Oxygen-tolerant denitrifying bacteria resistant to micro / nano-plastics and application thereof

Abstract

The present application belongs to the field of environmental microorganism and sewage treatment technology, and particularly relates to an aerobic denitrification bacterium tolerating micro / nano plastic and application thereof. In order to provide an aerobic denitrification strain with high-efficiency denitrification performance, low nitrite accumulation and micro / nano plastic tolerance, the present application screens an aerobic denitrification bacterium AD-7 from activated sludge, which is named as Pseudomonas mendocina (Pseudomonas mendocina) Ectopseudomonas mendocina ), preserved in China General Microbiological Culture Collection Center with a preservation number of CGMCC NO. 38411. The strain can realize high-efficiency denitrification under aerobic conditions when the initial concentration of NO3 ‑ - N is in the range of 100-300 mg / L, and has strong environmental tolerance to polyethylene terephthalate micro / nano plastic. The denitrification performance of the strain is less affected by the inhibition of polyethylene terephthalate micro / nano plastic, and the strain can still be operated efficiently and stably in composite pollution water bodies containing micro / nano plastic.

Description

Technical Field

[0001] This invention belongs to the field of environmental microbiology and wastewater treatment technology, specifically relating to an aerobic denitrifying bacterium tolerant to micro / nanoplastics and its application. Background Technology

[0002] Aerobic denitrification is a significant discovery in environmental microbiology in recent years, overturning the traditional understanding that denitrification must occur under anoxic conditions. Compared with the traditional two-stage denitrification process of anoxic denitrification-aerobic nitrification, aerobic denitrification technology has significant advantages: it can achieve simultaneous nitrification and denitrification, greatly saving reactor volume and infrastructure investment; at the same time, since it does not require strict oxygen control to maintain an anoxic environment, it effectively reduces process energy consumption and operational complexity. Aerobic denitrifying bacteria are the core functional bacteria of this technology. They are heterotrophic microorganisms that can carry out denitrification under aerobic conditions using nitrate or nitrite as electron acceptors. Their unique metabolic characteristics make them promising for applications in the field of biological nitrogen removal from wastewater.

[0003] However, currently reported aerobic denitrifying bacteria still suffer from low nitrogen removal efficiency and accumulation of the intermediate product nitrite in practical applications, and their tolerance and treatment stability to high-concentration nitrate wastewater need improvement. Furthermore, microplastics, as a novel pollutant, are widely detected in urban wastewater. Large quantities of microplastics enter urban wastewater, and some further decompose into nanoplastics, ultimately distributing throughout the wastewater treatment system and significantly impacting biological nitrogen removal. Studies have shown that micro / nanoplastics affect biological nitrogen removal efficiency by inhibiting nitrification and denitrification. The metabolic processes of aerobic denitrifying bacteria are highly sensitive to changes in environmental factors and are more easily affected by exogenous pollutants. Therefore, screening aerobic denitrifying strains with high nitrogen removal efficiency, low nitrite accumulation, and tolerance to micro / nanoplastics is of significant practical importance. Summary of the Invention

[0004] This invention addresses the aforementioned problems by providing an aerobic denitrifying bacterium tolerant to micro / nanoplastics and its applications. This strain can rapidly and stably remove nitrate nitrogen under aerobic conditions, with a low nitrite nitrogen accumulation rate, which simplifies traditional denitrification processes, reduces operating costs, and exhibits strong environmental tolerance to polyethylene terephthalate micro / nanoplastics.

[0005] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a strain of aerobic denitrifying bacteria tolerant to micro / nanoplastics, namely *Pseudomonas mendoza* (…). Ectopseudomonas mendocinaAD-7 was deposited on April 23, 2026, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen Road, Chaoyang District, Beijing, with accession number CGMCC NO.38411.

[0006] Furthermore, this strain was isolated from activated sludge in the aerobic tank of a wastewater treatment plant in Taiyuan City, Shanxi Province.

[0007] Furthermore, the colonies of strain AD-7 are milky white, round granules, about 1-2 mm in diameter, with a slightly raised center; under a biological scanning electron microscope, they appear as typical short rods with smooth and intact cell surfaces.

