JPH10108670A - Bacteria capable of decomposing polylactate resin and microbial decomposition of polylactate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain Staphylococcus hominis (FERM P-15867) capable of decomposing polylactate resin without exhausting gases in contrast to the incineration treatment, saving the time compared with land disposal and having extremely high value from the viewpoint of waste processing. SOLUTION: Staphylococcus hominis (FERM P-15867) or Staphylococcus epidermidis (FERM P-15868) capable of decomposing a polylactate resin is separated from the soil collected in the Tsukuba City, Ibaraki Prefecture, Japan.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for decomposing a polylactic acid resin by a novel biological treatment method and a microorganism having a resolution.

[0002]

2. Description of the Related Art Recently, the treatment of plastic waste has become a problem. The main treatment methods are incineration and landfill, but incineration has problems such as promotion of global warming, and landfill has problems such as reduction of landfills. In addition, polylactic acid resins are being developed for various uses as next-generation plastics, and it is fully expected that in the near future, waste problems will be highlighted in the same manner as plastics currently used.

[0003] Polylactic acid resin is a polymer that hydrolyzes in an aqueous system, and is currently used as a medical or pharmaceutical material. However, since it can be synthesized from renewable resources such as starch through lactic acid fermentation, environmental degradation occurs. It is attracting attention as a material for biodegradable plastics that can replace difficult general-purpose plastics. Depending on the type of the constituent monomer, the polylactic acid resin includes a poly-L-lactic acid, a poly-D-lactic acid, a poly-DL-lactic acid, or a copolymer with another polymer.

[0004]

It is known that hydrolysis of polylactic acid resin is promoted by an enzyme. However, to date, microorganisms for directly biologically degrading polylactic acid resin and its waste and a method for degrading the microorganisms have been disclosed by actinomycetes Amycolatopsismediter.
ranei (FERM P-14921) and degradation using this fungus only.

Accordingly, an object of the present invention is to provide a microorganism for directly biologically decomposing a polylactic acid resin and a plastic containing the same, and a method therefor.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, found a bacterium having an excellent polylactic acid decomposing activity by microbiological means, and completed this research. Reached.

That is, according to the present invention, there is provided a method for decomposing a polylactic acid resin, which comprises decomposing polylactic acid with bacteria. In addition, a polylactic acid resin and bacteria belonging to the genus Staphylococcus are contained in a medium containing inorganic salts. A method for decomposing a polylactic acid resin, which comprises adding and decomposing the lactic acid resin.
RM P-15867, FERM P-15868). The present invention further provides a method for decomposing the polylactic acid resin, wherein the culture conditions are pH 4.0 to 10.0 and the temperature is 10 to 60 ° C.

The term "polylactic acid resin" as used in the present invention refers to a polymer containing lactic acid as a main component, and a polylactic acid homopolymer such as poly-L-lactic acid and poly-D-lactic acid, and a poly-L / D-lactic acid. Polymers, and polylactic acid copolymers obtained by copolymerizing these with other polymers, and blends of the above polymers with other component polymers, wherein the weight ratio of the lactic acid component in the polymer is 10% or more.

The present invention makes it possible to decompose a polylactic acid resin under aerobic conditions by causing bacteria having the resolution thereof to decompose the polylactic acid resin.

Microorganisms having polylactic acid degrading activity are bacteria. Examples of the bacteria include those shown in Tables 1-1 to 1-4.

[0011]

[Table 1-1]

[0012]

[Table 1-2]

[0013]

[Table 1-3]

[0014]

[Table 1-4] Among them, bacteria belonging to Staphylococcus are particularly preferred, and their isolation and acquisition were performed by the following method.

The present inventors adopted soil from Tsukuba City, Ibaraki Prefecture, and isolated and obtained aerobic microorganisms that decompose polylactic acid resin through the operation described in detail below.

1 to 1 liter of the basic medium shown in Table 2 below
000 mg of polylactic acid resin was emulsified to prepare an agar plate medium containing 1.5% agar. 1g of each sample is 5m
are suspended in sterile water l, diluted in 10 to 10 ^2,
0.2 ml was applied to the prepared medium. The cultivation was performed in an incubator at 30 and 50 ° C. Among the colonies grown on the medium, those having a transparent area formed around the colonies were used as polylactic acid resin-decomposing bacteria, and the colonies were picked up with a platinum loop to perform an isolation operation.

