New methylobacterium extorquens strain capable of efficiently recovering rare earth ions from leachate and mineralizing rare earth phosphate in cells

Abstract

The invention relates to the technical field of environment-friendly biological rare earth recovery, in particular to methylobacterium extorquens C2 and a method for leaching rare earth elements in waste by using the methylobacterium extorquens C2. Specifically, the strain provided by the invention utilizes microorganisms and metabolites thereof to leach rare earth elements in the waste and mineralize nano or micron rare earth phosphate in cells, so that the problems of large chemical reagent dosage, high production cost, serious environmental pollution and the like in the chemical leaching process of the rare earth waste are solved. The strain provided by the invention is low in culture cost, high in growth speed and simple in leaching condition, has the capability of leaching rare earth ions in various wastes, and has a relatively good application prospect in the aspects of rare earth waste microorganism recovery and reutilization and the like.

Description

Technical Field

[0001] The invention relates to the technical field of environmentally friendly biological rare earth recovery, and in particular to a new Methylobacterium extorquens strain capable of efficiently recovering rare earth ions from waste leaching solution and mineralizing nano- or micron-sized rare earth phosphates in cells and a leaching method thereof. Background Art

[0002] Rare earth elements include fifteen lanthanide elements and two metallic elements, scandium and yttrium. As an important strategic resource, they are widely used in cutting-edge research and high-tech industries and are known as "industrial gold". However, due to their uneven distribution and limited reserves, with the widespread application of rare earth elements in permanent magnetic materials, industrial catalysis and other fields, it has become necessary to extract rare earths from such secondary rare earth resources.

[0003] Traditional methods for recovering and enriching rare earth elements from urban minerals mainly use physical and chemical methods with strong acids and organic solvents. However, these methods are complex, energy-intensive, and cause significant environmental pollution. Therefore, there is an urgent need to develop a new clean and efficient rare earth enrichment technology to ensure the enrichment rate and purity of rare earth elements while minimizing environmental pollution.

[0004] Biospecific intracellular mineralization enrichment using methylotrophic microorganisms is an environmentally friendly alternative. Methanol dehydrogenase (MDH) is considered to be a key and essential enzyme for methanol metabolism in Methylorubrum extorquens strains. Recent studies have shown that M. extorquens contains XoxF-type MDH with lanthanides as cofactors, as well as a series of proteins and organic molecules to ensure the correct binding and storage of lanthanides. This system can be utilized and modified through rational design to recover and separate rare earth ions based on the M. extorquens system. However, commercial methylotrophic microorganisms such as M. extorquens AM1, a model strain, have low efficiency and long time in recovering rare earth elements from waste FCC catalysts and NdFeB magnet leachates. This is mainly due to the poor tolerance of such microorganisms to high concentrations of rare earth ions. Therefore, screening and cultivating powerful microorganisms from methylotrophic microbial communities associated with rare earth mines and rare earth wastes is crucial to improve the efficiency of rare earth element bioenrichment. However, there are few reports on bioleaching based on such microorganisms. Therefore, providing a new Methylobacterium extorquens strain that can efficiently recover rare earth ions from waste leachate and mineralize nano- or micron-sized rare earth phosphates intracellularly can provide new options and pathways for biometallurgy, which is of great practical significance. Summary of the invention

[0005] In view of this, the present invention provides a new strain of Methylobacterium extorquens that can efficiently recover rare earth ions from waste leachate and mineralize nano- or micron-sized rare earth phosphates intracellularly, thereby solving the problems of large amount of chemical reagents, high production cost, and serious environmental pollution in the chemical recovery process of rare earth waste.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides Methylobacterium extorquens C2, whose deposit number is CGMCC No.30396.

[0008] In a second aspect, the present invention also provides a method for culturing the Methylobacterium extorquens C2, wherein the Methylobacterium extorquens C2 is picked and cultured for 2 to 4 days at 30° C. and 200 rpm by adding a tryptic soy broth (TSB) liquid culture medium.

[0009] In a third aspect, the present invention also provides one or more of the inactivated bacteria, exosomes or metabolites of Methylobacterium extorquens C2.

[0010] In a fourth aspect, the present invention also provides a method for preparing the microbial culture solution of the Methylobacterium extorquens C2, wherein the Methylobacterium extorquens C2 is picked up, and the culture is carried out for 2 to 4 days at 30° C. and 200 rpm by adding a tryptic soy broth (TSB) liquid culture medium to obtain a microbial culture solution.

[0011] In a fifth aspect, the present invention also provides a microbial culture solution obtained by the preparation method.