[0008] Furthermore, strain AD-7 exhibits environmental tolerance to polyethylene terephthalate microplastics and nanoplastics.

[0009] Furthermore, the microplastics have a particle size of 48 μm to 300 μm, and the nanoplastics have a particle size of 200 nm.

[0010] The present invention also provides the application of an aerobic denitrifying bacterium tolerant to micro / nanoplastics for degrading nitrate nitrogen with low nitrite accumulation in the treatment of nitrate-containing wastewater.

[0011] Furthermore, the aerobic denitrifying bacteria in the initial NO3 - -N concentration within 100~300 mg / L, NO3 - -N can be completely removed within 36 hours.

[0012] Furthermore, the bacteria in NO3 - When the -N concentration is 100 mg / L, NO2 - The -N accumulation rate was only 20.17%, and the strain grew well (OD). 600 Approximately 1.00).

[0013] Furthermore, the bacteria maintained extremely high and stable NO3 levels even under stress conditions of PET micro / nanoplastics with different particle sizes and concentrations. - -N removal rate.

[0014] Furthermore, the bacteria achieved a removal rate of over 96.70% for 48 hours within a concentration range of 0-1000 mg / L for polyethylene terephthalate micro / nanoplastics. Notably, even at a high concentration of 1000 mg / L, the bacteria maintained a denitrification efficiency of over 98%.

[0015] Compared with the prior art, the present invention has the following advantages: The aerobic denitrifying bacteria AD-7 of this invention, under aerobic conditions, NO3 -Highly efficient nitrogen removal can be achieved within an initial nitrogen concentration range of 100-300 mg / L, including NO3-. - When the initial concentrations of -N are 100, 150, 200, and 300 mg / L, NO3 - -N can be completely removed within 36 hours. NO3 - When the initial concentration of -N is 100 mg / L, NO2 - The -N accumulation rate is the lowest, at only 20.17%. This strain can be applied to the aerobic denitrification treatment of nitrate-containing wastewater, which can simplify the traditional denitrification process and reduce operating costs.

[0016] Furthermore, this strain exhibits strong environmental tolerance to polyethylene terephthalate micro / nanoplastics. Its denitrification performance is minimally inhibited by polyethylene terephthalate micro / nanoplastics, and it can still operate efficiently and stably in water bodies with complex pollution containing micro / nanoplastics. It demonstrates excellent and stable denitrification performance, significant stress resistance, and extremely high practical engineering application value. Attached Figure Description

[0017] Figure 1 Growth and denitrification characteristics of strains AD-7, AD-9, and AD-17; where (a) represents NO3. - -N concentration, (b) is NO2 - -N concentration, (c) is NH4 + -N concentration, (d) is OD 600 value.

[0018] Figure 2 The denitrification characteristics of strain AD-7 were determined.

[0019] Figure 3 For different initial NO3 - The effect of NO3- concentration on the denitrification characteristics of strain AD-7; among which, (a) NO3- - -N removal rate, (b)NO2 - -N accumulation rate, (c)NH4 + -N concentration, (d)OD 600 value.

[0020] Figure 4 This is a colony morphology diagram of strain AD-7.

[0021] Figure 5 This is a scanning electron microscope (SEM) image of strain AD-7.

[0022] Figure 6 A phylogenetic tree for strain AD-7 constructed based on the 16S rDNA gene sequence. Detailed Implementation

[0023] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0024] Example 1: Isolation of strain AD-7 (1) Dispersion of activated sludge: 10 mL of activated sludge sample from the aerobic tank of a wastewater treatment plant in Taiyuan City, Shanxi Province, was aseptically inoculated into a sterilized 250 mL Erlenmeyer flask. An appropriate amount of glass beads and 90 mL of 0.9% sterile physiological saline were added to the Erlenmeyer flask beforehand. The Erlenmeyer flask was placed in a constant temperature shaking incubator and shaken at 30℃ and 140 rpm for 20 min to fully disperse the bacterial community in the activated sludge, so that the bacteria were dispersed into the physiological saline in a single-cell state.

