Bacillus tequilensis with ability of degrading nitrite and application thereof

Abstract

This invention provides a strain of *Bacillus tekirae* GXMZU-G7 capable of degrading nitrite and its applications, belonging to the field of microbial technology. The *Bacillus tekirae* GXMZU-G7 has the preservation number CGMCC No. 37547. This bacterium exhibits highly efficient nitrite degradation capabilities in aquaculture wastewater, demonstrating nitrite degradation ability across a wide concentration range, making it suitable for treating aquaculture wastewater containing varying concentrations of nitrite. Simultaneously, *Bacillus tekirae* GXMZU-G7 also shows good degradation effects on ammonia nitrogen. Furthermore, *Bacillus tekirae* GXMZU-G7 is not only sensitive to common antibiotics but also harmless to aquaculture biosafety, posing no pollution risk, and has promising application prospects in aquaculture wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a strain of Bacillus tekiria GXMZU-G7 with the ability to degrade nitrite and its application. Background Technology

[0002] With the continuous growth in demand for aquatic products, aquaculture, like the livestock industry, is rapidly developing towards industrialization and large-scale production. Under factory-style, intensive aquaculture models, the input of feed and aquatic animal health products continues to increase, resulting in large amounts of uneaten feed and excrement entering the aquaculture water. This leads to excessive levels of ammonia nitrogen, nitrite, and total phosphorus in the water. If aquaculture wastewater is discharged directly without treatment, it will severely cause eutrophication, leading to the deterioration of the aquatic environment. This not only affects the safety of aquatic organisms but may also threaten human production and lives. Therefore, how to achieve water recycling in factory-style, large-scale aquaculture models has become an urgent problem for aquatic scientists to solve.

[0003] The levels of nitrite and ammonia nitrogen in aquaculture wastewater are important indicators for monitoring in aquaculture. Ammonia nitrogen in water exists in two different forms: ammonia in molecular form (NH3) and ammonium in ionic form (NH4). + Ammonia is highly toxic, while ammonium is non-toxic. Furthermore, ammonia and ammonium can interconvert in water. The harmful effects of ammonia nitrogen on aquatic animals are primarily caused by free ammonia, which is dozens of times more toxic than ammonium. Ammonia nitrogen can damage the gill tissue of fish, causing red blood cells to lose their ability to bind oxygen, resulting in decreased respiratory function. Ammonia nitrogen mainly attacks mucous membranes, especially the gill epidermis and intestinal mucosa of fish, and secondarily the nervous system, damaging the liver and kidney systems of fish and other aquatic animals, causing congestion of the body surface and internal organs, muscle hyperplasia, and tumors.

[0004] Ammonia nitrogen exists in water in a free or ionic state. Under certain conditions, organic nitrogen in water can be converted into NH4. + -N, NO2 ˉ It is NH4 + Converted to NO3 ˉ As an intermediate in the process of nitrification, nitrite accumulates rapidly in aquatic ecosystems if this reaction is disrupted. Excessive ammonia nitrogen and nitrite severely impact the survival and growth of aquatic organisms, causing significant economic losses to aquaculture. Excessive nitrite may be caused by imbalances among nitrifying bacteria and nitrogen cycling. Therefore, nitrite levels in aquaculture should be strictly controlled to prevent sub-lethal toxicity in ponds.

[0005] The mechanism of action of nitrite is similar to that of ammonia nitrogen. Nitrite can be absorbed by the gill epithelium of aquatic animals and accumulate in their body fluids. It then binds to oxygen-carrying proteins in the blood, reducing or eliminating their oxygen-carrying capacity, leading to decreased food intake and respiratory difficulties in aquatic animals, causing stress responses. Nitrite can damage the body's antioxidant protection mechanisms. Under nitrite stress, the levels of catalase, superoxide dismutase, and total antioxidant capacity of the liver in fish are significantly inhibited with increasing nitrite concentration, making fish more susceptible to disease, reducing survival rates, and leading to disease outbreaks and mass mortality. In high-density, intensive aquaculture, the problem of excessive nitrite levels urgently needs to be addressed.

