JP2023137115A - Biodegradable plastic decomposition control method, biodegradable plastic decomposition suppressing agent, biodegradable plastic decomposition promoter, biodegradable plastic decomposition suppression method, biodegradable plastic decomposition promotion method, and biodegradable plastic decomposition evaluation method - Google Patents

Abstract

To provide a biodegradable plastic decomposition control method enabling control of suppression and promotion of decomposition performance of biodegradable plastic.SOLUTION: The decomposition of biodegradable plastics is controlled by adding saccharides or nutritional salts to biodegradable plastic. It is also preferable to add plastic-degrading microorganisms and saccharides or nutritional salts to the biodegradable plastic. At this time, the decomposition of the biodegradable plastic is suppressed by adding saccharides to the biodegradable plastic. Further, by adding the above-mentioned nutritional salts to the biodegradable plastic, the decomposition of the biodegradable plastic is promoted. As the saccharides, it is preferable to use monosaccharides and/or disaccharides. Further, as the nutrient salts, it is preferable to use nitrogen and/or phosphorus.SELECTED DRAWING: Figure 2

Description

The present invention relates to a technology for decomposing plastics, and particularly to a technology for decomposing plastics using microorganisms.

Marine pollution caused by plastic has become a problem in recent years. In other words, most of the plastic that leaks into the environment flows into rivers and eventually ends up in the ocean, which has a huge negative impact on the marine ecosystem. The impact of plastics on the oceans is also harming industry, causing huge economic losses. Plastic becomes microplastic particles in the ocean, but general plastics do not naturally decompose even if they become small, and are thought to remain for hundreds of years or more.

Under these circumstances, the use of biodegradable plastics, which can naturally decompose, is becoming more widespread in place of conventional plastics.
However, even if biodegradable plastics are used, it takes time for them to naturally decompose, and the plastics remain in the ocean for a long time, making it difficult to solve the problem of ocean pollution using only biodegradable plastics. .

Japanese Patent Application Publication No. 11-113385 Japanese Patent Application Publication No. 2003-221461

By the way, while it is desirable for biodegradable plastics to be quickly decomposed after use, it is important to prevent them from being degraded and damaged during use.
For example, when biodegradable plastic is used as agricultural mulch, it must not break down and fall apart during the growing of crops.
Furthermore, biodegradable plastics may not decompose easily depending on the environmental conditions. In such cases, it is desirable to be able to control the rapid decomposition of biodegradable plastics.

That is, biodegradable plastics are desirably prevented from decomposing during use, and desirably decomposed quickly after use.
However, no technology has been known so far for suppressing or promoting the decomposition of biodegradable plastics depending on the situation.

Therefore, the present inventors conducted extensive research and found a method for controlling the suppression and acceleration of the decomposition performance of biodegradable plastics, thereby completing the present invention.
Specifically, by adding sugars to biodegradable plastics, they succeeded in suppressing the decomposition of biodegradable plastics.
Furthermore, by adding nutrient salts to biodegradable plastics, we succeeded in promoting the decomposition of biodegradable plastics.

Here, Patent Document 1 and Patent Document 2 describe techniques for improving the biodegradability of aliphatic polyester.
However, these documents neither describe nor suggest the use of sugars or nutritional salts to control the decomposition of biodegradable plastics.

The present invention has been made in view of the above circumstances, and provides a biodegradable plastic decomposition control method, a biodegradable plastic decomposition inhibitor, and a biodegradable plastic decomposition inhibitor capable of controlling the suppression and acceleration of the decomposition performance of biodegradable plastics. The purpose of the present invention is to provide a decomposition accelerator, a method for suppressing decomposition of biodegradable plastics, a method for promoting decomposition of biodegradable plastics, and a method for evaluating decomposition of biodegradable plastics.

In order to achieve the above object, the biodegradable plastic decomposition control method of the present invention is a method of controlling the decomposition of the biodegradable plastic by adding sugars or nutritional salts to the biodegradable plastic.
Moreover, it is also preferable that the biodegradable plastic decomposition control method of the present invention is a method in which plastic-degrading microorganisms and sugars or nutritional salts are added to the biodegradable plastic.