[0025] (2) Enrichment culture: Take 100 mL of denitrification enrichment medium and place it in a 250 mL Erlenmeyer flask. After autoclaving, cool it to room temperature. Inoculate 10 mL of the dispersed bacterial solution into the enrichment medium and incubate at 30°C and 140 rpm with shaking for 2 days. Then, transfer the culture to a new enrichment medium at an inoculation rate of 10% (v / v) and continue incubation under the same conditions for 2 days. Repeat the above transfer and incubation steps 2-3 times and observe the state of the culture medium. If the bacteria in the culture medium grow well and are evenly distributed, it indicates that the denitrifying bacteria have become the dominant bacteria group, and the enrichment culture medium can be stored for later use. If there are few bacteria or abnormal flocculation occurs in the culture medium, continue to transfer until the above state is achieved.

[0026] (3) Isolation and purification of strains: Separation and purification were performed using the gradient dilution method and the streak plate method: 1 mL of enrichment culture medium was taken from the enrichment culture conical flask and mixed thoroughly with 9 mL of sterile water to obtain 10... -1 Diluent; then, take 1 mL of the bacterial suspension from the diluent and add it to 9 mL of sterile water, mix thoroughly to obtain 10 -2 Diluent, repeat the above steps to prepare 10 -3 10 -4 10 -5 and 10 -6 Diluted bacterial suspensions at concentration gradients.

[0027] Take 0.1 mL of each of the above-mentioned serially diluted bacterial suspensions and spread them evenly on the surface of denitrification solid agar plates. Incubate in an inverted position at 30°C for 3 days. After the plates show clear bacterial growth, select single colonies with regular morphology and good growth for streaking isolation. Continue incubation at 30°C for 3 days until single colonies form. Repeat the above purification steps 2-3 times until the colonies are uniform in morphology and no abnormal colonies appear. The purified strain is then considered completely purified and transferred to slant agar for storage.

[0028] The formulation and conditions for the above denitrification enrichment medium are as follows: 5 g sodium citrate (C6H5Na3O7), 2 g potassium nitrate (KNO3), 1 g dipotassium hydrogen phosphate (K2HPO4), 1 g potassium dihydrogen phosphate (KH2PO4), 0.1 g magnesium sulfate heptahydrate (MgSO4·7H2O). Adjust the pH to 7.2-7.5 with 1 mol / L NaOH or HCl. Dissolve all the above components thoroughly in distilled water, then dispense into Erlenmeyer flasks (dosage not exceeding 1 / 2 of the flask's volume). Autoclave at 121℃ for 15 min. The denitrification solid plate medium is based on the liquid medium, with an additional 15-20 g agar powder added per liter.

[0029] Example 2: Screening of strain AD-7 (1) Initial screening of strains: A single colony of the final purified bacteria was picked using a sterile inoculation loop and inoculated into a 250 mL Erlenmeyer flask containing 100 mL of denitrification enrichment medium. The flask was then incubated at 30°C and 140 rpm for 24 h for activation. The activated bacterial solution was then inoculated into 100 mL of denitrification enrichment medium at a 1% (v / v) inoculation rate and incubated at 30°C and 140 rpm for another 48 h with shaking. After incubation, an appropriate amount of the bacterial solution was taken to determine the OD6 value. 00 The bacterial cell growth was detected by measuring the value; the remaining culture medium was filtered through a 0.45 μm filter membrane, and the NO3 content in the filtrate was measured. - -N concentration was calculated and removal rate was determined, and the growth and denitrification performance of each purified strain were comprehensively evaluated.

[0030] Eighteen purified single strains with good growth and potential denitrification ability were obtained and named AD-1 to AD-18. The growth and denitrification performance of each strain are shown in Table 1. (NO3...) - A total of 14 strains had NO3 removal rates higher than 50%; the three dominant strains, AD-7, AD-9, and AD-17, had NO3 removal rates higher than 50%. - -N removal rates were 96.96%, 96.98%, and 97.25%, respectively, OD 600 The values ​​were 0.955, 1.365 and 0.900, respectively.

