Preparation method and application of biofouling-resistant protein fiber material for extracting uranium from seawater

Abstract

The invention relates to a protein fiber material for extracting uranium from seawater. The invention relates to a preparation method and application of an anti-biofouling type protein fiber material for extracting uranium from seawater. The preparation method comprises the following steps: fusing a double-super-uranyl binding protein gene with ultrahigh uranium adsorption selectivity and binding affinity with a polypeptide gene with anti-biofouling and uranium adsorption properties by adopting a flexible coupling agent; preparing a biofouling-resistant protein fiber material for extracting uranium from seawater; the method comprises the following steps: S1, optimizing codons of a fusion gene on the basis of escherichia coli codon use preference; s2, carrying out chemical synthesis on the optimized gene, inserting a gene segment into an NdeI / XhoI site of an expression vector pET-22b (+), and then transferring into an escherichia coli BL-21 strain, so as to construct gene engineering for expressing the fusion protein; s3, performing protein expression, purification, concentration and bionic spinning self-assembly to obtain the protein fiber material. The preparation method is simple in process and mild in condition, and the prepared protein fiber material for extracting uranium from seawater is good in biological fouling resistance, high in uranium binding affinity and high in reusability.

Description

Technical Field

[0001] The invention relates to a method for preparing a protein fiber material for extracting uranium from seawater, and in particular to a method for preparing a new protein fiber material with high uranium selectivity and affinity and both anti-biological fouling and uranium adsorption properties. Background Art

[0002] As a green energy, nuclear energy meets the needs of environmental protection and the development of a good ecosystem, and has been listed as an important direction of my country's future energy development strategy. Uranium, as an important raw material for the nuclear energy industry, plays an irreplaceable role in the development of alternative energy. Compared with uranium mines on land, the ocean contains abundant uranium resources, which are nearly a thousand times that of uranium mines on land. In addition, compared with the mining of uranium mines on land, the extraction process of uranium in seawater is more environmentally friendly. Therefore, uranium extraction from seawater is considered to be a nuclear fuel resource research and development project with a high return rate and good development prospects. It has great strategic significance for the continuous supply of clean energy and the healthy development of the ecological environment in my country. Although the uranium content in seawater is huge, the extraction of uranium from seawater is huge due to the complex marine environment, low uranium concentration (3.3 ppb), complex coexisting interfering ions and marine biological pollution.

[0003] For the practical application of uranium extraction from seawater, exploring and developing functional uranium adsorbent materials with adsorption specificity and selectivity, fast adsorption rate, high adsorption capacity and excellent anti-biofouling activity is crucial to accelerate the process of uranium extraction from seawater.

[0004] The invention patent application with application number 201910580843.6 discloses a method for preparing a recombinant spider silk protein fiber material for extracting uranium from seawater. The spider silk protein gene fragment, the seawater uranium extraction functional protein gene fragment and the flexible connection gene are recombined to obtain the seawater uranium extraction recombinant spider silk protein encoding gene; then transferred into Escherichia coli, protein expression and purification are performed to obtain the seawater uranium extraction recombinant spider silk protein liquid; after concentration, the spinning buffer is pushed forward to self-assemble to obtain the seawater uranium extraction recombinant spider silk protein fiber. The process is simple, the conditions are mild, and it is easy to purify. The seawater uranium extraction recombinant spider silk protein fiber material prepared by this method has excellent mechanical properties, strong uranium adsorption capacity and high selectivity, and can be reused many times. However, the recombinant spider silk protein fiber material does not have anti-biological fouling properties. In order to solve this problem, antibacterial compounds are usually introduced into the adsorbent. For example, CN202010378458.6 discloses a method for preparing antibacterial amidoxime aerogel for uranium extraction from seawater. The preparation method comprises dissolving chitosan and polyacrylamide oxime in an acetic acid solution in a certain mass ratio, and stirring and adding glutaraldehyde to promote the cross-linking of the polymer to obtain a precursor solution; the precursor solution is injected into a mold, left to stand for aging, washed with water, and freeze-dried to obtain antibacterial amidoxime aerogel, but the introduced antibacterial compound does not have uranium adsorption properties. Therefore, its introduction does not promote the adsorption of uranium, but instead reduces the adsorption performance of the adsorbent material in simulated seawater. In addition, the chemical preparation process is complicated and the environmental pollution is serious.