Further, it is preferable that the biodegradable plastic decomposition control method of the present invention is a method of suppressing the decomposition of the biodegradable plastic by adding sugars to the biodegradable plastic.
Moreover, it is also preferable that the biodegradable plastic decomposition control method of the present invention uses a monosaccharide and/or a disaccharide as the saccharide.
Furthermore, it is also preferable that the biodegradable plastic decomposition control method of the present invention uses glucose or a sugar composition containing glucose as the saccharide.

Furthermore, the biodegradable plastic decomposition control method of the present invention is preferably a method of accelerating the decomposition of the biodegradable plastic by adding nutrients to the biodegradable plastic.
Moreover, it is also preferable that the biodegradable plastic decomposition control method of the present invention uses nitrogen and/or phosphorus as the nutrient salts.

Moreover, the decomposition inhibitor for biodegradable plastics of this embodiment has a structure in which saccharides are used as an active ingredient.
Moreover, it is also preferable that the decomposition inhibitor for biodegradable plastics of this embodiment has a structure in which active ingredients include saccharides and plastic-degrading microorganisms.

Moreover, the decomposition accelerator for biodegradable plastics of this embodiment is configured to contain nutritional salts as an active ingredient.
Moreover, it is also preferable that the decomposition accelerator for biodegradable plastics of this embodiment has a structure in which the active ingredients are nutrient salts and plastic-degrading microorganisms.

Furthermore, the method for suppressing decomposition of biodegradable plastics according to the present embodiment is a method of suppressing the decomposition of biodegradable plastics by adding sugars to the biodegradable plastics in a container or in the environment.
Furthermore, the method for promoting decomposition of biodegradable plastics of the present embodiment promotes the decomposition of biodegradable plastics by adding nutrients to the biodegradable plastics in a container, in the environment, in artificial seawater, or in natural seawater. There is a method.

Moreover, the biodegradable plastic decomposition evaluation method of this embodiment is a method of evaluating the degradability of the biodegradable plastic by adding sugars to the biodegradable plastic in a container or in the environment.
Furthermore, the biodegradable plastic decomposition evaluation method of this embodiment evaluates the degradability of the biodegradable plastic by adding nutrients to the biodegradable plastic in a container, in the environment, in artificial seawater, or in natural seawater. There is a way to do that.

According to the present invention, there is provided a biodegradable plastic decomposition control method capable of controlling suppression and promotion of the decomposition performance of biodegradable plastics, a biodegradable plastic decomposition inhibitor, a biodegradable plastic decomposition promoter, and a biodegradable plastic decomposition promoter. It becomes possible to provide a method for suppressing the decomposition of biodegradable plastics, a method for promoting the decomposition of biodegradable plastics, and a method for evaluating the decomposition of biodegradable plastics.

FIG. 3 is a diagram showing the results of a decomposition suppression test 1-1 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 2 is a diagram showing the results of a decomposition suppression test 1-2 using a biodegradable plastic decomposition control method according to an embodiment of the present invention. FIG. 3 is a diagram showing the results of a decomposition suppression test 1-3 using the biodegradable plastic decomposition control method according to the embodiment of the present invention. FIG. 7 is a diagram showing the results of a decomposition suppression test 2-1 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 3 is a diagram showing the results of a decomposition suppression test 2-2 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 3 is a diagram showing the results of a decomposition suppression test 2-3 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 3 is a diagram showing the results of a decomposition suppression test 3-1 using the biodegradable plastic decomposition control method according to the embodiment of the present invention. FIG. 7 is a diagram showing the results of a decomposition suppression test 3-2 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 7 is a diagram showing the results of a decomposition suppression test 3-3 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 4 is a diagram showing the results of a decomposition acceleration test 4-1 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. FIG. 4 is a diagram showing the results of a decomposition acceleration test 4-2 using the biodegradable plastic decomposition control method according to the embodiment of the present invention. FIG. 4 is a diagram showing the results of a decomposition acceleration test 4-3 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention. It is a figure which shows the measured value and the theoretical value of the esterase activity of the decomposition acceleration test 4 by the biodegradable plastic decomposition control method etc. which concern on embodiment of this invention. FIG. 5 is a diagram showing the results of a decomposition acceleration test 5-1 using the biodegradable plastic decomposition control method etc. according to the embodiment of the present invention. FIG. 7 is a diagram showing the results of a decomposition acceleration test 5-2 using the biodegradable plastic decomposition control method and the like according to the embodiment of the present invention.