[0006] Currently, there are three main methods for degrading nitrite: physical, chemical, and biological. Physical methods separate or remove pollutants through sedimentation and filtration (such as microfilters, activated carbon, and brushes), but these methods often result in incomplete separation. Chemical methods primarily remove pollutants through oxidation reactions, such as ultraviolet irradiation, ozone oxidation, or the addition of flocculants and coagulants, but these are costly and may lead to water pollution. Biological methods improve water quality by constructing or enhancing biological purification systems in the water body. These methods mainly include: microbial preparations using beneficial bacteria and microalgae; activated sludge processes utilizing suspended microbial communities; biofilm methods based on attached microbial films (such as adding packing material to biofilters); and aquatic plant methods utilizing plant absorption. These methods synergistically decompose organic matter and transform nutrients through biological processes, achieving ecological purification of effluent.

[0007] Physical and chemical methods require significant equipment and capital, and are prone to causing repeated environmental pollution. Biological methods, on the other hand, are highly efficient, economical, and produce no secondary pollution, making them widely used. In biological methods, microbial agents are commonly used additives. They not only convert toxic nitrites in water into harmless nitrates, thus purifying the water, but also promote the healthy growth of farmed animals. Bacillus bacteria can utilize nitrites as a nitrogen source for their growth and reduce the nitrite content in their environment through their own metabolic processes, making them ideal strains for the natural degradation of nitrites.

[0008] Therefore, screening out beneficial microorganisms that can efficiently degrade nitrite is the core technical support for promoting the green development of aquaculture and achieving environmental friendliness and improved quality and efficiency. Summary of the Invention

[0009] In view of the deficiencies in the prior art, the purpose of this invention is to provide a strain of Bacillus tektii GXMZU-G7 that can efficiently degrade nitrite and be used for the purification of aquaculture water.

[0010] The objective of this invention is achieved through the following technical solution: This invention provides a strain of Bacillus tekirae ( Bacillus tequilensis The Bacillus tekirae GXMZU-G7 has the accession number CGMCC No.37547.

[0011] This invention provides a microbial inoculant, comprising Bacillus tergentii GXMZU-G7 as described in the above technical solution.

[0012] This invention provides the application of Bacillus tergentii GXMZU-G7 or the microbial agent described in the above technical solution in the degradation of nitrite.

[0013] Preferably, the initial concentration of nitrite during degradation is 0.2~1.6 g / L.

[0014] This invention provides a method for degrading nitrite, comprising: The system containing nitrite was inoculated with a microbial agent containing Bacillus tekiria GXMZU-G7 as described in the above technical solution for treatment.

[0015] Preferably, the processing temperature is 25~45℃; the processing time is ≥12h.

[0016] Preferably, the pH value of the system containing nitrite is 6 to 11; and the concentration of nitrite in the system containing nitrite is 0.2 to 1.6 g / L.

[0017] This invention provides the application of Bacillus tergentii GXMZU-G7 or the microbial agent described in the above technical solution in the degradation of ammonia nitrogen.

[0018] This invention provides the application of Bacillus tergentii GXMZU-G7 or the microbial agent described in the above technical solution in the purification of aquaculture water.

[0019] Preferably, the aquaculture water purification includes reducing nitrite and / or ammonia nitrogen in the aquaculture water.

[0020] The beneficial effects of this invention are: This invention provides a strain of Bacillus tekirae ( Bacillus tequilensisThe *Bacillus tekirae* GXMZU-G7 strain, with accession number CGMCC No. 37547, exhibits highly efficient degradation capabilities for nitrite. It demonstrates good degradation effects under varying initial nitrite concentrations: when the initial nitrite concentration is 50–142 mg / L, the degradation rate reaches over 96% after 24 hours of cultivation; even when the initial concentration increases to 188–375 mg / L, a certain degradation rate is still achieved. The *Bacillus tekirae* GXMZU-G7 provided by this invention possesses nitrite degradation capabilities across a wide concentration range, making it suitable for treating aquaculture wastewater with varying nitrite concentrations. Furthermore, *Bacillus tekirae* GXMZU-G7 also shows good degradation effects on ammonia nitrogen. Furthermore, the Bacillus tekiria GXMZU-G7 is not only sensitive to common antibiotics, but also harmless to aquaculture biosafety and poses no pollution risk, showing good application prospects in aquaculture wastewater treatment.

