JP2015227482A - Method for separating rare earth element using microorganism and novel microorganism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of efficiently separating rare earth elements from a rare earth magnet, for example magnetic powder, a waste and a defective scrap as well as a recovery product while suppressing used amount of alkali and a microorganism selectively accumulating Fe.SOLUTION: Iron (Fe) in a liquid is reduced by accumulating Fe selectively to a microorganism in the liquid where Fe and rare earth elements co-exist.

Description

  The present invention relates to a method for separating rare earth elements using microorganisms. The present invention also relates to a novel microorganism that selectively accumulates Fe.

  Rare earth elements such as neodymium (Nd) and dysprosium (Dy) are used in a wide range of industrial products including magnetic materials such as magnets. For example, as a permanent magnet mounted on a motor or the like, conventionally, inexpensive ferrite magnets have been used frequently. However, with the miniaturization and high performance of motors, the use of higher performance rare earth magnets has increased year by year. ing. As typical rare earth magnets, samarium cobalt magnets and neodymium magnets are mainly known.

  Among these, neodymium magnets have the advantage that they have a very strong magnetic force, can be manufactured at low cost, and can be reduced in size and thickness. For this reason, neodymium magnets are used in various products such as electronic devices such as hard disks and air conditioners, and are also used in various motors and sensors used in hybrid vehicles and the like. Neodymium magnets are mainly composed of neodymium, iron (Fe), and boron (B), and dysprosium is used as an additive for improving the magnetic force at high temperatures.

  However, since rare earth elements, which are raw materials for rare earth magnets, are limited in their country of origin, it is expected that demand will exceed supply in the near future, and there are growing concerns about resource issues. For this reason, there is a strong need to recover and recycle target rare earth elements from magnet powder, scraps and defective scrap generated during the production of rare earth magnets, and recovered products.

  On the other hand, in addition to neodymium and dysprosium, rare earth elements used for rare earth magnets include cerium (Ce), praseodymium (Pr), samarium (Sm), and terbium (Tb). For the separation of these rare earth elements, an ion exchange resin method (solid-liquid extraction method) and a solvent extraction method (liquid-liquid extraction method) are known. As a solvent extraction method (liquid-liquid extraction method), there is a method in which a fired magnet is dissolved with a strong acid and the pH is controlled with a strong alkali to separate Fe (Patent Document 1). In industrial refining and separation of rare earth elements, a solvent extraction method is mainly used because large-scale processing can be efficiently performed by a continuous process.

Japanese Patent No. 5146658

  However, the method using a large amount of alkali is not a desirable method from the viewpoint of environmental protection in recent years, and further, care must be taken in handling the alkali from the viewpoint of safety. For example, ammonia is highly flammable and flammable and is toxic if inhaled. In addition, alkaline solutions are highly toxic to aquatic organisms when released into the environment.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a method for efficiently separating rare earth elements from rare earth magnets or the like while suppressing the amount of alkali used. Another object of the present invention is to provide a microorganism that selectively accumulates Fe and that can be suitably used in the method.

  As a result of intensive studies to solve the above problems, the present inventors have added microorganisms to a solution in which Fe and a rare earth element coexist so that Fe in the solution is selectively accumulated in the microorganisms. The inventors have succeeded in selectively separating rare earth elements in a solution and completed the present invention.

  According to the method of the present invention, Fe in a liquid can be reduced by selectively accumulating Fe in a liquid in a liquid in which Fe and a rare earth element coexist. In addition, according to the microorganism of the present invention, Fe can be selectively accumulated in a liquid in which Fe and rare earth elements coexist. Although the technical scope of the present invention is not limited in any way, it is presumed that Fe is accumulated in microorganisms by adsorption and / or incorporation of Fe in an ionic state.

FIG. 1 is a flowchart showing an embodiment of a rare earth element separation process by the method according to the present invention.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

  In the present specification, “X to Y” indicating a range means “X or more and Y or less”, and “weight” and “mass”, “wt%” and “mass%”, “part by weight” and “ “Part by mass” is treated as a synonym. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

  A first aspect of the present invention relates to a method for separating a rare earth element, which includes a step of bringing a microorganism into contact with a liquid containing Fe and a rare earth element to reduce Fe in the liquid containing Fe and the rare earth element. In the present invention, by bringing a microorganism that selectively accumulates Fe into contact with a liquid containing Fe and a rare earth element, the microorganism selectively accumulates Fe. For this reason, since the rare earth element remains in the liquid after contact, the rare earth element can be efficiently recovered. According to this method, Fe and rare earth elements can be separated while suppressing the amount of alkali used. The rare earth element separated from Fe can then be further refined by applying an ion exchange resin method or extraction with an organic solvent. The rare earth element separated from Fe can also separate neodymium and dysprosium, for example, by the method disclosed in Japanese Patent Application Laid-Open No. 2012-244914. Therefore, magnet powder such as grinding powder generated during the production of rare earth magnets, scraps and defective scraps, used rare earth magnets (collected products) (hereinafter also collectively referred to as “objects to be treated”), and target rare earth Elements can be recycled. Furthermore, since the amount of alkali used at the time of collection can be reduced, the load on the environment can be reduced, and there is an advantage in terms of safety.

[Microorganisms]
Examples of microorganisms that can be used in the present invention include fungi and bacteria (bacteria) that selectively accumulate iron (Fe). Any microorganism can be used in the present invention as long as it selectively accumulates iron (Fe). Specifically, the genus Bacillus, Paenibacillus, Corynebacterium, Staphylococcus, Cohella, Rhizobium, Rhizobium, Rhizobium, Rhizobium , Aerobacter, Thermoanaerobacter, Thermus, Clostridium, Enterobacter, Lactobacillus, Lactococcus, Lactococcus Seth (S bacteria (bacteria) such as reptomyces; Acremonium, Aspergillus, Cephalosporum, Chrysosporium, Cryptococcus, Cryptococcus Humicola, Mucor, Neurospora, Penicillium, Rhizomucor, Rhizopus, Thielaviola, Thielaviola And fungi such as filamentous fungi. Among them, a microorganism selected from the group consisting of a bacterium of the genus Coneella, a bacterium of the genus Mesorhizobium, and a fungus of the genus Penicillium, is feasible even when the selectivity of Nd / Fe and the low pH are low. It is preferable from the viewpoint that can be accumulated. Two or more of these microorganisms may be used in combination.

