High-salt-resistant antarbelella denitrificans and application thereof in denitrification of water body

Abstract

The invention relates to a high-salt-resistant Android bacillus denitrificans, which is preserved in the China General Microbiological Culture Collection Center (CGMCC) on June 2, 2022, and the preservation number of the high-salt-resistant Android bacillus denitrificans is CGMCC No.25000. The high-salt-resistant Android bacillus denitrificans is a high-salt-resistant Android bacillus denitrificans strain. The antarcinia denitrificans provided by the invention has the beneficial effects that (1) the antarcinia denitrificans is good in salt tolerance, can resist the salinity of 10% at most, and has the optimal growth salinity of 5-8%; (2) the degradation effect on nitrate and nitrite is excellent, under the anoxic condition, the initial nitrate concentration is 340 ppm, the nitrate degradation rate reaches 99% in 72 h when the salinity is 5-10%, the initial nitrite concentration is 100 ppm, and the nitrite degradation rate reaches 97-98% in 72 h when the salinity is 5-10%.

Description

Technical Field

[0001] The present invention relates to a strain of denitrifying Zabelella and a microbial agent containing the same, in particular to a strain of denitrifying Zabelella that is resistant to high salt and can efficiently degrade nitrogenous substances in water and an application thereof, belonging to the technical field of environmental microorganisms. Background Art

[0002] The main methods of sewage treatment are physical and chemical methods and biological methods. Physical and chemical methods include breakpoint chlorination method, ion exchange method, etc. The cost of sewage treatment is high and the impact on the environment is relatively large. Biological denitrification is currently recognized as the most economical and effective way to denitrify wastewater. Organic matter and nutrients such as nitrogen and phosphorus in sewage can be degraded and utilized by microorganisms through metabolism. Denitrifying bacteria are often needed to remove nitrates and nitrites in the process of water body remediation and sewage treatment. Numerous studies have shown that denitrifying bacteria need to be under anoxic conditions (dissolved oxygen 0.2-0.5 mg / L) to achieve better denitrification effects. At present, there are many reports on the application of denitrifying bacteria under these conditions, and the effect is also very excellent.

[0003] However, the wastewater from printing and dyeing, pesticide, coal chemical industry, papermaking, oil refining, seawater utilization, pharmaceutical industry and other industries is different from traditional urban sewage. They all produce high-salt wastewater. The salinity of nitrogen-containing wastewater produced by these industries is relatively high. The salinity of some wastewater can be as high as 10%. High salinity will inhibit the growth and metabolism of bacteria, reduce the activity of dehydrogenase, and even cause the separation and rupture of the bacterial cell wall, which will significantly affect the denitrification efficiency.

[0004] However, few of the strains screened so far have salt tolerance, which makes it difficult for them to exert their advantages in the treatment of high-salt wastewater. Therefore, screening out denitrification strains that can tolerate high salt is of great significance for solving the problem of high-salt wastewater treatment. Summary of the Invention

[0005] Aiming at the current situation that few existing strains have salt tolerance and cannot be used in high-salt wastewater during the biological treatment of nitrogen-containing wastewater, the present invention provides a denitrifying Zabelia bacterium that can be used at a salinity of up to 10% and its application in water denitrification.

[0006] A high-salt-tolerant strain of Zobellella denitrificans DB-NY01, whose 16S rDNA sequence is shown in SEQ ID No: 1, was deposited in the General Microbiology Center of the China Culture Collection Administration, located at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the accession number CGMCC No. 25000 and the deposit date being June 2, 2022.

[0007] Unless otherwise specified, the denitrifying Zabelella sp. mentioned in the present invention refers to the DB-NY01 strain.

[0008] The present invention also claims a microbial agent whose active ingredient comprises the above-mentioned denitrifying Zabelella.

[0009] The beneficial effects of the denitrifying Zabelella provided by the present invention are:

[0010] (1) It has good salt tolerance, and can tolerate a salinity of up to 10%. The optimal growth salinity is 5-8%.