[0021] Biological Preservation Information Description Bacillus tekirulae GXMZU-G7, Latin scientific name Bacillus tequilensis It was deposited on January 26, 2026, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 37547. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0023] Figure 1 Morphological diagram of strain GXMZU-G7; Figure 2 The image shows the Gram staining results of strain GXMZU-G7. Figure 3 A phylogenetic tree of the target strain GXMZU-G7 constructed based on 16S rRNA is shown. Figure 4 The growth curve and nitrite degradation curve of strain GXMZU-G7 are shown. Figure 5 Figure showing the effect of pH on the growth and nitrite degradation of strain GXMZU-G7; Figure 6 Figure showing the effect of temperature on the growth and nitrite degradation of strain GXMZU-G7; Figure 7 Figure showing the effect of inoculum size on the growth and nitrite degradation of strain GXMZU-G7; Figure 8Figure 1 shows the effect of initial sodium nitrite concentration on the growth and degradation of strain GXMZU-G7. Figure 9 The diagram shows the ammonia nitrogen degradation experiment of strain GXMZU-G7; Figure 10 This is a diagram of the hemolysis test for strain GXMZU-G7. Detailed Implementation

[0024] This invention provides a strain of Bacillus tekirae ( Bacillus tequilensis The Bacillus tekirae GXMZU-G7 has the accession number CGMCC No.37547.

[0025] The *Bacillus tekirae* GXMZU-G7 provided by this invention was isolated from the biological packing material of the biochemical tank in a land-based circular recirculating aquaculture system. *Bacillus tekirae* GXMZU-G7 appears as an irregular circle on LB solid medium with irregular edges, a rough surface, and is white and opaque; it is Gram-positive. *Bacillus tekirae* GXMZU-G7 is positive for starch hydrolysis, gelatin liquefaction, catalase, oxidase, nitrate reduction, and VP tests; negative for hydrogen sulfide and MR tests; and exhibits peptone formation in the milk breakdown test. It can utilize glucose, mannitol, and Simon's citrate, but cannot utilize xylose. The nucleotide sequence of the 16S rRNA of *Bacillus tekirae* GXMZU-G7 is shown in SEQ ID NO.1. A phylogenetic tree was constructed using the neighbor-joining method in MEGA 11.0 software. The results showed that *Bacillus tekirae* GXMZU-G7 is related to... Bacillustequilensis KCTC13622 are grouped together.

[0026] This invention provides a microbial inoculant, comprising *Bacillus tergentii* GXMZU-G7 as described in the above-mentioned technical solution. As an optional embodiment of this invention, the OD600nm value of the *Bacillus tergentii* GXMZU-G7 can be ≥0.5 or 0.78.

[0027] This invention does not specifically limit the preparation method of the microbial agent; any conventional preparation method in the art can be used. As an optional embodiment of this invention, the preparation method of the microbial agent can be: culturing the *Bacillus tekirii* GXMZU-G7 in a culture medium to obtain the microbial agent. As an optional embodiment of this invention, the culture medium can be LB medium or a fermentation medium. In this invention, the fermentation medium uses water as a solvent, and its composition can be: glucose 5 g / L, sodium acetate 2 g / L, sodium chloride 2 g / L, NaNO₂ 0.2~0.5 g / L, dipotassium hydrogen phosphate 3 g / L, potassium dihydrogen phosphate 3 g / L, MgSO₄·7H₂O 0.2 g / L, FeSO₄·7H₂O 0.1 g / L, pH 7.0. As an optional embodiment of the present invention, the culture temperature can be 20~45℃, or 20℃, 25℃, 30℃, 35℃, 37℃, 40℃, or 45℃; the culture time can be ≥12h, or 12~48h, or 12, 16, 20, 24, 28, 32, 36, 40, 44, or 48h; preferably, the culture process is accompanied by rotation, and the rotation speed can be 200 r / min. After the culture is completed, the present invention obtains a microbial inoculant.

[0028] This invention provides the application of *Bacillus tekirii* GXMZU-G7 or the microbial agent described in the above-mentioned technical solutions in the degradation of nitrite. As an optional embodiment of this invention, the initial concentration of nitrite during degradation can be 0.2~1.6 g / L, or 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, or 1.6 g / L.

