Microorganisms, method for decomposing urethane, method for manufacturing water-absorbing material, and method for manufacturing sound-absorbing material

Abstract

To provide a method for decomposing urethane using novel microorganisms that have a high decomposition capacity for urethane. [Solution] A method for decomposing urethane according to one embodiment of the present invention comprises the step of reacting a material to be treated containing urethane with microorganisms having urethane degrading properties in a culture medium for culturing the microorganisms, wherein the microorganisms having urethane degrading properties belong to the genus Priestia, and the culture medium contains sugars and amino acids.

Description

Technical Field

[0001] The present invention relates to microorganisms, a method for decomposing urethane, a method for producing a water-absorbing material, and a method for producing a sound-absorbing material.

Background Art

[0002] Since polyurethane has a crosslinked structure, it cannot be reused as a material by melting it like a thermoplastic resin. Therefore, it is actually disposed of as thermal recycling or landfill. Currently, in order to avoid this problem, reuse as a material using the decomposition action of environmentally friendly microorganisms, chemical recycling, and biodegradability are being studied in various fields. However, it takes time and effort to find effective bacteria. In addition, chemical recycling and biodegradability also have major technical problems, and there are almost no cases that have led to practical applications.

[0003] As a method for decomposing urethane using the decomposing ability of microorganisms, for example, the methods described in Patent No. 6489542 (Patent Document 1) and Patent No. 6439971 (Patent Document 2) are known. The methods described in these patent documents include a step of pretreating a material to be treated containing urethane with an unsaturated fatty acid such as oleic acid, and allowing a C13a strain (actinomycete) belonging to the genus Streptomyces, which has the ability to decompose urethane, to act on the pretreated material to promote decomposition.

[0004] In particular, Patent Document 2 describes that when the above microorganisms act on independent-foamed urethane, fine cavities are formed in the foam cells. Then, due to the fine cavities generated in the independent-foamed cells, the cells change to a structure in which they are connected. As a result, new properties such as water absorption, water retention, and sound absorption are imparted to the urethane material, and it is a technology for reusing it as a new material (NPORUS (NPORUS is a registered trademark of Nippon Plast Co., Ltd.)).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Patent No. 6489542 [Patent Document 2] Patent No. 6439971 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors have made further improvements to conventional methods for decomposing urethane, and have discovered a decomposition method that simplifies and shortens the decomposition process (patent pending: Japanese Patent Application No. 2023-216798). In this method, the culture conditions for the bacteria were changed from an inorganic salt medium aimed at improving the colonization of bacteria on the treated material (urethane) to an R2A medium containing nutrients. As a result, the growth rate of the urethane bacteria increased, and the morphology of the bacteria during growth changed from the conventional marimo-like form to a finely dispersed suspended form. This made it possible to improve the decomposition of urethane.

[0007] The R2A culture medium contains sugars and amino acids. This method of urethane decomposition eliminates the need for pretreatment with unsaturated fatty acids, and allows for the production of NPORUS with better water absorption and retention properties than conventional materials, even when the decomposition time is reduced from 24 hours to 6 hours. Furthermore, the urethane decomposition cycle was reduced to one-third of the conventional cycle.

[0008] If we can select a bacterial strain that has a higher decomposition rate for urethane, we can further shorten the decomposition time and improve production efficiency, which will contribute to reducing the manufacturing cost of NPORUS.

[0009] Therefore, the present invention aims to provide a method for decomposing urethane using a novel microorganism that has a high decomposition capacity for urethane. [Means for solving the problem]

