Microbial self-assembling fusion proteins and uses thereof

Abstract

The present application relates to the field of metal element adsorption, and particularly to a microbial self-assembly fusion protein and application thereof.The present application provides a fusion protein, comprising: a flagellin protein and a metal element binding protein.A functional microorganism capable of efficiently and selectively recovering rare earth element (REE) resources in water and a construction method thereof are disclosed.The bacteria have self-assembly curli pili with an imitation "octopus tentacle" structure, and a large number of lanthanide metal binding proteins fixed on the curli pili are used for selective adsorption of REEs.In the present application, lanthanide metal binding tags (LBTs) are fused with curli monomer csgA to form a large number of curli pili by using curli display technology on the surface of bacteria. A large number of REEs binding sites are distributed on the curli of the constructed engineering strain, which can selectively capture low-concentration lanthanide metal ions from water and enrich them on the surface of the curli.

Description

Technical Field

[0001] This invention relates to the field of metal element adsorption, and more particularly to microbial self-assembled fusion proteins and their applications. Background Technology

[0002] Rare earth elements (REEs) are widely used in energy, chemical, pharmaceutical, and defense industries due to their unique magnetic, optical, and mechanical properties. REEs are abundant in mine wastewater and seawater, and extraction and separation typically require methods such as chemical precipitation, electrodeposition, extraction, and ion exchange. However, these methods are generally energy-intensive and struggle to achieve highly selective separation of REEs. In recent years, biosorption technology has also begun to be used for the separation and recovery of REEs. Microorganisms utilize the numerous carboxyl and phosphate functional groups on their cell surfaces to bind to REEs, making it a low-cost and environmentally friendly method for REE separation. However, microorganisms have a weak adsorption capacity for REEs and also lack selectivity.

[0003] To address the poor selectivity of microbial REE adsorption, researchers have proposed a novel strategy to construct engineered strains that selectively adsorb REEs. This involves using bacterial surface display technology to immobilize rare earth binding tag proteins (LBTs) on the surface of microbial cells. LBTs exhibit extremely high affinity and specificity for REEs, enabling these engineered strains to achieve highly selective REE removal. However, the limited number of cell surface membrane proteins used for LBT anchoring and the difficulty in achieving large-scale in-situ assembly of LBT fusion proteins result in a maximum REE adsorption capacity of only 40 mg / gDCW (40 mg of REEs adsorbed per gram of cell dry weight).

[0004] Therefore, it remains difficult to achieve high-capacity, selective biosorption of REEs in water. Summary of the Invention

[0005] In view of this, the present invention provides a microbial self-assembled fusion protein and its applications. This invention discloses a functional microorganism capable of efficiently and selectively recovering REE resources from water and its construction method. This bacterium possesses self-assembled ciliary filaments with an "octopus tentacle" structure, utilizing the abundant surface area of ​​the ciliary filaments to immobilize a large number of LBTs as REE adsorption sites. This invention utilizes bacterial surface curli display technology to fuse LBTs with the curli monomer csgA for expression and extracellular self-assembly. The constructed engineered strain has a large number of REE ion adsorption and binding sites distributed on its filaments, enabling it to selectively capture low concentrations of lanthanide metal ions from water and enrich them on the ciliary surface. The bacterium exhibits an adsorption capacity for terbium (Tb) as high as 98.3 ± 3.5 mg / g DCW (cell dry weight), superior to other reported REE adsorption materials, and can be efficiently desorbed for reuse. Simultaneously, the engineered strain also shows good adsorption performance for various other REEs such as lanthanum (La), neodymium (Nd), and gadolinium (Gd), thus possessing great application potential in metal ion separation and recovery.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides fusion proteins, including: ciliary proteins and metal-binding proteins.

[0008] In some embodiments of the present invention, the cilia protein in the above-mentioned fusion protein includes: CsgA protein.

[0009] In some embodiments of the present invention, the metal-binding protein in the above-mentioned fusion protein includes: lanthanide metal-binding tag protein and / or gold ion-binding protein.

[0010] In some embodiments of the present invention, the lanthanide metal-binding tag protein in the above-mentioned fusion protein is LBTs.

[0011] In some embodiments of the present invention, the gold ion binding protein in the above-mentioned fusion protein is GolB.