[0029] In this invention, the *Bacillus tekirii* GXMZU-G7 exhibits highly efficient nitrite degradation capabilities. *Bacillus tekirii* GXMZU-G7 possesses nitrite degradation capabilities across a wide concentration range, making it suitable for treating water bodies with varying degrees of nitrite pollution.

[0030] This invention provides a method for degrading nitrite, comprising: The system containing nitrite was inoculated with a microbial agent containing Bacillus tekiria GXMZU-G7 as described in the above technical solution for treatment.

[0031] As an optional embodiment of the present invention, the pH value of the nitrite-containing system can be 6-11, or 6, 7, 8, 9, 10, or 11; the concentration of nitrite in the nitrite-containing system can be 0.2-1.6 g / L, or 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, or 1.6 g / L. As an optional embodiment of the present invention, the treatment temperature can be 25-45℃, or 20℃, 25℃, 30℃, 35℃, 37℃, 40℃, or 45℃; the treatment time is ≥12h, or 12-48h, or 12, 16, 20, 24, 28, 32, 36, 40, 44, or 48h.

[0032] The Bacillus tergentii GXMZU-G7 provided by this invention has the characteristics of alkali resistance and high temperature resistance. It can efficiently degrade nitrite under strong alkali or high temperature conditions, and the Bacillus tergentii GXMZU-G7 has good nitrite degradation ability over a wide range of nitrite concentrations.

[0033] This invention provides the application of Bacillus tergentii GXMZU-G7 or the microbial agent described in the above technical solution in the degradation of ammonia nitrogen.

[0034] This invention provides the application of Bacillus terrestris GXMZU-G7 or the microbial agent described in the above-mentioned technical solutions in aquaculture water purification. As an optional embodiment of this invention, the aquaculture water purification includes reducing nitrite and / or ammonia nitrogen in the aquaculture water.

[0035] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0036] The sample source for this embodiment: the aquaculture water sample was collected from Xinhai Aquatic Seedling Farm in Guigang City, Guangxi Zhuang Autonomous Region. The farm adopts a land-based circular pond recirculating aquaculture system, and the water sample was collected from the biochemical pond in the recirculation system.

[0037] Nitrite (NO2) - The concentrations of NH3-N and ammonia nitrogen were determined using a CIMA AR8407 water quality analyzer. The degradation rate was calculated as follows: Nitrite degradation rate (%) = ((blank control NO2) - Content - Sample NO2 - Content) / Blank control NO2 - Content) × 100%; Ammonia nitrogen degradation rate (%) = ((NH3-N content in blank control - NH3-N content in sample) / NH3-N content in blank control) × 100%.

[0038] Example 1: Isolation and Identification of Strain GXMZU-G7 The bacterial strain GXMZU-G7 was derived from the biological packing material in the biochemical tank of a land-based circular recirculating aquaculture system. Biofilm was scraped from the surface of the packing material using a sterile inoculation loop and placed in 100 μL of sterile distilled water, then thoroughly shaken to prepare a bacterial suspension. Subsequently, 50 μL of the suspension was evenly spread onto LB agar. After incubation at 37°C for 24 h, single colonies with different morphologies were picked, numbered, and streaked in three zones for purification. After activation by inoculation into LB agar, the purified strain was sequentially inoculated with fermentation media containing 0.2 g / L and 0.5 g / L NaNO₂, and cultured at 35°C and 200 r / min for 48 h with shaking. NO₂ levels were measured using a blank control group. - The concentration of nitrite was determined and the nitrite degradation rate was calculated. Finally, strain GXMZU-G7 with a high nitrite degradation rate was selected for subsequent experiments.

[0039] Strain GXMZU-G7 appears as irregularly round, irregularly shaped, rough-surfaced, white, and opaque specimens on LB solid medium. Figure 1 As shown, Gram staining is positive as... Figure 2 As shown in Table 1, the physiological and biochemical test results were positive for starch hydrolysis, gelatin liquefaction, catalase, oxidase, nitrate reduction, and VP tests; negative for hydrogen sulfide and MR tests; and peptone formation in the milk breakdown test. The strain can utilize glucose, mannitol, and Simon's citrate, but not xylose. Based on Bergey's Manual of Bacterial Identification and the Manual of Systematic Identification of Common Bacteria, the strain was preliminarily identified as belonging to the genus *Bacillus*.