  Examples of bacteria belonging to the genus Bacillus Coneella that can be preferably used in the present invention include Cornella sp. (C. sp., For example, RD1795), Cornella fontinalis (for example, NBRC 104957), Cornella. -Soli (C. soli, for example, NBRC 106486), Cornella suwonensis (C. suwonensis, for example, NBRC 106485), etc. can be mentioned.

  In the present invention, a bacterium of the genus Rhizobiales Mesolyzobium can also be used. Examples of the bacteria belonging to the genus Rhizobium, Mesozobium sp. (M. sp., For example, RD1780), Mesozobium albidi (for example, NBRC 107164), Mesozobium amorpha (for example, NBRC. Siseri (M. ciceri, eg NBRC 100309), Mesozobium roti (M. loti, eg NBRC 14779), Mesozobium Mediterraneum (M. mediterraneum, eg NBRC 102497), or Mesozobium purifarium (M. For example, NBRC 102498) can be mentioned.

  In general, fungi can grow in a state where the required water content is less than that of bacteria. For this reason, mass production is more easily achieved from the viewpoint of industrial use.

  Examples of fungi belonging to the genus Penicillium that can be used in the present invention include Penicillium brefeldianum (former name: Eupenicillium brefeldianum), Eupenicillium jabunicam (Eupic, Lupicum, etc.). -ID429 strain), Epenicillium limosum (Eupicillium limosum, for example, AFTOL-ID2014 strain), Penicillium jancinerum (for example, Zh9A strain) and Penicillium sp., For example, PSF30 , RA102 strain, RA403 strain, NA-4 strain (NITE P-01784)) but the like can be exemplified, Penicillium brefeldianum Diana beam or Penicillium sp. NA-4 strain is more preferable. Penicillium brefeldianum includes Penicillium brefeldinum (NBRC 31730), Penicillium brefeldinum (NBRC 31731), Penicillium brefeldinum (NBRC 6091), Penicillium brefeldinum (NBRC BRRC 7001) ), Penicillium brefeldinum (NBRC 8393), Penicillium brefeldinum (NBRC 106929), Eupenicillium brefeldinum M-2166 strain (Eupenicillium brefeldianum, FERM P-1104) or Upenicilium brefeldinum TZ- 16 strains can be mentioned. Among these fungi belonging to the genus Penicillium, the Penicillium sp. NA-4 strain (NITE P-01784) is more preferable. In the above strain, mutants obtained by mutating by natural or artificial means and capable of accumulating Fe are also used in the present invention.

  In the method according to the present invention, a microorganism that can selectively accumulate Fe, and in particular, can accumulate a large amount of Fe in the fungus body compared to rare earth elements is used. For this reason, when microorganisms are brought into contact with a mixture of Fe and a rare earth element (for example, a magnet solution), Fe and the rare earth element are efficiently separated, and the rare earth element remains in the mixture after the contact. Can be recovered efficiently. Furthermore, Fe can also be recovered by separating and purifying Fe from microbial cells. Therefore, the target rare earth element can be recycled from the magnet powder, scraps and defective scrap generated during the production of the neodymium magnet containing Fe, and the neodymium magnet.

  Here, when the microorganism accumulates a large amount of Fe as compared with the rare earth element, the accumulation ability of Fe is not particularly limited. That is, the microorganism of the present invention may accumulate Fe in preference to rare earth elements. Specifically, the property (selectivity) of accumulating Fe in preference to rare earth elements can be evaluated by Equation (1).

In Formula 1, Fe ¹ or Nd ¹ is the amount (mol) of Fe or Nd in the reaction solution before Fe accumulation by microorganisms under the following conditions, respectively, and Fe ² or Nd ² is Fe by microorganisms, respectively. This is the amount (mol) of Fe or Nd in the reaction solution after the accumulation.

  When a fungus is used as a microorganism, it is cultured for 168 hours in a PDB medium (pH 2.5, 27 ° C.) containing Fe and rare earth elements. The substance amounts of Fe and Nd in the reaction solution before and after the culture may be obtained by inductively coupled plasma emission spectroscopy, and the Nd / Fe selectivity represented by the formula (1) may be calculated. When bacteria such as Cornella or Mesozobium are used as microorganisms, Fe is accumulated in physiological saline containing Fe and rare earth elements (pH 2.5, 35 ° C.) for 1 hour, and expressed by the formula (1). What is necessary is just to calculate the selectivity of Nd / Fe.

  In the present invention, it is preferable to use a microorganism whose Nd / Fe selectivity represented by the formula (1) is 80% to 100%. It is more preferable to use a microorganism having a selectivity of Nd / Fe represented by the formula (1) of 90% to 100%, more preferably 95% to 100%, and particularly preferably more than 98% and 100% or less. It is.

  The microorganism culturing method may be any method as long as the microorganism can grow and proliferate. For example, the medium used for culturing the microorganism of the present invention may be either a solid or liquid medium, and a medium containing a carbon source, an appropriate amount of nitrogen source, an inorganic salt, and other nutrients that can be assimilated by the microorganism used. If so, either a synthetic medium or a natural medium may be used. Usually, a culture medium contains a carbon source, a nitrogen source, and an inorganic substance.

  The carbon source that can be used in the culture of microorganisms is not particularly limited as long as it is a carbon source that can be assimilated by the strain used. Specifically, in consideration of the assimilability of microorganisms, sugars such as glucose, fructose, cellobiose, raffinose, xylose, maltose, galactose, starch, starch hydrolysate, molasses, molasses, meat extract, peptone, casein And natural products such as casein-peptone, wheat and rice, alcohols such as glycerol, methanol and ethanol, and fatty acids such as acetic acid, gluconic acid, pyrpinic acid and citric acid. The carbon source is appropriately selected in view of assimilation by the microorganism to be cultured. Moreover, the said carbon source can be used 1 type or 2 types or more selected.

  Further, as a nitrogen source that can be used in the culture of microorganisms, meat extract, peptone, polypeptone, yeast extract, soybean hydrolysate, soybean powder, casein, milk casein, casamino acid, glycine, glutamic acid, aspartic acid and various amino acids, Organic nitrogen sources such as corn steep liquor, other animal, plant, and microorganism hydrolysates; ammonium salts such as ammonia, ammonium nitrate, ammonium sulfate, and ammonium chloride; nitrates such as sodium nitrate; inorganic nitrogen sources such as urea . The nitrogen source is appropriately selected in view of assimilation by the microorganism to be cultured. Further, one or more of the nitrogen sources can be selected and used.

