0016] The Prioccidioides giganteus DF3-2 provided by the present invention can treat nitrogen-containing sewage by denitrification and still maintain high activity in a low-temperature environment. The present invention expands the selection range of treating nitrogen-containing sewage and reduces energy consumption. Prioccidioides giganteus DF3-2 has high tolerance to high concentrations of nitrate nitrogen, fast denitrification speed, strong impact resistance, and reduces the generation of sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a curve chart of the degradation of nitrate nitrogen by the six strains in Example 1 of the present invention.

[0019] Figure 2 This is a colony picture of Priesteria gigantea DF3-2 in Example 1 of the present invention.

[0020] Figure 3 This is the Gram staining image of Priococcus giganteus DF3-2 in Example 1 of the present invention.

[0021] Figure 4 This is a graph showing the degradation rate of nitrate nitrogen by Priesteria gigantea DF3-2 at different temperatures in Example 2 of the present invention.

[0022] Figure 5 This is a graph showing the degradation rate of nitrate nitrogen in different carbon sources by Priocerium giganteum DF3-2 in Example 2 of the present invention.

[0023] Figure 6 This is a graph of the nitrate nitrogen degradation rate of Prioccidioides giganteus DF3-2 in Example 2 of the present invention at different nitrate nitrogen concentrations.

[0024] Figure 7 This is a graph of nitrate nitrogen degradation rates of Prioccidioides giganteus DF3-2 under different carbon-nitrogen ratios in Example 2 of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] Example 1

[0027] Isolation, Screening and Identification of Priesteria megaterium DF3-2

[0028] 1. Sampling

[0029] On July 8, 2024, the sewage from the anoxic biochemical pool was retrieved at the sewage treatment station of Jinxi Petrochemical Branch of China National Petroleum Corporation (address: No. 42, Xinhua Avenue, Huludao City, Liaoning Province).

[0030] 2. Separation

[0031] First, centrifuge at 8000 rpm for 10 min. Wash the obtained bacterial sludge with sterile water and centrifuge for 3 times. Collect the bacterial sludge and inoculate it into 200 ml sterilized denitrification medium at a weight ratio of 10% (denitrification medium formula is glucose 1 g / L, potassium dihydrogen phosphate 1 g / L, sodium nitrate 1.2 g / L, ferrous sulfate 0.5 g / L, calcium chloride 0.2 g / L, magnesium sulfate 1 g / L, trace element solution 10 ml / L, pH = 7.0, trace element solution: EDTA 50 g / L, ZnSO4 2.2 g / L, MnSO4·4H2O 5 g / L, Na2MoO4 1.1 g / L, CuSO4·5H2O 1.5 g / L, CoCl2·6H2O 1.6g / L, pH=6.0) in a shake flask, the initial shaker temperature was set to 15°C, the speed was 120rpm, the sealing film was covered, and the mixture was cultured in anoxic environment for 24h. During the culture period, the growth state of the mixed solution was observed, and the nitrate nitrogen content, nitrite nitrogen and other parameters were tested every 4 hours (equipment model: GNST-900, manufacturer: Henan Suijing Environmental Protection Technology Co., Ltd.). At the end of the culture, the nitrate nitrogen in the mixed solution dropped below 10ppm.

[0032] After enrichment culture, the bacterial suspension was spread on the plate by the doubling dilution method to isolate single colonies: 10 ml of the mixed solution was taken, added to 90 ml of sterile water with glass beads, and fully shaken on a rotary shaker at 200 r / min for 30 min to form a mother liquid bacterial suspension. 0.5 ml of the above mother liquid bacterial suspension was taken with a sterile pipette, added to 4.5 ml of sterile water, and serially diluted from 1 to 10 to obtain 1, 1×10, and 1×10, respectively. -1 , 1×10 -2 , 1×10 -3 , 1×10 -4 Diluted bacterial suspension.

[0033] To obtain single colonies, take three consecutive appropriate dilutions of 10 -4 , 10 -5 , 10 -6, use a sterile pipette to take 0.1ml of the bacterial suspension, add it to the pre-prepared denitrification solid medium (the formula of the denitrification solid medium is glucose 1g / L, sodium nitrate 1.2g / L, potassium dihydrogen phosphate 1g / L, ferrous sulfate 0.5g / L, calcium chloride 0.2g / L, magnesium sulfate 1g / L, agar 20g / L, pH=7.0) plate with bromothymol blue (BTB) color development, and use a sterile glass scraper to evenly apply the bacterial suspension of different dilutions on the surface of the culture medium, and culture at 15℃ under anoxic conditions. After 36 hours of culture, a blue halo appears around the colonies with denitrification. Take different types of single colonies with blue halos for smearing, staining, and microscopic examination. A total of 6 bacterial strains were screened and stored in 50% sterile glycerol tubes and stored in a -80°C refrigerator (labeled as DF3-1, DF3-2, DF3-3, DF,3-4, DF3-5, and DF3-6).

