Aerobic denitrifying Halomonas LHT6 and its application

Abstract

The present invention relates to an aerobic denitrifying Halomonas desiderata Halomonas tianxiuensis LHT6, with a preservation number of CGMCC No. 32312. This strain can tolerate salinity, heavy metal ions and antibiotic stress under low carbon-nitrogen ratio conditions to achieve efficient nitrogen removal, and has application significance in the actual treatment of water bodies such as aquaculture wastewater and pharmaceutical wastewater.

Description

Technical Field

[0001] The present invention relates to an aerobic denitrifying Halomonas aestuarii LHT6 and its application. Background Art

[0002] Nitrogen pollution is an important environmental issue of the contemporary era. Excessive nitrogen emissions can lead to blackening, stinking, and eutrophication of water bodies, seriously endangering the ecological balance and human health. At the same time, due to problems in the construction and maintenance of urban sewage pipe networks, the influent water quality of sewage treatment systems shows the characteristics of a low carbon-nitrogen ratio. The lack of carbon sources restricts the removal of nitrogen in water bodies. At the same time, natural water bodies also have the characteristics of a low carbon-nitrogen ratio because carbon sources cannot be added. Therefore, in the context of carbon peaking and carbon neutrality, in order to achieve carbon emission reduction, reduce carbon source addition, and develop new biological nitrogen removal technologies suitable for water bodies with a low carbon-nitrogen ratio is the general trend of the development of sewage treatment plants. The emergence of aerobic denitrification and the isolation of aerobic denitrifying bacteria have broken the limitations of traditional biological nitrogen removal technologies that need to be carried out in the same reactor and are widely used in biological nitrogen removal.

[0003] In addition, with the continuous development of the aquaculture industry, the pharmaceutical industry, etc., a large amount of wastewater is generated. This type of wastewater not only contains a large amount of nitrogen, but also has a high salinity and different types of antibiotics. Research shows that the presence of salinity will inhibit cell growth, cause the osmotic pressure inside and outside the cell to be unbalanced, leading to cell dehydration and even death; it will also change the nitrogen metabolism pathway of denitrifying bacteria and reduce the expression of denitrification genes. The broad antibacterial spectrum in antibiotics will kill or inhibit the growth and reproduction of microorganisms, and also inhibit the metabolic activities and enzyme activities of cells. At the same time, some saline wastewater also contains heavy metal ions such as Zn(II), Cu(II), Mn(II), and Fe(II), etc. The presence of heavy metal ions usually has a toxic effect on microorganisms and even causes the direct death of microorganisms. These factors also restrict the nitrogen removal efficiency of this type of water body and will affect the sewage treatment effect.

[0004] Therefore, screening out aerobic denitrifying bacteria that can tolerate salinity, heavy metal ions, and antibiotic stress and achieve efficient nitrogen removal under low carbon-nitrogen ratio conditions has application significance in the actual treatment of water bodies such as aquaculture wastewater and pharmaceutical wastewater. Summary of the Invention

[0005] The purpose of the present invention is to provide an Halomonas aestuarii LHT6 that can tolerate salinity, heavy metal ions, and antibiotic stress and achieve efficient nitrogen removal under low carbon-nitrogen ratio conditions and its application.

[0006] The present invention adopts the following technical solutions:

[0007] An aerobic denitrifying Halomonas aestuarii ( Halomonas tianxiuensis) LHT6, with the preservation number of CGMCC No. 32312, was preserved at the General Microbiology Center of the China Committee for Culture Collection of Microorganisms on October 23, 2024, and the address is Beijing, China.

[0008] Further, the Halomonas desiderata LHT6 can perform aerobic denitrification.

[0009] Further, the Halomonas desiderata LHT6 can denitrify under the condition of C / N being 2 - 10.

[0010] Particularly, the Halomonas desiderata LHT6 can efficiently denitrify under the condition of C / N being 4.

[0011] Further, the Halomonas desiderata LHT6 can grow and remove nitrate under the condition of pH being 7 - 11.

[0012] Particularly, the Halomonas desiderata LHT6 can grow and remove nitrate under the condition of pH being 10.

[0013] Further, the Halomonas desiderata LHT6 can grow and remove nitrate under the condition of containing 0% - 15% NaCl.

[0014] Particularly, the Halomonas desiderata LHT6 can grow and remove nitrate under the condition of containing 15% NaCl.

