Pseudomonas oryzae and application thereof

Abstract

The invention provides pseudomonas oryzae and application thereof. The strain provided by the invention is screened from an extreme environment, has the characteristics of high adsorption, high selectivity and the like, and can realize efficient enrichment of rare earth elements in multiple scenes of acid waste liquid, complex leachate and the like. The strain has wide application potential and can be used for biological purification and element recovery of rare earth smelting tail water, selective concentration of rare earth permanent magnet recovery liquid, sustainable mine restoration and residual resource reutilization, construction of a biological adsorption module to replace a traditional extraction agent and the like.

Description

Technical Field

[0001] This application belongs to the field of biodegradation technology, and in particular relates to a type of Pseudomonas oryzae and its uses. Background Technology

[0002] Rare earth elements, as crucial raw materials supporting key industries such as new energy, electronic information, high-end manufacturing, and national defense security, occupy an irreplaceable position in the national strategic resource system. Although the term "rare earth" implies scarcity, in fact, the abundance of these elements in the Earth's crust is no less than that of common metals such as copper and zinc. However, because rare earth elements typically exist in nature as symbiotic or associated forms with multiple elements, and their physical and chemical properties are extremely similar, the extraction and separation of rare earths has long been a technical challenge that has failed to be effectively overcome in the fields of metallurgy and materials science. With the increasing depletion of resources, growing environmental pollution, and rising supply chain security risks, existing resource development models and technological systems have exposed many deep-seated problems.

[0003] Current rare earth extraction and separation processes mainly rely on traditional chemical methods, including acid leaching, alkaline leaching, solvent extraction, and ion exchange. These methods are technically mature and adaptable, capable of supporting large-scale production and high-purity requirements. However, they are undeniably still extensive pathways characterized by high pollution, high energy consumption, and low resource utilization efficiency. Acid leaching generally suffers from high acid consumption, strong corrosiveness, and difficulty in achieving compliant wastewater discharge standards. Alkaline leaching and roasting leaching, while selectively advantageous for specific minerals, result in higher energy consumption and equipment complexity. Solvent extraction, although dominant in industrial separation, requires hundreds of cascaded operations to achieve high-purity products due to the extremely low separation factor of rare earth elements, leading to unacceptable process complexity and organic solvent consumption, as well as significant wastewater treatment and environmental risks. While ion exchange and chromatography have advantages in separating high-value-added rare earth materials, their low throughput and poor resin stability prevent large-scale application. Overall, these traditional chemical methods have fundamental shortcomings in environmental friendliness, energy efficiency, and adaptability to secondary resources.

[0004] In contrast, bioaccumulation technology has gained attention in recent years as a green and sustainable emerging method. Bioaccumulation primarily recovers rare earth ions through microbial surface adsorption, intracellular active uptake, and metabolite-mediated precipitation. Multiple studies have demonstrated that both natural microorganisms such as Bacillus, Streptomyces, and methyltrophic bacteria, as well as genetically engineered strains expressing rare earth binding proteins (such as LanM and dLBT), can achieve effective enrichment of rare earth ions under mild conditions. Bioaccumulation shows potential advantages in environmental friendliness, selectivity, and cost control, especially in the context of complex rare earth-metal systems and the difficulty in meeting the selectivity requirements of traditional chemical methods, offering new technological possibilities. However, from a rigorous scientific and engineering perspective, current bioaccumulation methods remain in the laboratory research stage. Their core bottlenecks lie in limited adsorption capacity, insufficient selectivity, poor operational stability, difficulty in desorption, and low enrichment flux. While functional groups on the surface of microbial cells can achieve rare earth adsorption, competitive adsorption is severe in multi-metal coexistence environments, and the adsorption-desorption cycle stability is poor. Although active uptake mechanisms offer higher enrichment efficiency, their flux is limited, making industrial scale-up difficult. While metabolite-mediated precipitation can improve separation purity, it suffers from low metabolic flux, limited selectivity, and difficulty in control, and a mature process system has yet to be established. Furthermore, bioaccumulation systems are often sensitive to environmental conditions, exhibiting unstable enrichment performance under fluctuations in pH, temperature, and metal concentration, making it difficult to meet the application requirements of complex wastes or low-concentration systems.