[0034] 3. Screening

[0035] (1) Strain activation: Streak the six strains stored in the glycerol tubes onto sterile plates containing denitrification solid culture medium, place them in a constant temperature incubator at 30°C, and culture them in anoxic conditions for 18-24 hours. After the bacteria have grown well, place the plates in a 4°C refrigerator for storage.

[0036] (2) All six isolated and purified bacteria have denitrification function, but it is not possible to determine whether one or several bacteria work at low temperatures. The six bacteria were activated for verification. The six activated bacteria were inoculated into 200 ml of sterile denitrification culture medium and cultured at 15°C and 120 rpm for 24 hours. Samples were taken every 4 hours to detect the nitrate nitrogen concentration. Based on the growth and nitrate nitrogen removal rate, a dominant strain numbered DF3-2 was finally selected. It can reduce nitrate nitrogen from 200 ppm to 25 ppm in 24 hours, with a removal rate of 87.5%. The other five strains have weak nitrate nitrogen degradation capabilities at low temperatures. The detection curves of the six strains are detailed in the following table. Figure 1 .

[0037] 4. Identification

[0038] The colony morphology of strain DF3-2 is as follows Figure 2 As shown, the colonies are light yellow, irregularly edged, round, and slightly mucous and smooth. The DF3-2 strain was subjected to Gram staining using a staining kit and the staining of the strain was observed under a microscope (equipment model: NikonEi100). The Gram staining of the DF3-2 strain is shown in Figure 3As shown, the bacteria are purple, which is a Gram-positive bacteria. After the strain DF3-2 was activated, the plate was sent to Beijing Qingke Biotechnology Co., Ltd. for gene identification, and the gene sequence of the strain DF3-2 was obtained as shown in SEQ ID NO.1. The identification result is Priesteria gigantea Priestia megaterium , Priesteria gigantea DF3-2 is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.32449, the deposit date is October 31, 2024, and the address of the deposit institution is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0039] Example 2

[0040] Verification of the denitrification performance of Priesteria gigantea DF3-2

[0041] 1. Effect of temperature on the denitrification performance of Priesteria gigantea DF3-2: The denitrification culture medium was as follows: glucose 1 g / L, sodium nitrate 1.2 g / L, potassium dihydrogen phosphate 1 g / L, ferrous sulfate 0.5 g / L, calcium chloride 0.2 g / L, magnesium sulfate 1 g / L, trace element solution 10 ml / L, pH = 7.0 (trace element solution: EDTA 50 g / L, ZnSO4 2.2 g / L, MnSO4·4H2O 5 g / L, Na2MoO4 1.1 g / L, CuSO4·5H2O 1.5 g / L, CoCl2·6H2O 1.6 g / L, pH = 6.0). Prepare 6 portions, each 200ml, inoculation volume 10%, respectively placed in 10℃, 15℃, 20℃, 25℃, 30℃ and 35℃ environment, sealed with sealing film, constant temperature shaker set speed 120rpm, 24h, test the initial nitrate nitrogen value before inoculation, and test the nitrate nitrogen value every 4h (equipment model: GNST-900, manufacturer: Henan Suijing Environmental Protection Technology Co., Ltd.). Test results are detailed in Figure 4 .Depend on Figure 4It can be seen that the optimal temperature of Priesteria gigantea DF3-2 is 30℃. In 20h, the nitrate nitrogen content of the test medium is reduced from 200mg / L to 0mg / L, and the nitrate nitrogen removal rate is 100%; the nitrate nitrogen content of the strain is reduced from 200mg / L to 45mg / L at 10℃, and the nitrate nitrogen removal rate is 77.5%; the nitrate nitrogen content is reduced from 200mg / L to 25mg / at 15℃, and the nitrate nitrogen removal rate is 87.5%; the nitrate nitrogen content is reduced from 200mg / L to 13mg / L at 20℃, and the nitrate nitrogen removal rate is 93.5%; the nitrate nitrogen content is reduced from 200mg / L to 6mg / L at 25℃, and the nitrate nitrogen removal rate is 97%; the nitrate nitrogen content is reduced from 200mg / L to 27mg / L at 35℃, and the nitrate nitrogen removal rate is 86.5%. Denitrification does not decrease significantly with the decrease in temperature, indicating that the strain can still maintain a high denitrification under low temperature conditions.