Hereinafter, the biodegradable plastic decomposition control method, biodegradable plastic decomposition inhibitor, biodegradable plastic decomposition promoter, biodegradable plastic decomposition inhibiting method, biodegradable plastic decomposition promoting method, and biodegradable plastic of the present invention will be described below. An embodiment of the decomposition evaluation method will be described in detail. However, the present invention is not limited to the specific contents of the embodiments and examples described below.

The biodegradable plastic decomposition control method of this embodiment is a decomposition control method by influencing the decomposition ability of microorganisms in the natural environment to which biodegradable plastic products are exposed or microorganisms placed in a container. .
That is, the biodegradable plastic decomposition control method of the present embodiment is characterized in that the decomposition of the biodegradable plastic is controlled by adding sugars or nutritional salts to the biodegradable plastic.
In this embodiment, "adding" saccharides or nutrient salts means adding saccharides or nutrient salts to biodegradable plastics in the natural environment, in warehouses, factories, containers, etc. Includes spraying, dipping, applying, etc.

The biodegradable plastic to be subject to decomposition control in this embodiment is not particularly limited as long as it can be decomposed by microorganisms in the natural environment.
Examples of biodegradable plastics include those having an ester bond in their chemical structure.

In addition, biodegradable plastics include polycaprolactone, polylactic acid, polylactic acid/polycaprolactone copolymer, polyglycolic acid, polylactic acid/polyether copolymer, butanediol/long chain dicarboxylic acid copolymer, and polybutylene adipate. /terephthalate copolymer, polytetramethylene adipate co-terephthalate, polyethylene terephthalate succinate, polybutylene succinate, polybutylene succinate adipate, polyvinyl alcohol, and the like.

It is also preferable that the biodegradable plastic decomposition control method of this embodiment be a method of adding plastic-degrading microorganisms and sugars or nutritional salts to the biodegradable plastic.
Here, it is thought that plastic-degrading microorganisms usually exist in the natural environment. For example, it is said that there are hundreds of millions of microorganisms in 1 g of soil, and about 100,000 microorganisms in 1 mL of seawater, and among these, there are also a certain number of microorganisms that can decompose biodegradable plastics. It is believed that there are. Although the rate of biodegradation changes depending on the type and ratio of microorganisms, the decomposition itself progresses.

Therefore, in the method for controlling the decomposition of biodegradable plastics of this embodiment, although it is not essential to add plastic-degrading microorganisms, by adding these and sugars or nutrients, biodegradable plastics can be decomposed more efficiently. It becomes possible to perform control.
That is, by adding plastic-degrading microorganisms and sugars to biodegradable plastic, it becomes possible to maintain its strength for a certain period of time and then decompose the biodegradable plastic.
Furthermore, by adding plastic-degrading microorganisms and nutrients to biodegradable plastics, it becomes possible to rapidly promote the decomposition of biodegradable plastics.

In this embodiment, the plastic-degrading microorganism is not particularly limited as long as it decomposes biodegradable plastic in the natural environment.
Examples of plastic-degrading microorganisms include filamentous fungi (molds).
Furthermore, examples of filamentous fungi include Fusarium, Aspergillus, Glomerella, and Altenaria.

Moreover, it is preferable that the biodegradable plastic decomposition control method of this embodiment is a method of suppressing the decomposition of the biodegradable plastic by adding sugars to the biodegradable plastic.
As the saccharide, it is preferable to use a monosaccharide and/or a disaccharide, and it is more preferable to use glucose or a sugar composition containing glucose such as trehalose or sucrose.

Moreover, it is preferable that the biodegradable plastic decomposition control method of this embodiment is a method of accelerating the decomposition of the biodegradable plastic by adding nutrients to the biodegradable plastic.
As the nutrient salt, it is preferable to use nitrogen or phosphorus, and it is more preferable to use both nitrogen and phosphorus together.
According to the biodegradable plastic decomposition control method of this embodiment, it is possible to suppress or accelerate the decomposition of biodegradable plastics depending on the situation.