[0012] In a sixth aspect, the present invention further provides the use of any of the following in leaching rare earth elements in waste materials and / or in intracellular mineralization of nano- or micron-sized rare earth phosphates;

[0013] (I), the Methylobacterium extorquens C2;

[0014] (II), one or more of the inactivated bacteria, exosomes or metabolites;

[0015] (III) the microbial culture solution.

[0016] In some specific embodiments of the present invention, the waste material includes one or more of waste FCC catalyst, waste NdFeB sludge or waste NdFeB powder.

[0017] In some specific embodiments of the present invention, the main framework of the spent FCC catalyst is aluminosilicate, containing rare earth elements and / or transition elements, the content of the rare earth elements and / or transition elements is 0.01% to 10%; the rare earth elements include but are not limited to lanthanum and / or cerium; the transition elements include but are not limited to nickel and / or vanadium;

[0018] The main component of the waste NdFeB sludge is NdFeB (Nd2Fe 14 B) magnet, containing 1% to 30% lubricating oil;

[0019] The main component of the waste NdFeB powder is Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, including cutting, compression molding or sintering processes.

[0020] In a seventh aspect, the present invention further provides a product, comprising any of the following:

[0021] (I), the Methylobacterium extorquens C2;

[0022] (II), one or more of the inactivated bacteria, exosomes or metabolites;

[0023] (III), the microbial culture solution;

[0024] The products include microecological products, probiotic products, synbiotic products and / or postbiotic products.

[0025] In an eighth aspect, the present invention also provides a method for leaching rare earth elements from waste materials and / or intracellularly mineralizing nano- or micron-sized rare earth phosphates, comprising mixing any of the following with the waste materials and incubating;

[0026] (I), the Methylobacterium extorquens C2;

[0027] (II), one or more of the inactivated bacteria, exosomes or metabolites;

[0028] (III), the microbial culture solution;

[0029] (IV) the product.

[0030] In some specific embodiments of the present invention, the waste material comprises one or more of waste FCC catalyst, waste NdFeB sludge or waste NdFeB powder;

[0031] Preferably, the main framework of the spent FCC catalyst is aluminosilicate, containing rare earth elements and / or transition elements, the content of the rare earth elements and / or transition elements is 0.01% to 10%; the rare earth elements include but are not limited to lanthanum and / or cerium; the transition elements include but are not limited to nickel and / or vanadium;

[0032] The main component of the waste NdFeB sludge is NdFeB (Nd2Fe 14 B) magnet, containing 1% to 30% lubricating oil;

[0033] The main component of the waste NdFeB powder is Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, including cutting, compression molding or sintering processes;

[0034] Preferably, the liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste FCC catalyst is 1:(1-100);

[0035] The liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste NdFeB oil sludge is 1:(1-100);

[0036] The liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste NdFeB powder is 1:(1-100);

[0037] Preferably, the incubation conditions are to culture in a tryptic soy broth (TSB) liquid culture medium at 30°C and 200rpm for 2 to 4 days, collect the bacteria by centrifugation at 8000rpm for 5min, and obtain rare earth-enriched bacteria after washing.

[0038] The present invention provides a new strain of Methylobacterium extorquens that can efficiently recover rare earth ions from waste leachate and mineralize nano- or micron-sized rare earth phosphates in the cell, solving the problems of large amount of chemical reagents, high production cost, and serious environmental pollution in the chemical recovery process of rare earth waste. The strain provided by the present invention has low cultivation cost, fast growth rate, simple enrichment conditions, and has the ability to selectively enrich rare earth ions in a variety of waste leachates, and has good application prospects in the recovery and reuse of rare earth waste microorganisms.

[0039] Biological Deposit Description

[0040] Strain: C2; the deposit date is April 22, 2024, the deposit number is CGMCC No.30397, the classification name is Methylobacterium extorquens, the name of the depository is: General Microbiology Center of China Microbiological Culture Collection Administration, and the address of the depository is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0042] Figure 1 The ICP-OES results of the enrichment of rare earth elements in the waste FCC catalyst leaching solution by the C2 strain are shown. The enrichment efficiency of La is 99.02%, and the enrichment efficiency of Ce is 96.82%;

[0043] Figure 2 The ICP results of the C2 strain enriching rare earth elements in the waste NdFeB oil sludge leaching solution are shown. The enrichment efficiency of Nd is 98.60%, the enrichment efficiency of Gd is 98.55%, the enrichment efficiency of Tb is 98.94%, and the enrichment efficiency of Dy is 98.95%;