[0005] With the surge in demand for rare earths and the environmental constraints faced by energy-intensive metallurgical methods, there is an urgent need to build a highly selective, low-energy-consumption, and environmentally friendly rare earth separation and recycling pathway. Summary of the Invention

[0006] The purpose of this application is to provide *Pseudomonas oryzae* and its uses.

[0007] Specifically, this application relates to the following aspects:

[0008] 1. A species of Pseudomonas oryzihabitans, which is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 35123.

[0009] 2. A method for surface modification of the *Pseudomonas oryzae* strain described in item 1, comprising surface modification of the strain using one or more of sodium trimetaphosphate, sodium polyacrylate, and sodium citrate.

[0010] 3. The method according to item 2, wherein the method includes the following steps:

[0011] The cells of *Pseudomonas oryzae* were placed in an aqueous solution of sodium tripolyphosphate and reacted at 30℃-60℃ for 6-48 hours.

[0012] After the reaction is complete, the bacterial cells are washed to remove unbound phosphates.

[0013] 4. The method according to item 2, wherein the method includes the following steps:

[0014] Place the cells of Pseudomonas oryzae in an aqueous solution of sodium polyacrylate and react at room temperature for 10-60 minutes.

[0015] After the reaction is complete, the bacterial cells are washed to remove unbound sodium polyacrylate.

[0016] 5. The method according to item 2, wherein the method includes the following steps:

[0017] Place the cells of Pseudomonas oryzae in sodium citrate buffer and react at 30℃-40℃ for 10-60 minutes;

[0018] After the reaction is complete, the bacterial cells are washed to remove unbound sodium citrate.

[0019] 6. A surface-modified *Pseudomonas oryzae*, obtained by any one of items 2-5.

[0020] 7. The use of *Pseudomonas oryzae* as described in item 1 or the surface-modified *Pseudomonas oryzae* as described in item 6 in the enrichment of rare earth elements.

[0021] 8. According to the use described in item 7, wherein the rare earth element is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, and Y.

[0022] 9. The use according to item 7 or 8, wherein said use includes one or more of the following:

[0023] Biological purification and element recovery of rare earth smelting tailwater, selective concentration of rare earth permanent magnet recovery liquid, sustainable mine restoration and reuse of residual resources, and construction of bio-adsorption modules to replace traditional extractants.

[0024] 10. A method for enriching rare earth elements, comprising contacting the *Pseudomonas oryzae* described in item 1 or the surface-modified *Pseudomonas oryzae* described in item 6 with a liquid containing rare earth elements.

[0025] 11. The method according to claim 10, wherein the rare earth element is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, and Y.

[0026] 12. The method according to item 10 or 11, wherein the liquid containing rare earth elements comprises one or more of the following:

[0027] Magnesium sulfate leaching solution from rare earth ore, biological leaching solution from rare earth ore, leaching solution from magnetic material waste, and tailings from rare earth smelting.

[0028] Beneficial effects of this application

[0029] The strains described in this application were screened from extreme environments and have the characteristics of high adsorption and high selectivity, enabling efficient enrichment of rare earth elements in various scenarios such as acidic waste liquids and complex leachates.

[0030] The strains described in this application have broad application potential and can be used for biological purification and element recovery of rare earth smelting tailwater, selective concentration of rare earth permanent magnet recovery liquid, sustainable mine restoration and reuse of residual resources, and construction of bio-adsorption modules to replace traditional extractants. Attached Figure Description

[0031] Figure 1 This is a screening chart of the adsorption capacity of the strains.

[0032] Figure 2 The adsorption capacity of microorganisms obtained after initial screening was determined by ICP-OES.

[0033] Figure 3 This shows the changes in isoelectric point and surface potential of the strain before and after chemical modification.

[0034] Figure 4 This shows the adsorption capacity of the strain before and after chemical modification.

[0035] Figure 5 The enrichment rate of magnesium sulfate leachate (southern ore) is shown.