[0040] Table 1. Physiological and biochemical tests of strain GXMZU-G7

[0041] Note: "+" indicates growth or a positive result; "-" indicates no growth or a negative result.

[0042] The strain GXMZU-G7 was inoculated into LB medium and cultured at 37℃ and 200 r / min for 16 h. One mL of fresh bacterial culture in the logarithmic growth phase was sent to Shanghai Ling'en Biotechnology Co., Ltd. for sequencing. The 16S rRNA sequencing results were compared with those of Bacillus tekirae on the EzBioCloud website (https: / / www.ezbiocloud.net). The results showed that it was similar to Bacillus tekirae. (Bacillus tequilensis The similarity between this strain and other strains reached 99.86%. A phylogenetic tree was further constructed using the neighbor-join method in MEGA 11.0 software, showing that this strain... Bacillus tequilensis KCTC 13622 clustered together, like Figure 3 As shown. Based on morphological, physiological and biochemical characteristics and 16S rRNA sequence analysis, this strain was identified and named *Bacillus tekirae* (…). B. tequilensis )GXMZU-G7.

[0043] The 16S rRNA sequence information of strain GXMZU-G7 is shown in SEQ ID NO.1, specifically:

[0044] The fermentation medium uses water as a solvent and includes: glucose 5 g / L, sodium acetate 2 g / L, sodium chloride 2 g / L, NaNO2 0.2~0.5 g / L, dipotassium hydrogen phosphate 3 g / L, potassium dihydrogen phosphate 3 g / L, MgSO4·7H2O 0.2 g / L, FeSO4·7H2O 0.1 g / L, pH 7.0.

[0045] Example 2: Growth and degradation curves of nitrite-degrading strain GXMZU-G7 The strain GXMZU-G7 was used at 2% ( The inoculum was added to fermentation medium containing 0.5 g / L NaNO2 and cultured at 30°C and 200 r / min for 48 h. Samples were taken every 4 h to measure the OD value. 600nm and nitrite degradation rate. Results are as follows: Figure 4 As shown.

[0046] Depend on Figure 4 It can be seen that the strain entered the logarithmic growth phase after 4 hours, and the degradation rate increased rapidly with the growth of strain GXMZU-G7, reaching 94.5% at 20 hours. After 24 hours, the strain entered the stable growth phase with a degradation rate of 99.9%, which indicates that the degradation of nitrite is closely related to the growth of the strain.

[0047] Example 3: Effect of different pH values ​​on the degradation of nitrite by strain GXMZU-G7 The strain was prepared at 2% ( The inoculum was inoculated into fermentation medium containing 0.5 g / L NaNO2 at pH values ​​of 5.0, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 10.0, and 11.0, respectively. After incubation at 30℃ and 200 r / min for 24 h, the OD values ​​were measured. 600nm and nitrite degradation rate. Results are as follows: Figure 5 As shown in Table 2, the changes in nitrite degradation rate under different pH conditions are detailed in Table 2; OD under different pH conditions 600nm The changes in values ​​are detailed in Table 3.

[0048] Figure 5 The results showed that within the pH range of 5 to 11, the growth rate and degradation rate of the strain first increased and then decreased with increasing pH, reaching their maximum values ​​at pH 7.5. Under pH conditions of 7.5 to 10, the degradation rate reached 99.5%.

[0049] Table 2. Changes in nitrite degradation rate under different pH conditions

[0050] Table 3 OD under different pH conditions600nm Changes in value

[0051] Example 4: Effect of different temperatures on the degradation of nitrite by strain GXMZU-G7 The strain was prepared at 2% ( The inoculum was inoculated into fermentation medium (pH 7.5) containing 0.5 g / L NaNO2 and cultured at 20℃, 25℃, 30℃, 35℃, 40℃, and 45℃ on a shaker at 200 r / min for 24 h. The OD value was then measured. 600nm and nitrite degradation rate. Results are as follows: Figure 6 As shown in Table 4, the changes in nitrite degradation rate under different temperature conditions are detailed in Table 4; OD under different temperature conditions 600nm The changes in values ​​are detailed in Table 5.