[0044] Figure 3 The ICP results of the C2 strain enriching rare earth elements in the waste NdFeB powder leaching solution are shown. The enrichment efficiency of Nd is 99.56%, the enrichment efficiency of Gd is 98.45%, the enrichment efficiency of Tb is 98.37%, and the enrichment efficiency of Dy is 98.08%;

[0045] Figure 4 HRTEM images showing the mineralization of rare earth elements in the spent FCC catalyst leachate by strain C2;

[0046] Figure 5 HRTEM image showing the mineralization of rare earth elements in the leaching solution of waste NdFeB sludge by C2 strain. DETAILED DESCRIPTION

[0047] The present invention discloses a new strain of Methylobacterium extorquens, which can efficiently recover rare earth ions from waste leachate and mineralize nano- or micron-sized rare earth phosphates in cells, and a leaching method thereof. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the desired effect. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0048] The present invention adopts the following technical solution:

[0049] (1) Screening of methylotrophic strains: The strains were screened using MM medium solid plates containing methanol (0.1-5% v / v) and rare earth (1 u M-50 mM). Methylorubrum extorquens C2 (CGMCC No. 30397), which can grow on MM medium solid plates containing methanol and rare earth, was selected for subsequent research.

[0050] (2) Cultivation of microorganisms: Methylobacterium extorquens C2 was cultured in a tryptic soy broth (TSB) liquid culture medium at 30° C. and 200 rpm for 2-4 days to obtain a microbial culture solution.

[0051] (3) Microbial enrichment of rare earth elements in the leaching solution of waste FCC catalyst (the main framework is aluminosilicate, containing rare earth elements such as lanthanum and cerium and transition elements such as nickel and vanadium, with a content of 0.01%-10%) (the source is the solution containing rare earth elements to be recovered during the microbial leaching of waste FCC catalyst, the same below): the culture solution of Methylobacterium extorquens C2 obtained in (2) is co-cultured with the waste FCC catalyst leaching solution at a ratio of 1:1-1:100 through a tryptic soy broth (TSB) liquid culture medium, and cultured at 30°C and 200rpm for 2-4 days. The cells are collected by centrifugation at 8000rpm for 5min, and the rare earth-enriched cells are obtained after washing with water 3 times.

[0052] (4) Microbial enrichment of waste NdFeB sludge (main component is NdFeB (Nd2Fe 14B) magnet, containing 1%-30% lubricating oil) leaching solution (derived from the solution containing rare earth elements to be recovered during the process of microbial leaching of waste NdFeB oil sludge, the same below): the culture solution of Methylobacterium extorquens C2 obtained in (2) is co-cultured with the waste NdFeB oil sludge leaching solution at a ratio of 1:1-1:100 through a tryptic soy broth (TSB) liquid culture medium, and cultured at 30°C and 200rpm for 2-4 days. The cells are collected by centrifugation at 8000rpm for 5min, and the rare earth-enriched cells are obtained after washing with water 3 times.

[0053] (5) Microbial enrichment of waste NdFeB powder (main component is NdFeB (Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, such as cutting, compression molding, sintering process, etc.) leaching solution (source is the solution containing rare earth elements to be recovered during the process of microbial leaching of waste NdFeB powder, the same below): the culture solution of Methylobacterium extorquens C2 obtained in (2) is co-cultured with the waste NdFeB powder leaching solution at a ratio of 1:1-1:100 through a tryptic soy broth (TSB) liquid culture medium, and cultured at 30°C and 200rpm for 2-4 days. The cells are collected by centrifugation at 8000rpm for 5min, and the rare earth-enriched cells are obtained after washing with water 3 times.

[0054] (6) The enrichment and purification ability of C2 was identified by detecting the rare earth element content and type of the enriched bacteria in steps (3), (4), and (5) using ICP-OES and ICP-MS.

[0055] (7) Using TEM and HRTEM to examine the intracellular mineralization of nano- or micron-sized rare earth phosphates in the enriched bacteria in steps (3), (4), and (5), and determining the mineralization type and effect by comparing its crystal lattice with a standard card.

[0056] The strain provided by the present invention has low culture cost, fast growth rate, simple enrichment conditions, and the ability to selectively enrich rare earth ions in various waste leachates. It has good application prospects in the recovery and reuse of rare earth waste microorganisms.

[0057] The invention provides a new Methylobacterium extorquens strain capable of efficiently recovering rare earth ions from waste leaching solution and mineralizing nanometer or micrometer rare earth phosphate in cells and raw materials and reagents used in the leaching method thereof, all of which can be purchased from the market.