[0010] A method for decomposing urethane according to one embodiment of the present invention is: The process involves a step of reacting a material to be treated containing urethane with microorganisms having urethane-degrading properties in a culture medium, The microorganism possessing urethane degradation ability is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, This is a method for disassembling urethane. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a method for decomposing urethane using a novel microorganism that has a high decomposition capacity for urethane. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows the results of identifying newly discovered microorganisms capable of degrading urethane. [Figure 2] Figure 2 is a magnified photograph showing the results of the growth state of a newly discovered microorganism with urethane degrading properties. [Figure 3] Figure 3 shows the composition of R2A medium. [Figure 4] Figure 4 is a graph showing the results of investigating the growth rate of the newly discovered Priestia megatherium R1 strain at various temperatures. [Figure 5] Figure 5 is a graph showing the results of an investigation into the optimal decomposition conditions when decomposing urethane using the R1 strain and the Streptomyces C13a strain. [Figure 6] Figure 6 is a graph showing the decomposition rate at various decomposition treatment times when urethane is decomposed by strains R1 and C13a. [Figure 7] Figure 7 shows a graph illustrating the water absorption of treated material decomposed by strains R1 and C13a, as well as untreated material, and a photograph showing the cross-sectional state. [Figure 8] Figure 8 is a photograph showing the state of R1 strain attached to the surface of the treated material. [Figure 9]Figure 9 is a schematic diagram showing various conditions of a novel urethane decomposition process by strain R1. [Figure 10] Figure 10 is a diagram showing the efficiency of the urethane decomposition cycle improved by strain R1.

Mode for Carrying Out the Invention

[0013] <Microorganisms with Urethane Degrading Ability> The inventors of the present invention succeeded in isolating degrading bacteria having a decomposing action on urethane using a standard solution of Impranil (registered trademark) for evaluating the degradability of microorganisms against polyurethane (see Figure 1). That is, as shown in Figure 1, on a kambe inorganic salt medium containing gelatin, yeast extract, and Impranil, cell colonies and decomposition circles derived from Impranil were confirmed. As a result, two types and six strains were isolated.

[0014] Among these, the strain showing the highest decomposing ability against urethane (that is, the one with the largest decomposition circle) was named strain R1 (see Figure 2), and the evaluation of its effectiveness for urethane decomposition was advanced. Regarding the nucleotide sequences of almost the entire length (about 1.5 kbp) of the 16S rRNA of the isolated urethane-degrading bacteria including strain R1, a homology search was performed by BLAST, and the genus and species names were identified. As a result, as shown in Figure 1, strain R1 was a bacterium belonging to Priestia megateruim. This Priestia megateruim strain R1 was deposited on March 1, 2024, with the Patent Microorganisms Depositary, National Institute of Technology and Evaluation under the accession number NITE P-04077.

[0015] Generally, bacteria belonging to Priestia megateruim are rod-shaped Gram-positive bacteria, mainly aerobic spore-forming bacteria, and are found in various habitats. Also, the maximum cell length is 4 μm and the diameter is 1.5 μm, which is quite large as bacteria. The cells are often bound by polysaccharides on the cell wall and exist in pairs and chains.

[0016] The growth rate of the bacteria significantly affects the ability to break down urethane. Therefore, we investigated the growth rate of strain R1 in relation to time. Generally, the growth curve of microorganisms during culture is divided into the induction phase, logarithmic phase, stationary phase, and death phase. The induction phase is a certain period after the start of culture during which microorganisms accumulate the energy necessary for cell division without undergoing cell division in the culture medium. The logarithmic phase is the period during which microorganisms begin to divide and grow, gradually increasing their division rate and growing logarithmically. The stationary phase is the period during which growth stops. The stationary phase is also called the quiescent phase. The death phase is the period after a certain period of the stationary phase has elapsed, during which the number of viable cells begins to decrease, microbial division stops, and a downward trend in the number of viable cells becomes apparent.

[0017] As described above, the R1 strain was cultured in R2A medium, and the relationship between culture temperature and growth rate was investigated. The composition of the R2A medium used is shown in Figure 3. Figure 4 shows graphs illustrating the growth rate of the R1 strain cultured in R2A medium at different culture temperatures of 20°C, 30°C, and 40°C. As shown in Figure 4, when the culture temperature of strain R1 was changed, it was confirmed that the induction period was shortest at 40°C, and the cell count reached its maximum within 6 hours. Since the cell count of conventional Streptomyces C13a strain (actinomycetes) reaches its maximum in R2A medium in 12 hours, the results obtained suggest that using strain R1 can reduce the degradation time.

