JP5126774B2 - A method for producing microorganism-encapsulated polymer gel beads and a soil modifying material. - Google Patents

Description

  The present invention relates to a method for producing microorganism-encapsulating polymer gel beads carrying useful microorganisms without inactivating them, and a soil modifying material containing gel beads obtained by this production method.

  When using microorganisms to modify soil and water systems, purifying various wastewaters and contaminated soil, and synthesizing, purifying or separating useful substances, the microorganisms are used as an appropriate carrier in order to improve the treatment efficiency and operability. It is necessary to immobilize and use. Conventionally, such a carrier is provided with a water-soluble synthetic resin such as polyvinyl alcohol (hereinafter abbreviated as PVA) or a water-soluble polymer polysaccharide such as alginate from the viewpoint of providing a good growth environment for microorganisms. Porous gel particles are frequently used.

  As such porous gel particles, in order to continuously exert the activity of microorganisms, the particles themselves are structurally stable and difficult to disintegrate, and it is difficult for microorganisms to dissipate in the gel structure and to prevent metabolism. It is important that it can be captured in the state, but in addition to being industrially used, mass production as a microorganism support, economic efficiency from raw materials and processes, safety during production and use, etc. are required. Furthermore, from the viewpoint of processing efficiency, it is also desired that the supporting density of microorganisms is high and that the particle size can be easily controlled in accordance with various uses and use conditions.

  Conventionally, as a means for obtaining polysaccharide-based porous gel particles, a method in which an aqueous solution of the polysaccharide is dropped into an aqueous calcium chloride solution to generate gel particles is generally used. Moreover, as means for obtaining PVA-based porous gel particles, a method of forming spherical gel particles by dropping an aqueous solution in which PVA and sodium alginate are dissolved into an aqueous calcium chloride solution (Patent Document 1), alginic acid containing microorganisms A method in which an aqueous solution of sodium is dropped into an aqueous calcium chloride solution to form gel particles, and then the gel particles are immersed in a high-concentration solution of soluble solids to contract (Patent Document 2). After infiltrating the aqueous solution, it is immersed in an aqueous solution in which a PVA polymer and sodium alginate are dissolved to form a gel layer on the outer side of the core, and then the core is immersed in a liquid containing a crosslinking agent. A method of dissolving the calcium alginate gel by immersing it in a sodium hydroxide aqueous solution and further dissolving and removing the calcium alginate gel has been proposed (Patent Document 3).

  However, in these methods, since an aqueous solution of a gel-forming polymer is dropped into an aqueous calcium chloride solution, large gel particles having an average particle size of several millimeters or more are generated. For example, an average particle size suitable as a soil modifier or the like. However, it is not suitable for both large capacity consumption applications such as soil and water system reforming and wastewater treatment, both in terms of supply capacity and cost. is there.

On the other hand, the present inventors have previously proposed several methods for producing minute microcapsules enclosing microorganisms. The first is that polymer beads such as sodium alginate containing microorganisms are emulsified and dispersed in an organic solvent in which a polymer used as the outer wall material of the microcapsule is dissolved. This is a method of obtaining microcapsules in which the core substance of microorganisms is covered with an outer wall material coating by gradually removing the solvent (Patent Document 4). Secondly, in an oil phase composed of an organic solvent A in which a wall material polymer is dissolved as a good solvent and an organic solvent B having a higher boiling point and a poor solvent for the wall material polymer, An aqueous solution containing a protective material polymer having a gel-forming property is added and emulsified to prepare a W / O emulsion in which water droplet fine particles containing a protective material polymer containing microorganisms are dispersed in an organic phase. A method of crystallizing a wall material polymer by sequentially evaporating and removing the good solvent and the poor solvent by heating or warming / depressurizing a W / O / W emulsion obtained by emulsifying and adding water to an aqueous phase (Patent Document 5). Furthermore, the third is to add and emulsify an aqueous solution containing a protective material polymer having gel-forming properties in microorganisms and water in an oil phase composed of an organic solvent containing a biodegradable polymer as a wall material polymer. Thus, a W / O emulsion in which water droplet fine particles containing a protective material polymer encapsulating microorganisms are dispersed in an organic phase is prepared, added to the aqueous phase and emulsified, and added to the W / O / W emulsion. This is a method of crystallizing the wall material polymer by evaporating and removing the organic solvent by heating or heating / reducing pressure (Patent Document 6).
JP-A-8-116974 JP-A-2005-224160 JP 2005-42037 A JP 2003-88747 A JP 2004-329159 A JP 2006-67956 A