[0012] In some embodiments of the present invention, the fusion protein described above, wherein the ciliated protein has:

[0013] (1) An amino acid sequence as shown in SEQ ID NO:1; or

[0014] (2) An amino acid sequence obtained by substituting, deleting, or adding one or more amino groups to the amino acid sequence shown in (1), and which has the same or similar function as the amino acid sequence shown in (1); or

[0015] (3) An amino acid sequence that is at least 80% identical to the amino acid sequence shown in (1) or (2); and

[0016] The metal-binding protein has the following characteristics:

[0017] (4) An amino acid sequence as shown in SEQ ID NO:2 or SEQ ID NO:3; or

[0018] (5) An amino acid sequence obtained by substituting, deleting, or adding one or more amino groups to the amino acid sequence shown in (4), and which has the same or similar function as the amino acid sequence shown in (4); or

[0019] (6) An amino acid sequence that is at least 80% identical to the amino acid sequence shown in (4) or (5).

[0020] In some embodiments of the present invention, the sequence of SEQ ID NO:1 in the above-mentioned fusion protein is: cilia protein (CsgA protein), MKLLKVAAIAAIVFSGSALAGVVPQYGGGGGNHGGGGNNSGPNSELNIYQYGGGNSALALQADARNSDLTITQHGGGNGADVGQGSDDSSIDLTQRGFGNSATLDQWNGKDSTMTVKQFGGGNGAAVDQTASNSSVNVTQVGFGNNATAHQY.

[0021] In some embodiments of the present invention, the sequence of SEQ ID NO:2 in the above-mentioned fusion protein is: LBTs protein, RSTSFIDTNNDGWIEGDELFIDTNNDGWIEGDELLAASPPAHGVTSAPDTRPAPGSTASFIDTNNDGWIEGDELFIDTNNDGWIEGDELLAASPPAHGVTSAPDTRPAPGSTASFIDTNNDGWIEGDELFIDTNNDGWIEGDELLAASPPAHGVTSAPDTRPAPGSTASFIDTNNDGWIEGDELFIDTNNDGWIEGDELLAASPPAHGVTSAPDTRPAPGSTASAA.

[0022] In some embodiments of the present invention, the sequence of SEQ ID NO:3 in the above-mentioned fusion protein is: GolB protein, MQFHIDDMTCGGCASTVKKTILTLDANATVRTDPATRLVDVETSLSAEQIAAALQKAGFPPRER.

[0023] The present invention also provides a nucleic acid molecule encoding the above-mentioned fusion protein, wherein the nucleic acid molecule encoding the CsgA protein has:

[0024] (7) A nucleotide sequence as shown in SEQ ID NO:4; or

[0025] (8) A nucleotide sequence obtained by substituting, deleting, or adding one or more bases to the nucleotide sequence shown in (7), and which has the same or similar function as the nucleotide sequence shown in (7); or

[0026] (9) A nucleotide sequence that is at least 80% identical to the nucleotide sequence shown in (7) or (8); and

[0027] The nucleic acid molecule encoding the metal-binding protein has:

[0028] (10) A nucleotide sequence as shown in SEQ ID NO:5 or SEQ ID NO:6; or

[0029] (11) A nucleotide sequence obtained by substituting, deleting, or adding one or more bases to the nucleotide sequence shown in (10), and which has the same or similar function as the nucleotide sequence shown in (10); or

[0030] (12) A nucleotide sequence that is at least 80% identical to the nucleotide sequence shown in (10) or (11).

[0031] The present invention also provides an expression vector comprising the above-described nucleic acid molecule and acceptable gene elements.

[0032] In some embodiments of the present invention, the expression vector further includes the backbone plasmid pET28.

[0033] The present invention also provides a host, transformation and / or transfection of the above expression vector.

[0034] In some embodiments of the present invention, the CsgA gene is knocked out in the host described above.

[0035] In some embodiments of the present invention, the host mentioned above includes Escherichia coli.

[0036] The present invention also provides products comprising: the above-described fusion protein, the above-described nucleic acid molecule, the above-described expression vector, and / or the above-described host.

