Method for degrading sulfamethoxazole by using QXT-31-Mn

Abstract

The invention discloses a method for degrading sulfamethoxazole by using QXT-31-Mn, and belongs to the technical field of sewage treatment. The QXT-31-Mn is preserved in the China General Microbiological Culture Collection Center on December 3, 2024, the preservation number is CGMCC NO.32889, the preservation address is No.3, Yard 1, Beichen West Road, Chaoyang District, Beijing, and the preservation number is Arthrobacter sp. The QXT-31-Mn has been preserved in the China General Microbiological Culture Collection Center, the preservation number is CGMCC NO.32889, and the preservation number is Arthrobacter sp. According to the invention, the cathode material which is safer and more environment-friendly is prepared by utilizing QXT-31-Mn, and SMX can be efficiently degraded by utilizing the cathode material.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method for degrading sulfamethoxazole by utilizing QXT-31-Mn. Background Art

[0002] Sulfadimethoxazole (SMX) has been widely used in the treatment of bacterial infections in humans, animal husbandry and aquaculture due to its excellent antibacterial effect. However, used SMX enters sewage treatment plants through various pathways, but it is difficult for sewage treatment plants to completely remove the antibiotic, causing it to become a point source of river pollution. Currently, sewage treatment plants mainly rely on activated sludge systems to remove antibiotics. In traditional sewage treatment, the removal of SMX mainly depends on the adsorption and biodegradation processes of sludge, but these processes are often slow.

[0003] In recent years, bioelectrochemical systems (BESs) have attracted extensive attention due to their ability to utilize electroactive microorganisms to achieve oxidation or reduction of antibiotics at the anode or cathode, thereby effectively removing antibiotics. Most of the existing BESs research focuses on the anode part, while the research on the cathode compartment is relatively insufficient. In most bioelectrochemical systems, the cathode reaction is usually abiotic, and the common one is the reduction of oxygen or ferrocyanide. Ferrocyanide has ideal properties as a cathode reactant, is not limited by solubility, and is independent of oxygen concentration. However, its toxicity to microorganisms limits its application in BES. In addition, the reduction kinetics of oxygen on solid electrodes are slow and its solubility in water is low, which poses a challenge to the practical application of oxygen as an oxidant. In response to these limitations, many abiotic cathode BES studies are committed to improving the efficiency of oxygen reduction on solid electrodes to promote the development of microbial fuel cells.

[0004] Based on the above background, some studies have attempted to use biomineralized manganese oxides as an oxygen substitute. In this alternative, oxygen serves as the final electron acceptor and plays the role of a redox mediator in the cathode reaction through the redox pair of manganese ions and manganese oxides.

[0005] Most cathodes in existing bioelectrochemical systems (BES) rely on non-biological reactions (such as the reduction of oxygen or ferrocyanide), which have limitations in performance and microbial compatibility. In addition, it is necessary to ensure the stability of the designed bioelectrochemical system during long-term operation and verify its sustainability in the process of antibiotic degradation to realize the possibility of practical application. Therefore, a biological manganese cathode composed of manganese oxidizing bacteria and manganese oxides was developed, and its structure and performance were optimized to achieve stable electron transfer and efficient SMX degradation. Summary of the invention

[0006] The invention provides an Arthrobacter sp. QXT-31-Mn with a preservation number of CGMCCNO.32889. The taxonomic name of the QXT-31-Mn is Arthrobacter sp.

[0007] The present invention also provides a cathode prepared using the above-mentioned Arthrobacter QXT-31-Mn, and the preparation method of the cathode comprises the following steps:

[0008] (1) culturing QXT-31-Mn to obtain QXT-31-Mn bacterial solution;

[0009] (2) Place the cathode in a container and use a solution containing 0.2-1 mM Mn 2+ QXT-31-Mn was cultured in a culture medium to induce its manganese oxide to generate manganese oxides that were deposited on it.

[0010] Preferably, the culture medium used for culturing QXT-31-Mn in step (1) is PYG culture medium.

[0011] More preferably, HEPES buffer is added to the PYG medium when culturing QXT-31-Mn in step (1).

[0012] More preferably, in step (2), Mn 2+ The concentration is 0.4 mM.

[0013] More preferably, in step (2), Mn 2+ From MnCl2.