[0036] Figure 6 This shows the enrichment rate of the enriched bioleach (magnet).

[0037] Figure 7 The changes in adsorption capacity of the strain after 10 cycles of use are shown.

[0038] Figure 8 The adsorption effect of eight circulating bacterial cell immobilization columns is shown.

[0039] Figure 9 This shows the preliminary separation results of La3+ / Sm3+ using the cell immobilization column. Detailed Implementation

[0040] The present application is further illustrated below with reference to embodiments. It should be understood that the embodiments are only used to further illustrate and explain the present application and are not intended to limit the present application.

[0041] Unless otherwise defined, technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. While similar or identical methods and materials may be applied in experimental or practical applications, materials and methods are described herein. In case of conflict, the definitions included herein shall prevail. Furthermore, materials, methods, and examples are for illustrative purposes only and are not intended to be limiting. The present application is further described below with reference to specific embodiments, but is not intended to limit the scope of the application.

[0042] Based on the problems existing in the prior art, this application provides a *Pseudomonas oryzihabitans* strain, which is classified and named *Pseudomonas oryzihabitans*. This *Pseudomonas oryzihabitans* strain was deposited on July 7, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35123. The address of CGMCC is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, 100101, China.

[0043] The strains used in this application were obtained from natural strains from various rare earth enrichment regions and were screened multiple times, exhibiting a strong rare earth element enrichment capacity.

[0044] Furthermore, the *Pseudomonas oryzae* cells of this application can still maintain a high adsorption capacity after multiple recycling, demonstrating good recycling performance and stability.

[0045] To further enhance the strain's ability to enrich rare earth elements, this application also provides a method for surface modification of Pseudomonas oryzae, including surface modification of the strain using one or more of sodium trimetaphosphate, sodium polyacrylate, and sodium citrate.

[0046] In some embodiments, sodium tripolyphosphate is used to modify the surface of *Pseudomonas oryzae*. This modification method enhances the microorganism's electrostatic adsorption capacity for rare earth cations by introducing polyphosphate structures on the cell surface to form a high-density negatively charged layer, mimicking the environment of natural phosphoproteins or mucopolysaccharides.

[0047] Specifically, the method may include the following steps:

[0048] S11: Place Pseudomonas oryzae cells in an aqueous solution of sodium tripolyphosphate and react at 30℃-60℃ for 6-48 hours;

[0049] S12: After the reaction is complete, wash the cells to remove unbound phosphate.

[0050] In step S11, the bacterial cells can be in the logarithmic growth phase. The bacterial cells can be washed with PBS buffer before being placed in a buffer containing sodium trimetaphosphate.

[0051] In some embodiments, the concentration of sodium trimetaphosphate in the aqueous solution can be 0.1-5 mM. In some embodiments, the aqueous solution of sodium trimetaphosphate is a physiological saline solution of sodium trimetaphosphate with a pH of 12. In some embodiments, the aqueous solution of sodium trimetaphosphate is a physiological saline solution of sodium trimetaphosphate with a pH of 12, and the concentration of sodium trimetaphosphate can be 0.1-5 mM.

[0052] In some embodiments, sodium polyacrylate is used to modify the surface of *Pseudomonas oryzae*. This modification method enhances the adsorption capacity and selectivity of rare earth ions by introducing high-density –COO- groups to provide a stable anionic interface to the bacteria.

[0053] Specifically, the method may include the following steps:

[0054] Step S21: Place the *Pseudomonas oryzae* cells in an aqueous solution of sodium polyacrylate and react at room temperature for 10-60 minutes;

[0055] Step S22: After the reaction is complete, wash the cells to remove unbound sodium polyacrylate.

[0056] In step S21, the bacterial cells can be cultured to OD200. 600 The bacterial cells have a volume of approximately 0.8 g / mL. They can be washed with PBS buffer before being placed in an aqueous solution of sodium polyacrylate. The concentration of sodium polyacrylate in the aqueous solution can be 0.1%–1% (w / v).