  Examples of inorganic substances that can be used in the present invention include magnesium, manganese, calcium, sodium, potassium, copper, iron (Fe), zinc, and other halogens such as phosphate, hydrochloride, sulfate, nitrate, acetate, and chloride. And the like. Plant extracts such as potato extract may be used. The said inorganic substance is suitably selected in consideration of the assimilation property by the microorganisms to culture. In addition, one or more of the above inorganic materials can be selected and used. Moreover, you may add a vegetable oil, surfactant, etc. in a culture medium as needed.

  In order to efficiently accumulate Fe in microorganisms or to maintain the selectivity of microorganisms, it is preferable to add Fe to the medium. The addition amount of Fe is not particularly limited, and can be appropriately selected in consideration of the selectivity by the microorganism to be cultured. Specifically, it is preferable to add Fe in a concentration of 1 to 100 mg, more preferably 5 to 50 mg in 1 L of the medium in terms of metal. With such an added amount, the microorganism can maintain high selectivity.

  Microorganisms can be cultured by ordinary methods. For example, depending on the type of microorganism, the microorganism is cultured under aerobic conditions or anaerobic conditions. In the former case, microorganisms are cultured by shaking or aeration stirring. The culture conditions are appropriately selected depending on the composition of the medium and the culture method, and are not particularly limited as long as the microorganisms of the present invention can grow, and can be appropriately selected according to the type of microorganism to be cultured. In the case of fungi, the culture temperature is preferably 20 to 35 ° C, more preferably 25 to 32 ° C. In the case of bacteria, the culture temperature is preferably 20 to 40 ° C, more preferably 25 to 38 ° C. The pH of the medium suitable for culture is preferably 2.0 to 8.0, more preferably 2.5 to 6.5, and still more preferably 3.0 to 5.0. In the rare earth separation method according to the present invention, an acid is added to a raw material to prepare a liquid containing Fe and a rare earth element. If it is a microorganism that can grow in an acidic region and has metal resistance, it is highly likely that it can survive in a liquid containing Fe and rare earth elements and accumulate Fe. Therefore, microorganisms that can grow in an acidic region are preferred.

[Liquid containing Fe and rare earth elements]
In the method for separating a rare earth element according to the present invention, a microorganism is brought into contact with a liquid containing Fe and the rare earth element to reduce Fe in the liquid containing Fe and the rare earth element. As the rare earth element, in addition to neodymium, dysprosium, and samarium contained in the neodymium magnet, lanthanoids such as cerium, praseodymium, and terbium, or scandium or yttrium may be used. By bringing the microorganism into contact with a liquid containing these rare earth elements and Fe, Fe can be accumulated in the microorganism and Fe in the liquid can be reduced. For the preparation of the liquid containing Fe and rare earth elements, magnet powder generated during the production of rare earth magnets, scraps and defective scraps, used rare earth magnets (recovered products), and the like are used, but are not limited thereto. A method for preparing a liquid containing Fe and rare earth elements from these raw materials containing Fe and rare earth elements (hereinafter also simply referred to as “raw materials”) will be described below.

  The raw material used in the preparation of the liquid containing Fe and rare earth elements is not particularly limited as long as it contains Fe and rare earth elements.

  In this specification, Fe and rare earth elements prepared from raw materials such as magnet powders such as grinding powder generated during the production of rare earth magnets, scraps and defective scraps, used rare earth magnets (recovered products), etc. The liquid containing is called a magnet solution. Therefore, one embodiment of the present invention is a method for separating a rare earth element, which includes a step of bringing a microorganism into contact with a magnet lysis solution to reduce Fe in the liquid containing Fe and the rare earth element.

  In preparing the liquid containing Fe and the rare earth element, a raw material (for example, an object to be treated) containing Fe and the rare earth element may be pulverized. When preparing the liquid containing Fe and the rare earth element, the raw material is pulverized and the acid treatment is performed after reducing the particle size, whereby the rare earth can be efficiently ionized and the yield of the rare earth element can be improved. In addition, the said mechanism is an estimation to the last, and does not restrict | limit the technical scope of this invention at all.

  The raw material pulverization method is not particularly limited, and a conventionally known method may be used. Specific examples include a ball mill, a sand mill, a vibration mill, a jet mill, a pin mill, and a mixer. The pulverization method may be wet or dry. Cyclohexane or the like can be used for the wet ball mill.

  The pulverized raw material may be classified to a desired particle size using a sieve. The particle size of the pulverized raw material is, for example, in the range of 10 to 1000 μm, and preferably in the range of 20 to 500 μm.

  In preparing a liquid containing Fe and rare earth elements, it is preferable to fire the raw material. Even from unfired raw materials, it is possible to separate Fe and rare earth elements by employing the method according to the present invention. However, by oxidizing Fe by firing, when an acid is added in a later step, it is possible to separate the acid-insoluble iron oxide and reduce the amount of Fe dissolved in the liquid. When baking a raw material, although baking temperature can be set arbitrarily, it is 700 to 1200 degreeC, for example, Preferably it is 750 to 1000 degreeC. The holding time may be arbitrarily adjusted in relation to the firing temperature, and is, for example, 0.2 hours to 5 hours, preferably 0.5 hours to 2 hours. Conventionally known means such as an electric furnace may be used for firing. Firing may be performed in the air or in an oxidizing gas atmosphere.

  The liquid containing Fe and rare earth elements can be prepared by adding an acid to the optionally pulverized, classified and / or calcined raw material. Acids added include inorganic acids such as sulfuric acid, nitric acid, carbonic acid, hydrochloric acid; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, benzoic acid, salicylic acid, oxalic acid Organic acids such as malonic acid, succinic acid, glutaric acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, etc. can be used, preferably sulfuric acid, nitric acid or hydrochloric acid, Particularly preferred. A combination of these acids may be used.

  As long as the pH of the mixture (slurry) of acid and raw material is less than 1, the amount of acid added to the raw material is not limited. For example, when sulfuric acid is used as the acid, a 0.1 mol / L to 5 mol / L, preferably 0.3 to 2 mol / L sulfuric acid solution, preferably a sulfuric acid aqueous solution is employed. This sulfuric acid solution is added in an amount of 0.5 L to 35 L, preferably 1 L to 10 L with respect to 1 mol of Fe in the raw material.