[0052] Figure 6 The results showed that when the fermentation temperature was 25-35℃, the nitrite degradation rate gradually increased with the increase of temperature, and the nitrite degradation rate reached 99.8% under the conditions of 30℃ and 35℃. The strain proliferation rate first accelerated and then slowed down, reaching the maximum value at 30℃.

[0053] Table 4. Changes in nitrite degradation rate under different temperature conditions

[0054] Table 5 OD under different temperature conditions 600nm Changes in value

[0055] Example 5: Effect of different inoculum amounts on the degradation of nitrite by strain GXMZU-G7 The bacterial cultures were inoculated into fermentation medium (pH 7.5) containing 0.5 g / L NaNO₂ at inoculation rates of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, respectively. The cultures were incubated at 30°C and 200 r / min on a shaker for 24 h. Oddi concentrations (OD) were measured at 12 h and 24 h. 600nm and nitrite degradation rate. Results are as follows: Figure 7 As shown.

[0056] Figure 7The results showed that when the inoculum size was between 1% and 10%, both the bacterial growth and degradation rate increased. At 12 hours, the degradation rate was 23.46% with a 1% inoculum, 53% with a 2% inoculum, 92.07% with a 3% inoculum, and 99.9% with a 4-10% inoculum. At 24 hours, the degradation rate was 59.08% with a 1% inoculum and 99.8% with a 2-10% inoculum. Therefore, considering nitrite degradation rate, bacterial concentration, and cost, 2% was selected as the optimal inoculum size.

[0057] Example 6: Effect of different initial sodium nitrite concentrations on nitrite degradation by strain GXMZU-G7 The sodium nitrite addition amounts were selected as 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 g / L, and the bacterial strain was added at 2% ( The inoculum was inoculated into 10 different fermentation media (pH 7.5) with different initial nitrite concentrations, and cultured at 30℃ and 200 r / min on a shaker for 24 h. The OD values ​​were then measured. 600nm Value and nitrite degradation rate. Results are as follows: Figure 8 As shown in Table 6, the changes in nitrite degradation rate under different initial sodium nitrite concentrations are detailed in Table 6; OD under different initial sodium nitrite concentrations... 600nm The changes in values ​​are detailed in Table 7.

[0058] Figure 8 The results showed that the degradation rate of nitrite by the strain gradually decreased with increasing sodium nitrite concentration, and the growth of the strain was inhibited at high concentrations. When the initial nitrite concentration was 50-142 mg / L (0.2-0.6 g / L), the degradation rate of the strain reached approximately 96% after 24 hours; when the initial nitrite concentration was 188-375 mg / L (0.8-1.6 g / L), the degradation rate of the strain was approximately 8%-38%; when the initial nitrite concentration was 412.5-450 mg / L (1.8-2.0 g / L), the degradation ability of the strain to nitrite decreased significantly, and the degradation rate approached 0.

[0059] Table 6. Changes in nitrite degradation rate under different initial sodium nitrite concentrations

[0060] Table 7 OD under different initial sodium nitrite concentrations 600nm Changes in value

[0061] Example 7: Ammonia nitrogen degradation test of strain GXMZU-G7 Under the optimized conditions described above, the bacterial culture was inoculated at a rate of 2% into a fermentation medium containing 0.5 g / L NaNO2 (pH 7.5), and cultured at 30°C with shaking at 200 r / min. The OD values ​​were measured at 12, 24, and 48 h. 600nm And the degradation rates of nitrite and ammonia nitrogen. Results are as follows: Figure 9 As shown in Table 8.

[0062] Figure 9 The results showed that the degradation rates of nitrite and ammonia nitrogen increased with the growth of the strain. The initial concentrations of nitrite and ammonia nitrogen were measured to be 120 mg / L and 112 mg / L, respectively (the ammonia nitrogen content may be due to residual byproducts of sodium nitrite reagent production, such as Fe). 2+ Impurities such as heavy metals catalyze the reduction of nitrite by glucose or sodium acetate under high temperature conditions, resulting in the release of NO2. - Transformed into NH4 + After 12 hours, the degradation rate of nitrite reached 45% and the degradation rate of ammonia nitrogen reached 50.5%. After 24 hours, the degradation rate of nitrite reached 99.9% and the degradation rate of ammonia nitrogen reached 66.8%. After 48 hours, the degradation rate of nitrite reached 99.9% and the degradation rate of ammonia nitrogen reached 80.2%.