[0017]

[Table 2] From the colonies that grew on the medium, the colonies of the sample that had a transparent area around them were picked up with a platinum loop, purely separated using a similar medium, and then used to degrade the polylactic acid resin.
hylococcus sp. (FERM P-15867 and FER
MP-15868) could be obtained.

The isolate was used as Nutrient Broth.
The cells were inoculated to form colonies, and the properties of the obtained cells were observed with a microscope, and the biochemical properties were examined. The results are shown in Tables 3 and 4 below.

[0019]

[Table 3]

[Table 4] The results shown in Tables 3 and 4 were compared with Bergey's Manual of Dete
When referred to the 9th edition of rminative Bacteriology, etc., the above strains are similar in properties to those of the genus Staphylococcus, and therefore FERM P-15867 is not compatible with Staphylococcus h.
ominis and FERM P-15868 are Staphylococcus
epidermidis was shown.

The strain used in the present invention is Staphylococcus
This strain (FER) is used for treating polylactic acid resin.
It is desirable to use a group of microorganisms containing MP-15867 and FERM P-15868).

The present strain or a microorganism group containing the present strain may be a lyophilized powder, a tablet obtained by mixing the powder with various vitamins and minerals and necessary nutrients, and then tableting, if necessary, a basic medium described above. It is provided for the treatment of a polylactic acid resin in the form of a culture solution grown and cultured therein.

The basal medium used in the cultivation of the present invention uses, for example, ammonium sulfate, ammonium phosphate, ammonium carbonate, etc. as a nitrogen source, and other inorganic salts such as potassium-potassium phosphate, dipotassium phosphate, magnesium sulfate, and the like. Sodium chloride, ferrous sulfate,
A commonly used culture source such as sodium molybdate, sodium tungstate and manganese sulfate is used, and its pH is 4.0 to 10.0, preferably 5.0.
８8.0. The culture temperature is 10 to 60 ° C, preferably 30 to 50 ° C.

The biological decomposition treatment of the polylactic acid of the present invention comprises
The above-described basic medium in the culture tank, polylactic acid resin to be treated, powder containing the above-mentioned strains and bacterial groups, it is desirable to perform by adding a tablet, a culture solution, the above-mentioned strain is activated sludge and It may be incorporated in compost. The amount of polylactic acid resin added to the basic medium was 0.0
1% to 10% by weight is desirable. The amount of microorganisms to be added may be extremely small, but is preferably 0.01% by weight or more based on the polylactic acid resin, since the amount of addition does not affect the processing time.

[0024]

【Example】

(Experimental Example 1) 1000 mg per liter of the basic medium shown in Table 2
An agar plate medium containing 1.5% agar emulsified with a polylactic acid resin (Mw: 1.89 × 10 ⁵ ) was prepared.
MP-15867 strain was inoculated and cultured at 30 ° C. for 2 weeks. As a result, as shown in FIG. 1, a transparent region was confirmed around the colony with the colony formation of the FERM P-15867 strain on the emulsified and cloudy agar plate medium.

(Experimental Example 2) Powdered polylactic acid resin (Mw: 1.89 × 1) was added to 100 ml of the basic medium shown in Table 2.
( ⁵ ) was added as a carbon source to prepare 100 mg, and FERM P-15868 strain was inoculated.
Cultured for a week. As shown in FIG. 2, the results were obtained on FERM P-15868 on an emulsified and cloudy agar plate medium.
With the colony formation of the strain, a transparent region was confirmed around the colony.

(Experimental Example 3) Powdered polylactic acid resin (Mw: 1.89 × 1) was added to 100 ml of the basic medium shown in Table 2.
0 ⁵⁾ was prepared which was 100mg added as a carbon source, inoculated with FERM P-15868 strain, two weeks powder processed polylactic acid resin at 50 ° C., and cultured at 180rpm rotary shaker. Recovery weight of polylactic acid resin due to decomposition of added powdered polylactic acid resin (chloroform extraction)
Was measured. The results, as shown in Table 5, show that the weight of the recovered polylactic acid resin was about 1 in comparison with the control without inoculation of the strain, where the weight hardly changed before and after the culture.
It decreased by 0%.