  The slurry is held at 50 ° C. to 90 ° C., preferably 60 ° C. to 80 ° C. for 3 hours to 20 hours, preferably 5 hours to 10 hours. Thereby, the rare earth elements and a part (or all) of Fe in the raw material are dissolved. While being held, the slurry may be stirred or shaken. After the holding, the residue insoluble in the slurry may be separated by any means such as filtration or centrifugation.

  The liquid containing Fe and rare earth elements thus obtained can be arbitrarily diluted and used in the method according to the present invention.

  The amount of Fe in the liquid containing Fe and rare earth elements is not particularly limited. Specifically, for example, Fe is 100 mg / L or less with respect to the whole liquid containing Fe and rare earth elements in terms of metal. It is preferable that it exists so that it may become 50 mg / L or less, More preferably, it is 30 mg / L or less. When the amount of Fe in the liquid containing Fe and rare earth elements is 100 mg / L or less, Fe is accumulated without inhibiting the growth of microorganisms. The NA-4 strain according to the present invention is particularly excellent in that growth and proliferation are not inhibited even in an environment where Fe is highly concentrated. The amount of Fe in the liquid containing Fe and rare earth elements is preferably 1 mg / L or more, more preferably 5 mg / L or more, and present at 8 mg / L or more from the viewpoint of working efficiency. More preferably. The liquid containing the rare earth element may be optionally diluted with a culture medium, physiological saline, or the like so that the amount of Fe falls within the above range.

  Further, the amount of the rare earth element in the liquid containing Fe and the rare earth element is not particularly limited. Specifically, for example, neodymium is present in an amount of 5 to 500 mg / L, preferably 10 to 300 mg / L with respect to the entire liquid containing Fe and rare earth elements in terms of metal. Further, the amount of other rare earth elements including dysprosium is not particularly limited. For example, it is preferable that other rare earth elements are present in an amount of 1 to 100 mg / L, preferably 5 to 50 mg / L, based on the total amount of the liquid containing Fe and rare earth elements. With such an amount, even when microorganisms are cultured in a liquid containing a rare earth element, Fe can be efficiently accumulated without inhibiting growth and proliferation.

  In the step of reducing Fe, the pH of the liquid containing Fe and rare earth elements is preferably 3.5 or less. Therefore, after adjusting the pH of the liquid containing Fe and rare earth elements to 3.5 or less, it may be used in the step of reducing Fe. The pH of the liquid containing Fe and rare earth elements is, for example, 1.5 or more from the viewpoint of the growth of microorganisms. The pH of the liquid containing Fe and rare earth elements is more preferably 1.8 to 3.0, further preferably 2.0 or more and less than 3.0, more than 2.0 and less than 3.0. It is particularly preferred that In the case where Fe is reduced by precipitating a poorly soluble iron salt by alkali treatment, alkali is usually added until the pH reaches about 5.0. In the present invention, the amount of alkali used can be suppressed by adjusting the pH to 3.5 or less. If the pH is 3.5 or less, the reaction volume does not become excessively large even when the pH is adjusted by dilution.

  The pH is adjusted, for example, by adding an alkali such as sodium hydroxide, potassium hydroxide, or ammonia, or by diluting a liquid containing Fe and rare earth elements with an appropriate solvent (for example, water or a medium). Just do it. Moreover, you may adjust pH by combining these means. It is preferable from the viewpoint of reducing the amount of alkali used to adjust pH by diluting a liquid containing Fe and rare earth elements with an appropriate solvent (for example, water, physiological saline, medium). When culturing fungi in a liquid containing Fe and a rare earth element, it is preferable to perform dilution in a medium in that the culture efficiency in the liquid containing Fe and the rare earth element can be improved.

  When the pH of the liquid containing Fe and rare earth elements is increased, a hardly soluble iron salt (for example, iron hydroxide) may be precipitated. When the hardly soluble iron salt is deposited, the hardly soluble iron salt may be optionally separated and removed by means such as filtration or centrifugation.

[Step of reducing Fe]
The method according to the present invention includes a step of bringing a microorganism into contact with a liquid containing Fe and a rare earth element prepared by the above-described method, and reducing Fe in the liquid containing Fe and the rare earth element (hereinafter simply referred to as “Fe. Also referred to as “reducing step”). The method for bringing the microorganism into contact with the liquid containing Fe and rare earth elements is not particularly limited. For example, a microorganism is added to a liquid containing Fe and a rare earth element, and the mixture is stirred or shaken. The microorganism is cultured in a liquid containing Fe and the rare earth element, or the liquid containing Fe and the rare earth element is contacted with the immobilized cells. Can be adopted. A plurality of these methods may be used in combination.

  In one embodiment of the present invention, the step of reducing Fe is performed by culturing a microorganism in a liquid containing Fe and a rare earth element. The genus Cornella (for example, Cornella sp. RD1795), the genus Mesozobium (for example, Mesozobium sp. RD1780), and the genus Penicillium (for example, Penicillium sp. Fe in the liquid containing Fe and rare earth elements can be accumulated. Therefore, Fe in the liquid containing Fe and rare earth elements can be efficiently reduced while suppressing the amount of alkali used.

  When culturing microorganisms in a liquid containing Fe and rare earth elements, the liquid containing Fe and rare earth elements preferably contains a medium component used for culturing microorganisms. For example, when a Penicillium fungus is used as a microorganism, a solution containing Fe and rare earth elements may be diluted with a PDB medium and used for fungal culture. The dilution rate with the medium may be adjusted to an arbitrary pH, and is usually about 5 to 1000 times, although it varies depending on the pH of the medium to be used.

  When culturing fungi including Penicillium genus in a liquid containing Fe and rare earth elements, it is preferable to use a medium containing the above-mentioned nitrogen source from the viewpoint of Fe selectivity. The amount of the nitrogen source in the total amount of the medium is preferably about 0.2 to 2.0% (w / v).

  Microorganisms are added to the liquid containing Fe and rare earth elements prepared as described above, and culture is performed. The amount of microorganisms to be added is not particularly limited, but is, for example, about one platinum loop. In addition, you may use the microorganisms after the preculture mentioned later. As for the culture conditions of microorganisms, the above culture conditions are referred to except for the pH range. That is, in the case of fungi, the culture temperature is preferably 20 to 35 ° C, more preferably 25 to 32 ° C. In the case of bacteria, the culture temperature is preferably 20 to 40 ° C, more preferably 25 to 38 ° C. The culture time in the liquid containing Fe and rare earth elements is not particularly limited, and may be set arbitrarily in consideration of the type of microorganism to be cultured, the amount of the medium, and the like. Usually, the culture time is 100 to 300 hours, preferably 150 to 250 hours. In the step of reducing Fe, the liquid containing Fe and rare earth elements is cultured in the pH range described above.