[0037] The present invention also provides the application of the above-mentioned fusion protein, the above-mentioned nucleic acid molecule, the above-mentioned expression vector and / or the above-mentioned host in the recovery and / or adsorption of metal elements.

[0038] In some embodiments of the present invention, in the above applications, the rare earth elements include one or more of La, Ce, Nd, Gd, Tb, Er, and Lu.

[0039] In some embodiments of the present invention, in the above applications, the rare earth element includes one or more of Nd, Gd and Tb.

[0040] In some embodiments of the present invention, the above-described applications include gold as a precious metal element.

[0041] The present invention also provides a method for recovering and / or adsorbing metal elements, wherein the above-mentioned host induction and expression are mixed with the sample.

[0042] In some embodiments of the present invention, the induction in the above method uses 0.02 mM IPTG.

[0043] In some embodiments of the present invention, the induction time in the above method is 20 to 25 hours.

[0044] In some embodiments of the present invention, when the sample contains rare earth elements, the mixing time is 30-60 minutes and the temperature is 30°C.

[0045] In some embodiments of the present invention, when the sample contains rare earth elements, the concentration of the sample is 20 to 4000 μM.

[0046] In some embodiments of the present invention, when the sample contains noble metal elements, the mixing time is 24 hours.

[0047] In some embodiments of the present invention, when the sample contains noble metal elements, the concentration of the sample is 10 to 50 μM.

[0048] This invention provides fusion proteins, including: ciliary proteins and metal-binding proteins.

[0049] The beneficial effects of this invention include:

[0050] (1) Traditional methods for recovering REEs, such as chemical precipitation, solvent extraction, molecular recognition technology, and membrane filtration, suffer from high costs and complex operations. Furthermore, technologies such as ion flotation, ion exchange, and magnetic separation also have limitations in terms of recovery efficiency and selectivity. In contrast, the bioadsorbent material based on ion-binding protein display technology proposed in this invention not only exhibits high selectivity but also boasts low production costs.

[0051] (2) This invention creatively proposes a protein extracellular self-assembly display technology, which, compared with existing technologies, enables the extracellular assembly of a larger amount of LBTs proteins, forming functionalized curli pili filaments with an "octopus tentacle" structure, thereby efficiently and selectively adsorbing rare earth elements. Currently, existing engineered bacteria all employ membrane surface display technology, i.e., constructing an ompA membrane protein-LBTs fusion protein and assembling it on the membrane surface, with a maximum adsorption capacity of 28.7 mg / g DCW for terbium (Tb). Figure 2 B), and its REE adsorption capacity reaches saturation when the REE concentration is only 100 μM. Limited by the relatively small number of membrane proteins, the REE adsorption capacity of existing bioadsorption systems is weak. This invention, for the first time, uses ciliary surface display technology to fuse LBTs with ciliary proteins and obtain a large number of functionalized cilia through extracellular self-assembly, significantly increasing the LBT loading capacity. The constructed E. coli-ΔcsgA / pU130 engineered strain not only achieves a saturation adsorption concentration of up to 3000 μM for REEs, but also has a Tb adsorption capacity as high as 98.3 ± 3.5 mg / g DCW, far superior to existing bioadsorption systems ( Figure 2 A).

[0052] (3) The technology proposed in this invention can be extended to the construction of various bioadsorbent materials to achieve selective recovery of other metals. For example, the gold ion-binding protein GolB can be immobilized on cell cilia for highly selective and efficient gold recovery. Currently, surface-display engineered strains constructed using GolB and membrane protein ompA also face the problem of low gold recovery rates, especially for high-concentration gold ions (>50 μM), the recovery efficiency is generally below 65%. After achieving extracellular self-assembly display of GolB using the method of this invention, the gold ion recovery rate of the constructed engineered bacteria is increased to 90% ( Figure 5 ). Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0054] Figure 1 This diagram shows the plasmids constructed in this invention.

[0055] Figure 2 The Tb adsorption saturation capacity of E. coli-ΔcsgA / pU130-4LBTs is shown; where: A represents the adsorption capacity of the engineered bacteria at different Tb ion concentrations (20, 400, 800, 1500, 2000, 3000 and 4000 μM); B represents the Tb adsorption saturation capacity of microorganisms reported in existing literature.