[0011] (2) It has excellent degradation effect on nitrate and nitrite. Under anoxic conditions, the initial nitrate concentration is 340ppm, and the salinity is 5-10% within 72 hours, the nitrate degradation rate reaches 99%. The initial nitrite concentration is 100ppm, and the salinity is 5-10% within 72 hours, the nitrite degradation rate reaches 97-98%.

[0012] The present invention also claims a fermentation method of the above-mentioned denitrifying Zabelella, comprising the following steps:

[0013] (1) Primary seed culture: Under sterile conditions, take denitrifying Z. denitrificans and inoculate it into an enrichment medium. Cultivate it at 25-35°C and 100-150 rpm for 24-48 hours to obtain a primary seed culture solution.

[0014] (2) Secondary seed culture: Under sterile conditions, the primary seed culture solution was inoculated into an enrichment medium at an inoculum volume of 0.5-5 vol%, and cultured at 25-35°C and 100-150 rpm for 24-48 h to obtain a secondary seed culture solution;

[0015] (3) Fermentation: The fermentation medium is sterilized, and the secondary seed culture obtained in step (2) is inoculated into the fermentation medium at an inoculum amount of 0.1-10 vol%, and the fermentation is carried out under the conditions of controlling the temperature to 25-35° C., normal pressure, a ventilation ratio of 1:(1-2), and a rotation speed of 150-300 rpm. Fermentation is stopped when the dissolved oxygen begins to rise to obtain a fermentation liquid.

[0016] Furthermore, the composition of the enrichment medium is as follows: 1-5 g / L potassium nitrate, 0.1-1 g / L dipotassium hydrogen phosphate, 0.1-1 g / L magnesium sulfate, 20-50 g / L potassium sodium tartrate, and the balance is water, and the pH is 6.5-8.

[0017] Furthermore, the fermentation medium is composed of: 15-30 g / L carbon source, 5-15 g / L nitrogen source, K + 0.2-0.4g / L, Mg 2+ 0.05-0.1g / L, Na+ 15-30g / L, Mn 2+ (1.5-3.5)×10 -3 g / L, Fe 3+ or Fe 2+ (1-2)×10 -3 g / L, the balance being water, and the pH being 6.5-8.

[0018] Furthermore, the carbon source is selected from one or more of glucose, sucrose, starch, sodium acetate or sodium succinate, and the nitrogen source is selected from one or more of yeast powder, peptone, urea or potassium nitrate.

[0019] Preferably, the K + The source is one or more of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium sulfate, potassium chloride, and potassium nitrate, and the Mg 2+ The source is one of magnesium sulfate and magnesium chloride or a combination of the two, the Na + The source is one or more of sodium sulfate, sodium nitrate or sodium chloride, and the Mn 2+ The source is one or more of manganese sulfate monohydrate, manganese nitrate, and manganese chloride, and the Fe 3+ The source is one or more of ferric chloride, ferric sulfate, and ferric nitrate. 2+ The source is one or more of ferrous sulfate, ferrous chloride, and ferrous ammonium sulfate.

[0020] The ventilation ratio described in the fermentation method refers to the ratio of the volume of air introduced into the fermentation tank per minute to the total volume of the fermentation liquid.

[0021] The beneficial effects of this fermentation method are:

[0022] By adopting the fermentation process of the present invention, the fermentation cycle is shortened to 10 hours, the number of viable bacteria is as high as 30 billion cfu / mL, the fermentation liquid obtained under high salt conditions is not easily contaminated with bacteria, and the number of viable bacteria does not decrease when stored at room temperature for more than 2 months. The cost of the liquid product is lower, far lower than other products on the market.

[0023] The present invention also claims a method for purifying water using denitrifying Zabelella or a microbial agent containing the strain, comprising the step of inoculating the water with denitrifying Zabelella or a microbial agent containing the strain.

[0024] Preferably, the inoculation amount of the denitrifying bacteria or microbial agent is 50 ppm or more, more preferably 50-1000 ppm, and most preferably 100-1000 ppm;

[0025] Preferably, the applicable temperature for the water purification process is 25-45°C, more preferably 30-42°C, further preferably 30-40°C, and most preferably 35-40°C;

[0026] Preferably, the salinity of the water body is below 10%, most preferably 5-8%.