[0018] Next, we investigated the optimal degradation conditions for urethane degradation using the R1 strain. Specifically, to determine the optimal culture temperature and degradation treatment temperature when urethane degradation is performed in R2A medium using the R1 strain, we measured the urethane degradation rate at temperatures ranging from 30°C to 50°C, respectively. The urethane decomposition rate is calculated by comparing the weight of the urethane (the material being treated) before decomposition begins with the weight of the urethane after decomposition treatment in a liquid culture medium for a certain period of time, and expressing the percentage decrease in the weight of the urethane as a percentage. The definitions of culture temperature and decomposition treatment temperature are as follows. Culture temperature: The temperature at which urethane-degrading bacteria are introduced into the culture medium and allowed to grow. Decomposition treatment temperature: The urethane material to be treated is placed in a culture medium containing proliferated urethane-decomposing bacteria. The temperature at which the material is introduced and decomposed. The degradation time for strain R1 was set to 3 hours. The results are shown in Figure 5. For comparison, the degradation rate when strain C13a was subjected to a 6-hour degradation treatment is also shown.

[0019] As shown in Figure 5, when urethane was decomposed using the R1 strain, the maximum decomposition rate was achieved when both the culture temperature and the decomposition treatment temperature were 40°C. Furthermore, the decomposition time with the R1 strain was 3 hours, which was comparable to the decomposition rate achieved when the C13a strain was decomposed in R2A medium for 6 hours. This suggests that when using the R1 strain to decompose urethane, the decomposition time can be reduced from 6 hours to 3 hours by setting both the culture temperature and the decomposition treatment temperature to 40°C.

[0020] <How to disassemble urethane> A method for decomposing urethane according to an embodiment of the present invention comprises the step of reacting a material to be treated containing urethane with microorganisms having urethane-degrading properties in a culture medium in which such microorganisms are cultured. The microorganisms having urethane-degrading properties used in this case belong to the genus Priestia. The culture medium also contains sugars and amino acids.

[0021] The microorganism belonging to the genus Priestia that has urethane degrading ability is preferably the Priestia megatherium R1 strain, identified by accession number NITE P-04077. By using the Priestia megatherium R1 strain to degrade urethane, the urethane degrading time can be reduced by half compared to when using a known urethane-degrading bacterium (Streptomyces C13a strain).

[0022] The sugars added to the culture medium are not particularly limited and include, for example, soluble starch and glucose. The amino acids added to the culture medium are not particularly limited and include, for example, peptones and casamino acids.

[0023] Examples of culture media that can be used in the urethane decomposition method according to the embodiment of the present invention include R2A medium having the composition shown in Figure 3. R2A medium contains amino acids such as casamino acids and peptones, as well as nutrients such as glucose, which can enhance the growth rate and urethane decomposition ability of urethane-degrading bacteria.

[0024] The material to be treated in the urethane decomposition method according to the embodiment of the present invention is not particularly limited as long as it contains urethane. Examples of materials to be treated include waste (waste liquid) and soil containing urethane, particularly polyurethane. The term "urethane" as used above refers to a compound formed by the dehydration condensation of an amino group and an alcohol group via a carbonyl group, i.e., a carbamic acid ester. In this invention, the urethanes targeted for decomposition include all urethanes having urethane bonds in their molecular structure, from low molecular weights such as ethyl carbamate to polymers such as polyurethane.

[0025] The polyurethanes mentioned above are polymers formed by polymerization through urethane bonds, and are used in paints, adhesives, urethane foams, textile products, shoes, automotive parts, and building materials. Furthermore, polyurethanes come in various forms, from linear to branched, including those containing crosslinks, elastic materials, and foams, and can be broadly classified into ester-based and ether-based types. In this invention, the urethane and polyurethane contained in the material to be decomposed are not particularly limited, but it is desirable to use urethane with relatively large particle sizes so that the process of the material becoming opaque due to its large particle size becoming transparent after adsorption and decomposition by microorganisms can be visually observed. If the material to be treated is too large, such as waste urethane foam, it is preferable to crush it to an appropriate size before allowing the microorganisms to act on it.

[0026] The method for applying the microorganisms to the material to be treated is not particularly limited, and it is sufficient to ensure that the material to be treated and the microorganisms come into contact in the culture medium described above. For example, one method is to add the material to be treated to a culture medium in which the microorganisms are being cultured and continue culturing the microorganisms as is. Alternatively, the material to be treated may be added to a culture medium that does not contain the microorganisms, and then the microorganisms may be newly inoculated into it to start culturing.