[0015] Further, the Halomonas desiderata LHT6 is resistant to oxacillin, cefuroxime sodium, streptomycin, lincomycin, vancomycin, polymyxin B, co-trimoxazole, clindamycin, doxycycline, and metronidazole.

[0016] Further, the Halomonas desiderata LHT6 can grow and remove nitrate under the condition of containing Zn(II) ions, Cu(II) ions, Mn(II) ions, and / or Fe(II) ions.

[0017] An application of the above-mentioned Halomonas desiderata LHT6 in sewage treatment.

[0018] An application of the above-mentioned Halomonas desiderata LHT6 in treating saline, antibiotic, and / or heavy metal ion-containing aquaculture wastewater or pharmaceutical wastewater under the condition of low carbon-nitrogen ratio.

[0019] A sewage treatment agent containing the above-mentioned Halomonas desiderata LHT6.

[0020] The beneficial effects of the present invention are as follows: Halomonas tianxiuensis LHT6 of the present invention has excellent characteristics of salt tolerance, heavy metal tolerance, alkali tolerance, and antibiotic tolerance. Especially under the condition of C / N being 4, it can still perform aerobic denitrification, achieving efficient nitrogen removal in harsh environments, and has application significance in the actual treatment of water bodies such as aquaculture wastewater and pharmaceutical wastewater. Brief Description of the Drawings

[0021] Figure 1 It is a scanning electron micrograph of strain LHT6.

[0022] Figure 2 It is a phylogenetic tree of strain LHT6.

[0023] Figure 3 It is the denitrification characteristics of strain LHT6 under different carbon-nitrogen ratios.

[0024] Figure 4 It is the denitrification characteristics of strain LHT6 under different carbon sources.

[0025] Figure 5 It is the removal rates of NO3 - -N and TDN of strain LHT6 under the influence of different pH values.

[0026] Figure 6 It is the removal rates of NO3 - -N and TDN of strain LHT6 under the influence of different rotation speeds.

[0027] Figure 7 It is a picture of the plate result of the drug sensitivity test of strain LHT6.

[0028] Figure 8 It is the removal rates of NO3 - -N and TDN of strain LHT6 under the influence of different concentrations of sulfamethoxazole.

[0029] Figure 9 It is the removal rates of NO3 - -N and TDN of strain LHT6 under the influence of different concentrations of tetracycline.

[0030] Figure 10 It is the denitrification performance of strain LHT6 under the influence of different salinities.

[0031] Figure 11 It is the nitrate nitrogen removal ability of strain LHT6 under the influence of different concentrations of heavy metals. Detailed Embodiments

[0032] Example 1 Isolation and Screening of LHT6

[0033] 10 mL of fresh activated sludge samples taken from a pharmaceutical wastewater treatment plant in Shijiazhuang were added to a 250 mL conical flask containing 100 mL of enrichment medium (LB medium) for enrichment culture. The culture conditions were 25 °C and 120 rpm. The medium was changed every 2 days for a total of 4 days. After the culture ended, 7.5 mL of the mixed solution was taken into a 250 mL conical flask containing 150 mL of denitrification medium and still cultured at 25 °C and 120 rpm. The pharmaceutical wastewater and the denitrification medium were formulated into acclimation media according to the ratios of 0 / 10, 1 / 9, 2 / 8, 3 / 7, 4 / 6, 5 / 5, 6 / 4, 7 / 3, 8 / 2 (v / v). Each concentration of the medium was cultured for 3 days and repeated twice. The acclimation process took about 54 days.

[0034] 1 mL of the bacterial suspension after acclimation was taken into 9 mL of buffer solution, and successively diluted by a factor of 10 -1 , 10 -2 , 10 -3 , 10 -4 , 10 -5 , 10 -6 . 0.2 mL was taken from the mixed solution at a concentration of 10 -6 and transferred to the solid denitrification medium. The bacterial solution was spread evenly on the agar plate with a sterile spreading rod after autoclaving, sealed and incubated at 25 °C until visible colonies appeared. A sterile inoculation loop that had been heated and cooled by a Bunsen burner was used to pick colonies with different shapes and sizes on the agar plate for streaking. After separating single colonies, streaking was performed multiple times to obtain purified single colonies, which were placed in a 4 °C refrigerator for storage waiting for screening.