[0056] Figure 3This demonstrates the recovery of REEs by E. coli-ΔcsgA / pU130-4LBTs;

[0057] Figure 4 E. coli-ΔcsgA / pU130-4LBTs shows the elution and cycling stability of Tb; in the middle: A shows the desorption rate of Tb at different elution volumes; B shows the Tb recovery by the strain. 3+ Cyclic stability;

[0058] Figure 5 Demonstrates the construction of a metal recycling platform to recover Au ions;

[0059] Figure 6 The diagram illustrates the extracellular self-assembly of proteins as they recover and / or adsorb metal elements. Detailed Implementation

[0060] This invention discloses microbial self-assembled fusion proteins and their applications.

[0061] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0062] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0063] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0064] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0065] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means an actual value within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0066] Inspired by the efficient predator-capturing capabilities of octopus tentacle suckers, we utilized extracellular protein self-assembly display technology to assemble a large number of lanthanide metal-binding proteins (similar to suckers) within microbial cilia (similar to octopus tentacles) to enhance the microorganisms' ability to capture REEs (such as...). Figure 6 (As shown). Curli amyloid fibrils are an important component of biomembranes, composed of seven genes associated with fibril specificity (CsgA, CsgB, CsgC, CsgD, CsgE, CsgF, and CsgG). CsgA is secreted extracellularly and continuously self-assembles to form curli cilia. By fusing LBTs with csgA, LBTs can be assembled onto microbial cilia, resulting in "tentacle-like suckers" with unique REE-trapping capabilities for highly efficient and selective REE adsorption.

[0067] Specifically, this invention combines biomimetic principles to achieve the large-scale assembly of metal-binding proteins (such as lanthanide metal-binding tag proteins LBTs and gold ion-binding proteins GolB) on the cell surface, overcoming the limitation of the limited number of conventional cell surface display proteins and significantly improving the bioadsorption capacity and selectivity of target metals.

[0068] In some implementations, csgA is further knocked out of engineered E. coli strains.

[0069] All reagents used in the examples were commercially available; LB liquid culture medium (Tryptone: 10g / LYeastExtract: 5g / L NaCl: 10g / L) was prepared using distilled water and autoclaved at 121°C for 20 min; the engineered strain was inoculated at 1% into an LB solution containing kanamycin 50 (50 μg / mL).

[0070] The proteins involved in this invention include: the previously reported 4LBTs, csgABCDEFG from Nissle E.coli 1917, and the gold ion-binding protein (GolB) from Salmonella enterica.

[0071] The gene sequence involved in this invention is shown below:

[0072]

[0073]

[0074] In Examples 1 to 4 of this invention, all raw materials and reagents used can be purchased from the market.

[0075] The present invention will be further illustrated below with reference to the embodiments:

[0076] Example 1

[0077] 1. Plasmid construction and identification

[0078] For gene fragment amplification, chain polymerase reaction (PCR) was performed using designed primers (see Table 1). The targets for amplification included csgA-LBTs, csgB-pET28-ske, csgCDEFG, and CsgA-GolB gene fragments. The PCR reaction system was as follows: premstar mix, ddH2O, upstream / downstream primers, and template. After 30 cycles, the PCR products were recovered for later use.

[0079] The first three gene fragments (csgA-LBTs, csgB-pET28-ske, and csgCDEFG) were ligated using a Gibson kit to construct the pU130-4LBTs plasmid; the latter three gene fragments (csgB-pET28-ske, csgCDEFG, and CsgA-GolB) were ligated to form the pU126-GolB plasmid. Next, the pU130-4LBTs and pU126-GolB plasmids were introduced into *E. coli* BL21 using a heat shock method. The cultures were incubated at 37°C and 200–300 rpm for 1–1.5 hours, then the bacterial culture was evenly spread on a plate containing kanamycin and incubated overnight at 37°C. Afterward, single clones were selected from the colonies for validation, and the integrity of the plasmids was verified by Sanger sequencing.