[0027] The time for which the microorganisms are applied to the material to be treated is not particularly limited, and should be set so that the urethane is sufficiently decomposed, taking into account the urethane content in the material to be treated and the amount of microorganisms applied. The longer the time the microorganisms are applied, the more the urethane will decompose, but if the time is too long, the cost of decomposing the urethane will increase, so it is preferable to set a moderate time. For example, conventional patent documents 1 and 2 describe allowing microorganisms to act on the material to be treated for several days to several weeks. In contrast, in the urethane decomposition method according to the embodiment of the present invention, the time for which microorganisms are allowed to act on the material to be treated can be limited to about 3 to 6 hours. This makes it possible to stabilize the urethane decomposition ability of microorganisms.

[0028] The temperature at which the microorganisms are applied to the material to be treated should be set to a temperature suitable for microbial growth and urethane decomposition. For example, it can be set to around 20°C to 40°C. The temperature at which the microorganisms are applied to the material to be treated should be appropriately selected depending on the type of microorganism. For example, if the microorganism is Priestia megatherium R1 strain, applying it at 40°C is optimal as it increases the decomposition efficiency.

[0029] In contrast, the methods described in conventional patent documents 1 and 2 involve pre-treating the material to be treated with an unsaturated fatty acid such as oleic acid before allowing microorganisms to act on it. In contrast, the method for decomposing urethane according to the embodiment of the present invention does not require pre-treatment with an unsaturated fatty acid, as will be shown in the examples described later. This difference is thought to stem from the fact that conventional methods make it easier for microorganisms to adsorb onto the urethane material to be treated, and utilize the urethane as a nutrient source, whereas the urethane decomposition method according to the embodiment of the present invention involves growing microorganisms using nutrients contained in the culture medium, and then decomposing the urethane through the action of urethane-degrading enzymes produced in that process.

[0030] The urethane decomposition method according to the embodiment of the present invention eliminates the need for pretreatment of the material to be treated with unsaturated fatty acids, thereby significantly reducing the time and cost required for decomposing the material containing urethane. Naturally, the urethane decomposition method according to the embodiment of the present invention does not preclude the use of pretreatment with unsaturated fatty acids.

[0031] As described above, materials decomposed by microorganisms can be pulverized much more easily than materials before decomposition. Urethane, which has closed cells before microbial action, is difficult to pulverize and requires treatment such as freezing and solidification. In contrast, when microorganisms are applied to the material, microscopic cavities are formed in the cells, creating numerous points that serve as fracture initiation points during pulverization. Therefore, even elastic materials can be easily pulverized at room temperature using a centrifugal pulverizer. After being treated with microorganisms and further crushed to an appropriate size, the treated material can be used as a material for synthesizing new urethane, or as a material for use as a water absorbent or sound absorbent.

[0032] <Method for manufacturing water-absorbing material> A method for producing an absorbent material according to an embodiment of the present invention comprises the step of reacting a material to be treated, which includes foamed urethane having closed cells, with microorganisms having urethane degrading properties in a culture medium for culturing the microorganisms. As the microorganisms having urethane degrading properties, microorganisms belonging to the genus Priestia are used. The culture medium also contains sugars and amino acids. Preferably, the microorganism belonging to the genus Priestia that has urethane degrading properties is the Priestia megatherium R1 strain identified by accession number NITE P-04077. The microorganisms used in the manufacturing method of the water-absorbing material, the culture medium, and the method of applying the microorganisms to the material to be treated can be configured in the same way as the urethane decomposition method described above.

[0033] As described above, in the urethane decomposition method according to the embodiment of the present invention, a water-absorbing material can be produced by using a material to be treated that includes foamed urethane having closed cells. This is because by acting microorganisms on the material to be treated, fine cavities are formed in the closed cells of the foamed urethane, resulting in a structure in which at least some of the cells of the foamed urethane are connected.

[0034] Generally, foamed resins with independent bubbles have bubbles separated by walls, containing air, and gases and liquids cannot pass through them. In contrast, by treating them with microorganisms, at least some of the bubbles become connected by microscopic cavities of a few microns (1 μm to 5 μm), allowing them to absorb liquids such as water. At this time, the liquid is absorbed into the connected bubbles by capillary action. The absorbed liquid is then less likely to be released due to surface tension. As a result, materials treated with microorganisms have improved water absorption and water retention, making them usable as absorbent materials.