[0035] The isolated single colonies were respectively inoculated into 100 mL of LB medium for enrichment culture for 2 days. After the culture ended, the bacterial mixed solution was centrifuged at 6000 r / min. The obtained bacterial cells were shaken with buffer solution, and 10 mL was taken and inoculated into a 250 mL conical flask containing 150 mL of fresh denitrification medium to identify the denitrification ability respectively. Single bacteria with a nitrate nitrogen removal rate of more than 90% were screened out, and the denitrification efficiency was verified at least 3 times again. The single strain LHT6 with a nitrate nitrogen removal rate maintained above 90% was screened out.

[0036] The specific components of each of the above media are as follows:

[0037] LB medium: Tryptone 10 g / L, yeast extract powder 5 g / L, NaCl 10 g / L, sterilized at 121 °C for 30 min.

[0038] Denitrification medium: CH3COONa 4.69 g / L, KNO3 0.722 g / L, vitamin salt solution (including K2HPO4·3H2O 0.75 g / L, NaH2PO4·2H2O 0.25 g / L, NaCl 0.12 g / L, MnSO4·H2O 0.01 g / L, MgSO4·7H2O 0.05 g / L, FeSO4·7H2O 0.01 g / L), autoclaved at 121 °C for 30 min.

[0039] Solid denitrification medium: CH3COONa 4.69 g / L, KNO3 0.722 g / L, K2HPO4·3H2O 0.75 g / L, NaH2PO4·2H2O 0.25 g / L, NaCl 0.12 g / L, MnSO4·H2O 0.01 g / L, MgSO4·7H2O 0.05 g / L, FeSO4·7H2O 0.01 g / L, agar 20 g / L, autoclaved at 121 °C for 30 min.

[0040] Buffer: NaCl 8 g / L, KCl 0.2 g / L, Na2HPO4·12H2O 3.63 g / L, KH2PO4 0.24 g / L, adjust the pH to 7.4.

[0041] Example 2 Morphological and Molecular Identification of LHT6

[0042] Observation of strain LHT6 under an electron microscope showed that the cells had a rod-shaped appearance (as Figure 1 shown). Genomic DNA of this strain was extracted, and the PCR product was amplified using the universal primers 27F / 1492R for bacterial 16S rRNA gene, and then sent to Shanghai Majorbio Bio-pharm Technology Co., Ltd. for sequence sequencing. The sequencing results (as shown in SEQ ID No.1) were compared and analyzed in the NCBI database to identify its species relationship, and it was found that strain LHT6 had a high similarity with Halomonas tianxiuensis and the phylogenetic tree of strain LHT6 was constructed using MEGA (11.0) as Figure 2 shown.

[0043] Based on the above results analysis, strain LHT6 was identified as: Halomonas desiderata ( Halomonas tianxiuensis ). This strain was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on October 23, 2024. The address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Beichen West Road, Chaoyang District, Beijing, and the deposit number is CGMCC No. 32312.

[0044] Example 3 Effects of Different C / N on the Aerobic Denitrification Characteristics of Strain LHT6

[0045] The activated seed liquid of strain LHT6 was inoculated into denitrification media with C / N ratios of 2, 4, 6, 8, and 10 at an inoculation amount of 5% (while keeping the KNO3 content constant and controlling the C / N ratio by changing the content of CH3COONa, and the other components of the media were the same as in Example 1). The cultures were incubated at 25 °C and 120 rpm for 72 h with constant shaking, and samples were taken at 0 h, 12 h, 24 h, 36 h, 48 h, 60 h, and 72 h to measure OD 600 , nitrate nitrogen (NO3 - -N), ammonia nitrogen (NH4 + -N), nitrite nitrogen (NO2 - -N), and total dissolved nitrogen (TDN).

[0046] The results are as Figure 3 shown. When the C / N ratios were 2, 4, 6, 8, and 10 respectively, strain LHT6 could achieve efficient denitrification, and the removal rates of TDN were 98.85%, 98.15%, 97.14%, 97.25%, and 98.17% respectively. When the C / N ratios were 4, 6, and 8, the denitrification rate of the strain was higher than that when the C / N ratios were 2 and 10. Considering the requirement of energy-saving and efficient nitrogen reduction under the "dual-carbon background", a C / N ratio of 4 was selected as the optimal C / N ratio for this strain.

[0047] Denitrification medium (C / N = 4): CH3COONa 1.3667 g / L, KNO3 0.722 g / L, vitamin solution (including K2HPO4·3H2O 0.75 g / L, NaH2PO4·2H2O 0.25 g / L, NaCl 0.12 g / L, MnSO4·H2O 0.01 g / L, MgSO4·7H2O 0.05 g / L, FeSO4·7H2O 0.01 g / L), pH 7.5, autoclaved at 121 °C for 30 min.