  According to the above three methods according to the proposal of the present inventors, a microcapsule (including a useful microorganism, having an average particle size of a small particle size of several tens of μm, and being physically and chemically stable ( It has been demonstrated that (gel beads) can be produced. However, the first method requires a separate solidification step for preparing polymer beads encapsulating microorganisms, and the manufacturing process becomes longer as a whole. Also, in the other two methods, since the protective material polymer is used in addition to the wall material polymer, there is a problem that the material cost increases accordingly. Further, in any of these methods, since an organic solvent is used and finally the organic solvent is evaporated under heating, there is a problem in terms of work environment.

  In view of the above-mentioned circumstances, the present invention enables mass production of high-performance fine gel beads, in which useful microorganisms are immobilized at high density and high activity, efficiently and at low cost and safely by a very simple method. An object of the present invention is to provide means capable of arbitrarily adjusting the particle size in a wide range and a soil conditioner using the gel beads.

In order to achieve the above object, a method for producing a microbially encapsulated polymer gel bead according to claim 1 of the present invention is the first W / in which an aqueous solution containing a useful microorganism and a water-soluble polymer for gel formation is dispersed in an oil phase. An O emulsion and a second W / O emulsion in which an aqueous solution containing a polyvalent cation that gels the water-soluble polymer for gel formation is dispersed in an oil phase, and one of both W / O emulsions is prepared. Stirring, adding the other W / O emulsion to the one W / O emulsion under stirring and mixing by stirring, thereby causing the droplets of the dispersed phases in both W / O emulsions to collide with each other. It is characterized by producing gel beads in which useful microorganisms are immobilized.

  As a preferred embodiment of the method for producing such microbial-encapsulating polymer gel beads, in the invention of claim 2, the oil phase of the first and second W / O emulsions is a natural fat and oil that does not harm useful microorganisms. In the invention of claim 3, the natural fat or oil in claim 2 is rapeseed oil, in the invention of claim 4 the useful microorganism of the first W / O emulsion is lactic acid bacteria or / and yeast, invention of claim 5 Then, the water-soluble polymer for gel formation of the first W / O emulsion is a water-soluble polymer polysaccharide. In the invention of claim 6, the water-soluble polymer polysaccharide in claim 5 is an alginate. The invention of Item 7 employs a configuration in which a dispersion stabilizer is included in the first W / O emulsion.

  On the other hand, the soil modifying material according to the invention of claim 8 includes microbial inclusion polymer gel beads obtained by the production method according to any of claims 1 to 7. As a preferred embodiment of such a soil modifying material, the invention of claim 9 employs a configuration in which the microorganism-encapsulating polymer gel beads enclose one or both of lactic acid bacteria and yeasts.

  According to the method for producing a microbially encapsulated polymer gel bead according to the invention of claim 1, water droplet particles containing a useful microorganism which is a dispersed phase of the first W / O emulsion and a water-soluble polymer for gel formation, and a second W / O The water droplet particles containing polyvalent cations that are the dispersed phase of the O emulsion collide with each other by stirring and mixing the two W / O emulsions, but the combined droplets are separated by the oil phase that is the continuous phase. The gelation reaction of the polymer proceeds in each droplet unit, and the droplet particles are directly converted into hydrogel beads, and all the useful microorganisms contained in the water droplet particles of the first W / O emulsion leak. Without being incorporated into the gel beads.

  Therefore, the resulting gel beads become fine particles reflecting the particle size as the dispersed phase of the emulsion during stirring and mixing, and the stirring speed, W / O ratio, and dispersion stabilizer are used when preparing both W / O emulsions. Depending on the setting of the concentration of the dispersion stabilizer, the particle size can be arbitrarily controlled in a wide range of 3 μm to 900 μm, and useful microorganisms are immobilized at a high density of 10 to 20 billion / g. it can. In addition, since the gelation reaction proceeds in units of droplets as described above, the generated gel beads have an appropriately rough porous structure that does not prevent the entry and exit of substances required for metabolism of microorganisms contained in the outer shell. Thus, it functions as a high-performance microorganism carrier that can stably hold microorganisms without inactivating them over a long period of time.

  Furthermore, in this production method, the desired microorganism-encapsulating polymer gel beads can be mass-produced at once by simply stirring and mixing the two types of W / O emulsions. Therefore, the production cost is extremely simple in operation and high production efficiency. In addition, there is an advantage that a special material such as a core material or a protective material is not required and the material cost can be reduced accordingly.