(Experimental Example 4) An agar plate medium containing the basic medium shown in Table 2 was prepared, and a polylactic acid resin (Mw: 1.89 × 1) was prepared.
0 ⁵ ) was processed into FERM P-1586
Immersed in a suspension of 8 strains, and immersed in a plate medium;
Cultured for 0 days. Wash the film pieces after culturing with sterile water,
Air-dry and scan with a scanning electron microscope JST-T220 (manufactured by JEOL Ltd.) at a magnification of 1,000 times and an accelerating voltage of 15 kV.
As a result, it was confirmed that the surface became rough as shown in FIG.

From the above, it has been clarified that the isolated strain can degrade a high molecular weight polylactic acid resin. FIG. 1 shows the state of a colony decomposing a polylactic acid resin in an agar plate medium by FERM P-15867 after two weeks of culture. Figure 2 shows FERM P-1586
8 shows the state of the colony degrading the polylactic acid resin in the agar plate medium after two weeks of culturing according to No. 8.

FIG. 3A shows the inoculation of FERM P-15868, and FIG. 2B shows the inoculation of FERM P-15868.

[Table 5]

[0030]

The method for decomposing a polylactic acid resin according to the present invention is a method for treating polylactic acid resin waste, which does not generate exhaust gas unlike conventional incineration, and saves much time as compared with landfill treatment. It is a technology and a very valuable way of treating waste. Also, by using the treatment method of the present invention in a composting facility, it is possible to convert polylactic acid resin into useful substances such as organic acids and compost.

[Brief description of the drawings]

FIG. 1. Two weeks after culture of colonies degrading polylactic acid resin in agar medium by FERM P-15867.

FIG. 2 shows the state of a colony degrading a polylactic acid resin in an agar medium after two weeks of culture by FERM P-15868.

FIG. 3 shows the decomposition of a film by FERM P-15868, and the surface structure of the film after 40 days of culture.

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[Procedure amendment]

[Submission date] January 16, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a micrograph of a colony degrading a polylactic acid resin in an agar medium using FERM P-15867 after 2 weeks of culture.

FIG. 2 is a micrograph of a colony degrading a polylactic acid resin in an agar medium using FERM P-15868 after 2 weeks of culture.

FIG. 3 shows decomposition of a film by FERM P-15868, and is a micrograph of the film after 40 days of culture.

[Document name] Notification of change of accession number

[Submission date] October 9, 1997

[Name of the former depositary institution] Institute of Biotechnology, Industrial Technology Institute

[Old Accession Number] FERM P-15867

[Name of the new depositary organization] Institute of Biotechnology, Industrial Technology Institute

[New accession number] FERM BP-6108

[Document name] Notification of change of accession number

[Name of the former depositary institution] Institute of Biotechnology, Industrial Technology Institute

[Old Accession Number] FERM P-15868

[Name of the new depositary organization] Institute of Biotechnology, Industrial Technology Institute

[New accession number] FERM BP-6109

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // (C12N 1/20 C12R 1:44) (C12N 1/20 C12R 1:45) (C12S 13/00 C12R 1:44) (72) Inventor Hiroyuki Ashiya 3- 17-1 Azuma, Tsuzuba-shi, Ibaraki Pref., Shimadzu Corporation, Tsukuba Branch (72) Inventor Naoko Nagai 3- 17-1 Azuma, Azuma, Tsukuba-shi, Ibaraki Pref., Tsukuba Branch, Shimadzu Corporation

Claims (9)

[Claims] 1. Staphylo having the resolution of polylactic acid resin
coccus hominis (FERM P-15867). 2. Staphylo having the resolution of polylactic acid resin
coccus epidermidis (FERM P-15868). 3. A method for decomposing a polylactic acid resin, comprising decomposing the polylactic acid resin with bacteria. 4. The bacterium according to claim 3, wherein the bacterium is Staphylococcus.
The method for decomposing a polylactic acid resin according to claim 3, which is a bacterium belonging to the genus. 5. The method according to claim 4, wherein the bacterium belonging to the genus Staphylococcus is at room temperature. 6. The method according to claim 4, wherein the bacteria belonging to the genus Staphylococcus are heat-resistant. 7. The bacterium according to claim 3, wherein the bacterium is Staphylococcus.
The method for decomposing a polylactic acid resin according to claim 3, which is hominis or Staphylococcus epidermidis. 8. The method for decomposing a polylactic acid resin according to claim 7, wherein the Staphylococcus hominis according to claim 7 is at room temperature. 9. The Staphylococcus epidermidis of claim 7
8. The method for decomposing a polylactic acid resin according to claim 7, wherein the resin is heat-resistant.