[0035] The water-absorbing material obtained in this way can be used, for example, in planters for growing plants or as a humidity control material. Due to its excellent water retention properties, it is preferable for use in plant cultivation and can also be applied to greening rooftops of buildings. Furthermore, the treated material after microorganism treatment can be used as an absorbent material in its original state, or it can be molded into a desired shape. To process it into a desired shape, for example, a binder such as an isocyanate-based prepolymer can be added to the treated material after microorganism treatment, or its pulverized form, and then heated and pressed while steam is blown onto it. The treated material after microorganism treatment can also be finely pulverized. Therefore, by using finely pulverized material, it is possible to process it into more complex shapes, enabling its application in a wide range of fields.

[0036] <Method for manufacturing sound-absorbing materials> A method for producing sound-absorbing material according to an embodiment of the present invention comprises the step of reacting a material to be treated, which includes foamed urethane having closed cells, with microorganisms having urethane-degrading properties in a culture medium for culturing the microorganisms. As the microorganisms having urethane-degrading properties, microorganisms belonging to the genus Priestia are used. The culture medium also contains sugars and amino acids. Preferably, the microorganism belonging to the genus Priestia that has urethane-degrading properties is the Priestia megatherium R1 strain, which is identified by accession number NITE P-04077. The microorganisms used in the manufacturing method of sound-absorbing materials, the culture medium, and the method of applying the microorganisms to the material to be treated can be configured in the same way as the aforementioned method for decomposing urethane.

[0037] As described above, in the urethane decomposition method according to the embodiment of the present invention, sound-absorbing material can be manufactured by using a material to be treated that includes foamed urethane having closed cells. This is because by acting microorganisms on the material to be treated, fine cavities are formed in the closed cells of the foamed urethane, resulting in a structure in which at least some of the cells of the foamed urethane are connected.

[0038] Generally, the sound-absorbing effect of sound-absorbing materials is achieved by absorbing sound vibration energy and converting it into thermal energy. As described above, the treated material after being treated with microorganisms can be easily crushed into powder. Furthermore, the powdered material itself is elastic and easily absorbs energy, and because it is finely ground, the powder itself vibrates at a macroscopic level. It is thought that the synergistic effect of these two phenomena results in an excellent sound-absorbing effect.

[0039] The sound-absorbing material obtained in this way can be preferably used as a sound-absorbing and heat-insulating material for, for example, refrigerators and vending machines. Furthermore, similar to the water-absorbing materials obtained as described above, the treated material after microorganism action can be used as a sound-absorbing material in its original state, or it can be molded into a desired shape before use.

[0040] The microorganisms according to the embodiments of the present invention include the following embodiments. (1) Belonging to the genus Priestia, possessing urethane decomposability, Microorganisms. (2) The microorganism is the Priestia megatherium R1 strain identified by accession number NITE P-04077. The microorganisms described in (1) above.

[0041] The method for decomposing urethane according to an embodiment of the present invention includes the following embodiments. (3) The process involves a step of reacting a material to be treated containing urethane with microorganisms having urethane-degrading properties in a culture medium, The microorganism possessing urethane degradation ability is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, How to disassemble urethane. (4) The microorganism belonging to the genus Priestia is the Priestia megatherium R1 strain identified by accession number NITE P-04077. The method for disassembling urethane as described in (3) above. (5) The sugars include soluble starch and glucose. The method for disassembling urethane as described in (3) or (4) above. (6) The amino acids are amino acids that include peptones and / or casamino acids. The method for disassembling urethane as described in (3) or (4) above.

[0042] A method for manufacturing a sound-absorbing material according to an embodiment of the present invention includes the following embodiments. (7) The process involves a step of reacting a material to be treated, which includes foamed urethane having closed cells, with microorganisms having urethane degrading properties in a culture medium, The microorganism possessing urethane degradation ability is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, A method for manufacturing absorbent materials. (8) The microorganism belonging to the genus Priestia is the Priestia megatherium R1 strain identified by accession number NITE P-04077. A method for producing the water-absorbing material described in (7) above.