  Thus, in such a method for producing a microbe-incorporating polymer gel bead, if natural oils and fats that do not harm useful microorganisms are used in the oil phases of the first and second W / O emulsions as in the invention of claim 2, an organic solvent is used. There are no dangers and hazards like the above, so that it can operate safely and does not cause any problems in terms of environmental conservation. In particular, if rapeseed oil is used as the natural fat and oil as in the invention of claim 3, it is very convenient for the growth of immobilized microorganisms, and rapeseed oil can be obtained at low cost, so that there is an advantage that the material cost can be reduced.

  If lactic acid bacteria or yeasts are used as useful microorganisms as in the invention of claim 4, the obtained microorganism-encapsulating polymer gel beads can be suitably used as a fermentable material. In addition, if a water-soluble polymer polysaccharide as in the invention of claim 5 is used as the water-soluble polymer for gel formation of the first W / O emulsion, particularly an alginate as in the invention of claim 6, More convenient for growth.

  Furthermore, as in the invention of claim 7, by including a dispersion stabilizer in the first W / O emulsion, the emulsification / dispersion state of the emulsion is stabilized, and finally the microbially encapsulated polymer gel beads obtained are obtained. Excellent uniformity.

  On the other hand, since the soil modifier according to the invention of claim 8 includes the microbial inclusion polymer gel beads obtained by the above production method, it is included in the soil by being mixed in the soil or sprayed on the ground surface. Microbial activity such as fermentation by microorganisms can be stably exhibited over a long period of time. And, as in the invention of claim 9, the soil modifying material using one or both of lactic acid bacteria and yeast as microbial inclusion gel beads is very useful for the formation of fermented soil suitable for crop growth. is there.

  Hereinafter, embodiments of the method for producing a microbially encapsulated polymer gel bead according to the present invention including specific operations and materials used in each step will be specifically described.

In the production method of the present invention, as described above, the first W / O emulsion in which an aqueous solution containing a useful microorganism and a gel-forming water-soluble polymer is dispersed in the oil phase, and the gel-forming water in the oil phase. By stirring and mixing with a second W / O emulsion in which an aqueous solution containing a polyvalent cation that gels a soluble polymer is dispersed, the droplets in the dispersed phase in both W / O emulsions collide with each other to create an interior. To produce gel beads on which useful microorganisms are immobilized.

  The water-soluble polymer for gel formation used in the first W / O emulsion is a component that forms the gel structure of the gel beads finally obtained, has compatibility with the target microorganism, and has the ability to form a gel in water. It is not particularly limited as long as it has, but water-soluble high molecular polysaccharides such as alginates such as sodium alginate, κ-carrageenan, and water-soluble synthetic resins such as polyvinylpyrrolidone and polyvinyl alcohol are mentioned. Molecular polysaccharides are preferable in that they are excellent in compatibility with microorganisms such as lactic acid bacteria and yeasts. Among them, alginates are most recommended.

  The useful microorganisms used in the first W / O emulsion may be selected according to the intended use of the gel beads, and are not limited at all. However, lactic acid bacteria and yeasts are particularly recommended for the purpose of fermentation. Moreover, these lactic acid bacteria and yeasts may be used together depending on the use of the gel beads, in addition to using each of them alone.

  Further, the oil phase component forming the continuous phase of the emulsion may be any oil-free component as long as it does not harm the target microorganism, but natural fats and oils such as rapeseed oil are preferred from the viewpoint of compatibility with microorganisms. Rapeseed oil that is particularly excellent in compatibility and available at low cost is recommended.

  In order to prepare the first W / O emulsion, a useful microorganism is added to and mixed with the polymer aqueous solution, and the polymer aqueous solution containing the microorganism is added and mixed in the oil phase to be emulsified. At this time, the polymer concentration of the polymer aqueous solution is preferably about 1 to 5% by weight, and the W / O ratio, that is, the weight ratio of the aqueous solution / oil phase is preferably about 0.1 to 10.

  In the preparation of the first W / O emulsion, it is desirable to contain a dispersion stabilizer in the system in order to make the gel beads finally produced in a stable state. The content of such a dispersion stabilizer in the emulsion varies according to the particle size of the target gel beads, the type and concentration of the water-soluble polymer for gel formation, the W / O ratio, etc., but is 0.1 to 5% by weight. The range is good.