[0057] In some embodiments, sodium citrate is used to modify the surface of *Pseudomonas oryzae*. This modification method uses sodium citrate as a low-molecular-weight organic carboxylic acid modifier, which forms a flexible adsorption layer on the cell surface through its carboxyl and hydroxyl groups, thereby enhancing the adsorption affinity of microorganisms for rare earth ions. It is particularly suitable for use in conjunction with light rare earth adsorption and weak complexation enrichment processes.

[0058] Specifically, the method may include the following steps:

[0059] Step S31: Place the *Pseudomonas oryzae* cells in sodium citrate buffer and react at 30℃-40℃ for 10-60 minutes;

[0060] Step S32: After the reaction is complete, wash the cells to remove unbound sodium citrate.

[0061] In step S31, the bacterial cells can be in the logarithmic growth phase. Before placing the bacterial cells in sodium citrate buffer, they can be washed with PBS buffer. The sodium citrate buffer can be 1-20 mM sodium citrate buffer with a pH of 6.0.

[0062] This application also provides a surface-modified *Pseudomonas oryzae*, which is obtained by any of the methods described above.

[0063] This application also provides the use of the above-mentioned Pseudomonas oryzae or surface-modified Pseudomonas oryzae in the enrichment of rare earth elements.

[0064] The rare earth elements mentioned can cover various rare earth elements known in the art, such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, etc.

[0065] By enriching rare earth elements, the *Pseudomonas oryzae* or surface-modified *Pseudomonas oryzae* of this application can be used for one or more of the following applications:

[0066] Biological purification and element recovery of rare earth smelting tailwater, selective concentration of rare earth permanent magnet recovery liquid, sustainable mine restoration and reuse of residual resources, and construction of bio-adsorption modules to replace traditional extractants.

[0067] This application also provides a method for enriching rare earth elements, which includes contacting the above-mentioned Pseudomonas oryzae or surface-modified Pseudomonas oryzae with a liquid containing rare earth elements.

[0068] The feed solution containing rare earth elements can be of various types, such as magnesium sulfate leaching solution from rare earth ore, biological leaching solution from rare earth ore, leaching solution from magnetic material waste, and tailings from rare earth smelting.

[0069] The rare earth elements mentioned can cover various rare earth elements known in the art, such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, etc.

[0070] In some implementations, the enrichment method includes the following steps:

[0071] S1: Culture the above-mentioned Pseudomonas oryzae or surface-modified Pseudomonas oryzae to collect bacterial cells;

[0072] S2: Contact the bacterial cells with a liquid containing rare earth elements.

[0073] The bacterial cells in step S1 can be cultured to the end-log phase (OD). 600The bacterial cells are approximately 1.0%. Specifically, the bacterial cells can be brought into contact with a liquid containing rare earth elements under dynamic or static conditions for a period of time, such as 10 minutes to 2 hours.

[0074] Example

[0075] This application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., weight percentage. Reagents or instruments used, unless otherwise specified, are all commercially available conventional reagent products.

[0076] Example 1: Strain source, screening and identification

[0077] Sample collection and preprocessing

[0078] Sampling environment and type:

[0079] Typical environmental samples were collected from rare earth enrichment areas, including: weathered soil on the surface of rare earth mines (collection depth 0–10m); surface cover of tailings dumping areas; sedimentary sludge and wastewater in wastewater sedimentation ponds of rare earth smelters; groundwater samples from weathered zones; and magnetic waste.

[0080] Collect no fewer than 20 samples of each type, store them at low temperature immediately, and transport them back to the laboratory.

[0081] Pre-enrichment culture:

[0082] Liquid enrichment culture was performed using LB medium or UP water, and incubated at 30°C on a shaker (220 rpm) for 20 min.

[0083] Initial screening and functional screening

[0084] Rare earth ion growth tolerance screening:

[0085] Dilute the enrichment solution and plate it onto a solid culture medium (such as Y-type medium) containing different concentrations (50–500 μM) of rare earth ions. 3+ 、Nd 3+ La 3+ );

[0086] Select strains with significant growth ability and stable colony morphology.