[0063] Table 8 OD at 12, 24 and 48 h 600nm Degradation rate of nitrite and ammonia nitrogen

[0064] Example 8 The strain GXMZU-G7 was inoculated into LB liquid medium and cultured at 35℃ for 14 h to obtain the fermentation broth. Its OD value was then measured. 600nm It is 0.78.

[0065] Aquaculture wastewater from different locations was selected, namely, wastewater from locations A, B, and C. The water samples were divided into two groups: 1 mL of bacterial fermentation broth was added to the experimental group, while no bacterial strain was added to the control group. The samples were incubated at room temperature (28-30℃) for 24 hours (simulating the aquaculture environment), and the nitrite content in the samples was detected. The nitrite degradation rate was calculated, and the results are shown in Table 9.

[0066] Table 9. Changes in nitrite content in aquaculture water samples after inoculation with strain GXMZU-G7

[0067] Table 9 shows that strain GXMZU-G7 can almost completely degrade nitrite in water, while the nitrite content in the control group remains almost unchanged.

[0068] Example 9: Safety test of strain GXMZU-G7 1. Drug resistance test of strain GXMZU-G7 Antimicrobial susceptibility testing of the strain was performed using the KB disk diffusion method. The susceptibility testing criteria were based on CLSI M100-S32 (https: / / clsi.org / ). 100 µL of bacterial suspension (OD200) was taken. 600nm =0.5) was evenly spread onto LB solid medium and incubated at 35℃ for 24 h. The diameter of the inhibition zone (mm) was measured, and the antibiotic sensitivity of the strain was determined based on the diameter. The results are shown in Table 10.

[0069] Table 10. Antimicrobial susceptibility test results for strain GXMZU-G7

[0070] Table 10 shows that the antibiotic susceptibility test results indicate that strain GXMZU-G7 is resistant to lincomycin and highly sensitive to nine antibiotics: chloramphenicol, trimethoprim-sulfamethoxazole, ciprofloxacin, erythromycin, tetracycline, gentamicin, ceftriaxone, ampicillin, and penicillin, meeting the standards for use in aquaculture.

[0071] 2. Hemolysis plate test Strain strain GXMZU-G7 was inoculated onto blood agar plates and incubated upside down at 30°C for 48 hours. Hemolysis was then observed. Figure 10 As shown.

[0072] Figure 10 The results showed that after incubation at 30℃ for 48 hours, no hemolytic zone was formed on the hemolytic plate, and no hemolysis was observed. From the specific perspective of hemolytic toxicity, its potential safety for mammals is relatively high.

[0073] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A strain of Bacillus tekiria ( Bacillus tequilensis GXMZU-G7, characterized in that, The preservation number of the Bacillus tekirulae GXMZU-G7 is CGMCC No. 37547.

2. A microbial inoculant, characterized in that, Includes Bacillus tekirulae GXMZU-G7 as described in claim 1.

3. The application of Bacillus tergentii GXMZU-G7 of claim 1 or the microbial agent of claim 2 in the degradation of nitrite.

4. Use according to claim 3, characterized in that, During the degradation of nitrite, the initial concentration of nitrite is 0.2~1.6 g / L.

5. A method of degrading nitrite, characterized by, include: The system containing nitrite is treated by inoculating it with a microbial agent containing Bacillus tekiria GXMZU-G7 as described in claim 1.

6. The method of claim 5, wherein, The processing temperature is 25~45℃; the processing time is ≥12h.

7. The method of claim 5, wherein, The pH value of the system containing nitrite is 6-11; the concentration of nitrite in the system containing nitrite is 0.2-1.6 g / L.

8. The application of Bacillus tergentii GXMZU-G7 of claim 1 or the microbial agent of claim 2 in the degradation of ammonia nitrogen.

9. The application of Bacillus tekirulae GXMZU-G7 as described in claim 1 or the microbial agent as described in claim 2 in the purification of aquaculture water.

10. Use according to claim 9, characterized in that, The aquaculture water purification includes reducing nitrite and / or ammonia nitrogen in the aquaculture water.

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