  After contacting the microorganism with the liquid containing Fe and the rare earth element, the microorganism in which Fe is accumulated is separated from the liquid containing the rare earth element. Separation may be performed, for example, by filtration or centrifugation. When separating microorganisms by filtration, a membrane having a pore size of about 0.2 μm that does not pass microorganisms, such as a filter for filter sterilization, may be used. By separating the microorganism in which Fe is accumulated from the liquid containing the rare earth element, Fe can be separated from the rare earth element. The recovery rate of rare earth elements can be increased by washing the separated microorganisms with a suitable solvent such as water and collecting the washing solution.

  The culture in the liquid containing Fe and rare earth elements may be repeated a plurality of times (for example, 2 to 20 times). That is, after culturing, the microorganisms and optionally supplement medium components are added again to the treatment liquid after separating the microorganisms, and the process of reducing Fe is performed again. Fe in the liquid can be further reduced by performing the culture in the liquid containing Fe and the rare earth element a plurality of times.

  The step of reducing Fe may be performed by adding a pre-cultured microorganism to a liquid containing Fe and a rare earth element. That is, one embodiment of the method according to the present invention further includes a step of pre-culturing the microorganism before the step of reducing Fe. By including the step of pre-culturing, the number of bacteria used for the step of reducing Fe can be increased, and the time of the step of reducing Fe can be shortened.

The aforementioned culture conditions are also taken into consideration for the pre-culture conditions. The pre-culture time may be arbitrarily set depending on the type of microorganism to be cultured, and is, for example, 24 to 500 hours, preferably 36 to 400 hours. The amount of bacteria used for the step of reducing Fe after pre-culture can be arbitrarily set. For example, the amount is 1 × 10 ³ to 1 × 10 ⁹ CFU / mL in a liquid containing Fe and rare earth elements. In addition, it is preferable to provide one that has reached the logarithmic growth phase in which the bacteria are in a physiologically favorable state during pre-culture. The concentration of bacteria can also be evaluated by means such as turbidity measurement (OD600 or the like).

  When contacting liquids containing Fe and rare earth elements with the immobilized cells, construct the microorganisms by immobilizing them on a carrier and placing this carrier in a tank through which the liquid containing Fe and rare earth elements flows. Can do. Moreover, you may install a control apparatus, a pump, various sensors, etc. Here, the carrier for immobilizing the microorganism is not particularly limited as long as it can immobilize the microorganism, and the carrier generally used for immobilizing the microorganism may be the same or It is used after being appropriately modified. For example, a method of including and fixing on a gel material such as alginic acid, polyvinyl alcohol, gellan gum, agarose, cellulose, dextran, and a method of adsorbing and fixing to a surface of glass, activated carbon, polystyrene, polyethylene, polypropylene, wood, silica gel, etc. Can be used.

  Further, the method for immobilizing the microorganism on the carrier is not particularly limited, and a general method for immobilizing the microorganism is used in the same manner or appropriately modified. For example, an immobilization method by pouring a microorganism culture solution into a carrier, an immobilization method by pouring the microorganism culture solution into a carrier using an aspirator, and a culture medium in which a strain culture solution is sterilized For example, a method of pouring into a mixture of a carrier and a carrier, culturing with shaking, and naturally drying the carrier taken out of the mixture.

  Accumulation of Fe by microorganisms can be performed in any manner such as a batch system, a semi-batch system, and a continuous system. The temperature of the liquid containing Fe and the rare earth element is not particularly limited, but considering the selectivity of Fe, it is preferable to adjust the temperature to about 20 to 35 ° C, more preferably about 25 to 32 ° C. . The process may be repeated a plurality of times.

  After the Fe in the liquid containing Fe and the rare earth element is reduced by the above process, the rare earth element may be separated and purified from the liquid after the treatment, and the method is not particularly limited. For example, a method of purifying the liquid subjected to the above treatment by using a conventionally known method alone or in combination, such as an ion exchange resin method (solid-liquid extraction method) and a solvent extraction method (liquid-liquid extraction method). It is done.

[Penicilium sp. NA-4 strain]
The second aspect of the present invention relates to a microorganism belonging to the genus Penicillium, which selectively accumulates Fe, a subcultured progeny of the microorganism, or a mutant derived from the microorganism. Such a microorganism can be suitably used in the first embodiment of the present invention.

  The fungus according to this embodiment was isolated from a sample collected from the soil in the site of Nissan Motor Co., Ltd., No. 1 Natsushima-cho, Yokosuka City, by the following screening method. That is, an appropriate amount of sample (soil) was diluted in pure water and smeared on the primary screening agar medium (pH: 6.5) prepared by the method described in Example 1. For 7 to 28 days and primary screening was performed. The primary screening yielded strains that could grow even in the presence of high concentrations of Fe.

  Next, secondary screening was performed as follows. That is, inoculate each isolated bacterium purified by the above-mentioned primary screening into a liquid medium for secondary screening (50 ml) prepared by the method described in Example 1 one by one with a platinum loop. And cultured with shaking at 27 ° C. for 7 days. Further, according to the following method, the concentration of iron (Fe), neodymium (Nd) and dysprosium (Dy) remaining in the culture supernatant was measured, and the Fe concentration in the culture supernatant was decreased from the initial concentration, and Nd and Bacteria whose decrease from the initial concentration of Dy was small were selected as candidate bacteria. In this way, a strain that efficiently accumulates Fe and does not accumulate rare earth elements (Nd or Dy) (a strain that selectively accumulates Fe) was screened. As a result, a strain that selectively accumulates Fe was isolated (separated).

  In the screening method, the iron (Fe), neodymium (Nd), and dysprosium (Dy) concentrations remaining in the culture supernatant are measured according to the following measurement method. After inoculating and culturing the strain to be screened, 1 ml of the medium is placed in a centrifugal filtering unit and centrifuged (8000 rpm, 4 ° C., 10 minutes) to obtain a filtrate. Quantitative analysis of Fe, Nd, and Dy in the filtrate was performed by inductively coupled plasma emission spectroscopy (ICP-AES / inductively coupled plasma emission spectrometer SPS-1700 HVR manufactured by SII Nanotechnology). Standard lines are dysprosium nitrate solution for inductively coupled plasma emission spectroscopy (Wako Pure Chemical Industries), neodymium nitrate solution for inductively coupled plasma emission spectroscopy (manufactured by Wako Pure Chemical Industries), and iron nitrate for inductively coupled plasma emission spectroscopy. It was prepared using a solution (manufactured by Wako Pure Chemical Industries).