[0087] Screening for rare earth binding / adsorption capacity:

[0088] Single colony acquisition: The pre-enriched mixed culture medium was placed in a container containing rare earth ions (e.g., 100 μM Nd). 3+ Or La 3+ Dilute and spread on solid agar medium and incubate at 30°C for 24–48 h;

[0089] Single colony selection: Select single colonies with distinct morphology and regular edges. Repeat streaking to obtain single colonies, and then perform 16S rRNA sequencing. Inoculate the obtained single colonies into 96-well deep-layer plates, with 200 μL of LB liquid medium per well, and incubate at 38°C and 220 rpm until the logarithmic growth phase (OD50). 600 Approximately 0.8–1.0);

[0090] Washing and resuspension: After the culture was terminated, the cells were washed twice with MES buffer (pH 6.0) and resuspended in a test solution containing rare earth ions (100 μM) for 30–60 minutes.

[0091] Preparation for colorimetric reaction: Centrifuge to remove cells, take 50 μL of supernatant and react with an equal volume of As-III indicator; let the reaction stand at room temperature in the dark for 10 minutes; use an ELISA reader to read the absorbance at a wavelength of 660 nm, which indicates the concentration of the remaining unadsorbed rare earth ions in the solution.

[0092] Normalization of bacterial concentration: Parallel blank control wells were set up, and bacterial culture samples were taken before the reaction and their absorbance (OD600) at 600 nm was measured; this value was used as an indicator for estimating bacterial concentration and correcting the comparison error of adsorption amount.

[0093] Adsorption capacity estimation: It is assumed that the absorbance at 660 nm in the As-III colorimetric system is linearly related to the concentration of unbound rare earth elements. The rare earth removal capacity per unit cell of each strain is calculated using a standard curve.

[0094] Data processing and screening of highly adsorbent strains: The A... 660 Plot a scatter plot with OD600; the minimum slope obtained from the fitted data (i.e., the strain that consumes rare earth elements to the maximum extent under the same bacterial load) represents the strongest adsorption capacity (e.g., ...). Figure 1 As shown in the diagram, yellow dots represent strains with strong enrichment capabilities. The strains with the strongest adsorption capacity are selected for the next round of verification.

[0095] Further ICP-OES measurements were performed to obtain specific enrichment values, and the results are as follows: Figure 2 As shown in the figure. Strain 0111, which exhibited significant enrichment capacity, was selected. The 16SRNA sequence of this strain is shown in SEQ ID NO:1.

[0096]

[0097] The strain was deposited on July 7, 2025, at the China General Microbiological Culture Collection Center (CGMCC), Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China, with accession number CGMCC No. 35123.

[0098] Example 2: Surface-Modified Strains

[0099] The strain preserved in Example 1 was selected, and its surface was modified using the following three types of modifiers:

[0100] (1) Surface phosphorylation modification method based on sodium trimetaphosphate: This embodiment provides a cell surface phosphorylation modification method based on sodium trimetaphosphate (P3m) to enhance the electrostatic adsorption capacity of microorganisms for rare earth cations. This method introduces polyphosphate structures on the cell surface to form a high-density negative charge layer, simulating the environment of natural phosphoproteins or mucopolysaccharides.

[0101] The specific procedure is as follows: After collecting the bacterial cells in the logarithmic growth phase, wash them twice with PBS buffer (pH 7.0), then resuspend them in physiological saline containing 1 mM sodium trimetaphosphate, adjust the pH to 12, and react with shaking at 50°C for 6-48 hours. After the reaction is complete, wash three times with PBS to remove unbound phosphate. The modified bacterial cells can be directly used for zeta potential detection and rare earth adsorption performance evaluation. Experiments show that the zeta potential of the cells treated by this method shifts negatively overall, and the isoelectric point decreases from pH 4.2 before modification to approximately pH 3.5, indicating enhanced surface electronegativity. Figure 3 Further in 100 μM La 3+ In the static adsorption experiment in solution, the adsorption capacity of rare earth ions by this strain was 48.6% higher than that of the unmodified group. Figure 4 ).

[0102] (2) Carboxylation modification method based on sodium polyacrylate: This embodiment proposes a surface carboxylation modification strategy based on sodium polyacrylate (PAA-Na). By introducing high-density –COO- groups, a stable anionic interface is given to the bacteria to enhance its adsorption capacity and selectivity for rare earth ions.