[0027] The present invention also claims to protect the use of the denitrifying Zabelella and a microbial agent containing the strain in denitrification of water bodies.

[0028] Preferably, the denitrifying bacteria and the microbial agent containing the same are used to degrade nitrogen-containing substances in water under anoxic conditions. More preferably, the nitrogen-containing substances are substances containing nitrate nitrogen and nitrite nitrogen. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] Example 1. Strain screening and performance testing

[0031] Wastewater from a chemical plant was collected and 10 mL of the wastewater was transferred to a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH 7.20). The solution was incubated at 8°C for 7 days for the first enrichment. Another 10 mL of the enrichment solution was then added to fresh enrichment medium and incubated at 8°C for 7 days for the second enrichment. A third enrichment was performed using the same enrichment method.

[0032] 1. Initial screening

[0033] The third enrichment solution was diluted to 10 -6 , absorb 10 -3 , 10 -4 , 10 -5 , 10 -6 Add 200 μL of each dilution to isolation medium (2 g / L potassium nitrate, 0.5 g / L potassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, 20 g / L agar powder, adjusted to pH 7.20). Spread evenly and invert the plate to incubate at 30°C for approximately 48 hours until single colonies form. Select morphologically distinct single colonies and transfer them to isolation medium on a slant in a test tube. Incubate at 30°C for approximately 48 hours, then transfer to a 4°C refrigerator for storage.

[0034] According to the above isolation method, a total of 4 strains were obtained, numbered as: DB-NY00, DB-NY01, DB-NY02, and DB-NY03.

[0035] 2. Rescreening

[0036] In a sterile environment, one loopful of each of the four strains obtained from the initial screening was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH = 7.20), and cultured at 30 ° C for 48 h to obtain the activation solution of each strain.

[0037] 5 μL of activation solution from each strain was inoculated into 100 mL of sterile evaluation medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, pH adjusted to 7.20) in a 250 mL Erlenmeyer flask and incubated at 30°C. Sterile water was used instead of activation solution as a blank. Three replicates were set up for each experimental group. The total nitrogen content of the culture medium was regularly monitored; the results are shown in Table 1.

[0038] The total nitrogen detection method is carried out in accordance with "HJ_636-2012_Water Quality_Determination of Total Nitrogen_Alkaline Potassium Persulfate Digestion Ultraviolet Spectrophotometry".

[0039] Table 1 Total nitrogen degradation ability of each strain

[0040]

[0041] According to the test results in Table 1, among the four strains initially screened, DB-NY01 showed a stronger ability to remove total nitrogen than the other strains, with a total nitrogen degradation rate of 95% within 96 hours and a degradation efficiency of 99% within 120 hours.

[0042] 4. Evaluation of nitrate nitrogen degradation capacity

[0043] In a sterile environment, strain DB-NY01 was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH = 7.20) and incubated at 30°C for 48 h for activation to obtain the activation solution.

[0044] 5 μL, 10 μL, and 20 μL of the activation solution were inoculated into 250 mL Erlenmeyer flasks containing 100 mL of sterile evaluation medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, pH adjusted to 7.20) and incubated at 30°C. Sterile water was used instead of the activation solution as a blank, and three replicates were set up for each experimental group. The nitrate nitrogen content in the culture medium was regularly monitored, and the results are shown in Table 2.

[0045] The detection method of nitrate nitrogen is in accordance with GB_T 7480-1987 Water quality-Determination of nitrate nitrogen-Phenol disulfonic acid spectrophotometric method.

[0046] Table 2 Degradation ability of strain DB-NY01 on nitrate nitrogen

[0047]

[0048] According to the test results in Table 2, strain DB-NY01 has an excellent ability to degrade nitrate nitrogen under anoxic conditions, and under the same other conditions, the degradation rate and efficiency of nitrate nitrogen gradually increase with the increase of the addition amount.

[0049] Example 2. Detection and identification of the denitrifying strain Z. denitrificans DB-NY01

[0050] The DB-NY01 strain slant was sequenced for 16S rDNA gene sequence, and the sequencing results were compared in NCBI (https: / / blast.ncbi.nlm.nih.gov / Blast.cgi?PROGRAM=blastn&PAGE_TYPE=BlastSearch&LINK_LOC=blasthome). The sequence with the greatest similarity was selected as the species identification result, and the identification result was Zobellella denitrificans.