Furthermore, the biodegradable plastic decomposition inhibitor of the present embodiment is characterized in that it contains saccharides as an active ingredient.
Moreover, it is also preferable that the biodegradable plastic decomposition inhibitor of this embodiment has a structure in which the active ingredients are saccharides and plastic-degrading microorganisms.

As for the saccharide, it is preferable to use a monosaccharide and/or a disaccharide, and it is more preferable to use glucose or a sugar composition containing glucose such as trehalose or sucrose.
According to the biodegradable plastic decomposition inhibitor of this embodiment, when it is desired to suppress the decomposition of biodegradable plastic, by adding it to the biodegradable plastic, the decomposition can be suppressed. becomes possible.

Furthermore, the biodegradable plastic decomposition accelerator of this embodiment is characterized by containing nutritional salts as an active ingredient.
Moreover, it is also preferable that the biodegradable plastic decomposition accelerator of this embodiment has a structure in which the active ingredients are nutrient salts and plastic-degrading microorganisms.

As the nutrient salts, it is preferable to use nitrogen or phosphorus, and it is more preferable to use both nitrogen and phosphorus together.
According to the biodegradable plastic decomposition accelerator of this embodiment, when it is desired to promote the decomposition of biodegradable plastic, the decomposition of the biodegradable plastic can be promoted by adding it to the biodegradable plastic. becomes possible.

Furthermore, the method for suppressing the decomposition of biodegradable plastics according to the present embodiment suppresses the decomposition of biodegradable plastics by adding sugars to biodegradable plastics in containers such as test tubes and petri dishes, or in environments such as fields. Characterized by suppression.
At this time, it is also preferable to add plastic-degrading microorganisms together with sugars.

According to this method of suppressing the decomposition of biodegradable plastics, it is possible to suppress the decomposition of biodegradable plastics by adding sugars in experiments or in situations where it is necessary to maintain the strength of biodegradable plastics. It is.

Furthermore, the method for promoting the decomposition of biodegradable plastics of the present embodiment promotes the decomposition of biodegradable plastics by adding nutrients to the biodegradable plastics in a container, in the environment, in artificial seawater, or in natural seawater. It is characterized by
At this time, it is also preferable to add plastic-degrading microorganisms together with nutritional salts.

According to such a method for promoting the decomposition of biodegradable plastics, it is possible to accelerate the decomposition of biodegradable plastics in artificial seawater or natural seawater in a container in an experiment by adding nutrients.

Furthermore, the biodegradable plastic decomposition evaluation method of the present embodiment is characterized in that the degradability of the biodegradable plastic is evaluated by adding sugars to the biodegradable plastic in a container or in the environment.
Furthermore, the biodegradable plastic decomposition evaluation method of this embodiment evaluates the degradability of biodegradable plastics by adding nutrients to the biodegradable plastics in a container, in the environment, in artificial seawater, or in natural seawater. It is characterized by

According to such a biodegradable plastic decomposition evaluation method, it is possible to judge whether the decomposition of biodegradable plastics is suppressed by the addition of sugars, and it is also possible to determine whether the decomposition of biodegradable plastics is suppressed by the addition of nutrient salts. It is possible to determine whether or not decomposition is being promoted.

Furthermore, in the above embodiment, when adding or adding a plastic-degrading microorganism, a culture medium suitable for culturing the plastic-degrading microorganism may also be added. As the culture medium, for example, Czapek agar medium (Czapek medium) can be used.

Hereinafter, a biodegradable plastic decomposition control method, a biodegradable plastic decomposition inhibitor, a biodegradable plastic decomposition promoter, a biodegradable plastic decomposition inhibiting method, a biodegradable plastic decomposition promoting method, and a biodegradable plastic decomposition promoting method according to embodiments of the present invention will be described below. We will explain the tests conducted to confirm the effectiveness of the biodegradable plastic degradation evaluation method.