[0005] Therefore, in order to promote the application of uranium extraction from seawater and cope with the increasingly serious marine pollution, it is urgent to develop new uranium extraction materials with high selectivity, high binding affinity, high anti-biofouling activity and green environmental protection. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a method for preparing an anti-biofouling protein fiber material for extracting uranium from seawater. The method is applied to extracting uranium from seawater, solving the problems of low adsorption selectivity and serious interference by microorganisms in the existing uranium extraction materials.

[0007] The present invention provides a method for preparing anti-biofouling protein fibers for extracting uranium from seawater, wherein the double transuranic acid binding protein gene and the polypeptide gene are fused together through a flexible connector, and then a water-rich gel product is obtained through protein expression, purification, concentration, bionic spinning and self-assembly, and then a protein fiber material is obtained through freeze drying. The details are as follows: A method for preparing an anti-biofouling protein fiber material for extracting uranium from seawater comprises the following steps: using a flexible connector to fuse a double transuranic acid binding protein gene, i.e., DSUP gene, having ultra-high uranium adsorption selectivity and binding affinity, with an omiganan peptide gene, i.e., OP gene, having both anti-biofouling and uranium adsorption properties, to avoid the steric hindrance of the two functional protein domains.

[0008] First, the codons of the fusion gene were optimized based on the codon usage preference of E. coli; Then, the optimized gene was chemically synthesized, and the gene fragment was inserted into the NdeI / XhoI site of the expression vector pET-22b(+) and then transformed into the Escherichia coli BL-21 strain to construct a genetic engineering for expressing the fusion protein.

[0009] Finally, protein fiber materials were obtained through protein expression, purification, concentration, biomimetic spinning and self-assembly. The DSUP and OP monomer sequences are:

[0010] LDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEGGGGGGSGGGGSGGGGSLDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEG

[0011] ILRWPWWPWRRK-NH2.

[0012] The method for preparing the protein fiber material and the expression of the fusion protein DSUP-OP: First, the constructed engineered bacteria were incubated in LB medium containing 10 mg / L ampicillin at 37°C and 180 rpm overnight; Then, the bacterial culture was inoculated into fresh LB broth at a volume ratio of 0.5 / 100-1 / 100 and cultured for 3-4 h until the absorbance at 600 nm reached 0.8; Afterwards, isopropyl-β-D-thiogalactoside (IPTG) was added to the culture to induce the expression of the fusion protein for 2-3 h; the culture medium was then centrifuged to obtain the bacterial cells; the bacterial cells were then washed several times with PBS containing 1% Triton-100 and PBS, respectively; the final concentration of the inducer IPTG used during protein expression was 0.4 mM.

[0013] Finally, the cell pellet was resuspended in lysis buffer to lyse the bacterial cells for 2-3 h, and the supernatant containing the denatured fusion protein was collected by centrifugation.

[0014] The protein fiber material preparation method: the lysis solution used in the bacterial cell lysis process is a urea solution with a pH of 8.0: the lysis solution used is 8M urea, 100mM NaH2PO4, 100mM Tris, 10% glycerol, pH 8.0.

[0015] The protein fiber material preparation method uses a Ni-NTA column to perform in situ refolding and purification of the fusion protein DSUP-OP: First, the supernatant was filtered through a 0.22 μm filter and loaded onto a Ni-NTA column; Then, the nickel column is washed with a washing buffer; then, the nickel column is washed with a refolding buffer containing different concentrations of urea to refold the protein bound to the resin; Finally, the renatured fusion protein is eluted with elution buffer.

[0016] In the protein fiber material preparation method, the washing buffer used in the protein purification process is a urea solution with a pH of 6.3; the washing buffer used for protein purification is: 8M urea, 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 6.3.