[0014] The present invention also provides a method for degrading sulfamethoxazole, which comprises the following steps:

[0015] (1) The activated sludge is inoculated in the anode chamber of the dual-chamber microbial electrochemical system and domesticated, and the domesticated biofilm will adhere to the anode;

[0016] (2) using the cathode as the cathode of a dual-chamber microbial electrochemical system;

[0017] (3) adding cathode and anode electrolytes to the cathode chamber and anode chamber of the dual-chamber microbial electrochemical system, respectively;

[0018] (4) Apply an external voltage of -0.5 to -1 V to degrade SMX.

[0019] Preferably, the cathode electrolyte in step (3) is PYG culture medium.

[0020] More preferably, in step (4), the external voltage is -0.8V.

[0021] The present invention also provides the use of the above-mentioned Arthrobacter QXT-31-Mn in the preparation of a product for degrading sulfamethoxazole.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) By replacing traditional toxic cathode reactants such as ferrocyanide with a bio-manganese cathode, the present invention provides a safer and more environmentally friendly cathode material, which reduces the toxic effects on microorganisms.

[0024] (2) The use of a biomanganese cathode that combines electroactive microorganisms with manganese oxides significantly enhances the efficiency of electron transfer, allowing the system to remain stable during long-term operation and ensure continuous and efficient antibiotic degradation.

[0025] (3) By controlling the external resistance and the appropriate external voltage to adjust the system performance, the efficiency of electron transfer and redox reaction is significantly improved, and the overall performance of the bioelectrochemical system is optimized.

[0026] Biodeposit description of QXT-31-Mn:

[0027] Depository: General Microbiology Center, China Microbiological Culture Collection Administration;

[0028] Deposit number: CGMCC NO.32889;

[0029] Deposit date: December 3, 2024;

[0030] Storage address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing;

[0031] Taxonomic nomenclature: Arthrobacter sp. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Figure 1 shows the (a) OD600 change and (b) Mn 2+ Concentration changes.

[0033] Figure 2 This is the cyclic voltammetry curve of manganese oxide in Example 2.

[0034] Figure 3 In Example 3, (a) the current when 1000Ω is applied, (b) the current at a constant potential of -0.8V, (c) the manganese reduction concentration at the biomanganese cathode, and (d) the electrochemical synergistic SMX degradation effect at the biomanganese cathode.

[0035] Figure 4 This is a graph showing the change in manganese ion concentration in the dual-chamber electrochemical system in Example 4. DETAILED DESCRIPTION

[0036] In the following examples, Mn 2+ All refer to MnCl2.

[0037] Example 1 Study on the growth characteristics of manganese oxidizing bacteria

[0038] Cultivation of manganese oxidizing bacteria: Scrape the manganese oxidizing bacteria from the solid culture medium and inoculate into 50 mL of Mn-free 2+ The culture medium was placed in a conical flask containing a high temperature sterilized PYG medium (formula: MgSO4·7H2O 0.5g, CaCl2·2H2O 0.06g, glucose 0.25g, yeast extract 0.25g, tryptone 0.25g, distilled water 1L, pH 7.0-7.2), and shaken at 30°C and 170rpm for 12 hours. The cultured bacterial solution was inoculated into a new PYG medium at a volume ratio of 3%, and the HEPES buffer was filtered through a 0.22μm sterile filter membrane and added to the above PYG to make the final concentration of the HEPES buffer 0.5M (pH 7.2), thereby obtaining a manganese-containing bacterial solution.

[0039] In order to investigate the effect of micro-electric field stimulation on the growth of manganese oxidizing bacteria and manganese oxidation, a single-chamber electrochemical system was used to apply 0.1, 0.3, and 0.5 V external voltages to QXT-31-Mn bacteria. Both the working electrode and the counter electrode were platinum mesh. First, the effect of different applied voltages on the growth of QXT-31-Mn was investigated. Figure 1 a), the electrolyte was PYG medium with added MnCl2, the addition amount of QXT-31-Mn bacterial solution was 10% (45 ml PYG medium, 5 ml bacterial solution), the initial concentrations of MnCl2 were 0.1V: 41.13 mg / L, 0.3V: 44.50 mg / L, 0.5V: 36.25 mg / L, open circuit (OC): 37.83 mg / L.

[0040] The results showed that the growth curves under the conditions of 0.1V and 0.3V were relatively similar, with the bacterial growth rate at 0.3V slightly lower than that at 0.1V, but both showed rapid initial growth, followed by a gradual stabilization of the growth rate. Under the 0.5V voltage stimulation condition, the bacterial growth density was low at first, but began to rise rapidly from the 6th day, and by the 10th day, the OD 600 However, there was no significant difference in OD between the different applied voltages and open circuit (OC) groups.