[0051] Example 3. Study on the salinity tolerance of denitrifying bacteria

[0052] In a sterile environment, the DB-NY01 strain was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH 7.0) and incubated at 30°C and 200 rpm for 48 h for activation to obtain an activation solution.

[0053] 5 μL of activation solution was inoculated into 250 mL Erlenmeyer flasks containing 100 mL of sterilized evaluation medium (potassium nitrate 5 g / L, sodium succinate 5.62 g / L, Weiss salt 50 ml / L, solvent is water, pH = 7.0). The salinity of the evaluation medium was adjusted to 0-15% with sodium chloride, and the culture was incubated at 30 ° C for 24 h. The absorbance OD was detected. 600 (OD 600 It indicates the absorbance of the solution at a wavelength of 600nm. This value is used to measure the concentration of bacterial culture solution. It is usually used to refer to the density of bacterial cells. The growth of bacteria can be measured by OD 600 The results are shown in Table 3.

[0054] Table 3 Growth of strain DB-NY01 at different salinities

[0055]

[0056]

[0057] According to the test results in Table 3, the 24h absorbance value OD of DB-NY01 strain was 7% at salinity. 600 The highest number of viable bacteria reached 16×10 8 CFU / mL, the optimal growth salinity of this strain is 5-8%, which is most suitable for its growth.

[0058] Example 4. Evaluation of the nitrate and nitrite degradation ability of the denitrifying strain Z. denitrificans DB-NY01 at different salinities

[0059] 4.1. Evaluation of nitrate degradation ability of Z. denitrificans strain DB-NY01 at different salinities

[0060] In a sterile environment, the DB-NY01 strain was inoculated into a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH 7.0) and incubated at 30°C and 200 rpm for 48 h for activation to obtain an activation solution.

[0061] 5 μL of the activation solution was inoculated into 250 mL Erlenmeyer flasks containing 100 mL of sterilized evaluation medium (2 g / L potassium nitrate, 5.62 g / L sodium succinate, 50 mL / L Wicker's salt, water as the solvent, pH adjusted to 7.0). The salinity of the evaluation medium ranged from 5 to 8%, and the cells were incubated at 30°C. Sterile water was used instead of the activation solution as a blank. Three replicates were set up for each experimental group, and the nitrate nitrogen content in the culture medium was regularly tested. The nitrate nitrogen detection method was carried out in accordance with GB_T 7480-1987 Water Quality - Determination of Nitrate Nitrogen - Phenoldisulfonic Acid Spectrophotometric Method. The results are shown in Table 4.

[0062] Table 4 Nitrate degradation ability of DB-NY01 strain under different salinity conditions

[0063]

[0064]

[0065] According to the test results in Table 4, the degradation efficiency of nitrate by strain DB-NY01 can reach 99% in 72 hours at a salinity of less than 10%, and the best degradation effect is achieved when the salinity is 7-9%.

[0066] Evaluation of nitrite degradation ability of Z. denitrificans strain DB-NY01 at different salinities

[0067] 5 μL of activation solution was inoculated into 250 mL Erlenmeyer flasks containing 100 mL of sterilized evaluation medium (glucose 5 g / L, sodium nitrite 0.1 g / L, sodium chloride 1 g / L, potassium hydrogen phosphate 0.5 g / L, magnesium sulfate heptahydrate 0.25 g / L, adjusted to pH 7.2). The salinity of the evaluation medium was 5-8%, and the cells were incubated at 30°C. Sterile water was used instead of the activation solution as a blank. Three replicates were set up for each experimental group, and the nitrite nitrogen content in the culture medium was regularly tested. The nitrite nitrogen detection method was carried out in accordance with GB_T 7493-1987 Water Quality - Determination of Nitrite Nitrogen - Spectrophotometric Method.

[0068] Table 5 Nitrite degradation ability of DB-NY01 strain under different salinity conditions

[0069]

[0070] According to the test results in Table 5, the degradation efficiency of nitrite by strain DB-NY01 can reach 97-98% in 72 hours at a salinity of less than 10%, and the degradation effect is best when the salinity is 6-9%.