[0043] A method for producing a water-absorbing material according to an embodiment of the present invention includes the following embodiments. (9) The process involves a step of reacting a material to be treated, which contains foamed urethane having closed cells, with microorganisms having urethane degrading properties in a culture medium, The microorganism possessing urethane degradation ability is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, A method for manufacturing sound-absorbing materials. (10) The microorganism belonging to the genus Priestia is the Priestia megatherium R1 strain identified by accession number NITE P-04077. A method for manufacturing the sound-absorbing material described in (9) above. [Examples]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0045] [Example 1] (Material to be treated) The material used for processing was waste foamed polyurethane, which had been used in automobile steering systems, crushed into pieces approximately 5 mm square. The waste polyurethane foam was crushed using a cutting mill SM300 manufactured by Verder Scientific Co., Ltd. (formerly Lecce Co., Ltd.). (microorganisms) We used a microorganism (strain: Priestia megatherium R1) identified under accession number NITE P-04077 as having the ability to decompose urethane. (culture medium) We used R2A medium "Daigo" manufactured by Shiotani MS Co., Ltd. (distributed by Fujifilm Wako Pure Chemical Corporation) (with the composition shown in Figure 3). (Decomposition of urethane) Priestia megatherium strain R1 was inoculated into 100 mL of R2A medium and cultured by shaking to obtain a preculture medium. The preculture conditions for strain R1 were 40°C, 140 rpm, and 1 day. 1 mL of the pre-culture solution of the R1 strain prepared as described above and the sample to be treated were added to 100 mL of new R2A medium, and the culture was performed at 40°C and 140 rpm for 6 hours. After 2, 4, and 6 hours, the treated materials were washed and dried, and their weight was measured. The decomposition rate was evaluated by comparing the weight of each material to the weight of the treated material before microbial action. The results are shown in Figure 6.

[0046] [Comparative Example 1] Streptomyces C13a was used as the microorganism capable of degrading urethane. The urethane was degraded in the same manner as in Example 1, except that the pre-culture was performed at 40°C and 140 rpm for 1 day, and the urethane was degraded at 40°C and 140 rpm for 6 hours. After 2, 4, and 6 hours, the treated materials were washed and dried, and their weight was measured. The decomposition rate was evaluated by comparing the weight of each material to the weight of the treated material before microbial action. The results are shown in Figure 6.

[0047] As shown in Figure 6, the R1 strain and the C13a strain showed almost the same degradation rate for the first two hours, but after two hours, the R1 strain showed a higher degradation rate. This indicates that the R1 strain has a higher decomposition rate.

[0048] [Example 2] (Water absorption test) The material properties (water absorption) were confirmed using the decomposed treated material obtained in Example 1 as follows. For comparison, water absorption tests were also performed in the same manner on a treated material decomposed using the C13a strain (Comparative Example 1) and an untreated material (crushed foamed urethane). First, the treated material that was decomposed in Example 1 was treated for 3 hours, and the treated material that was decomposed in Comparative Example 1 was treated for 6 hours, after which the bacterial solution was discarded and the treated material was rinsed with distilled water. The untreated material was also rinsed with distilled water in the same manner. Then, each material was ultrasonically cleaned with 99% ethanol. After that, each material was washed with distilled water and then thoroughly dried (overnight) at 40°C. The dried treated materials obtained as described above were mixed with a binder, which is an adhesive component. A water-curing isocyanate prepolymer (manufactured by Token Resin Co., Ltd.) was used as the binder. Then, a molded product measuring 30 cm in length, 30 cm in width, and 5 cm in thickness was produced by press molding while passing steam through the mixture. A steam press was used for press molding. Three test specimens, each approximately 25 mm thick, 25 mm wide, and 25 mm long, were cut from each molded product, and their dimensions were measured to the nearest 0.1 mm. After drying each test specimen at 100°C for 24 hours, they were immersed in a container of pure water at room temperature, completely submerged 30 mm below the water surface. The water was stirred slowly every few hours, and the specimens were allowed to absorb water for 24 hours. After 24 hours, the specimens were removed, placed on a sieve inclined at approximately 45° from the vertical, and left for 30 seconds. The mass of each specimen was then measured to the nearest 0.01 g. This was defined as the water absorption amount, converted to a value per liter, and the average of the three values ​​was calculated for evaluation. The results of the water absorption test are shown in Figure 7.