[Test 1]
A test was conducted to confirm that the decomposition of biodegradable plastics can be suppressed by adding sugars to them.
In this test, biodegradable plastics in the environment were simulated by placing blocks of biodegradable plastics in a solid or liquid medium. Moreover, the addition of sugars was carried out by adding sugars prior to placing the biodegradable plastic mass in the preparation of the solid medium or liquid medium. These tests were also conducted in the same manner as described below to confirm that the decomposition of biodegradable plastics can be promoted by adding nutrient salts.

First, a medium containing biodegradable plastic was prepared. Specifically, Czapek medium without sucrose (to 1000 ml of purified water, add 3 g of NaNO ₃ , 1 g of K ₂ HPO ₄ , 0.5 g of MgSO ₄ 7H ₂ O, 0.5 g of KCL, 0.01 g of FeSO ₄ 7H ₂ O to 1000 ml of purified water) (dissolution, pH 7.3) was prepared in advance.
Next, this medium was divided into four parts: one without added sugars, one with glucose added at 3.0% by weight of the medium, and one with trehalose added at 3.0% by weight of the medium. A medium in which sucrose was added to the medium and a medium in which sucrose was added to the medium at a concentration of 3.0% by weight were prepared.

In addition, polycaprolactone was added to each medium at a concentration of 0.5% by weight, and the liquid medium was stirred with heat using a heat stirrer (set at around 280°C) and suspended while crushing the pellets with a spatula. Obtained.
Then, agar was added to the liquid medium at a concentration of 1.5% by weight, autoclaved, and dispensed into petri dishes with a diameter of 90 mm and solidified at room temperature to obtain an agar medium. Each agar medium obtained contained biodegradable plastic lumps with a size of 0.1 mm to 1 mm.

Next, filamentous fungi of the genus Fusarium (NBRC9971), Aspergillus flavus (NBRC6343), and Glomerella cingulata (NBRC107004) were cultured in PDA (Potato Dextrose Agar) medium, and growth was determined. A bacterial disk with a diameter of 5 mm was punched out from the colony using a cork borer.
Then, a bacterial disk was brought into contact with each agar medium, static culture was started in the dark at 30°C, and the state of the biodegradable plastic was observed using a microscope over time. The results are shown in Figure 1-3.

Figure 1 shows the results of the decomposition inhibition test 1-1 using filamentous fungi of the genus Fusarium (NBRC9971), with an agar medium without sugar added in Comparative Example 1 and an agar medium with 3.0% glucose. Example 1 is an agar medium containing 3.0% trehalose, Example 2 is an agar medium containing 3.0% sucrose, and Example 3 is an agar medium containing 3.0% sucrose.

In FIG. 1, photographs showing the state of the biodegradable plastic before inoculation, on the 10th day of culture, on the 17th day of culture, on the 28th day of culture, and on the 46th day of culture are shown. The number of days after hyphae reached the biodegradable plastic in the comparative example and each example was 4-6 days on the 10th day of culture, 11-13 days on the 17th day of culture, and 22-24 days on the 28th day of culture. On the 46th day of culture, it was 40-42 days.
Note that the size of the scale bar in the upper left photograph is 100 μm.

As shown in FIG. 1, in Comparative Example 1 (no sugar added), the biodegradable plastic lump was decomposed on the 10th day of culture.
On the other hand, in Example 1 (glucose 3.0%), the biodegradable plastic lump was decomposed on the 46th day of culture, and in Example 2 (trehalose 3.0%), the biodegradable plastic mass was decomposed on the 17th day of culture. In Example 3 (sucrose 3.0%), the biodegradable plastic lumps were decomposed on the 28th day of culture.
These results revealed that the decomposition of biodegradable plastics can be suppressed by adding sugars to the biodegradable plastics.

Figure 2 shows the results of decomposition inhibition test 1-2 using filamentous fungi of the genus Aspergillus (NBRC6343), in which an agar medium without added sugar was used in Comparative Example 2, and an agar medium with 3.0% glucose was used in Comparative Example 2. Example 4 is an agar medium containing 3.0% trehalose, Example 5 is an agar medium containing 3.0% sucrose, and Example 6 is an agar medium containing 3.0% sucrose.