[0041] Secondly, the effect of different applied voltages on the oxidation of manganese in QXT-31-Mn was investigated. Figure 1 b) All conditions are the same as above, Mn 2+The concentration of (MnCl2) remained relatively stable in the early stage of the experiment (about the first 4 days). From the 4th day, the concentration of manganese ions under all conditions began to decrease significantly, but there was no significant difference in the rate of decrease. By the 10th day of the experiment, the concentration of manganese ions under all conditions was close to or reached 0 mg / L, and all of them generated BioMnOx and attached to the electrodes. These changes may indicate that the existence and size of voltage have an effect on Mn 2+ In conclusion, micro-electric field stimulation has no inhibitory effect on the growth of manganese oxidizing bacteria and manganese oxidation, and can be used as a cathode.

[0042] Example 2 Electrochemical Characterization of Biomanganese Oxides

[0043] In order to evaluate the redox ability of biogenic manganese oxides, cyclic voltammetry (CV) was used to characterize the biogenic manganese oxides ( Figure 2 ). Manganese oxidizing bacteria and biological manganese oxides were deposited (QXT-31-Mn was cultured in PYG medium containing 0.75mM MnCl2) on indium tin oxide (ITO) conductive glass as the working electrode, platinum mesh as the counter electrode, Ag / AgCl as the reference electrode, and the electrolyte was 0.1M saturated Na2SO4 solution. Cyclic voltammetry scanning was performed to observe the electrochemical state of biological manganese oxides. The magnitude of the current generated by biological manganese oxides is closely related to the amount of Mn present on the surface of Mn oxides. Based on the peak shape, we infer that the reduction peaks at 0.28V and -0.46V are attributed to the reduction of Mn(IV) to Mn(II) and Mn(IV) to Mn(III), respectively. The reduction of Mn(IV) to Mn(II) may be to promote bacterial utilization. In addition, the peaks at 0.92 and 0.01V are consistent with the dissolved Mn 2+ The CV curves are related to the oxidation of Mn(IV) to Mn(IV) and Mn(II) to Mn(III), respectively. Therefore, the CV curves provide information on the conversion of Mn in different electrochemical states, which helps to understand the electron transfer mechanism in Mn-based electrochemical systems, especially the redox kinetics of Mn.

[0044] Example 3: Feasibility of biomanganese cathode and study on the degradation effect of bioanode on SMX

[0045] In order to explore the feasibility of biological manganese oxide as a cathode material, a biological manganese cathode containing manganese oxide and manganese oxidizing bacteria QXT-31-Mn was constructed in this example. First, a carbon felt electrode was placed in a shake flask filled with PYG culture medium containing 0.75mM MnCl2, and QXT-31-Mn was inoculated and cultured to promote its oxidation of manganese to generate manganese oxide deposited on the carbon felt electrode. After 48 hours of culture, the carbon felt electrode can be used as the cathode of the dual-chamber electrochemical system, and the PYG culture medium in the shake flask is used as the cathode liquid.

[0046] At the same time, potassium ferrocyanide was used to domesticate activated sludge and cultivate a microbial community dominated by electroactive bacteria, which was used to construct a biological anode for the biological manganese cathode.

[0047] Acclimation step: The anode chamber was inoculated with activated sludge from a sewage treatment plant and an anode solution (2.77 g / L NaH2PO4·2H2O, 11.55 g / L Na2HPO4·12H2O, 0.31 g / L NH4Cl, 0.13 g / L KCl, 1 mL / L vitamin solution (the vitamin solution (per liter of distilled water) contains: 2.0 mg biotin, 2.0 mg folic acid, 10.0 mg pyridoxine hydrochloride, 5.0 mg thiamine hydrochloride, 5.0 mg riboflavin, 5.0 mg niacin, 5.0 mg D-(+)-calcium pantothenate, 0.5 mg vitamin B 12 , 5mg p-aminobenzoic acid and 5mg lipoic acid), 1mL / L of mineral elements (the vitamin solution (per liter of distilled water) contains: 1.5gN(CH2COOH)3, 3g MgSO4·7H2O, 0.5g MnSO4·H2O, 1g NaCl, 0.1g FeSO4·7H2O, 0.1g CoCl2·6H2O, 0.1g CaCL2, 0.1g ZnSO4·7H2O, 0.01g CuSO4·5H2O, 0.01g AlK(SO4)2·12H2O, 0.01g boric acid, 0.01g NaMoO4·2H2O), 0.5g / L of sodium acetate solution), mixed in a ratio of 1:3 (v / v), 0.1mM potassium ferrocyanide solution was added to the cathode chamber, and the external resistor was 510Ω. The anode solution and cathode solution were replaced simultaneously for four days until a periodic current that first increased and then decreased appeared, indicating successful acclimation. New anode solution was replaced and 1 mg / L of SMX was added for subsequent experiments.