[0042] 2. Effect of carbon source type on denitrification performance of Priesteria gigantea DF3-2: Preparation of denitrification test medium 1: sodium nitrate 1.2g / L, potassium dihydrogen phosphate 1g / L, ferrous sulfate 0.5g / L, calcium chloride 0.2g / L, magnesium sulfate 1g / L, trace element solution 10ml / L, pH=7.0 (trace element solution: EDTA 50g / L, ZnSO42.2g / L, MnSO4·4H2O 5g / L, Na2MoO41.1g / L, CuSO4·5H2O 1.5g / L, CoCl2·6H2O 1.6g / L, pH 6.0) 4 portions, each 200ml, according to the same COD equivalent, add 1.37g / L sodium acetate, 0.71g / L methanol, 1g / L glucose, 2g / L molasses, respectively. After the above 4 portions of culture medium are prepared, seal the medium with sealing film, inoculate at 10%, place it in anoxic 30℃ constant temperature shaker with a speed of 120rpm, record the initial nitrate nitrogen value and test it every 4h (equipment model: GNST-900, manufacturer: Henan Suijing Environmental Protection Technology Co., Ltd.), the results are as follows Figure 5 As shown. Figure 5 It can be seen that under the conditions of four different carbon sources, glucose has the fastest decrease rate for Priesteria gigantea DF3-2, and nitrate nitrogen can be reduced from the initial value of 200 mg / L to 0 mg / L in 20 hours, while methanol is the slowest, from 200 mg / L to 87 mg / L. This may be because this strain adapts to methanol toxicity slowly, indicating that Priesteria gigantea DF3-2 tends to perform denitrification when glucose is the carbon source.

[0043] (3) Effect of nitrate nitrogen concentration on the denitrification performance of Priesteria gigantea DF3-2: Preparation of denitrification test medium II: glucose 1g / L, potassium dihydrogen phosphate 1g / L, ferrous sulfate 0.5g / L, calcium chloride 0.2g / L, magnesium sulfate 1g / L, trace element solution 10ml / L, pH = 7.0 (trace element solution: EDTA 50g / L, ZnSO42.2g / L, MnSO4·4H2O 5g / L, Na2MoO41.1g / L, CuSO4·5H2O 1.5g / L, CoCl2·6H2O 1.6g / L, pH=6.0) 4 portions, each 200ml, according to different concentrations of nitrate nitrogen, add sodium nitrate 0.8g / L, 1.2g / L, 1.6g / L, 2.0g / L (i.e. initial nitrate nitrogen 130ppm, 200ppm, 266ppm, 333ppm), seal with sealing film, inoculate at 10%, place in 30℃ constant temperature shaker with anoxic state and set the speed at 120rpm, detect the initial nitrate nitrogen value and detect it every 4h, the results are as follows Figure 6 As shown. Figure 6 It can be seen that regardless of low or high nitrate nitrogen concentrations, Priococcus giganteus DF3-2 can maintain efficient denitrification with a comparable slope, and the NO3-N degradation rate is not affected by the nitrate nitrogen concentration, indicating that Priococcus giganteus DF3-2 has the ability to tolerate high nitrate nitrogen concentrations and has a strong ability to resist sewage shock.

[0044] (4) Effect of carbon / nitrogen ratio on denitrification performance of Priesteria gigantea DF3-2: Preparation of denitrification test medium III: sodium nitrate 1.2 g / L, potassium dihydrogen phosphate 1 g / L, ferrous sulfate 0.5 g / L, calcium chloride 0.2 g / L, magnesium sulfate 1 g / L, trace element solution 10 ml / L, pH = 7.0 (trace element solution: EDTA 50 g / L, ZnSO4 2.2 g / L, MnSO4·4H2O 5 g / L, Na2MoO4 1.1 g / L, CuSO4·5H2O 1.5 g / L, CoCl2·6H2O 1.6g / L, pH=6.0) 5 portions, each 200ml, according to the carbon-nitrogen ratio of 3, 5, 7, 9, 11, add glucose 0.56g / L, glucose 1g / L, glucose 1.31g / L, glucose 1.68g / L, glucose 2.06g / L respectively, seal with sealing film, inoculation amount 10%, place in 30℃ constant temperature shaker with anoxic state and set the speed to 120rpm, detect the initial value of nitrate nitrogen and detect the nitrate nitrogen value every 4h and record it. The data results are as follows Figure 7When the carbon-nitrogen ratio was 3, nitrate nitrogen dropped to about 70 ppm in 16 hours and no longer decreased, which should be caused by insufficient carbon source. When the carbon-nitrogen ratio was 5, 7, 9, and 11, the nitrate nitrogen all dropped to 0 mg in 20 hours. With the increase of carbon source, the degradation rate did not change, and when the carbon-nitrogen ratio was 7, 9, and 11, COD residuals could be detected, indicating that the carbon source was excessive. The optimal carbon-nitrogen ratio of Priesteria gigantea DF3-2 was 5, which not only ensured the denitrification rate but also reduced the amount of carbon source added and the production of sludge.