[0103] In the experiment, the culture will be grown to OD. 600 Bacterial cells with a molecular weight of approximately 0.8 g were washed twice with PBS, resuspended in 0.1% (w / v) PAA-Na aqueous solution (pH 6.5), and incubated with gentle shaking at room temperature for 30 minutes to achieve surface adsorption modification. They were then washed three times with PBS buffer to remove unbound polymers, and the modified cells were used for subsequent experiments.

[0104] The modified bacteria exhibited a significant increase in negative charge in the zeta potential-pH test, with the isoelectric point decreasing from the original pH 4.2 to pH 3.8. Particularly within the pH range of 5–7, the zeta potential remained between -25 and -35 mV, demonstrating a highly stable negatively charged environment. Figure 3 ICP-OES analysis showed that this modification significantly improved the resistance to heavy rare earth elements (such as Gd). 3+ 、Tb3+ The adsorption performance of ) was improved, and the maximum adsorption capacity Qmax was increased by approximately 42.3%. Figure 4 ).

[0105] (3) Low molecular weight carboxylic acid modification method based on sodium citrate: In this embodiment, sodium citrate is used as a low molecular weight organic carboxylic acid modifier. Through its carboxyl and hydroxyl structures, a flexible adsorption layer is formed on the cell surface, which enhances the adsorption affinity of microorganisms for rare earth ions. It is especially suitable for combining with light rare earth adsorption and weak complexation enrichment processes.

[0106] The experimental procedure was as follows: Bacterial cells cultured to the logarithmic growth phase were collected, washed, and resuspended in 10 mM sodium citrate buffer (pH 6.0). The cells were then incubated at 37°C with gentle shaking for 20 minutes to promote the directional adsorption of small organic acids on the surface. After the reaction, the cells were washed twice with PBS to remove free molecules. Zeta potential testing showed that the zeta potential of the bacteria shifted negatively overall after citric acid modification, and the isoelectric point decreased to around pH 4.0, especially forming a stable weakly negatively charged layer in the pH range of 5–6. Figure 3 In rare earth adsorption experiments, the modified bacteria exhibited good adsorption properties for La. 3+ 、Nd 3+ It exhibits higher adsorption affinity, with an adsorption capacity increase of approximately 33.5%. Figure 4 ).

[0107] BLK represents unmodified bacteria.

[0108] Example 3: Rare Earth Enrichment and Recycling Experiment Based on Free Bacterial Cells

[0109] 1. Cell preparation and pretreatment

[0110] The microbial strain preserved in Example 1 was selected and cultured in LB medium at 30°C and 220 rpm until the end-log phase (OD2). 600 ≈1.0), collect bacterial cells, wash twice with PBS (pH 7.0) buffer, and finally resuspend to the target concentration (e.g., 2 g / L wet weight) for later use.

[0111] 2. Adsorption reaction steps (1) Adsorption solution:

[0112] • Leachate from rare earth ore and magnetic waste (e.g., containing REE 10–80 μM, i.e., total rare earth element content of 10–80 μM, pH 2–4);

[0113] • The sample is used after preliminary neutralization and filtration.

[0114] (2) Adsorption conditions:

[0115] • Temperature: 30℃; Cell concentration: 20g / L; Reaction time: 1-8h; Method: Static mixing (rotary mixer, 50rpm)

[0116] (3) Adsorption performance determination:

[0117] • After the reaction, centrifuge or filter, and take the supernatant to determine the residual concentration of rare earth elements using ICP-OES;

[0118] • Calculate the adsorption capacity per unit dry cell weight (mg REE / g dry cells);

[0119] • Calculate the separation factor when testing different metals (La, Nd, Gd, Yb).

[0120] The results are as follows Figure 5 and Figure 6 As shown.

[0121] in Figure 5 This study focuses on the microbial recovery of raw ore leachate, with sampling taken every hour for 1-8 hours. The vertical axis represents the recovery rate of total rare earth ions.