  Examples of the dispersion stabilizer include tri- or distyryl phenyl ether added with polyoxyethylene, alcohol ether added with polyoxyethylene, tween surfactant such as sorbitan oleate added with polyoxyethylene, sorbitan Spun surfactants such as oleate, sodium alkylnaphthalene sulfonate, sodium lauryl sulfate, sodium dodecyl sulfate, sodium lignin, formaldehyde condensate of sodium alkyl naphthalene sulfonate, formaldehyde condensate of sodium phenol sulfonate, isobutylene-anhydrous Maleic acid copolymer, sodium polycarboxylate, sodium alkylbenzene sulfonate, polyglycenol condensed ricinoleate, monolaurate Glycerin, gelatin, gum arabic, casein, dextrin, pectin, sodium alginate, methyl cellulose, ethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, tribasic calcium phosphate, L- glutamic acid dioleyl ribitol and the like. These dispersion stabilizers may be used alone or in combination of two or more.

  The polyvalent cation of the aqueous solution used as the dispersed phase of the second W / O emulsion is a component that gels the water-soluble polymer for gel formation used in the first W / O emulsion, such as calcium or aluminum. Multivalent metal ions are preferred.

  As the oil phase component forming the continuous phase of the emulsion, natural oils and fats are preferable from the viewpoint of compatibility with microorganisms, as in the case of the first W / O emulsion, and rapeseed oil is particularly recommended. The same oil phase component as that of the first W / O emulsion may be used.

  Therefore, in order to prepare the second W / O emulsion, an aqueous solution of a polyvalent metal salt such as calcium chloride or aluminum sulfate may be added and mixed in the oil phase and emulsified. At this time, the concentration of the aqueous solution of the polyvalent metal salt is preferably about 1 to 20% by weight, and the W / O weight ratio of the emulsion is preferably about 0.01 to 1.

  In the production method of the present invention, the first W / O emulsion and the second W / O emulsion described above are stirred and mixed to generate gel beads in which useful microorganisms are immobilized. At this time, the blending ratio (weight) of the second W / O emulsion to the first W / O emulsion is preferably in the range of about 0.1 to 1. The produced gel beads are separated from the oil phase by an appropriate filtration means, washed with water and collected.

The above stirring and mixing is performed by adding the other W / O emulsion to one W / O emulsion under stirring (usually the first W / O emulsion). The stirring and mixing means is not particularly limited, but when a rotary stirring device such as a stirring blade is used, the stirring speed (rotational speed) is preferably set in the range of about 50 to 15000 rpm.

  Thus, if the first W / O emulsion and the second W / O emulsion are stirred and mixed, the droplets of the dispersed phases in both W / O emulsions collide with each other and coalesce. A polyvalent cation acts on the gel-forming polymer to cause a gelation reaction. However, since the droplets are separated by an oil phase that is a continuous phase, the gelation reaction proceeds in units of droplets. The droplet particles are directly converted into water-containing gel beads, and all useful microorganisms contained in the water droplet particles of the first W / O emulsion are incorporated into the gel beads without leakage.

  Therefore, in the production method of the present invention, since the size of the gel beads obtained reflects the particle size as the dispersed phase of the emulsion during stirring and mixing, both W / O emulsions, particularly the first W / O emulsion, are used. The particle size of the gel beads to be generated can be controlled by setting the stirring speed at the time of preparation, W / O ratio, the concentration of the dispersion stabilizer when using the dispersion stabilizer, and the like. That is, the faster the stirring speed, the lower the W / O ratio, and the higher the concentration of the dispersion stabilizer, the smaller the gel beads. Thus, according to the present invention, it has been demonstrated that the particle size of the gel beads can be arbitrarily set in a wide range of 3 μm to 900 μm by adjusting these control factors.

  In addition, according to the production method of the present invention, as described above, the droplets during the stirring and mixing of the first and second emulsions are directly converted into the hydrogel beads and are contained in the water droplet particles of the first W / O emulsion. Since the useful microorganisms that have been taken in are incorporated into the hydrogel beads without omission, the useful microorganisms can be immobilized at a high density of 10 to 20 billion / g. The gel beads thus obtained have a porous structure with an appropriate roughness in the outer shell due to the gelation reaction in units of droplets as described above, thus preventing the entry and exit of substances required for metabolism of the contained microorganisms. Therefore, since the microorganism can be retained without being deactivated for a long period of time, it functions as a high-performance microorganism carrier that continuously exhibits good and stable microorganism activity.