[0048] As shown in Table 1, a total of five modes were set to operate the reactor: when the external resistance was 1000Ω, the cathode had only QXT-31-Mn (denoted as MFC) and the cathode contained both QXT-31-Mn and manganese oxide (denoted as BioMnOx-MFC); when the external voltage was -0.8V, the cathode had only QXT-31-Mn (denoted as -0.8V) and the cathode contained both QXT-31-Mn and manganese oxide (denoted as -0.8V-BioMnOx) and open circuit operation control.

[0049] The cathode with only QXT-31-Mn (denoted as MFC) was compared with the cathode containing both manganese oxidizing bacteria and manganese oxides (denoted as BioMnOx-MFC). 2+ , only add bacterial solution.

[0050] Cathodic chamber solution:

[0051] (1) External resistor 1000 ohms

[0052] ①MFC, PYG solution (biofree manganese oxide)

[0053] ②BioMnOx-MFC, PYG solution (with biological manganese oxide)

[0054] (2) External voltage - 0.8V

[0055] ③-0.8V, PYG solution (biofree manganese oxide)

[0056] ④-0.8V-BioMnOx, PYG solution (with biological manganese oxide)

[0057] (3) Open circuit

[0058] ⑤OC: PYG solution (with biological manganese oxide)

[0059] Table 1

[0060]

[0061]

[0062] The current monitoring results of different groups showed ( Figure 3 a and 3b), when the external resistor is running, the current of the cathode containing biological manganese oxide (BioMnOx-MFC) shows a change of first rising and then falling. The maximum current in the first cycle reaches 0.03mA, and the maximum current in the second cycle increases slightly to 0.05mA, while the current of the cathode without biological manganese oxide (MFC) is always 0, which shows that biological manganese oxide can effectively accept electrons from the anode and participate in the reduction reaction, which shows that biological manganese oxide has good electron acceptance and transfer ability, so that the current can form a closed loop. When the external voltage is running, the current of the cathode containing biological manganese oxide (-0.8V-BioMnOx) increases rapidly to 0.14mA and remains stable, while the current of the cathode without biological manganese oxide (-0.8V) is also always 0, which further emphasizes the efficiency of the biological manganese oxide cathode in providing stable current output, and this rapid and stable current increase shows that the biological manganese oxide cathode can more efficiently transfer electrons and output energy under voltage drive. In addition, the efficiency of current generation in the applied voltage operation mode is significantly higher than that in the mode with only an external resistor, which indicates that the electrochemical activity of biomanganese oxide is more fully utilized under higher potential driving.

[0063] In addition, in order to explore the reduction reaction of biological manganese cathode, this example also carried out 2+ Detection ( Figure 3c) The results of the study found that Mn can be detected 2+ When an external voltage of -0.8 V is applied, Mn 2+ The dissolution rate of Mn was 1.20 mg / (L·h), which was significantly higher than that of the external resistor and open circuit groups. 2+ The dissolution rates of the biomanganese cathode were 0.45 and 0.22 mg / (L·h). This finding indicates that the reduction reaction of the biomanganese cathode is more active under the condition of -0.8 V applied voltage, thus promoting more Mn 2+ In contrast, under external resistance and open circuit conditions, Mn 2+ The release rate of Mn is low, which may be due to the fact that the increase in current significantly accelerates the electrochemical reduction process of Mn. The higher applied voltage provides a greater driving force, prompting the rapid reduction of Mn ions at the biological Mn cathode. This rapid electrochemical activity not only increases the Mn 2+ The generation rate also shows that the application of voltage can effectively control and accelerate the reduction process.