[0071] Example 5: Fermentation method of denitrifying Zolbertella

[0072] (1) Primary seed culture: One ring of the denitrifying Z. denitrificans DB-NY01 strain was selected in a sterile environment and inoculated into a 250 mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, pH = 7.0), and cultured at 30°C and 120 rpm for 48 h to obtain the primary seed culture solution;

[0073] (2) Secondary seed culture: In a sterile environment, 5 mL of the primary seed culture solution was transferred to four 1 L Erlenmeyer flasks containing 500 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L dipotassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH = 7.0), and cultured at 30 °C and 120 rpm for 24 h to obtain the secondary seed culture solution;

[0074] (3) Disinfection and sterilization: All materials are mixed in the batching tank and then pumped into a 1t fermentation tank. The composition of the fermentation medium is as follows: 25g sodium succinate, 10g yeast powder, 0.8g potassium dihydrogen phosphate, 0.3g magnesium sulfate, 50g sodium chloride, 0.01g manganese sulfate monohydrate, 0.01g ferrous sulfate heptahydrate and 0.5g defoaming agent per 1L of fermentation medium. Position 600L and start disinfection and sterilization. The actual disinfection conditions of the fermentation tank are: steam directly enters the inner layer to heat up, and starts to exhaust when the temperature reaches 118℃. The exhaust time is 20 minutes and the exhaust temperature is 115℃. The actual disinfection conditions of the fermentation tank culture medium are: steam directly enters the inner layer to heat up to 118℃ and starts to exhaust. The exhaust time is 30 minutes and the exhaust temperature is 121℃. The volume after disinfection is about 700L, and then it is cooled to 30℃ and waits for inoculation.

[0075] (4) Fermentation: 2000 ml of the secondary seed culture solution was inoculated into the fermentation medium of the fermenter by differential pressure inoculation. The initial pH was adjusted to 7.2, the temperature was controlled at 30°C, and the ventilation ratio was controlled at 1:1.25 (m 3 min / m 3 ), the tank pressure was 0.05 MPa, the stirring speed was 200 rpm, and the changes in dissolved oxygen were observed during the fermentation process. The dissolved oxygen gradually decreased from 100% at the beginning to 0%. After a fermentation period of about 10 hours, the dissolved oxygen began to rise again, and the fermentation was stopped immediately. At this time, the fermentation was at the end of the logarithmic phase, and the number of viable bacteria was as high as 30 billion cfu / mL. At this time, the bacteria were most active, there were fewer residual fermentation nutrients, and the number of viable bacteria decayed less during storage.

[0076] Example 5. Evaluation of the total nitrogen removal capacity of denitrifying bacteria in sewage from a certain industrial park in Qingdao

[0077] 5.1. Activation of bacteria

[0078] In a sterile environment, one ringlet of DB-NY01 strain was picked and inoculated into a 250-mL Erlenmeyer flask containing 100 mL of enrichment medium (2 g / L potassium nitrate, 0.5 g / L potassium hydrogen phosphate, 0.2 g / L magnesium sulfate, 35 g / L potassium sodium tartrate, adjusted to pH = 7.0). The culture was placed at 30°C and 120 rpm for 48 h to obtain an activated bacterial solution, and the viable bacterial content was diluted to 5 billion cfu / mL for later use.

[0079] 5.2. Evaluation of the total nitrogen reduction ability of strain DB-NY01

[0080] 5 μL, 10 μL, and 100 μL of activated bacterial solution were added to 250 mL Erlenmeyer flasks containing 100 mL of sewage from a certain industrial park in Qingdao (sodium chloride was added to adjust the salinity to 7%). The total nitrogen content in the wastewater was tested every 24 h. A total of three parallel experimental groups and one blank control group in which sterile water was used instead of the activated bacterial solution were set up.

[0081] The sewage indicators are as follows: total nitrogen content 1120 mg / L, COD 4325 mg / L, pH = 7.35.