  Furthermore, according to the production method of the present invention, the desired microorganism-encapsulated polymer gel beads that form fine particles can be mass-produced at once by simply stirring and mixing the two types of W / O emulsions. In addition, the manufacturing cost can be reduced with high production efficiency, and no special material such as a core material or a protective material is required for gel formation, and the material cost can be reduced accordingly.

  Such a microbe-encapsulating polymer gel bead can be used in various applications depending on the type of immobilized useful microorganisms, and one suitable application is a soil modifier. That is, the soil modifying material containing the polymer-encapsulating polymer gel beads is stably mixed for a long period of time with a microbial activity such as fermentation by microorganisms encapsulated in the soil by being mixed in the soil or sprayed on the ground surface. Can demonstrate. In particular, according to the soil modifier using microbial encapsulated gel beads containing one or both of lactic acid bacteria and yeast, since these lactic acid bacteria and yeast are gradually released from the gel beads into the soil, Even if there is a lot of soil, it can be gradually converted to a fermented soil suitable for crop growth, and it can be expected to suppress disease and pest damage, improve crop quality and harvesting, and reduce continuous cropping damage.

  In addition, such a soil modifier may consist only of the above-mentioned microorganism-encapsulated polymer gel beads, but together with the gel beads, compost, green manure, grass, rice straw, straw, residue, rice bran, rice husk, ammonium sulfate, etc. May be blended.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to an Example. In the following description,% means weight% (w / w).

Example 1
2% sodium alginate aqueous solution in which lactic acid bacteria (Raccobacilis bulgaricus) are suspended at a rate of 7.7 × 10 ⁸ cells / ml as a first inner aqueous phase, 10% calcium chloride aqueous solution as a second inner aqueous phase, Rapeseed oil in which 0.5% of a dispersion stabilizer (sorbitan monooleate: Span 80 manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved was prepared as an oil phase. Then, 1000 ml of the first inner aqueous phase was added to 5000 ml of the oil phase, and the mixture was stirred at 40 ° C. for 1 hour at a speed of 180 rpm using a stirring blade to prepare a first W / O emulsion. Similarly, a second W / O emulsion was prepared by adding 150 ml of the second inner aqueous phase to 1500 ml of the oil phase and emulsifying at room temperature using a vibration emulsifier. Next, the second W / O emulsion is added to the first W / O emulsion stirred at a speed of 150 rpm with a stirring blade at a liquid temperature of 30 ° C., and the same stirring speed is maintained while maintaining 30 ° C. After stirring and mixing for 15 hours, the produced lactic acid bacteria-encapsulated calcium alginate gel beads were filtered with a Kiriyama funnel, washed with distilled water, and then collected. The average particle size of the obtained gel beads was about 100 μm, and the recovered amount was 498.5 g.

Examples 2-4
Lactic acid bacteria-encapsulated calcium alginate gel beads in the same manner as in Example 1 except that the stirring speed during preparation of the first W / O emulsion was changed to 50 rpm in Example 2, 100 rpm in Example 3, and 250 rpm in Example 4. Manufactured. The average particle size of the obtained gel beads was about 800 μm in Example 2, about 300 μm in Example 3, and about 5 μm in Example 4.

  From the results of Examples 1 to 4, even when all other conditions except the stirring speed at the time of preparation of the first W / O emulsion were all the same, the particle size of the gel beads produced by changing the stirring speed was large. It can be seen that the particle size changes and its particle size varies inversely depending on the stirring speed. Therefore, according to the method of the present invention, the particle size of the gel beads to be generated can be extremely reduced from several μm to about 1 mm by changing the stirring speed at the time of preparing the first W / O emulsion and without changing other conditions. It is clear that it can be easily controlled.