In FIG. 2, photographs showing the state of the biodegradable plastic before inoculation, on the 10th day of culture, on the 17th day of culture, on the 28th day of culture, and on the 46th day of culture are shown. The number of days after hyphae reached the biodegradable plastic in the comparative example and each example was 2-6 days on the 10th day of culture, 9-13 days on the 17th day of culture, and 20-24 days on the 28th day of culture. On the 46th day of culture, it was 38-42 days.

As shown in FIG. 2, in Comparative Example 2 (no sugar added), the biodegradable plastic lump was decomposed on the 10th day of culture.
In contrast, in Example 4 (glucose 3.0%), the biodegradable plastic mass was not yet decomposed even on the 46th day of culture. In Example 5 (3.0% trehalose), the biodegradable plastic lumps were decomposed on the 46th day of culture, and in Example 6 (sucrose 3.0%), the biodegradable plastic lumps still remained on the 46th day of culture. had not been disassembled.
These results also revealed that the decomposition of biodegradable plastics can be suppressed by adding sugars to the biodegradable plastics.

Figure 3 shows the results of Decomposition Suppression Test 1-3 using filamentous fungi of the genus Glomerella (NBRC107004), with an agar medium without added sugar in Comparative Example 3 and an agar medium with 3.0% glucose in Comparative Example 3. Example 7 is an agar medium containing 3.0% trehalose, Example 8 is an agar medium containing 3.0% sucrose, and Example 9 is an agar medium containing 3.0% sucrose.

In FIG. 3, photographs showing the state of the biodegradable plastic before inoculation, on the 10th day of culture, on the 17th day of culture, on the 28th day of culture, and on the 46th day of culture are shown. The number of days after hyphae reached the biodegradable plastic in the comparative example and each example was 2-6 days on the 10th day of culture, 9-13 days on the 17th day of culture, and 20-24 days on the 28th day of culture. On the 46th day of culture, it was 38-42 days.

As shown in FIG. 3, in Comparative Example 3 (no sugar added), the biodegradable plastic lump was decomposed on the 10th day of culture.
In contrast, in Example 7 (glucose 3.0%), Example 8 (trehalose 3.0%), and Example 9 (sucrose 3.0%), the biodegradable plastic lumps were still decomposed even on the 46th day of culture. It wasn't.
These results also revealed that the decomposition of biodegradable plastics can be suppressed by adding sugars to the biodegradable plastics.

[Test 2]
A test was conducted to confirm the effect of sugar concentration on suppressing the decomposition of biodegradable plastics by adding sugars to them.
First, as in Test 1, a medium containing biodegradable plastic was prepared. Specifically, Czapek medium without sucrose (to 1000 ml of purified water, add 3 g of NaNO ₃ , 1 g of K ₂ HPO ₄ , 0.5 g of MgSO ₄ 7H ₂ O, 0.5 g of KCL, 0.01 g of FeSO ₄ 7H ₂ O to 1000 ml of purified water) (dissolution, pH 7.3) was prepared in advance.

Next, this medium was divided into four parts: one without added sugars, one with sucrose added at a concentration of 0.03% by weight relative to the medium, and one containing 0.3% by weight of sucrose relative to the medium. and 3.0% by weight of sucrose to the medium were prepared.

In addition, polycaprolactone was added to each medium at a concentration of 0.5% by weight, and the liquid medium was stirred with heat using a heat stirrer (set at around 280°C) and suspended while crushing the pellets with a spatula. Obtained.
Then, agar was added to the liquid medium at a concentration of 1.5% by weight, autoclaved, and dispensed into petri dishes with a diameter of 90 mm and solidified at room temperature to obtain an agar medium. Each agar medium obtained contained biodegradable plastic lumps with a size of 0.1 mm to 1 mm.

Next, filamentous fungi of the genus Fusarium (NBRC9971), Aspergillus flavus (NBRC6343), and Glomerella cingulata (NBRC107004) were cultured in PDA medium, and the diameters were determined from the grown colonies. A bacterial disk was prepared by punching it out with a 5 mm cork borer.
Then, a bacterial disk was brought into contact with each agar medium, static culture was started in the dark at 30°C, and the state of the biodegradable plastic was observed using a microscope over time. The results are shown in Figure 4-6.