[0017] In the protein fiber material preparation method, the buffer used for refolding during protein purification is urea solution of different concentrations, 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 8.0; the urea concentrations are 6M, 4M, 2M, 1M, 0.5M, and 0M. The elution buffer used in the protein purification process is an imidazole solution of pH 7.5: 50 mM Tris base, 300 mM NaCl, 400 mM imidazole, 10% glycerol, pH 7.5.

[0018] The protein was concentrated by ultrafiltration tube concentration method, the molecular weight cutoff of the ultrafiltration tube was 10~15 KDa, and the centrifugal speed was 4000~5000 rpm.

[0019] Bionic spinning of fusion protein DSUP-OP: Self-assembly spinning of anti-biofouling protein fibers for uranium extraction from seawater was carried out, and the transparent and viscous protein obtained after high concentration was pumped into the spinning buffer to obtain anti-biofouling protein fibers for uranium extraction from seawater; the spinning buffer used for bionic spinning was: 100 mM sodium phosphate, pH>5.5; 100 mM sodium acetate, pH 4.0~5.5; 200 mM citric acid, pH<4.0.

[0020] Beneficial effects of the invention: 1. The method for preparing anti-biofouling protein fibers for extracting uranium from seawater of the present invention comprises fusing a double transuranic acid binding protein gene having high uranium selectivity and affinity with a polypeptide gene having both anti-biofouling and uranium adsorption properties through a flexible connector to prepare a fusion protein, and then obtaining a protein fiber material through protein expression, purification, concentration, bionic spinning and self-assembly. The process is simple, the conditions are mild, it is green and environmentally friendly, and it can be prepared in large quantities, thus providing a high-efficiency adsorbent for the extraction and adsorption of uranium in natural seawater.

[0021] 2. The method for preparing anti-biofouling protein fibers for extracting uranium from seawater of the present invention has high mechanical strength, strong binding affinity and selectivity, and significant antibacterial effect.

[0022] 3. The method for preparing anti-biofouling protein fibers for extracting uranium from seawater of the present invention uses a Ni-NTA column in the protein purification process and adopts a purification and renaturation method. The obtained protein solution has a high yield and purity. Each liter of bacterial solution can express 40 to 50 mg of DSUP-OP protein. The purity of the purified DSUP-OP protein is as high as 98%.

[0023] 4. The method for preparing the anti-biofouling protein fiber for extracting uranium from seawater of the present invention uses an ultrafiltration tube to obtain a high-concentration protein solution by centrifugation during protein concentration. The operation is convenient and the conditions are mild. The method can prevent the denaturation and precipitation of proteins, better maintain the activity of biological macromolecules, and has a high recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the recombination of the protein gene for extracting uranium from seawater of the present invention; Figure 2 The spinning effect of the anti-biofouling protein for extracting uranium from seawater in the present invention in spinning buffers with different pH values, and the corresponding numbers of each container in the figure are pH values; Figure 3 This is a scanning electron microscope image of the protein fiber DSUP-OP of the present invention; Figure 4 This is a graph showing the selectivity test results of the protein fiber DSUP-OP of the present invention for uranyl ions and other related metal ions; Figure 5 This is a graph showing the test results of the binding affinity of the protein fiber DSUP-OP of the present invention to uranyl ions and carbonate ions.

[0025] Figure 6 This is a diagram showing the antibacterial effect of the protein fiber DSUP-OP of the present invention on Gram-positive bacteria, Gram-negative bacteria, marine bacteria, and natural seawater microorganisms; Figure 7 The antibacterial activity of the protein fiber DSUP-OP of the present invention against Gram-positive bacteria, Gram-negative bacteria, marine bacteria, and natural seawater microorganisms; DETAILED DESCRIPTION

[0026] In order to make the technical concept and advantages of the present invention more clearly understood, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the following embodiments are only used to explain and illustrate the preferred implementation methods of the present invention, and should not be regarded as and do not constitute a limitation on the scope of patent protection claimed by the present invention.