[0080] The pU123 plasmid fragment was amplified using single-base editing technology with primer pairs (pU123-ske-F / R-4401 and pU123-seg-F / R-5635). The complete pU123 plasmid was then obtained through similar PCR and ligation procedures. Subsequently, the pU123 plasmid was introduced into *E. coli* BL21 using a heat shock method. The culture was incubated at 37°C and 200–300 rpm for 1–1.5 hours, and the bacterial culture was evenly spread on plates containing chloramphenicol and incubated overnight at 37°C. Single colonies were selected for verification, and the integrity of the plasmid and the accuracy of the csgA knockout were verified by Sanger sequencing. Finally, the successfully edited BL21 strain was diluted and spread on plates containing 10% sucrose to eliminate plasmid pU123, thus obtaining the *E. coli*-ΔcsgA strain.

[0081] Table 1

[0082]

[0083]

[0084] 2. Construction of engineered strains

[0085] The plasmid (pU130-4LBTs) carrying lanthanide metal-binding proteins was electroporated into the strain (E. coli-ΔcsgA) to obtain the E. coli-ΔcsgA / pU130 engineered strain encoding the csgA-4LBTs gene. The integrity of the plasmid was verified by Sanger sequencing.

[0086] The plasmid (pU126-GolB) carrying the gold ion-binding protein was electroporated into microbial cells (E. coli-ΔcsgA) to obtain the E. coli-ΔcsgA / pU126 engineered strain encoding the csgA-GolB gene. The integrity of the plasmid was verified by Sanger sequencing.

[0087] 3. Preferably, the culture medium used to culture the E.coli-ΔcsgA / pU130 engineered bacteria in the above steps is LB medium.

[0088] csgA-4LBTs expression was induced by IPTG as an inducer.

[0089] csgA-GolB expression was induced using IPTG as an inducer.

[0090] The culture period is 24–36 hours.

[0091] 4. Rare Earth Element Recycling

[0092] E. coli-ΔcsgA / pU130-4LBTs were induced with 0.02 mM IPTG, and bacteria were collected at 16,000 g for 5 min. The cells were washed three times with MES buffer (10 mM NaCl, 10 mM 2-(N-morpholino)ethanesulfonic acid, pH 6.0) and resuspended to allow the bacterial cells to reach OD500. 600 The value was adjusted to 0.3, and different Tb values ​​were adjusted. 3+ Concentrations (20, 400, 800, 1500, 2000, 3000, and 4000 μM) were incubated in a shaker at 30 °C for 30 min. After centrifugation at 16,000 g for 5 min, the supernatant was collected, and the Tb ion concentration was measured by inductively coupled plasma mass spectrometry (ICP-MS).

[0093] Bacterial cells were added to solutions containing different concentrations of Tb. 3+ In solutions of varying concentrations, bacterial OD 600 The solution was incubated at 0.3°C on a shaker for 30 min, centrifuged at 16,000 g for 5 min, and the supernatant was used to determine the Tb ion concentration by ICP-MS.

[0094] In addition to Tb adsorption, the material provided by this invention can also be used for the adsorption of other lanthanide metals in water, such as lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), europium (Eu), erbium (Er), and ruthenium (Lu).

[0095] WT, E. coli / pU126 and E. coli-ΔcsgA / pU126 were used for Au ion recovery. After incubation with 0.02 mM IPTG for 4–6 hours, OD… 600 The concentration of Au ions was increased to 0.6–0.8, and different concentrations of Au ions were added and cultured for another 24 hours. After centrifugation at 16,000g for 5 minutes, the supernatant was collected and the Au ion concentration was measured by ICP-MS.

[0096] Example 2

[0097] REE recovery: E. coli-ΔcsgA / pU130 cells were induced with IPTG for 24 h and then centrifuged at 16,000 g for 5 min. The collected bacterial cells were washed three times with MES buffer and resuspended in MES buffer; the bacterial OD was adjusted. 600 The concentration was 0.3. 100 μM of each of the seven REEs (La, Ce, Nd, Gd, Tb, Er, and Lu) were added, and the mixture was incubated at 30 °C on a shaker for 30 min. Finally, the mixture was centrifuged at 16,000 g for 5 min, and the supernatant was used to determine the REE ion concentration by ICP-MS.