[0031] Table 1. Growth and denitrification performance of the initially screened strains

[0032] (2) Secondary screening of strains: After initial screening, strains AD-7, AD-9, and AD-17, with superior denitrification performance, were selected for secondary screening. Single colonies of each strain were aseptically picked and reactivated (under the same activation conditions as the initial screening). Then, they were inoculated at a 1% (v / v) inoculation rate into 100 mL of denitrification enrichment medium and cultured with shaking at 30°C and 140 rpm. At 0, 24, 48, 72, and 96 h, 5 mL of the bacterial culture was aspirated, a portion of which was used directly for OD detection. 600 The value was used to determine NO3 after the remaining portion was filtered through a 0.45 μm filter membrane. - -N, NO2 - -N and NH4 + -N concentration. Based on the test results, aerobic denitrifying bacteria with high nitrogen removal capacity were screened, inoculated into test tube slant culture medium, and stored for later use.

[0033] The results show (see) Figure 1 The AD-7 strain can reduce the initial concentration of NO3 to approximately 300 mg / L within 0-24 hours. - -N rapidly degraded to below 20 mg / L, with a removal rate as high as 93.11%, significantly higher than AD-9 (69.69%) and AD-17 (71.68%); and AD-7 had a lower OD200 after 24 hours. 600 The optimal overall performance was 1.288, and AD-7 was selected as the target strain for further research. The culture medium formulation and conditions used were the same as in Example 1.

[0034] Example 3: Study on the basic denitrification characteristics of strain AD-7 (1) Denitrification characteristics of strain AD-7 After activating strain AD-7, it was inoculated into 100 mL of denitrification enrichment medium at a 1% (v / v) inoculum and cultured with shaking at 30℃ and 140 rpm. At 0, 6, 12, 18, 24, 30, 36, 42, and 48 h, 5 mL of the bacterial culture was collected, a portion of which was used directly for OD detection. 600 The value was used to determine NO3 after filtration through a 0.45 μm filter membrane. - -N, NO2 - -N and NH4 + -N concentration.

[0035] The results show (see) Figure 2 Within 0-18 hours, this strain will produce NO3 - -N concentration decreased from 302.04 mg / L to 86.81 mg / L; after 48 h of culture, NO3- - -N concentration was 68.25 mg / L, with an overall removal rate of 77.40%; NO2 --N accumulated to 154.24 mg / L after 18 hours, then showed a fluctuating downward trend; NH4 + -N accumulated in small amounts, reaching 8.25 mg / L at 48 h; bacterial OD 600 The value rapidly increased to 1.388 within 0-18 h. These results indicate that strain AD-7 possesses stable aerobic denitrification capacity.

[0036] (2) Different initial NO3 - Effect of -N concentration on the denitrification characteristics of strain AD-7 Prepare NO3 using KNO3 as the sole nitrogen source. - Denitrification performance testing media with initial NO3- concentrations of 100, 150, 200, 250, and 300 mg / L were autoclaved before use. The activated bacterial suspension was inoculated at a 1% (v / v) inoculation rate with different NO3- concentrations. - The culture medium was incubated with a -N concentration gradient in a constant temperature shaking incubator at 30℃ and 140 rpm. At 0, 6, 12, 18, 24, 36, and 48 h, 5 mL of bacterial suspension was taken, a portion of which was used directly for OD detection. 600 The value was used to determine NO3 after filtration through a 0.45 μm filter membrane. - -N, NO2 - -N and NH4 + -N concentration. The optimal initial NO3 concentration will be determined based on the experimental results for subsequent experiments. - -N concentration.

[0037] The results show (see) Figure 3 ): When the initial NO3 - When the NO3- concentration is 100, 150, 200, and 300 mg / L, nitrate nitrogen can be completely removed within 36 hours. At an initial concentration of 250 mg / L, NO3-... - -N removal rates reached 94.88%, with each group exhibiting stable and efficient denitrification performance. With the initial NO3... - Increased -N concentration leads to increased NO2 - The accumulation rate of NO2- increased progressively, with the accumulation rates at 48 h being 20.17%, 42.75%, 64.22%, 69.87%, and 76.95% for each group, respectively. The initial NO2 concentration was 100 mg / L. - -N accumulation rate is the lowest, and this concentration group of NH4 + -N accumulation was only 5.61 mg / L, and bacterial growth was good (OD). 600 Approximately 1.00).