  Hereinafter, the taxonomic properties of the fungus isolated above will be described.

  With respect to the isolated strain, the nucleotide sequences of the 18S rDNA and 26 / 28S rDNA internal transcription spacer (ITS) regions and the 26 / 28S rDNA D1 / D2 region were determined. The determined base sequence of rDNA in the ITS region of the isolated microorganism is shown in SEQ ID NO: 1, and the base sequence of rDNA in the D1 / D2 region is shown in SEQ ID NO: 2.

  The homology between the base sequence of the rDNA ITS region of the isolated microorganism and the base sequence of the rDNA ITS region of various known microorganisms was compared. Moreover, the homology of the base sequence of the rDNA D1 / D2 region of the isolated microorganism with the base sequence of the rDNA D1 / D2 region of various known microorganisms was compared.

  As a result, the isolated microorganism completely matched the base sequence of the ITS region with the Penicillium brefeldianum TZ-16 strain. In addition, the isolated microorganism completely matched the nucleotide sequence of the D1 / D2 region with the Eupenicillium javanicum AFTOL-ID429 strain and the Eupenicillium limosum AFTOL-ID2014 strain. Information on the culture properties and morphological characteristics of the above three species of Eupenicillium microorganisms (Pitt, JI (1979), “Penicillium genus and its teleomorph generations Eupenicillium and Talalomyces (The genus Penicillium and itts) telemorphic states (Epenicillium and Talaromyces) ”, Academic Press, London, and Ueda, S. (1995),“ Mycoscience ”, 36: 451-454) were compared to isolated microorganisms. As a result, the isolated microorganism is Penicillium brefeldianum (former name: Eupenicillium Believed to be similar to the features of Le Fell Diana beam (Eupenicillium brefeldianum)), it was estimated to be Penicillium sp is related species of Penicillium brefeldianum Diana beam ((Penicillium sp.).

  The culture / morphological properties and physiological / chemical taxonomic properties of the isolated microorganism are described below.

1. Culture and morphological properties The following were used for morphological observation.
Microscope: Stereo microscope SZH10 (manufactured by Olympus), optical microscope BX51 (differential interference observation, manufactured by Olympus)
Mount liquid: Lactphenol liquid, Lactphenol cotton blue liquid.

  1-1. Cultural and morphological properties of Czapek Yeast Extract Agar (CYA) medium (25 ° C, 1 week)

  1-2. Cultural and morphological properties in Czapek Yeast Extract Agar (CYA) medium (37 ° C, 1 week)

  1-3. Culture and morphological properties of malt extract agar (MEA) medium (25 ° C, 1 week, but microscopic observation (the morphological properties of teleomorph and anamorph) is 4 weeks)

  1-4. Culture and morphological properties in glycerol nitrate agar (G25N) medium (25 ° C, 1 week)

2. Physiological and chemical taxonomic properties Table 5 shows the colony diameter when the isolated microorganism was pre-cultured in PDA medium, inoculated in the center of PDA medium, and cultured at 25 ° C for 1 week.

  The optimum growth pH was considered to be around pH 4-5 within the range in which the test was conducted.

3. Deposit of isolated fungus The fungus isolated by the above-described method can selectively accumulate iron (Fe) in a liquid in which Fe and a rare earth element coexist.

  The isolated microorganism was judged to be a novel microorganism from its various properties. This strain was named Penicillium sp. NA-4 strain (hereinafter also simply referred to as “NA-4 strain”). In addition, this NA-4 strain was deposited with the Patent Microorganisms Depositary Center (National Institute for Product Evaluation and Technology, 2-5-8, Kisarazu-shi, Chiba Prefecture) on December 24, 2013, The accession number is NITE P-01784.

  It should be noted that mutants obtained by mutating natural or artificial means in the above strain and capable of accumulating Fe are also included in the present invention as long as Fe is accumulated in preference to rare earth elements. Here, “mutant” refers to a strain whose gene composition differs from that of the parent strain due to, for example, substitution, insertion or deletion of at least one base or amino acid. The above-mentioned “substitution, insertion or deletion of at least one base or amino acid” means substitution, deletion, addition or insertion of a base or amino acid that does not substantially affect the property of selectively collecting Fe. Means. The mutant of the present invention may be generated spontaneously or by a known method. The method in the latter case is not particularly limited. For example, the mutant may be a chemical mutation (for example, a chemical mutant such as N-methyl-N′-nitro-N-nitrosoguanidine (NTG). Use), transposon, or by mutagenesis, such as by radiation or UV irradiation. Furthermore, the mutant of the present invention may be a recombinant having a recombinant nucleic acid sequence. For example, a variant can be a strain carrying another nucleic acid sequence (eg, a sequence that has been transformed, transduced, or otherwise inserted into the cells of its parent strain). The other nucleic acid sequence may encode a polypeptide that is expressed to exhibit Fe selectivity. Alternatively, the other nucleic acid sequence may encode a nucleic acid sequence (eg, antisense, ribozyme, or any other nucleic acid sequence) that can alter cell physiology. Alternatively, the nucleic acid may be inserted into an endogenous gene to change (enhance or destroy) the function of the endogenous gene. For example, the inserted nucleic acid can be a knockout construct that inactivates the endogenous gene, or an artificial enhancer or promoter that increases transcription of the endogenous gene.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

Example 1: Isolation of NA-4 strain The NA-4 strain was isolated from a sample collected from the soil of Nissan Motor Co., Ltd., No. 1 Natsushima-cho, Yokosuka City. That is, an appropriate amount of sample (soil) is diluted in pure water and smeared on a primary screening agar medium (pH: 3.5) prepared by the following method, and this agar medium is 7-28 at 27 ° C. The primary screening was performed after culturing for one day. Note that sulfuric acid and sodium hydroxide were used to adjust the pH of the medium.