[0049] As shown in Figure 7, the treated material decomposed using strain R1 showed an 8% improvement in water absorption compared to the treatment using strain C13a. Furthermore, it was confirmed that using strain R1 allowed for the formation of micropores in the urethane foam cells in just 3 hours, half the time required when using strain C13a, demonstrating sufficient decomposition.

[0050] (Cross-sectional observation of the treated material) The cross-sectional state of the treated material after decomposition and the untreated material obtained in Example 1 and Comparative Example 1 was observed using a scanning electron microscope (SEM). The results are shown in Figure 7. Figure 8 shows a magnified photograph of the cross-sectional state of the treated material after decomposition obtained in Example 1.

[0051] As shown in Figure 7, after treatment with urethane-degrading microorganisms, the treated material showed the formation of micropores with diameters of approximately 1 μm to 10 μm on the walls of independent cells. Furthermore, these micropores appeared to penetrate into the interior of the foam cells. Such micropores were not observed in the untreated material (that had not been treated with any microorganisms). Thus, when the treated material was decomposed while culturing the R1 strain using R2A medium, the formation of micropores was confirmed even without pretreatment with unsaturated fatty acids and with a decomposition time of 3 hours. Therefore, it can be said that this method has a urethane decomposition effect equivalent to or better than that of the conventional methods described in Patent Documents 1 and 2. Furthermore, it was confirmed that the R1 strain of bacteria was adhering to the walls of the foam cells of the treated material after the decomposition treatment. From this, it is thought that the improved adsorption to urethane when using the R1 strain compared to the conventional C13a strain may be a factor in the improved urethane decomposition ability. As described above, it was confirmed that when using the R1 strain, properties superior to those of the conventional NPORUS (registered trademark) can be obtained even with a 3-hour treatment.

[0052] As described above, it was confirmed that using the novel urethane-degrading bacterium, Priestia megatherium R1 strain, shortens the urethane degradation time compared to using the conventional Streptomyces C13a strain. Figure 9 shows the various conditions of the novel urethane degradation process using strain R1. Figure 10 shows the efficiency of the urethane degradation cycle improved by strain R1. As shown in Figures 9 and 10, when using the R1 strain, the decomposition time is reduced from 6 hours to 3 hours compared to when using the C13a strain. Even when combined with other processes such as primary crushing (0.5 hours) and washing (1 hour), the urethane decomposition cycle can be shortened by 40%. This is expected to significantly streamline the manufacturing of NPORUS.

Claims

1. It belongs to the genus Priestia and has urethane decomposing properties. Microorganisms.

2. The aforementioned microorganism is Priestia megatherium strain R1, identified by accession number NITE P-04077. The microorganism described in claim 1.

3. The process involves a step of reacting a material to be treated containing urethane with microorganisms having urethane-degrading properties in a culture medium, The microorganism having urethane degrading properties is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, How to disassemble urethane.

4. The microorganism belonging to the genus Priestia is Priestia megatherium strain R1, identified by accession number NITE P-04077. The method for decomposing urethane according to claim 3.

5. The aforementioned sugars include soluble starch and glucose. The method for decomposing urethane according to claim 3 or 4.

6. The aforementioned amino acids are amino acids containing peptones and / or casamino acids. The method for decomposing urethane according to claim 3 or 4.

7. The process involves a step of reacting a material to be treated, which includes foamed urethane having closed cells, with microorganisms having urethane degrading properties in a culture medium, The microorganism having urethane degrading properties is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, A method for manufacturing absorbent materials.

8. The microorganism belonging to the genus Priestia is Priestia megatherium strain R1, identified by accession number NITE P-04077. A method for producing a water-absorbing material according to claim 7.

9. The process involves a step of reacting a material to be treated, which includes foamed urethane having closed cells, with microorganisms having urethane degrading properties in a culture medium, The microorganism having urethane degrading properties is a microorganism belonging to the genus Priestia. The culture medium contains sugars and amino acids, A method for manufacturing sound-absorbing materials.

10. The microorganism belonging to the genus Priestia is Priestia megatherium strain R1, identified by accession number NITE P-04077. A method for manufacturing sound-absorbing material according to claim 9.

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