[0058] The present invention will be further described below in conjunction with embodiments:

[0059] Example 1 Screening of methylotrophic strains

[0060] A purified single colony of Methylorubrum extorquens C2 was picked from a MM solid culture medium containing 0.5% (v / v) methanol and 100uM rare earth elements (the same below) and added to 4mL of MM liquid culture medium containing 0.5% (v / v) methanol and 100uM rare earth elements, and cultured overnight at 30°C and 200rpm in a constant temperature shaking shaker. 2μL of the bacterial liquid was added dropwise to a MM culture medium solid culture plate containing 0.5% (v / v) methanol and 100uM rare earth elements. After five days of culture, the results were observed and recorded. The presence of obvious colonies was recorded as positive, indicating that the strain had the ability to grow in methyl nutrition. The strain was biologically preserved with a preservation number of CGMCC No.30397 and was classified and named Methylobacterium extorquens.

[0061] Example 2C2 Microbial Co-cultivation to Enrich Rare Earth Elements in Spent FCC Catalyst Leachate

[0062] From the MM solid medium containing 0.5% (v / v) methanol and 100uM rare earth elements, a single colony of purified C2 (deposited as CGMCC No.30397) was picked into 4mL TSB liquid medium and cultured overnight in a constant temperature shaking incubator at 30°C and 200rpm as a seed liquid. A 1% volume ratio of the seed liquid was inoculated into a TSB liquid medium containing a 1:1-1:100 ratio of the waste FCC catalyst (the main framework is aluminosilicate, containing rare earth elements such as lanthanum and cerium, and transition elements such as nickel and vanadium, with a content of 0.01%-10%) leachate. Cultured in a constant temperature shaking incubator at 30°C and 200rpm for 2-4 days. The cells were collected by centrifugation at 8000rpm for 5min, and rare earth-enriched cells were obtained after washing 3 times with water.

[0063] Example 3 C2 Microbial Co-cultivation to Enrich Rare Earth Elements in Waste NdFeB Sludge Leachate

[0064] From the MM solid medium containing 0.5% (v / v) methanol and 100uM rare earth elements, a single colony of purified C2 (deposited as CGMCC No.30397) was picked and placed in 4mL TSB liquid medium, and cultured overnight in a constant temperature shaking incubator at 30°C and 200rpm as seed liquid. A 1% volume ratio of seed liquid was inoculated into TSB liquid medium, which contained waste NdFeB oil sludge (the main component of which is NdFeB (Nd2Fe 14 B) magnet, containing 1%-30% lubricating oil) extract. Cultivate in a constant temperature shaking shaker at 30°C and 200rpm for 2-4 days. Collect the bacteria by centrifugation at 8000rpm for 5min, and wash with water 3 times to obtain rare earth-enriched bacteria.

[0065] Example 4C2 Microbial co-cultivation to enrich rare earth elements in waste NdFeB powder leachate

[0066] From the MM solid medium containing 0.5% (v / v) methanol and 100uM rare earth elements, a single colony of purified C2 (deposited as CGMCC No.30397) was picked and placed in 4mL TSB liquid medium, and cultured overnight in a constant temperature shaking incubator at 30°C and 200rpm as seed liquid. A 1% volume ratio of the seed liquid was inoculated into TSB liquid medium, which contained waste NdFeB powder (the main component of which is Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, such as cutting, pressing, sintering process, etc.) leachate leachate. Cultivate in a constant temperature shaking shaker at 30°C and 200rpm for 2-4 days. Collect the cells by centrifugation at 8000rpm for 5min, and obtain rare earth-enriched cells after washing 3 times.

[0067] Example 5 Detection of C2 enrichment ability by ICP-OES and ICP-MS

[0068] The enriched cells in Examples 2, 3, and 4 were digested using a nitric acid-perchloric acid (10:1) mixed acid system on a 210°C hot plate. After the solution became clear and transparent, it was diluted to a constant volume until the target element content was 1 ppb-10 ppm. ICP-OES and ICP-MS were used to conduct qualitative and quantitative analysis of the rare earth elements and other metal elements in the digestion solution. The experimental results are shown in Figure 1 , 2, 3.