[0064] Based on the feasibility of the biological manganese cathode verified above, the bioanode provides 1 mg / L SMX (1 mg / L SMX is added to the activated sludge after acclimation) for removal ( Figure 3 d). The results showed that SMX could be completely removed within four days. When the applied voltage was -0.8V, the removal rate of SMX was 0.78mg / (L·d), which was also significantly higher than that of the external resistor and open circuit group Mn 2+ The removal rates of SMX and Mn were 0.53 and 0.42 mg / (L·h). This indicates that the applied voltage can effectively improve the ability of the bioanode to treat SMX. It is worth noting that the efficient degradation of SMX and Mn 2+ The rapid reduction of manganese and the increase in current grow synchronously under the applied voltage, indicating that the electrochemical driving force plays a key role in enhancing the reduction reaction of manganese and the biodegradation of SMX. This electrochemical activation may have led to more efficient reduction of manganese oxides and stronger electron acceptance, thereby improving the pollutant treatment performance of the entire system.

[0065] Example 4 Sustainability of Biomanganese Cathode

[0066] In this example, the QXT-31-Mn bacteria were first provided with Mn for solubility. 2+ , place a carbon felt electrode in a shake flask and use 0.4 mM Mn 2+ QXT-31-Mn was cultured to promote its oxidation of manganese to form manganese oxides and deposit them on the surface. QXT-31-Mn bacteria could completely oxidize manganese in 36 hours, and the manganese oxidation rate was 0.83 mg / (L·h). This result showed that QXT-31-Mn bacteria had efficient manganese oxidation ability and could quickly convert Mn 2+When these biologically generated manganese oxides are used as cathodes in bioelectrochemical systems, they can be efficiently reduced back to Mn 2+ , and has the same rate as oxidation 0.83 mg / (L·h). The other experimental conditions are the same as those in Example 3 (④-0.8V-BioMnOx, PYG solution (with biological manganese oxide), except that Mn 2+ The concentrations are different ( Figure 4 ). This symmetrical oxidation and reduction rate not only indicates the equilibrium of the process, but also highlights the high efficiency and controllability of the system. This reversible redox property of manganese oxide gives the system a remarkable reproducibility.

[0067] The mechanism of the cathode reaction includes the initial deposition of BioMnOx on the electrode surface and the subsequent reduction of electrons from the anode reaction, resulting in the release of manganese ions. Since the release of divalent manganese occurs close to the electrode surface where the manganese oxidizing bacteria are attached, the divalent manganese is immediately reoxidized to BioMnOx by the manganese oxidizing bacteria, forming a cycle. The anode reaction mechanism is mainly that the electroactive bacteria use sodium acetate and SMX as a co-carbon source to degrade SMX and continuously provide electrons to the cathode. This mode of operation can achieve the dual benefits of pollutant removal and resource recovery at the same time, showing the great potential of bioelectrochemical technology in environmental management and resource recovery.

[0068] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A strain of Arthrobacter QXT-31-Mn with a deposit number of CGMCC NO.32889, characterized in that: The taxonomic name of QXT-31-Mn is Arthrobacter sp.

2. A cathode prepared using the Arthrobacter QXT-31-Mn according to claim 1, characterized in that: The preparation method of the cathode comprises the following steps: (1) culturing QXT-31-Mn to obtain QXT-31-Mn bacterial solution; (2) Place the cathode in a container and use a solution containing 0.2-1 mM Mn 2+ QXT-31-Mn was cultured in a culture medium to induce its manganese oxide to generate manganese oxides that were deposited on it.

3. The cathode according to claim 2, characterized in that The culture medium used for culturing QXT-31-Mn in step (1) is PYG culture medium.

4. The cathode according to claim 3, characterized in that When culturing QXT-31-Mn in step (1), HEPES buffer is added to the PYG culture medium.

5. The cathode according to claim 4, characterized in that In the step (2), Mn 2+ The concentration is 0.4 mM.

6. The cathode according to claim 5, characterized in that In the step (2), Mn 2+ From MnCl2.

7. A method for degrading sulfamethoxazole, characterized in that: The method comprises the following steps: (1) The activated sludge is inoculated in the anode chamber of the dual-chamber microbial electrochemical system and domesticated, and the domesticated biofilm will adhere to the anode; (2) Using the cathode described in any one of claims 2 to 6 as the cathode of a dual-chamber microbial electrochemical system; (3) adding cathode and anode electrolytes to the cathode chamber and anode chamber of the dual-chamber microbial electrochemical system, respectively; (4) Apply an external voltage of -0.5 to -1 V to degrade SMX.

8. The method according to claim 7, characterized in that In the step (3), the cathode electrolyte is PYG culture medium.

9. The method according to claim 8, characterized in that In step (4), the external voltage is -0.8V.

10. Use of the Arthrobacter QXT-31-Mn according to claim 1 in preparing a product for degrading sulfamethoxazole.

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