[0122] Figure 6 This study focuses on the microbial recovery of magnetite leachate. The recovery rate was calculated after 8 hours. The REE in the figure represents the total recovery rate of all rare earth elements.

[0123] 3. Gentle desorption and bacterial cell recycling

[0124] (1) Selection of desorption reagent:

[0125] • 50mM sodium citrate (pH 4.5);

[0126] • Reaction time: 20–30 minutes, with gentle stirring or flow elution.

[0127] (2) Desorption rate calculation:

[0128] • The ratio of REE content in the desorption solution to the total enrichment during the adsorption stage;

[0129] • If the desorption rate is >90% and the bacterial cells are not significantly destroyed, it is considered an effective desorbent.

[0130] (3) Repeated loop process:

[0131] • Adsorption-desorption occurs continuously for 5–10 cycles;

[0132] • The adsorption capacity retention rate is measured after each cycle;

[0133] • Record changes in bacterial cell appearance, aggregation degree, and survival rate;

[0134] • Evaluate the cell recyclability and stability.

[0135] The results of the adsorption change after 10 cycles of use are as follows: Figure 7 As shown in the figure. The results show that the bacterial cells of this application can still maintain a high adsorption capacity after 10 cycles, and have good cycling performance and stability.

[0136] Example 4: Microbial adsorption column constructed by agarose immobilization

[0137] The preparation process of microbial immobilized agarose microspheres is as follows: 1) Preparation of agarose aqueous solution: Dissolve 4% agarose in water, heat and stir thoroughly to form a homogeneous aqueous solution. After slight cooling, add 10% (wet weight) of bacterial suspension (the strain preserved in Example 1 was cultured in a shake flask of LB medium at 30°C and 220 rpm for 8-10 hours until the bacterial suspension reached the logarithmic growth phase (OD600≈0.6-0.8). Subsequently, the bacterial cells were collected by centrifugation at 8000 rpm for 10 min, and the bacterial cells were resuspended in UP water and washed three times to remove residual components of the culture medium and interference from inorganic salts to obtain the bacterial suspension). Continue stirring to uniformly disperse the bacterial cells in the agarose solution. 2) Emulsification to form microspheres: Dissolve 1% (w / w) of Span80 in liquid paraffin as the organic phase and heat at 80°C. Subsequently, the aqueous solution and organic phase were mixed at a ratio of 10% (v / v), and emulsified continuously for about 30 minutes to form a preliminary agarose microsphere structure. 3) Structure stabilization and washing: After emulsification, the temperature of the mixture was gradually reduced at a rate of 1-2℃ / min until room temperature was reached to ensure complete stabilization of the agarose microsphere structure. Then, deionized water was added and the mixture was allowed to stand for at least 2 hours to remove the organic phase and wash the microspheres, obtaining uncrosslinked agarose microspheres. 4) Crosslinking stabilization treatment: 100 mL of 1M sodium hydroxide solution, 2 mL of epichlorohydrin, and 2 g of sodium borohydride were added to every 100 g (wet weight) of agarose microspheres. After stirring at room temperature for 1 hour, the temperature was raised to 60℃ and stirring continued for 1 hour. This process achieved crosslinking of the microspheres, enhancing their structural stability and adsorption performance. Finally, the microspheres were thoroughly washed with cold water to remove residual chemical reagents and stored for later use.

[0138] Stability Test: Microbial-agarose microspheres were resuspended in ultrapure water and then packed into a chromatography column by gravity. Before adsorption experiments, the column was washed with 20.0 g / L citrate buffer (pH 5) and equilibrated with MES buffer (25 mM MES, pH adjusted to 6 using 12 M hydrochloric acid and concentrated sodium hydroxide). After equilibration, a rare earth solution (LaCl3, 1 mM, dissolved in pH 6 MES buffer) was added to the column at a flow rate of 1.00 mL / min. The column was then desorbed and eluted with 20 g / L citrate solution, and the flowthrough was collected. Ten column volumes of the column were then washed with ultrapure water, and the process was repeated. The rare earth element content in the flowthrough and eluent was determined by ICP-OES to assess the reusability of the microbial-agarose microsphere packed column.