[0082] The specific experimental arrangements are as follows:

[0083] Blank control group 1: no activated bacterial solution added;

[0084] Experimental group 2: activated bacterial solution added at 50 ppm, cultured at 35°C;

[0085] Experimental group 3: 100 ppm of activated bacterial solution was added and cultured at 35°C;

[0086] Experimental group 4: Activated bacterial solution was added at a dosage of 1000 ppm and cultured at 35°C.

[0087] 3. Experimental results

[0088] The evaluation test results are shown in the table below.

[0089] Table 6 Evaluation results of the total nitrogen reduction ability of strain DB-NY01 in sewage from a certain industrial park in Qingdao

[0090]

[0091] Table 10 shows that under 7% salinity, 35°C, and an inoculum size of 1000 ppm, the strain had the fastest total nitrogen degradation rate and the highest degradation rate, reaching 99% in 72 hours. Furthermore, under the same conditions, the strain's total nitrogen degradation capacity increased with increasing inoculum size.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-salt-tolerant strain of Zobellella denitrificans was deposited in the General Microbiology Center of the China Culture Collection Administration with the accession number CGMCC No. 25000.

2. A microbial agent, characterized in that: The active ingredient comprises the denitrifying bacteria according to claim 1.

3. The fermentation method of the denitrifying bacteria according to claim 1, characterized in that: The steps include: (1) Primary seed culture: Under sterile conditions, take denitrifying Z. denitrificans and inoculate it into an enrichment medium. Cultivate it at 25-35°C and 100-150 rpm for 24-48 hours to obtain a primary seed culture solution. (2) Secondary seed culture: Under sterile conditions, the primary seed culture solution was inoculated into an enrichment medium at an inoculum volume of 0.5-5 vol%, and cultured at 25-35°C and 100-150 rpm for 24-48 h to obtain a secondary seed culture solution; (3) Fermentation: The fermentation medium is sterilized, and the secondary seed culture obtained in step (2) is inoculated into the fermentation medium at an inoculum amount of 0.1-10 vol%, and the fermentation is carried out under the conditions of controlling the temperature to 25-35° C., normal pressure, a ventilation ratio of 1:(1-2), and a rotation speed of 150-300 rpm. Fermentation is stopped when the dissolved oxygen begins to rise to obtain a fermentation liquid.

4. The fermentation method according to claim 3, characterized in that The enrichment medium is composed of: 1-5 g / L potassium nitrate, 0.1-1 g / L dipotassium hydrogen phosphate, 0.1-1 g / L magnesium sulfate, 20-50 g / L potassium sodium tartrate, and the balance is water, with a pH of 6.5-8; The composition of the fermentation medium is as follows: carbon source 15-30 g / L, nitrogen source 5-15 g / L, K + 0.2-0.4g / L, Mg 2+ 0.05-0.1g / L, Na + 15-30g / L, Mn 2+ (1.5-3.5)×10 -3 g / L, Fe 3+ or Fe 2+ (1-2)×10 -3 g / L, the balance being water, and the pH being 6.5-8.

5. The fermentation method according to claim 4, characterized in that The carbon source is selected from one or more of glucose, sucrose, starch, sodium acetate or sodium succinate; The nitrogen source is selected from one or more of yeast powder, peptone, urea or potassium nitrate.

6. A method for purifying water, comprising the step of inoculating an effective amount of the denitrifying Zolbertella according to claim 1 or the microbial agent according to claim 2 into the water. Preferably, the inoculation amount of the denitrifying Zolbertella or the microbial agent is 50 ppm or more, more preferably 50-1000 ppm, and most preferably 100-1000 ppm.

7. The method according to claim 6, characterized in that The applicable temperature for the water purification process is 25-45°C, preferably 30-42°C, more preferably 30-40°C, and most preferably 35-40°C.

8. The method according to claim 6 or 7, characterized in that The salinity of the water body is below 10%, most preferably 5-8%.

9. Use of the denitrifying Zabelella according to claim 1 and the microbial agent according to claim 2 in denitrification of water bodies.

10. The use according to claim 9, characterized in that The denitrifying bacteria of claim 1 and the microbial agent of claim 2 are used to degrade nitrogen-containing substances in water under anoxic conditions. More preferably, the nitrogen-containing substances are nitrate nitrogen and nitrite nitrogen.

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