<Method for preparing agar medium for primary screening>
Potato dextrose agar medium (composition: potato extract 0.4% (w / v), glucose 2% (w / v), agar 1.5% (w / v)) (PDA medium) as follows Prepared. That is, 4 g of potato extract and 20 g of glucose were dissolved in 1 L of deionized water, and this solution was divided into 200 ml portions. To this medium solution, dysprosium (III) sulfate octahydrate (manufactured by Soekawa Riken) is added so that the Dy content in the medium solution is 0.1 mM, 1 mM, 3 mM, 6 mM, and there is a dilution series A solution was made. Next, 1.5% (w / v) of agar was added to each, and then separately sterilized under high pressure, and dispensed into a petri dish to obtain a plate medium.

  Next, the colonies formed on the agar medium (Dy content 1 mM) were picked and re-smeared on the agar medium (Dy content 1 mM). This operation was repeated several times to purify the strain. By such primary screening, a fungus capable of growing even in the presence of a high concentration of Dy was obtained.

  Next, secondary screening was performed as follows. That is, inoculate each isolated bacterium purified by the above primary screening with a platinum loop into a liquid medium for secondary screening (50 ml) that has been prepared by the following method. Cultured with shaking for 7 days. Further, according to the following method, the concentration of iron (Fe), neodymium (Nd) and dysprosium (Dy) remaining in the culture supernatant was measured, and the Fe concentration in the culture supernatant was decreased from the initial concentration, and Nd and Bacteria whose decrease from the initial concentration of Dy was small were selected as candidate bacteria. In this way, a strain that efficiently accumulates Fe and does not accumulate rare earth elements (Nd or Dy) (a strain that selectively accumulates Fe) was screened.

<Method for preparing secondary screening medium>
Dissolve 4 g of potato extract and 20 g of glucose in 1 L of deionized water, and autoclave potato dextrose liquid medium (composition: potato extract 0.4% (w / v), glucose 2% (w / v)) (PDB medium). Sterilized. Next, the magnet solution described in Example 2 was sterilized by filtration, and the solution A was added to the PDB medium so that the Fe content was 0.16 mM to prepare a secondary screening medium (pH 2.5). Note that sulfuric acid and sodium hydroxide were used to adjust the pH of the medium.

  In the above method, the concentration of iron (Fe), neodymium (Nd), and dysprosium (Dy) remaining in the culture supernatant is measured according to the following measurement method. After inoculating and culturing the strain to be screened, 1 ml of the medium is placed in a centrifugal filtering unit and centrifuged (8000 rpm, 4 ° C., 10 minutes) to obtain a filtrate. Quantitative analysis of Fe, Nd, and Dy in the filtrate was performed by inductively coupled plasma emission spectroscopy (ICP-AES / inductively coupled plasma emission spectrometer SPS-1700 HVR manufactured by SII Nanotechnology). Standard lines are dysprosium nitrate solution for inductively coupled plasma emission spectroscopy (Wako Pure Chemical Industries), neodymium nitrate solution for inductively coupled plasma emission spectroscopy (manufactured by Wako Pure Chemical Industries), and iron nitrate for inductively coupled plasma emission spectroscopy. It was prepared using a solution (manufactured by Wako Pure Chemical Industries).

  The microorganism obtained by the above screening method was judged to be a novel microorganism, and this strain was named Penicillium sp. NA-4 strain. As of December 24, 2013, this NA-4 strain was assigned to the National Institute of Technology and Evaluation Patent Microorganisms Deposit Center (2-5-8, Kazusa Kamashi, Kisarazu City, Chiba Prefecture) under the accession number NITE P-01784. Deposited.

Example 2: Separation of rare earth element by NA-4 strain <Preparation of liquid containing Fe and rare earth element>
A grinding powder having a particle diameter of 75 to 100 μm generated in the magnet processing step was used as a treatment object, and a liquid (magnet solution) containing Fe and rare earth elements was prepared.

Composition of grinding powder: Fe: 65.4 wt%, Nd: 24.2 wt%, Dy: 6.6 wt%, Co: 2.3 wt%, B: 1.0 wt%, Al: 0.25 Wt%, Cu: 0.18 wt%, Zr: 0.04 wt%
The composition analysis of the grinding powder was performed by the above-described inductively coupled plasma emission spectroscopy.

  This grinding powder was fired at 800 ° C. for 1 hour using an electric furnace.

  0.65 g of the ground powder after firing was weighed, 50 ml of 0.5 mol / L sulfuric acid aqueous solution was added, and the mixture was held at 70 ° C. for 8 hours.

  The pH of the solution after the reaction (hereinafter also referred to as “solution A”) was 0.66. Table 6 shows the results of analysis of Fe, Nd, and Dy in solution A.

  A sterilized PDB medium (Nihon Becton Dickinson) containing 0.5% (w / v) yeast extract (Nihon Becton, Dickinson) was prepared (hereinafter also referred to as “solution B”). Sterilization was performed by autoclaving at 121 ° C. for 15 minutes.

  1 ml of solution A was diluted with 48 ml of solution B to adjust the pH, and a liquid containing Fe and rare earth elements was obtained. The pH after dilution was 2.5.

<Fe accumulation and separation>
FIG. 1 shows an embodiment of a rare earth element separation process according to the method of the present invention.

  To solution A diluted with solution B, 1 ml of NA-4 strain was added. The NA-4 strain used was precultured at 27 ° C. for 7 days in a PDB medium. Solution A to which the NA-4 strain was added was cultured at 27 ° C. for 1 week with shaking (150 rpm), and Fe was accumulated in the NA-4 strain.

  After culturing, the microorganisms and the treatment liquid (liquid in which Fe was reduced) were separated with a filter (pore diameter 0.22 μm) manufactured by Merck Millipore. Table 7 shows the results of analysis of Fe, Nd, and Dy in the treatment liquid thus obtained by inductively coupled plasma emission spectrometry.

Example 3: Separation of rare earth elements by bacteria of the genus Bacillus Cornella (Cornella) Cornella sp. (RD1795), a bacterium belonging to the genus Cornella purchased from the National Institute of Technology and Evaluation Biotechnology Center, was sterilized in a YASM0002 medium. Pre-cultured. The sterilized YASM0002 medium was prepared as follows. That is, 2.0 g ammonium sulfate, 0.1 g potassium chloride, 0.5 g potassium dihydrogen phosphate, 0.5 g magnesium sulfate heptahydrate, 0.01 g calcium nitrate, and 2.0 g triply Chick soy broth (purchased from Nippon Becton Dickinson) was dissolved in 1 L of pure water and sterilized by autoclave. Cornella SP (RD1795) was cultured with shaking at 150 ° C. for 2 weeks (150 rpm) in the YASM0002 medium prepared as described above.