Figure 4 shows the results of the degradation inhibition test 2-1 using filamentous fungi of the genus Fusarium (NBRC9971). Reference Example 1 is an agar medium containing 0.03% sucrose, Example 10 is an agar medium containing 0.3% sucrose, and Example 11 is an agar medium containing 3.0% sucrose.

In FIG. 4, photographs showing the state of the biodegradable plastic before inoculation, on the 8th day of culture, on the 13th day of culture, and on the 27th day of culture are shown. The number of days after mycelia reached the biodegradable plastic in Comparative Examples, Reference Examples, and Examples was 4 days on the 8th day of culture, 9 days on the 13th day of culture, and 23 days on the 27th day of culture. there were.
Furthermore, a photograph showing the appearance of the surface of each medium on the 13th day of culture is shown at the right end.

As shown in FIG. 4, in Comparative Example 4 (0% sucrose), the biodegradable plastic lump was decomposed on the 8th day of culture. Also, in Reference Example 1 (sucrose 0.03%), the biodegradable plastic lumps were decomposed on the 8th day of culture.
On the other hand, in Example 10 (0.3% sucrose), the biodegradable plastic lump was decomposed on the 13th day of culture, and in Example 11 (3.0% sucrose), on the 27th day of culture, A chunk of biodegradable plastic was being decomposed.

Furthermore, when referring to the appearance of the surface of each medium on the 13th day of culture, nothing particularly noticeable was observed in Comparative Example 4 and Reference Example 1, but in Example 10 and Example 11, it appeared to be covered with hyphae. It can be observed.
From this, it is thought that in Examples 10 and 11, the medium contained abundant sugar as a nutrient, which inhibited filamentous fungi from using biodegradable plastic as a nutrient, that is, from degrading it. It will be done.

From the above results, it has become clear that the decomposition of biodegradable plastics can be suitably suppressed by adding saccharides at a concentration of 0.3 to 3.0% by weight.
Therefore, when adding sugars to biodegradable plastics, it is desirable to set the amount and frequency of addition in consideration of the concentration.

Figure 5 shows the results of the degradation inhibition test 2-2 using filamentous fungi of the genus Aspergillus (NBRC6343). Reference Example 2 is an agar medium containing 0.03% sucrose, Example 12 is an agar medium containing 0.3% sucrose, and Example 13 is an agar medium containing 3.0% sucrose.

In FIG. 5, photographs showing the state of the biodegradable plastic before inoculation, on the 8th day of culture, on the 27th day of culture, and on the 58th day of culture are shown. The number of days after mycelia reached the biodegradable plastic in Comparative Examples, Reference Examples, and Examples was 4 days on the 8th day of culture, 23 days on the 27th day of culture, and 54 days on the 58th day of culture. there were.
Furthermore, a photograph showing the appearance of the surface of each medium on the 13th day of culture is shown at the right end.

As shown in FIG. 5, in Comparative Example 5 (0% sucrose), the biodegradable plastic lump was decomposed on the 8th day of culture. Furthermore, in Reference Example 2 (sucrose 0.03%), the biodegradable plastic lumps were decomposed on the 8th day of culture.
On the other hand, in Example 12 (0.3% sucrose), the biodegradable plastic lump was decomposed on the 27th day of culture, and in Example 13 (3.0% sucrose), on the 58th day of culture, A chunk of biodegradable plastic was being decomposed.

Furthermore, when referring to the appearance of the surface of each medium on the 13th day of culture, in Comparative Example 5 and Reference Example 2, nothing particularly noticeable was observed, but in Example 12 and Example 13, it appeared to be covered with hyphae. It can be observed.
From this, in Examples 12 and 13, as in Degradation Suppression Test 2-1, the filamentous fungi use biodegradable plastic as nutrients because the culture medium contains abundant sugar as nutrients. In other words, it is thought that decomposition was suppressed.
The above results also revealed that the decomposition of biodegradable plastics can be suitably suppressed by adding saccharides at a concentration of 0.3 to 3.0% by weight.