[0098] Although LBTs are primarily designed based on the physicochemical properties of Tb, the engineered strain E. coli-ΔcsgA / pU130 still exhibits excellent recovery capabilities for REEs, with recovery efficiencies exceeding 80% for various REEs, indicating that LBTs are suitable for the recovery of all REE elements. Notably, this strain showed the best recovery rates for Nd and Gd, reaching 88% and 92%, respectively, suggesting slight differences in the binding efficiency of LBTs to different REEs. Curli-display demonstrates excellent REE recovery capabilities and can be used for the separation and recovery of REEs from real-world environmental samples (such as...). Figure 3 (As shown).

[0099] Example 3

[0100] Cyclic stability: Recovery of 100 μM Tb 3+ The engineered strain was eluted using different volumes of 10 mM, pH 5.0 buffer. After each elution, the sample was centrifuged at 16,000 g for 5 min, and the supernatant was collected for ICP-MS determination of Tb concentration.

[0101] After confirming complete elution of Tb 3+ Then, 100 μM Tb was added again. 3+ Repeat the above recycling of Tb 3+ The experiment was repeated 5 times.

[0102] Elution with 2 times the volume of citrate resulted in the effective elution of approximately 95% of Tb, while elution with 5 times the volume yielded near-complete elution, indicating that citrate effectively disrupts the binding between LBTs and REEs. After 5 adsorption-elution cycles, the engineered strain maintained a REE recovery efficiency of 94% (e.g., ...). Figure 4 As shown in the figure, the curli cilia exhibit high stability in citrate buffer. This means that the engineered strain maintains a high level of adsorption and recovery performance for REEs even after multiple cycles, demonstrating excellent adsorption performance and stability in REE recovery.

[0103] Example 4

[0104] Au ion recovery: After incubation with 0.02 mM IPTG for 4–6 hours, strains WT, E. coli / pU126, and E. coli-ΔcsgA / pU126 showed ODg recovery. 600 After adjusting the pH to 0.6–0.8, add gold ions of different concentrations (10–50 μM) and continue culturing for 24 h. Centrifuge at 16,000 g for 5 min, and measure the Au ion concentration of the supernatant by ICP-MS.

[0105] E. coli-ΔcsgA / pU126 exhibited the best recovery performance at a 50 μM Au ion concentration, with a recovery efficiency as high as 89%, which is 10% and 25% higher than WT and E. coli / pU126, respectively. The recovery efficiency of the engineered strain for Au also reached the highest level reported to date (e.g., Figure 5 As shown in the figure, this indicates that curli also has great potential in the recycling of precious metals.

[0106] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, such as changing the chassis strain, metal-binding proteins, adsorption / recovery of other metals, similar intracellular / extracellular self-assembly strategies, experimental environments, etc., but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fusion protein, characterized in that, The fusion protein is either CsgA protein-4LBTs protein or CsgA protein-GolB protein; The sequence of the CsgA protein is as shown in SEQ ID NO:1; The sequence of the 4LBTs protein is as shown in SEQ ID NO:2; The sequence of the GolB protein is as shown in SEQ ID NO:

3.

2. A nucleic acid molecule encoding the fusion protein as described in claim 1, characterized in that, The sequence of the nucleic acid molecule encoding the CsgA protein is as follows: the nucleotide sequence shown in SEQ ID NO:4; and The sequence of the nucleic acid molecule encoding the 4LBTs protein is as follows: the nucleotide sequence shown in SEQ ID NO:5; and The sequence of the nucleic acid molecule encoding the GolB protein is as shown in SEQ ID NO:

6.

3. An expression carrier, characterized in that, Includes nucleic acid molecules as described in claim 2 and acceptable gene elements.

4. The host, characterized in that, Transformation and / or transfection of the expression vector as described in claim 3.

5. The product, characterized in that, include: The fusion protein as described in claim 1, the nucleic acid molecule as described in claim 2, the expression vector as described in claim 3, and / or the host as described in claim 4.

6. The application of the fusion protein as described in claim 1, the nucleic acid molecule as described in claim 2, the expression vector as described in claim 3, and / or the host as described in claim 4 in the recovery and / or adsorption of metal elements; The metallic element is one or more of the following: lanthanum, cerium, neodymium, samarium, europium, erbium, ruthenium, gadolinium, terbium, and gold.

7. A method for recovering and / or adsorbing metal elements, characterized in that, After host induction and expression as described in claim 4, the mixture is mixed with the sample.

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