  The precultured cells were collected by centrifugation at 8000 rpm for 10 minutes and washed with physiological saline.

  A solution containing Fe and rare earth elements (pH 2.5 after dilution) was prepared in the same manner as in Example 2 except that solution A was diluted with physiological saline instead of solution B, and 1 ml of washed cells was added. And then shaken at 150 ° C. for 1 hour (150 rpm).

  Thereafter, the reaction solution was centrifuged at 8000 rpm (3600 g) for 10 minutes to recover the supernatant, and the microorganism and the treatment solution were separated by an ASONE GD / X syringe filter (pore size: 0.2 μm). Table 7 shows the results of analysis of Fe, Nd, and Dy in the treatment liquid thus obtained by inductively coupled plasma emission spectrometry.

Example 4: Separation of rare earth elements by bacteria of the genus Rhizobiales Mesorhizobium Cornella SP (RD1795) in Example 3 was purchased from a mesozobium bacterium purchased from the National Institute of Technology and Evaluation Biotechnology Center. A treatment solution was obtained in the same manner as in Example 3 except that the solution was changed to a certain Mesozobium sp (RD1780). Table 7 shows the analysis results of Fe, Nd and Dy in the treatment liquid thus obtained.

Comparative Example: Separation of Rare Earth Elements by Alkali Treatment The pH was adjusted to 5 by adding 5.8 ml of 5 mol / L sodium hydroxide aqueous solution to 50 ml of Solution A. Table 7 shows the analysis results of Fe, Nd, and Dy in the treatment liquid obtained by removing the precipitated sparingly soluble salt.

  Based on the analysis results of Fe, Nd, and Dy, the residual ratio of Fe, Nd, and Dy before and after the accumulation by microorganisms or alkali treatment, and the selectivity of Nd / Fe were calculated. The results are shown in Table 8. The residual ratio in the treatment liquid was calculated as the ratio of the amount of substance after treatment to the amount of substance before treatment for each element. The “Nd / Fe selectivity” in the comparative example was calculated based on the above formula (1) from the amounts of Fe and Nd in the reaction solution before and after the alkali treatment.

  As shown in Table 8, according to the present invention, rare earth elements can be separated efficiently while suppressing the amount of alkali used.

  Moreover, the microorganisms of the genus Penicillium according to the present invention can selectively accumulate Fe.

Claims (9)

  A method for separating a rare earth element, comprising a step of bringing a microorganism into contact with a liquid containing Fe and a rare earth element to reduce Fe in the liquid containing Fe and the rare earth element.   The method for separating a rare earth element according to claim 1, wherein the liquid containing Fe and the rare earth element is a magnet solution.   The method for separating rare earth elements according to claim 1 or 2, wherein the step of reducing Fe is performed by culturing the microorganism in a liquid containing the Fe and rare earth elements.   The method for separating a rare earth element according to any one of claims 1 to 3, further comprising a step of pre-culturing the microorganism before the step of reducing Fe.   The method for separating a rare earth element according to any one of claims 1 to 4, wherein the pH of the liquid containing Fe and the rare earth element is 3.5 or less.   A microorganism belonging to the genus Penicillium, which selectively accumulates Fe, a subcultured progeny of the microorganism, or a mutant derived from the microorganism. The microorganism according to claim 6 having the following properties, a subcultured progeny of the microorganism, or a mutant derived from the microorganism:
(1) In zupek yeast extract agar medium (25 ° C., 1 week)
The shape of the surface of the colony is velvety to fluffy and forms radial grooves,
The color tone of the surface of the colony is yellow wish white (2A-2) to white (2A-1),
The color tone of the back of the colony is dark yellow (4C-8) to orange yellow (4B-8)
The soluble pigments are light orange (5A-5) to light yellow (4A-5);
(2) In zupek yeast extract agar medium (37 ° C., 1 week)
The shape of the surface of the colony is velvety to fluffy and forms radial grooves,
The color tone of the surface of the colony is dull yellow (3B-3), or pale yellow (3A-2) to white (3A-1),
The color tone of the back of the colony is olive brown (4E-8) to orange yellow (4B-8),
The soluble pigment is light yellow (4A-5);
(3) In malt extract agar medium (25 ° C., 1 week, but microscopic observation is 4 weeks)
The morphological nature of tereomorphs (sexual age) forms immature mycorrhizal cysts,
The morphological properties of anamorph (asexual era) are that conidia are grown directly from vegetative mycelia, height is 15-100 μm, width is 2-3 μm, colorless, the surface is smooth, and Penicillus is mainly monocyclic / Slightly bicyclist, Metre is cylindrical with a length of 10-25 μm and width of 2-3 μm, Fialide is ampoule with a length of 6-8 μm, width of 2-3 μm, and conidia are fiaro type It is a born child, formed in a chain from a phialide, subspherical to elliptical, 2 to 3 μm long, 3 to 3.5 μm wide, and has a smooth surface structure,
The surface shape of the colony is velvety,
The color tone of the surface of the colony is white (3A-1) to yellow wish white (3A-2),
The color tone of the back of the colony is pastel yellow (3A-4) to pale yellow (3A-3),
No soluble pigment is observed;
(4) In glycerol nitrate agar (G25N) medium (25 ° C., 1 week)
The surface of the colony has a velvety and radial groove,
The color tone of the surface of the colony is white (2A-1) to yellow wish white (2A-2),
The color of the back of the colony is yellow (3A-7-8)
No soluble pigment is observed;
(5) It can grow at pH 3.5 or less. The selectivity of Nd / Fe represented by the following formula (1) after 168 hours in a PDB medium (pH 2.5, 27 ° C.) containing Fe and rare earth elements is 80% to 100%. The microorganism according to claim 6 or 7, a progeny of the microorganism subcultured, or a mutant derived from the microorganism:
In Formula 1, however, Fe ¹ or Nd ¹ is the amount (mole) of Fe or Nd in the reaction solution before accumulation by microorganisms under the following conditions, and Fe ² or Nd ² is due to microorganisms, respectively. This is the amount (mol) of Fe or Nd in the reaction solution after the accumulation.   The microorganism according to any one of claims 6 to 8, which is a Penicillium sp. NA-4 strain (Accession No. NITE P-01784), a subcultured progeny of the microorganism, or the microorganism Variant derived from.