[0038] Example 4: Denitrification performance of aerobic denitrifying strains under poly(ethylene terephthalate) micro / nanoplastics stress with different particle sizes and concentrations. This embodiment uses aerobic denitrifying bacteria obtained through screening as the test strain, and polyethylene terephthalate microplastics (PET-MPs) and nanoplastics (PET-NPs) as stress factors. The PET-MPs have particle sizes of 50 mesh (approximately 300 μm), 100 mesh (approximately 150 μm), and 300 mesh (approximately 48 μm); the PET-NPs have a particle size of 200 nm. Experimental and control groups are set up for each particle size. The experimental groups are set with concentration gradients of 25, 50, 100, 200, 400, 600, 800, and 1000 mg / L, while the control group does not add micro / nanoplastics. The activated bacterial suspension is inoculated at a 1% (v / v) inoculation rate into denitrification performance testing medium containing PET-MPs / NPs of different particle sizes and concentrations (initial NO3). - (N concentration 100 mg / L) was incubated at 30℃ and 140 rpm with shaking. At 0, 6, 12, 18, 24, 36, and 48 h, 5 mL of culture medium was taken, a portion of which was used directly for OD measurement. 600 The NO3 value was determined to investigate the effects of different forms, particle sizes, and concentrations of PET micro / nanoplastics on the growth of the bacterial strain; the remaining portion was filtered through a 0.45 μm filter membrane to obtain a water sample, and NO3 was measured. - -N concentration, with a focus on analyzing NO3 at 12 h and 48 h. - -N removal rate, the results are shown in Table 2.

[0039] Table 2. Denitrification performance of bacterial strains under PET micro / nanoplastics stress with different particle sizes and concentrations.

[0040] The results showed that under PET micro / nanoplastic plastic stress conditions with different particle sizes and concentrations, this aerobic denitrifying bacterium could still maintain extremely high and stable NO3 levels. - -N removal rate. The removal rate of the PET-MPs treatment group was higher than 96.70% after 48 h. The removal rate of the PET-NPs treatment group was stable between 96.90% and 98.85% after 48 h. Even under extremely high concentration conditions of 1000 mg / L, the strain could still maintain a nitrogen removal efficiency of over 98%. The above results indicate that this strain has extremely strong environmental tolerance to PET micro / nanoplastics. Its nitrogen removal performance is less inhibited by PET micro / nanoplastics. It can still operate efficiently and stably in water bodies with complex pollution containing micro / nanoplastics, exhibiting excellent and stable nitrogen removal performance and significant stress resistance, thus possessing extremely high practical engineering application value.

[0041] Example 5: Identification of strain AD-7 (1) Observation of colony morphology Using a sterile inoculation loop, pick up a single AD-7 colony and streak it onto a denitrification solid agar plate. Incubate upside down in a 30°C biochemical incubator for 3 days. Morphological characteristics are as follows: Figure 4 As shown: the colonies are round, about 1-2 mm in diameter, milky white and opaque in color; the edges of the colonies are smooth and neat, the surface is relatively dry, the texture is dense and granular, and the center is slightly raised.

[0042] (2) Strain biological scanning electron microscopy (SEM) observation The activated bacterial suspension was inoculated at a rate of 1% (v / v) into a culture medium containing the aforementioned micro / nanoplastics and cultured with shaking at 30°C and 140 rpm. The bacterial cell pellet was collected at the 12-hour mark when the difference between each experimental group and the control group was most significant. After washing 2-3 times with 0.01 mol / L PBS buffer, 2.5% glutaraldehyde fixative solution pre-chilled at 4°C was added to the bacterial pellet, and the pellet was fixed overnight at 4°C. The fixed bacterial samples were washed 2-3 times with PBS buffer and then sequentially dehydrated with 30%, 50%, 70%, 80%, 90%, and 95% ethanol solutions, each for 15 min. Finally, the samples were transferred to 100% ethanol for further dehydration for 20 min. The dehydrated bacterial cells were dried in a critical point desiccator, and after surface gold sputtering, the microscopic morphology of the strains was observed using a scanning electron microscope (Hitachi Regulus 8100).