[0027] The chemical reagents and other raw materials involved in the following examples were purchased from conventional reagent companies. Example

[0028] like Figure 1 As shown, the method for preparing the anti-biofouling protein fiber for extracting uranium from seawater of the present invention comprises the following steps: (1) Genetic recombination: The polypeptide gene fragment OP and the ditransuranyl binding protein gene fragment DSUP are synthesized by conventional methods using a flexible linker to obtain the anti-biofouling recombinant protein DSUP-OP encoding gene for uranium extraction from seawater; (2) Expression and purification of fusion protein DSUP-OP: The engineered bacteria were incubated in LB medium containing 10 mg / L ampicillin at 37°C and 180 rpm overnight. Then, the bacterial culture was inoculated into fresh LB broth at a volume ratio of 1 / 100 and cultured for 3-4 h until the absorbance at 600 nm reached 0.8. After that, the inducer isopropyl-β-D-thiogalactoside, also known as IPTG, was added to the culture to a final concentration of 0.4 mM to induce the expression of the fusion protein for 2.5 h. Next, the culture was centrifuged to obtain bacterial cells. Then, the bacterial cells were washed several times with PBS containing 1% Triton-100 and PBS, respectively. Finally, the cell pellet was resuspended in lysis buffer to lyse the bacterial cells for 2 h, and the supernatant containing the denatured fusion protein was collected by centrifugation.

[0029] The fusion protein was purified by in situ refolding using a Ni-NTA column. First, the supernatant was filtered through a 0.22 μm filter and loaded onto the Ni-NTA column. Then, the nickel column was washed with a wash buffer. Next, the nickel column was washed with a refolding buffer containing different concentrations of urea to refold the protein bound to the resin. Finally, the refolded fusion protein was eluted with an elution buffer. The purified protein was analyzed by SDS-PAGE.

[0030] (3) Bionic spinning of fusion protein DSUP-OP: The transparent and viscous protein obtained after high concentration is pumped into the spinning buffer at an appropriate speed to obtain anti-biofouling protein fibers for uranium extraction from seawater. Example

[0031] The method for preparing the anti-biofouling protein fiber material for extracting uranium from seawater of the present invention comprises: using a flexible connector to fuse a double transuranic acid binding protein gene having ultra-high uranium adsorption selectivity and binding affinity with a polypeptide gene having both anti-biofouling and uranium adsorption properties, so as to prepare the anti-biofouling protein fiber material for extracting uranium from seawater; the process comprises: Step S1, optimizing the codons of the fusion gene based on the codon usage preference of Escherichia coli; Step S2, chemically synthesizing the optimized gene, inserting the gene fragment into the NdeI / XhoI site of the expression vector pET-22b(+) and then transforming it into the Escherichia coli BL-21 strain to construct a genetic engineering for expressing the fusion protein; Step S3, obtaining the protein fiber material through protein expression, purification, concentration, bionic spinning and self-assembly.

[0032] The monomer sequences of the ditransuranyl binding protein, DSUP, and the polypeptide, omiganan peptide, OP, are:

[0033] LDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEGGGGGGSGGGGSGGGGSLDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEG

[0034] ILRWPWWPWRRK-NH2.

[0035] The flexible linker sequence is: NH2-GGGGGGGGGGSGGGGS-COOH. Example

[0036] The method for preparing the protein fiber material of this embodiment is different from that of Embodiment 2 in that: in step S3, the expression process of the fusion protein DSUP-OP is as follows: First, the engineered bacteria were incubated in LB medium containing 10 mg / L ampicillin at 37°C, 180 rpm overnight; then, the bacterial culture was inoculated into fresh LB medium / LB broth at a volume ratio of 1 / 100 (the inoculation ratio is determined according to the bacterial culture time. If the culture time is long and the bacterial concentration is high, the inoculation ratio will be slightly lower. If the culture time is short and the bacterial concentration is not high, the inoculation ratio will be increased, generally at 0.5 / 100~1 / 100), and the culture was continued for 3~4 h until the absorbance at 600 nm reached 0.8.