[0048] Example 4 Effect of Different Carbon Sources on Aerobic Denitrification Characteristics of Strain LHT6

[0049] After changing the C / N ratio, the activated seed liquid of strain LHT6 was inoculated into fresh denitrification medium at an inoculation amount of 5% (the C / N ratio was determined to be 4, and the medium formulation was the same as in Example 3 except for changing the carbon source type). The cultures were incubated at 25 °C and 120 rpm for 72 h with constant shaking, and samples were taken at 0 h, 12 h, 24 h, 36 h, 48 h, 60 h, and 72 h to measure OD 600 , nitrate nitrogen, ammonia nitrogen, nitrite nitrogen, and total dissolved nitrogen.

[0050] The results are as Figure 4As shown in the figure, when sodium acetate was used as the sole carbon source, the removal rates of nitrate nitrogen and total dissolved nitrogen at 72 h were 92.88% and 92.66% respectively, which were significantly higher than those when succinate, sodium citrate and sucrose were used as single carbon sources respectively. When succinate, sodium citrate and sucrose were used as the sole carbon source respectively, the removal efficiency of the strain was low and accompanied by the accumulation of nitrite nitrogen. Especially when succinate was used as the carbon source, the removal rates of nitrate nitrogen and total dissolved nitrogen by the strain were only 22.03% and 14.53% respectively. Therefore, sodium acetate was selected as the optimal single carbon source for strain LHT6.

[0051] Sodium acetate was determined as the single carbon source, and the composition of the subsequent experimental denitrification medium was as follows: CH3COONa 1.3667 g / L, KNO3 0.722 g / L, vitamin salt solution (including K2HPO4·3H2O 0.75 g / L, NaH2PO4·2H2O 0.25 g / L, NaCl 0.12 g / L, MnSO4·H2O 0.01 g / L, MgSO4·7H2O 0.05 g / L, FeSO4·7H2O 0.01 g / L), pH 7.5, autoclaved at 121 °C for 30 min.

[0052] Example 5 Effect of different pH values on the aerobic denitrification characteristics of strain LHT6

[0053] The cell mixture of the activated strain LHT6 was inoculated into fresh denitrification medium (the medium composition was the same as that in Example 4) at an inoculation amount of 5%, and incubated at a constant temperature of 25 °C and 120 rpm for 120 h. Samples were taken at 24 h, 48 h, 72 h and 120 h to measure OD 600 , nitrate nitrogen, ammonia nitrogen, nitrite nitrogen and total dissolved nitrogen.

[0054] The results were as Figure 5 shown. There were obvious differences in the nitrogen removal efficiency of strain LHT6 under the influence of different pH values. When the pH was 5, 6 and 12, the strain could hardly remove nitrogen; while when the pH was 7 - 11, strain LHT6 could remove more than 90% of nitrate nitrogen and there was no accumulation of nitrite nitrogen. Among them, when the pH was 10, the growth and nitrogen removal rate of the strain were the fastest. It could remove 96.97% of nitrate nitrogen at 24 h, with a small amount of nitrite nitrogen accumulation (3.76 mg / L), and all nitrogen was removed at 48 h (the removal rate of total dissolved nitrogen was 98.26%). Therefore, strain LHT6 could grow and efficiently remove nitrate at pH 7 - 11, indicating that this strain was suitable for survival in an alkaline environment, and the optimal pH was 10.

[0055] Example 6 Denitrification characteristics of strain LHT6 under the influence of different rotation speeds

[0056] The activated cell mixture was inoculated into fresh denitrification medium (the medium formula was the same as that in Example 4) at an inoculation amount of 5%, and the rotation speeds were set to 0, 40, 80, 120, 160, and 200 rpm respectively, and incubated at a constant temperature of 25°C for 72 h. Samples were taken every 12 h to measure OD 600 , nitrate nitrogen, ammonia nitrogen, nitrite nitrogen, and dissolved total nitrogen.

[0057] The results are as Figure 6 shown. Strain LHT6 could efficiently remove nitrate under different rotation speed conditions. When the rotation speed was 0 rpm, the growth and denitrification rate of the strain were slow, and the nitrogen removal rate reached over 90% at 48 h of reaction. When the rotation speed was 40 - 200 rpm, it was found that the nitrogen removal rate of the strain reached over 90% at 24 h, and during the reaction process, the higher the rotation speed, the faster the growth and denitrification rate of the strain, which was also related to the dissolved oxygen (DO) matching different rotation speeds. Therefore, for strain LHT6, when the rotation speed was not less than 120 rpm, the strain could grow rapidly and had a high denitrification efficiency.