Comparative Example 1
In accordance with the method for producing microbial encapsulated biodegradable microcapsules disclosed in Patent Document 6 (Japanese Patent Laid-Open No. 2006-67956) described above, first, the same lactic acid bacteria as in Example 1 were suspended in the same ratio as the inner aqueous phase. Contains 12.5 ml of 2% aqueous sodium alginate solution, 25 ml of dichloromethane in which 5% polyε caprolactam and 3% sorbitan monooleate are dissolved as the organic phase, 1% polyvinyl alcohol and 30% calcium triphosphate as the outer aqueous phase 600 ml of a slurry mixed with distilled water at a ratio of 10% was prepared. Then, the inner aqueous phase is added to the outer aqueous phase that is being stirred with a magnetic stirrer, and stirred at 5 ° C. for 10 minutes to prepare a W / O emulsion. The W / O emulsion is stirred at 5 ° C. A W / O / W emulsion was prepared by adding to the outer aqueous phase and stirring for 30 minutes. Next, the W / O / W emulsion was heated to 25 ° C. while stirring, stirred at this temperature for 1 hour, further heated to 30 ° C., reduced in pressure to 700 hPa, and stirred for 3 hours, whereby dichloromethane was removed. The lactic acid bacteria inclusion microcapsule was produced by removal. Then, 600 g of 0.1 M hydrochloric acid aqueous solution was added to the system containing the microcapsules, stirred for 10 minutes, filtered through a Kiriyama funnel, washed with distilled water, and then recovered.

[Recovery of lactic acid bacteria]
After 5 g of the gel beads obtained in Example 1 were put into 55 mM trisodium citrate aqueous solution and the gel beads were dissolved by stirring for 5 minutes, this solution was applied to a centrifuge (made by Kokusan Centrifuge Co., Ltd.) at 8000 rpm. Centrifugation was performed to collect lactic acid bacteria. On the other hand, 5 g of the microcapsules obtained in Comparative Example 1 were crushed with a mortar, suspended in physiological saline, and then centrifuged in the same manner as above to collect lactic acid bacteria.

[Activity test of lactic acid bacteria]
Lactic acid bacteria 2 × 10 ⁸ cells recovered from the gel beads in Example 1 and the microcapsules in Comparative Example 1 were added to 803 medium [10% polypeptone, 0.5% yeast extract, 5% glucose, 0.2% lactose, 0.05% Teen 80 (polyoxyethylene sorbitan monooleate manufactured by Wako Pure Chemical Industries, Ltd., 0.1% magnesium sulfate heptahydrate) is added to 100 ml, and this is allowed to stand in an incubator (37 ° C.). The activity of lactic acid bacteria based on lactic acid production was examined by analyzing the conversion rate of glucose to lactic acid after the day by high performance liquid chromatography. As a result, the amount of lactic acid produced by the lactic acid bacteria collected from the microcapsules of Comparative Example 1 was 0.5 mM, whereas the amount of lactic acid produced by the lactic acid bacteria collected from the gel beads of Example 1 was 3 mM. From this result, it is clear that the obstruction to the lactic acid bacteria to be encapsulated is much lower in the gel beads obtained in Example 1 than in the microcapsules obtained in Comparative Example 1.

Claims (9)

A first W / O emulsion in which an aqueous solution containing a useful microorganism and a gel-forming water-soluble polymer is dispersed in an oil phase, and an aqueous solution containing a polyvalent cation that gels the gel-forming water-soluble polymer in the oil phase. A second W / O emulsion in which the W / O emulsion is dispersed, one of the two W / O emulsions is stirred, and the other W / O emulsion is added to the one W / O emulsion under stirring. A method for producing a microbial-encapsulated polymer gel bead characterized in that, by stirring and mixing, droplets of dispersed phases in both W / O emulsions collide with each other to generate gel beads in which useful microorganisms are immobilized.   The method for producing microorganism-encapsulated polymer gel beads according to claim 1, wherein the oil phases of the first and second W / O emulsions are natural fats and oils that do not harm the useful microorganisms.   The method for producing microbial-encapsulated polymer gel beads according to claim 2, wherein the natural fat is rapeseed oil.   The method for producing a microorganism-encapsulating polymer gel bead according to any one of claims 1 to 3, wherein useful microorganisms of the first W / O emulsion are lactic acid bacteria and / or yeasts.   The method for producing microbial-encapsulated polymer gel beads according to any one of claims 1 to 4, wherein the water-soluble polymer for gel formation of the first W / O emulsion is a water-soluble polymer polysaccharide.   The method for producing microbial-encapsulated polymer gel beads according to claim 5, wherein the water-soluble polymer polysaccharide is an alginate.   The method for producing microbial-encapsulated polymer gel beads according to any one of claims 1 to 6, wherein the first W / O emulsion contains a dispersion stabilizer.   A soil modifying material comprising microorganism-encapsulated polymer gel beads obtained by the production method according to any one of claims 1 to 7.   The soil modifying material according to claim 8, wherein the microorganism-encapsulating polymer gel beads enclose one or both of lactic acid bacteria and yeast.