[0045] Example 3

[0046] Preparation of bacterial agent containing Priesteria gigantea DF3-2

[0047] 1. Denitrification medium: glucose 1g / L, potassium dihydrogen phosphate 1g / L, sodium nitrate 1.2g / L, ferrous sulfate 0.5g / L, calcium chloride 0.2g / L, magnesium sulfate 1g / L, trace element solution 10ml / L (trace element solution: EDTA 50g / L, ZnSO42.2g / L, MnSO4·4H2O 5g / L, Na2MoO41.1g / L, CuSO4·5H2O 1.5g / L, CoCl2·6H2O 1.6g / L, pH=6.0), pH=7.0.

[0048] 2. Preparation of liquid bacterial agent containing Priesteria gigantea DF3-2: The activated Priesteria gigantea DF3-2 was inoculated into the denitrification medium, and the temperature was 30±1℃. The fully automatic fermentation equipment was used for fermentation for 24 hours to obtain a liquid bacterial agent containing Priesteria gigantea DF3-2 with a colony count of 3.2×10 9 CUF / ml.

[0049] 3. Preparation of solid bacterial agent containing Priococcus giganteus DF3-2: The above liquid bacterial agent was freeze-dried to obtain a solid bacterial agent containing Priococcus giganteus DF3-2, with a colony count of 3.0×10 10 CUF / g.

[0050] Example 4

[0051] On-site nitrogen-containing wastewater experiment

[0052] This experiment was conducted in a petroleum refining wastewater company with a wastewater treatment capacity of 500m3 per day. 3. The average temperature on site is between 5℃ and 15℃. The inlet water temperature is usually around 18℃, and the water temperature will be further reduced after the treatment process. The average inlet total nitrogen (TN) concentration is 40mg / L. 50kg of solid bacterial agent containing Priesteria gigantea DF3-2 is added to the anoxic sewage pool at one time to meet the denitrification needs. After a period of operation, the total nitrogen in the effluent is stabilized below 10mg / L, meeting the discharge standard. The treated water volume remains stable and has not dropped significantly due to low temperature. See Table 1 for specific data.

[0053] Table 1- Monitoring results of nitrogen-containing wastewater treatment

[0054]

[0055] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A strain of Priesteria gigantea DF3-2, characterized in that: Priesteria gigantea ( Priestia megaterium )DF3-2 is deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.32449, the deposit date is October 31, 2024, and the address of the deposit institution is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

2. A bacterial agent containing the Prioccidioides giganteus DF3-2 as claimed in claim 1, wherein the bacterial agent is a solid bacterial agent or a liquid bacterial agent.

3. The bacterial agent according to claim 2, characterized in that The preparation method of the liquid bacterial agent comprises the following steps: preparing a denitrification culture medium, the ingredients of which are as follows: 1 g / L glucose, 1 g / L potassium dihydrogen phosphate, 1.2 g / L sodium nitrate, 0.5 g / L ferrous sulfate, 0.2 g / L calcium chloride, 1 g / L magnesium sulfate, 10 ml / L trace element solution, and pH=7.0; then inoculating the activated Prioccidioides giganteus DF3-2 into the denitrification culture medium, and fermenting at 30±1°C for 24 hours to obtain a liquid bacterial agent containing Prioccidioides giganteus DF3-2.

4. The bacterial agent according to claim 3, characterized in that The preparation method of the solid bacterial agent comprises the following steps: taking a liquid bacterial agent and freeze-drying it to obtain a solid bacterial agent containing Priesteria gigantea DF3-2.

5. Use of Priesteria gigantea DF3-2 as claimed in claim 1 in treating nitrogen-containing wastewater, characterized in that: Priesteria megaterium DF3-2 degrades nitrate nitrogen in sewage through denitrification.

6. The use according to claim 5, characterized in that The temperature of denitrification is ≤35℃.

7. The use according to claim 5, characterized in that During denitrification, the carbon-nitrogen ratio in nitrogen-containing wastewater is controlled at 5~11.

8. The use according to claim 5, characterized in that When the carbon-nitrogen ratio is less than 5, a carbon source is added to increase the carbon-nitrogen ratio; the carbon source is selected from glucose, sodium acetate, methanol or molasses.

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