[0037] Afterwards, isopropyl-β-D-thiogalactoside was added to the culture to induce the expression of the fusion protein for 2.5 h; the culture solution was then centrifuged to obtain the bacterial cells; the bacterial cells were then washed several times with PBS containing 1% Triton-100 and PBS, respectively; Finally, the cell pellet was resuspended in lysis buffer to lyse the bacterial cells for 2 h, and the supernatant containing the denatured fusion protein was collected by centrifugation.

[0038] The final concentration of the inducer isopropyl-β-D-thiogalactoside, i.e. IPTG, used in the protein expression process was 0.4 mM; the lysis solution used in the bacterial cell lysis process was a urea solution with a pH of 8.0: 8 M urea, 100 mM NaH2PO4, 100 mMTris, 10% glycerol, pH 8.0.

[0039] In step S3, the fusion protein DSUP-OP is purified by in situ refolding using a Ni-NTA column: First, the supernatant was filtered through a 0.22 μm filter and loaded onto a Ni-NTA column; Then, the nickel column is washed with a washing buffer; then, the nickel column is washed with a refolding buffer containing different concentrations of urea to refold the protein bound to the resin; Finally, the renatured fusion protein is eluted with elution buffer.

[0040] The washing buffer used in the protein purification process was a urea solution at pH 6.3: 8M urea, 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 6.3; the renaturation buffer was a solution containing different concentrations of urea at pH 8.0: 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 8.0; the urea concentrations were 6M, 4M, 2M, 1M, 0.5M, and 0M, respectively.

[0041] The elution buffer used in the protein purification process was an imidazole solution at pH 7.5: 50 mM Tris base, 300 mM NaCl, 400 mM imidazole, 10% glycerol, pH 7.5.

[0042] In step S3, the purified fusion protein is concentrated by ultrafiltration tube concentration method, the cut-off molecular weight of the ultrafiltration tube is 10 ~ 15 KDa, and the centrifugal speed is 4000 ~ 5000 rpm. Then, the concentrated fusion protein DSUP-OP is subjected to biomimetic spinning treatment: the transparent and viscous protein obtained by high concentration is pumped into the spinning buffer to obtain the anti-biofouling protein fiber for uranium extraction from seawater; the spinning buffer used for biomimetic spinning is: 100 mM sodium phosphate, pH>5.5; 100 mM sodium acetate, pH 4.0~5.5; 200 mM citric acid, pH<4.0. Example

[0043] The method for preparing the protein fiber material of this embodiment is different from that of embodiment 3 in that: in step S3, the anti-biofouling protein fiber for extracting uranium from seawater is self-assembled and spun using spinning buffers with different pH values. Figure 2 The experimental results show that the protein fibers obtained by self-assembly spinning in a spinning buffer with a pH of 2.0 are continuous and uniform in diameter. This may be because the continuous decrease in pH leads to an increase in the hydrophobicity of the protein fibers, inducing the separation of water molecules from the protein, causing the protein to transform from a solution to a gel, increasing the concentration of the spinning buffer and promoting the formation of fibers. This process is similar to the spinning process of spiders, that is, the solidification process of spider silk from a liquid solution to a strong solid fiber also depends on the pH value of the solution.

[0044] The above results show that the pH value of the spinning buffer is crucial to the self-assembly of protein fibers. Figure 3 As shown, FE-SEM of dry protein fibers showed that the DSUP-OP fibers had a rough surface and a diameter of 22 ± 1.5 μm.

[0045] The following is a test of the uranium adsorption specificity and antibacterial activity of the anti-biofouling protein fiber for uranium extraction from seawater prepared in Example 1, i.e., an application experiment of uranium extraction from seawater. The experimental process and results are as follows: The test method and results of the adsorption specificity of uranium by the anti-biofouling protein fiber DSUP-OP for uranium extraction from seawater compared with other metal ions are as follows: Based on the solubility of metal ions, 100 ml of a mixture of 500 nM uranyl and different concentrations of metal ions was prepared. Then, 2 mg of DSUP-OP protein fiber was placed in the above mixture until adsorption equilibrium was reached, and the uranium concentration in the adsorbed solution was determined by ICP-MS. When the maximum ratio of competing ions to uranium was 10 6 The competitiveness of protein fibers for metal ions and uranyl ions was determined under the conditions of 1:1. If uranyl ions were detected, the concentration of the competing ions was diluted 10 times and the process was repeated until no uranium was detected.