[0058] Example 7 Drug sensitivity test of strain LHT6

[0059] The disk diffusion method was used to conduct a drug sensitivity test on strain LHT6. 0.2 mL of the mixed bacterial liquid cultured in denitrification medium for 24 h was evenly spread on the surface of LB solid medium. After the plate was placed in the ultra-clean workbench and left to stand for 2 - 3 minutes until the bacterial liquid was dry, sterile forceps were used to pick up the drug sensitivity disk and stick it on the surface of the plate and gently press the disk to make it fit tightly, and then it was placed in an incubator at a constant temperature of 35°C for 18 - 24 hours. Three parallel samples were set for each experiment.

[0060] After the culture was completed, the diameter of the inhibition zone was measured with a caliper, and the results were judged according to the antibiotic sensitivity standard of the Clinical and Laboratory Standards Institute (CLSI) of the United States. The results of the drug sensitivity test are as Figure 7 shown. The results of the antibiotic resistance experiment are shown in Table 1. According to the performance of the strain in the resistance test, it can be used as an indicator organism in aquaculture.

[0061] Table 1 Drug sensitivity test results of strain LHT6

[0062] .

[0063] Example 8 Denitrification characteristics of strain LHT6 under the influence of different concentrations of sulfamethoxazole (sulfonamide antibiotic)

[0064] According to the performance of the strain in Example 7, sulfamethoxazole, which showed drug resistance characteristics in the drug resistance experiment and was widely used in practice, was selected. The activated seed liquid of strain LHT6 was inoculated into fresh denitrification media containing different concentrations of sulfamethoxazole (0, 50, 100, 250, 500, 1000 μg / L) at an inoculation amount of 5% (the composition of the denitrification medium was the same as that in Example 4). The culture was incubated at a constant temperature of 25°C and 120 rpm with shaking, and samples were taken regularly to measure nitrate nitrogen, ammonia nitrogen, nitrite nitrogen, and total dissolved nitrogen.

[0065] As Figure 8 shown, after adding different concentrations of sulfamethoxazole to the denitrification culture, strain LHT6 almost removed all nitrogen (the removal rate reached over 99%) at 48 h. There was a small amount of nitrite accumulation during the reaction process, but it could be completely removed eventually. These results indicate that strain LHT6 can tolerate the influence of sulfamethoxazole within the range of 1000 μg / L and has good nitrogen removal performance, and can be applied to the treatment of antibiotic wastewater to achieve efficient nitrogen removal.

[0066] Example 9 Nitrogen removal characteristics of strain LHT6 under the influence of different concentrations of tetracycline (tetracycline antibiotics)

[0067] According to the performance of the strain in Example 7, tetracycline, which showed sensitive characteristics in the drug resistance experiment and was frequently detected in the sewage treatment system, was selected. The activated seed liquid of strain LHT6 was inoculated into fresh denitrification media containing different concentrations of tetracycline (0, 50, 100, 250, 500 μg / L) at an inoculation amount of 5% (the composition of the denitrification medium was the same as that in Example 4). The culture was incubated at a constant temperature of 25°C and 120 rpm with shaking, and samples were taken every 24 h to measure nitrate nitrogen, ammonia nitrogen, nitrite nitrogen, and total dissolved nitrogen.

[0068] The results are as Figure 9 shown. When different concentrations of tetracycline were added to the denitrification medium, the removal rate of nitrate by strain LHT6 could reach over 95% at 144 h; the removal efficiency was the highest without adding tetracycline, and the removal rates of nitrate nitrogen and total dissolved nitrogen within 48 h could reach 97.77% and 97.33% respectively. Among them, the nitrogen removal rate of strain LHT6 decreased with the increase in the concentration of tetracycline in the medium. Compared with without adding tetracycline, strain LHT6 could completely remove all nitrogen at 144 h when 500 μg / L of tetracycline was added. Thus, it can be seen that although the strain showed sensitivity to tetracycline in the drug sensitivity test, the strain can still tolerate a certain concentration range of tetracycline and can be applied to the treatment of wastewater containing sensitive antibiotics.