[0069] Table 1 ICP-OES results of enrichment of rare earth elements in spent FCC catalyst leachate by strain C2

[0070]

[0071] Table 2 ICP-OES results of enrichment of rare earth elements in waste NdFeB oil sludge leaching solution by strain C2

[0072]

[0073] Table 3 ICP-OES results of enrichment of rare earth elements in waste NdFeB powder leaching solution by strain C2

[0074]

[0075] Example 6 Detection of C2-enriched phosphate crystals by HRTEM

[0076] The intracellular mineralization of nano- or micron-sized rare earth phosphates in the enriched bacteria in Examples 3, 4, and 5 was detected by HRTEM, the elemental composition of the mineralized material was determined by EDS, the mineralization type and effect were determined by comparing the lattice with the standard card, and the composition and purity were quantitatively analyzed. The experimental results are shown in Figure 4 , 5. Microorganisms mineralize and form rare earth phosphate crystals in the cells, with interplanar spacings of 0.2247 and 0.3324 nm, corresponding to the interplanar spacings of lanthanum phosphate (031) and neodymium phosphate (002), respectively. EDS elemental analysis determined the composition of the rare earth phosphate crystals.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Methylobacterium extorquens C2, characterized in that Its deposit number is CGMCC No.30396.

2. The method for culturing Methylobacterium extorquens C2 according to claim 1, characterized in that: The Methylobacterium extorquens C2 was picked up and cultured for 2 to 4 days at 30° C. and 200 rpm by adding a tryptic soy broth (TSB) liquid culture medium.

3. One or more of the inactivated bacteria, exosomes or metabolites of Methylobacterium extorquens C2 as claimed in claim 1.

4. The method for preparing a microbial culture solution of Methylobacterium extorquens C2 according to claim 1, characterized in that: The Methylobacterium extorquens C2 was picked up, and cultured at 30° C. and 200 rpm for 2 to 4 days by adding a tryptic soy broth (TSB) liquid culture medium to obtain a microbial culture solution.

5. The microbial culture solution obtained by the preparation method as claimed in claim 4.

6. Use of any of the following in leaching rare earth elements from waste materials and / or in intracellular mineralization of nano- or micro-sized rare earth phosphates; (I), Methylobacterium extorquens C2 as described in claim 1; (II) one or more of the inactivated bacteria, exosomes or metabolites according to claim 3; (III) The microbial culture solution according to claim 5.

7. The use according to claim 6, characterized in that The waste material includes one or more of waste FCC catalyst, waste NdFeB sludge or waste NdFeB powder.

8. The use according to claim 7, characterized in that The main framework of the spent FCC catalyst is aluminosilicate, containing rare earth elements and / or transition elements, the content of the rare earth elements and / or transition elements is 0.01% to 10%; the rare earth elements include but are not limited to lanthanum and / or cerium; the transition elements include but are not limited to nickel and / or vanadium; The main component of the waste NdFeB sludge is NdFeB (Nd2Fe 14 B) magnet, containing 1% to 30% lubricating oil; The main component of the waste NdFeB powder is Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, including cutting, compression molding or sintering processes.

9. A product, characterized in that Includes any of the following: (I), Methylobacterium extorquens C2 as described in claim 1; (II) one or more of the inactivated bacteria, exosomes or metabolites according to claim 3; (III) The microbial culture solution according to claim 5; The products include microecological products, probiotic products, synbiotic products and / or postbiotic products.

10. A method for leaching rare earth elements from waste materials and / or intracellular mineralization of nano- or micro-sized rare earth phosphates, characterized in that: Take any of the following and mix with waste material and incubate; (I), Methylobacterium extorquens C2 as described in claim 1; (II) one or more of the inactivated bacteria, exosomes or metabolites according to claim 3; (III) The microbial culture solution according to claim 5; (IV) The product as claimed in claim 9; Preferably, the waste material comprises one or more of waste FCC catalyst, waste NdFeB sludge or waste NdFeB powder; Preferably, the main framework of the spent FCC catalyst is aluminosilicate, containing rare earth elements and / or transition elements, the content of the rare earth elements and / or transition elements is 0.01% to 10%; the rare earth elements include but are not limited to lanthanum and / or cerium; the transition elements include but are not limited to nickel and / or vanadium; The main component of the waste NdFeB sludge is NdFeB (Nd2Fe 14 B) magnet, containing 1% to 30% lubricating oil; The main component of the waste NdFeB powder is Nd2Fe 14 B), produced in various links of industrial production of NdFeB magnets, including cutting, compression molding or sintering processes; Preferably, the liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste FCC catalyst is 1:(1-100); The liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste NdFeB oil sludge is 1:(1-100); The liquid-to-solid ratio of the Methylobacterium extorquens C2 to the waste NdFeB powder is 1:(1-100); Preferably, the incubation conditions are to culture in a tryptic soy broth (TSB) liquid culture medium at 30°C and 200rpm for 2 to 4 days, collect the bacteria by centrifugation at 8000rpm for 5min, and obtain rare earth-enriched bacteria after washing.

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