[0139] Separation Experiment: Microbial-agarose microspheres were resuspended in ultrapure water and then packed into a chromatography column by gravity. Before adsorption experiments, the column was washed with 20.0 g / L citrate buffer (pH 5) and equilibrated with MES buffer (25 mM MES, pH adjusted to 6 using 12 M hydrochloric acid and concentrated sodium hydroxide). After equilibration, rare earth solutions (1 mM each of LaCl3 and SmCl3 dissolved in pH 6 MES buffer) were added to the column at a flow rate of 1.00 mL / min. Gradient elution was then performed using 20-400 mg / L citrate buffer, and the flowthrough was collected. The rare earth element content in the flowthrough and eluent was determined by ICP-OES to evaluate the separation performance of the microbial-agarose microsphere packed column.

[0140] Experimental results show that the microbial immobilized agarose microsphere column prepared by this method possesses good structural stability and excellent adsorption capacity. The reusability of the immobilized column was fully verified. After eight cycles, its adsorption and separation effects remained good, demonstrating extremely high stability and economy. Figure 8 ).

[0141] In addition, the immobilized separation column showed a certain separation effect on rare earth ions La3+ and Sm3+. Figure 9 From the elution curve, it can be observed that under citric acid elution conditions, La 3+ and Sm 3+ The elution behaviors of the two ions showed significant differences. During the experiment, as the elution volume increased, the two ions exhibited peak values ​​at different time points, with Sm... 3+ The elution peak was significantly earlier than that of La. 3+ And in the early stages of elution (after the dotted line), Sm 3+A prominent elution peak was observed, while La 3+ The amount of elution is relatively low at this point. As elution continues, La... 3+ The elution volume gradually increases, reaches a peak within the subsequent elution volume range, and then slowly decreases.

Claims

1. A species of Pseudomonas oryzihabitans, which is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 35123.

2. A method for surface modification of the *Pseudomonas oryzae* strain according to claim 1, comprising using one or more of sodium trimetaphosphate, sodium polyacrylate, and sodium citrate to modify the surface of the strain.

3. The method according to claim 2, wherein the method comprises the following steps: The cells of *Pseudomonas oryzae* were placed in an aqueous solution of sodium tripolyphosphate and reacted at 30℃-60℃ for 6-48 hours. After the reaction is complete, the bacterial cells are washed to remove unbound phosphates.

4. The method according to claim 2, wherein the method comprises the following steps: Place the cells of Pseudomonas oryzae in an aqueous solution of sodium polyacrylate and react at room temperature for 10-60 minutes. After the reaction is complete, the bacterial cells are washed to remove unbound sodium polyacrylate.

5. The method according to claim 2, wherein the method comprises the following steps: Place the cells of Pseudomonas oryzae in sodium citrate buffer and react at 30℃-40℃ for 10-60 minutes; After the reaction is complete, the bacterial cells are washed to remove unbound sodium citrate.

6. A surface-modified *Pseudomonas oryzae*, obtained by the method of any one of claims 2-5.

7. The use of *Pseudomonas oryzae* as described in claim 1 or the surface-modified *Pseudomonas oryzae* as described in claim 6 in the enrichment of rare earth elements.

8. The use according to claim 7, wherein the rare earth element is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, and Y.

9. The use according to claim 7 or 8, wherein the use includes one or more of the following: Biological purification and element recovery of rare earth smelting tailwater, selective concentration of rare earth permanent magnet recovery liquid, sustainable mine restoration and reuse of residual resources, and construction of bio-adsorption modules to replace traditional extractants.

10. A method for enriching rare earth elements, comprising contacting the *Pseudomonas oryzae* of claim 1 or the surface-modified *Pseudomonas oryzae* of claim 6 with a liquid containing rare earth elements. Preferably, the rare earth element is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, and Y; More preferably, the liquid containing rare earth elements comprises one or more of the following: Magnesium sulfate leaching solution from rare earth ore, biological leaching solution from rare earth ore, leaching solution from magnetic material waste, and tailings from rare earth smelting.

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