[0043] SEM observation results ( Figure 5 The results showed that strain AD-7 was a typical short rod-shaped cell with uniform length and regular shape. There was no obvious constriction, rupture or deformation. The cells were plump and had clear outlines. The cell structure was intact and the cell walls were smooth without wrinkles or damage.

[0044] (3) 16S rDNA identification The highly efficient aerobic denitrifying strain AD-7, which was finally screened, was sent to Shanghai Meiji Biomedical Technology Co., Ltd. for 16S rDNA sequence analysis. The obtained 16S rDNA gene sequence was compared with known sequences in the GenBank database using the BLAST program, and a phylogenetic tree was constructed using MEGA 12 software to determine the species classification of this strain.

[0045] The partial 16S rDNA sequence of strain AD-7 is as follows: The obtained 16S rDNA sequence was compared with known sequences in the GenBank database using the BLAST program to determine the bacterial species to which it belonged. The results showed that the sequence of strain AD-7 was similar to that of *Pseudomonas* (…). Pseudomonas Several strains of the species showed high sequence similarity, and were therefore preliminarily identified as belonging to the genus *Pseudomonas*. A phylogenetic tree was constructed using the *Pseudomonas* strains with high homology listed in Table 3 as references (see Table 3). Figure 6 ). Among them, with Ectopseudomonas mendocina The similarity was as high as 100%, further indicating that strain AD-7 is... Ectopseudomonas mendocina .

[0046] Table 3. Reference strains used to construct the phylogenetic tree of strain AD-7 NR_114472.1 NR_04421.1 NR_178783.1 NR_115874.1 NR_180550.1 NR_179700.1 NR_116172.1 NR_114224.1 NR_165768.1 NR_180457.1 NR_024910.1 NR_181196.1 NR_041715.1 NR_042450.1 The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A strain of aerobic denitrifying bacteria tolerant to micro / nanoplastics, characterized in that, The bacteria were *Pseudomonas mendoza* (…). Ectopseudomonas mendocina AD-7 is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC NO.38411.

2. The aerobic denitrifying bacterium tolerant to micro / nanoplastics according to claim 1, characterized in that, The bacterial colonies are milky white, round granules, 1-2 mm in diameter, with a slightly raised center; under a biological scanning electron microscope, they appear as typical short rods with smooth and intact cell surfaces.

3. The aerobic denitrifying bacterium tolerant to micro / nanoplastics according to claim 1, characterized in that, The bacteria exhibit environmental tolerance to polyethylene terephthalate microplastics and nanoplastics.

4. The aerobic denitrifying bacterium tolerant to micro / nanoplastics according to claim 3, characterized in that, The microplastics have a particle size of 48 μm to 300 μm, and the nanoplastics have a particle size of 200 nm.

5. The application of the aerobic denitrifying bacteria tolerant to micro / nanoplastics as described in claim 1, characterized in that, It is used to efficiently degrade nitrate nitrogen and has a low accumulation of nitrite.

6. The application of the aerobic denitrifying bacteria tolerant to micro / nanoplastics according to claim 5, characterized in that, The bacteria in the initial NO3 - -N concentration within 100~300 mg / L, NO3 - -N can be completely removed within 36 hours.

7. The application of the aerobic denitrifying bacteria tolerant to micro / nanoplastics according to claim 6, characterized in that, The bacteria in NO3 - When the -N concentration is 100 mg / L, NO2 - The cumulative rate of -N is only 20.17%.

8. The application of the aerobic denitrifying bacteria tolerant to micro / nanoplastics according to claim 5, characterized in that, The bacteria were able to maintain extremely high and stable NO3 levels even under stress conditions of PET micro / nanoplastics with different particle sizes and concentrations. - -N removal rate.

9. The application of the aerobic denitrifying bacteria tolerant to micro / nanoplastics according to claim 8, characterized in that, The bacteria achieved a removal rate of over 96.70% for 48 hours within a concentration range of 0–1000 mg / L for polyethylene terephthalate micro / nanoplastics. Notably, even at a high concentration of 1000 mg / L, the bacteria maintained a denitrification efficiency of over 98%.

Images