[0046] Figure 4 The experimental results show that DSUP-OP has good adsorption specificity for uranium and can specifically recover uranium from uranium-containing solutions even in the presence of various interfering ions.

[0047] The competitive test of uranyl by anti-biofouling protein fiber DSUP-OP and carbonate for uranyl extraction from seawater and the results are as follows: pH 8.9 solutions containing different concentrations of carbonate were prepared with sodium carbonate, and DSUP-OP was added to the mixture containing 10 µM uranyl and different concentrations of carbonate to make the final concentration 10 µM. The uranium adsorption capacity of DSUP-OP in different solutions was determined and analyzed by ICP-MS. The Hill equation in Origin 9.0 was used to fit the data to analyze the binding affinity of the material and calculate the binding Kd of uranyl.

[0048] Figure 5 The experimental results showed that the dissociation constant of the adsorbent for uranyl was extremely low, 378.5 fM, confirming the excellent binding affinity of DSUP-OP for uranyl.

[0049] The antibacterial test process and results of the anti-biofouling protein fiber DSUP-OP for uranium extraction from seawater are as follows: The bacterial culture in the exponential growth phase was transferred to a fresh liquid LB medium at a ratio of 2%, and then the sterile DSUP-OP was placed in the above liquid medium. After culturing in a constant temperature oscillator at 37°C for 3 hours, the microbial concentration was tested by the plate count method. In order to test the antibacterial activity of DSUP-OP against mixed communities of marine microorganisms, untreated natural seawater was used instead of the culture of a single microorganism. The bacterial concentration in the culture medium was determined as described above. The inhibition rate IR was determined according to the following formula:

[0050] in Ci (CFU / mL) represents the bacterial concentration of the untreated culture. Ca (CFU / mL) indicates the bacterial concentration of the culture fluid treated with DSUP-OP.

[0051] Figure 6 , Figure 7 The experimental results showed that DSUP-OP had significant antibacterial effects against Escherichia coli, Staphylococcus aureus and Vibrio vulnificus, with the antibacterial activities reaching 96.3%, 98.3% and 92%, respectively.

[0052] In summary, the method for preparing the anti-biofouling protein fiber DSUP-OP for extracting uranium from seawater of the present invention utilizes genetic engineering and bionic spinning technology to prepare the DSUP-OP protein fiber, which has a simple process and is green and environmentally friendly. The prepared protein fiber has high mechanical strength, strong binding affinity and selectivity, and significant antibacterial effect.

[0053] The above description is only a preferred embodiment of the present invention and does not constitute a limitation of the present invention. Under the guidance of the prior art, those skilled in the art can make other modifications to the implementation of the present invention without creative work. Any modification made within the spirit and principle of the present invention or simple replacement or equivalent replacement, improvement, etc. made by conventional technical means in the field should be included in the protection scope of the present invention.

Claims

1. A method for preparing an anti-biofouling protein fiber material for extracting uranium from seawater, characterized in that: A flexible linker is used to fuse a double transuranic acid binding protein gene with ultra-high uranium adsorption selectivity and binding affinity with a polypeptide gene having both anti-biofouling and uranium adsorption properties to prepare the anti-biofouling protein fiber material for extracting uranium from seawater; The process includes: Step S1, optimizing the codons of the fusion gene based on the codon usage preference of Escherichia coli; Step S2, chemically synthesizing the optimized gene, inserting the gene fragment into the NdeI / XhoI site of the expression vector pET-22b(+) and then transforming it into the Escherichia coli BL-21 strain to construct a genetic engineering for expressing the fusion protein; Step S3, obtaining protein fiber material through protein expression, purification, concentration, bionic spinning and self-assembly.