[0069] Example 10 Salt tolerance characteristics and mechanism analysis of strain LHT6

[0070] The activated seed culture solution of strain LHT6 was inoculated into fresh denitrification media with salinities (NaCl) of 0%, 3%, 5%, 8%, 10%, 12% and 15% at an inoculation amount of 5% (the media formula was the same as that in Example 4), and incubated at a constant temperature with shaking at 25 °C and 120 rpm. Samples were taken at regular intervals to measure nitrate nitrogen, ammonia nitrogen, nitrite nitrogen and total dissolved nitrogen.

[0071] The results of the nitrogen removal effect of strain LHT6 under the influence of different salinities (0% - 15%) are as Figure 10 shown. When C / N was 4, under the influence of salinities from 0% to 12%, strain LHT6 removed almost all nitrates at 36 h, 3 d, 5 d, 9 d, 18 d and 35 d respectively, and there was no accumulation of nitrite nitrogen; under the influence of 15% salinity, the removal rates of nitrate and total nitrogen by strain LHT6 were 95.55% and 82.38% respectively, and there was a small amount of nitrite nitrogen accumulation (11.86 mg / L). These results indicate that salinity has an inhibitory effect on the growth and nitrogen removal effect of the strain, and the higher the salinity, the longer the adaptation time required for the strain to grow. However, this strain can grow under salinity stress within 15% and achieve nitrogen removal under the condition of C / N being 4, indicating its relatively wide salt tolerance ability.

[0072] Relevant salt tolerance genes of strain LHT6 were obtained through whole-genome analysis nha C, ect B, ots A, gdh A, pro ABC, kdp system, trk system and bet B. The strain can relieve the pressure of the high-salt environment on the cells by ingesting, synthesizing and accumulating small-molecule compatible substances in the cells, mainly including tetrahydropyridine synthesized by ect B, ots trehalose synthesized by gdh A, pro glutamate synthesized by bet A, + proline synthesized by

[0073] ABC and glycine betaine synthesized with the participation of

[0074] B. These genes can also act as osmoregulators to help LHT6 cope with the high-salt environment. In addition, the strain can also resist high-salt stress by transporting small-molecule compatible substances in the cells, such as the kdp system and the trk system, which contribute to the accumulation of intracellular k + concentration. These mechanisms endow strain LHT6 with high salt tolerance potential and can be applied to the treatment of actual saline wastewater.

[0073] Example 11 Tolerance of Strain LHT6 to Different Heavy Metal Ions

[0074] The suspension bacterial liquid of strain LHT6 in the logarithmic phase was inoculated into denitrification media containing different concentrations of heavy metal ions Zn(II), Cu(II), Mn(II) and Fe(II) at an inoculation amount of 5% respectively. The denitrification medium without adding heavy metal ions was used as the blank control. The cultures were incubated at 25 °C and 120 rpm. Among them, the medium with added Zn(II) ions was cultured for 72 h, the medium with added Cu(II) ions was cultured for 120 h, and the media with added Mn(II) and Fe(II) ions were both cultured for 24 h. Samples were taken regularly to measure the nitrate nitrogen concentration in the medium, and the tolerance of strain LHT6 to different types of heavy metal ions was analyzed.

[0075] The results are as Figure 11 shown. With the increase in concentration, heavy metal ions Zn(II) and Cu(II) showed certain inhibitory effects on the growth and nitrate nitrogen removal performance of strain LHT6. When 50 mg / L of Zn(II) and Cu(II) ions were added respectively, compared with the medium without adding heavy metal ions, at 72 h and 120 h of culture respectively, the nitrate nitrogen removal rates of strain LHT6 decreased from 87.07% and 91.12% to 25.64% and 29.29% respectively. However, Mn(II) and Fe(II) ions within a certain concentration range showed obvious promoting effects on the denitrification efficiency of strain LHT6. When the media with added Mn(II) and Fe(II) ions were cultured for 24 h, the nitrate nitrogen removal rates both reached over 95%; and when 100 mg / L of Mn(II) and Fe(II) ions were added to the medium respectively, the nitrate nitrogen removal rates of strain LHT6 both increased from 91.56% to 100%.

Claims

1. A type of Halomonas spp. Halomonas tianxiuensis ) LHT6, characterized in that, Its deposit number is CGMCC No.32312.

2. Use of the Halomonas truncatula LHT6 as claimed in claim 1 in sewage treatment.

3. An application of the Halomonas LHT6 as described in claim 1 in treating aquaculture wastewater or pharmaceutical wastewater containing salt, antibiotics and / or heavy metal ions under low carbon-nitrogen ratio conditions.

4. A sewage treatment agent comprising the Halomonas LHT6 as claimed in claim 1.

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