2. The method for preparing a protein fiber material according to claim 1, characterized in that: The monomer sequences of the ditransuranyl binding protein, DSUP, and the polypeptide, omiganan peptide, OP, are: DSUP LDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEGGGGGGSGGGGSGGGGSLDCRERIEKDLEDLEKELMEMKSIKLSDDEEAVVERALNYRDDSVYYLEKGDHITSFGCITYAEGLLDSLRMLHRIIEG OP ILRWPWWPWRRK-NH2.

3. The method for preparing a protein fiber material according to claim 1, characterized in that: The flexible linker sequence is NH2-GGGGGGGGGGSGGGGS-COOH.

4. The method for preparing a protein fiber material according to claim 1, 2 or 3, characterized in that: In step S3, the expression process of the fusion protein DSUP-OP is as follows: First, the engineered bacteria were incubated in LB medium containing 10 mg / L ampicillin at 37°C and 180 rpm overnight; then, the bacterial culture was inoculated into fresh LB medium at a volume ratio of 0.5 / 100-1 / 100 and cultured for 3-4 hours until the absorbance at 600 nm reached 0.8; Afterwards, the inducer was added to the culture to induce the expression of the fusion protein for 2-3 h; the culture medium was then centrifuged to obtain the bacterial cells; the bacterial cells were then washed several times with PBS containing 1% Triton-100 and PBS respectively; Finally, the cell pellet was resuspended in lysis buffer to lyse the bacterial cells for 2-3 h, and the supernatant containing the denatured fusion protein was collected by centrifugation.

5. The method for preparing a protein fiber material according to claim 4, characterized in that: The inducer is isopropyl-β-D-thiogalactoside, and the final concentration of the inducer used in the protein expression process is 0.4 mM; the lysis solution used in the bacterial cell lysis process is a urea solution with a pH of 8.0: 8M urea, 100mM NaH2PO4, 100mM Tris, 10% glycerol, pH 8.

0.

6. The method for preparing a protein fiber material according to claim 1, 2, 3 or 5, characterized in that: In step S3, the fusion protein DSUP-OP is purified by in situ refolding using a Ni-NTA column: First, the supernatant was filtered through a 0.22 μm filter and loaded onto a Ni-NTA column; Then, the nickel column is washed with a washing buffer; then, the nickel column is washed with a refolding buffer containing different concentrations of urea to refold the protein bound to the resin; Finally, the renatured fusion protein is eluted with elution buffer.

7. The method for preparing a protein fiber material according to claim 6, characterized in that: The washing buffer used in the protein purification process was a urea solution at pH 6.3: 8 M urea, 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 6.3; The refolding buffer was urea solution with different concentrations, 100 mM NaH2PO4, 100 mM Tris, 10% glycerol, pH 8.0; the urea concentrations were 6M, 4M, 2M, 1M, 0.5M, and 0M, respectively.

8. The method for preparing a protein fiber material according to claim 6, characterized in that: The elution buffer used in the protein purification process was an imidazole solution at pH 7.5: 50 mM Tris base, 300 mM NaCl, 400 mM imidazole, 10% glycerol, pH 7.

5.

9. The method for preparing a protein fiber material according to claim 1, 2, 3, 5, 7 or 8, characterized in that: In step S3, the purified fusion protein is concentrated by ultrafiltration tube concentration method, the molecular weight cutoff of the ultrafiltration tube is 10~15 KDa, and the centrifugal speed is 4000~5000 rpm; then, the concentrated fusion protein DSUP-OP is subjected to biomimetic spinning treatment: the transparent and viscous protein obtained by high concentration is pumped into the spinning buffer to obtain anti-biofouling protein fiber for uranium extraction from seawater; the spinning buffer used for biomimetic spinning is: 100 mM sodium phosphate, pH>5.5; 100 mM sodium acetate, pH 4.0~5.5; 200 mM citric acid, pH<4.

0.

10. Use of the protein fiber material prepared by the method for preparing the protein fiber material according to claim 1 in a process or project of extracting uranium from seawater.

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