Figure 6 shows the results of decomposition inhibition test 2-3 using filamentous fungi of the genus Glomerella (NBRC107004). Reference Example 3 is an agar medium containing 0.03% sucrose, Example 14 is an agar medium containing 0.3% sucrose, and Example 15 is an agar medium containing 3.0% sucrose.

In FIG. 6, photographs showing the state of the biodegradable plastic before inoculation, on the 8th day of culture, on the 58th day of culture, and on the 72nd day of culture are shown. The number of days after mycelia reached the biodegradable plastic in Comparative Examples, Reference Examples, and Examples was 5 days on the 8th day of culture, 55 days on the 58th day of culture, and 69 days on the 72nd day of culture. there were.
Furthermore, a photograph showing the appearance of the surface of each medium on the 13th day of culture is shown at the right end.

As shown in FIG. 6, in Comparative Example 6 (0% sucrose), the biodegradable plastic lump was decomposed on the 8th day of culture. Also, in Reference Example 3 (sucrose 0.03%), the biodegradable plastic lumps were decomposed on the 8th day of culture.
On the other hand, in Example 14 (0.3% sucrose), the biodegradable plastic lump was decomposed on the 58th day of culture, and in Example 15 (3.0% sucrose), on the 72nd day of culture, About half of the biodegradable plastic chunks had decomposed.

Furthermore, when referring to the appearance of the surface of each medium on the 13th day of culture, nothing particularly noticeable was observed in Comparative Example 6 and Reference Example 3, but in Example 14 and Example 15, it appeared to be covered with hyphae. It can be observed.
From this, in Examples 14 and 15, similar to Decomposition Suppression Test 2-1, the filamentous fungi use biodegradable plastic as nutrients because the culture medium contains abundant sugar as nutrients. In other words, it is thought that decomposition was suppressed.
The above results also revealed that the decomposition of biodegradable plastics can be suitably suppressed by adding saccharides to the biodegradable plastics at a concentration of 0.3 to 3.0% by weight.

[Test 3]
A test was conducted to confirm by esterase activity that the decomposition of biodegradable plastics can be suppressed by adding sugars to them.
That is, plastic-degrading microorganisms decompose biodegradable plastics by hydrolyzing ester bonds in the chemical structure of biodegradable plastics using esterase. Therefore, we confirmed whether the esterase activity of extracts of plastic-degrading microorganisms could be suppressed by adding sugars.

First, a medium containing biodegradable plastic was prepared. Specifically, Czapek medium without sucrose (to 1000 ml of purified water, add 3 g of NaNO ₃ , 1 g of K ₂ HPO ₄ , 0.5 g of MgSO ₄ 7H ₂ O, 0.5 g of KCL, 0.01 g of FeSO ₄ 7H ₂ O to 1000 ml of purified water) (dissolution, pH 7.3) was prepared in advance.

Next, this medium was divided into four parts: one without added sugars, one with sucrose added at a concentration of 0.03% by weight relative to the medium, and one containing 0.3% by weight of sucrose relative to the medium. and 3.0% by weight of sucrose to the medium were prepared.

In addition, polycaprolactone was added to each medium at a concentration of 0.5% by weight, stirred with heat using a heat stirrer (set at around 280°C), suspended while crushing the pellets with a spatula, and then autoclaved to form a liquid. A medium was obtained. The liquid medium was dispensed into 24 flasks in total, 6 flasks for each sucrose concentration.

In addition, filamentous fungi of the genus Fusarium (NBRC9971), Aspergillus flavus (NBRC6343), and Glomerella cingulata (NBRC107004) were cultured in PDA medium, and the grown colonies were cultured with a diameter of 5 mm. A bacterial disk punched out with a cork borer was prepared. These bacterial disks were then placed in each liquid medium.

Comparative Example 7, Reference Example 4, and Implementation were conducted using liquid media containing Fusarium fungi with sucrose concentrations of 0% by weight, 0.03% by weight, 0.3% by weight, and 3.0% by weight, respectively. Example 16 and Example 17.
In addition, Comparative Example 8 and Reference Example 5 were prepared using liquid media containing Aspergillus filamentous fungi with sucrose concentrations of 0% by weight, 0.03% by weight, 0.3% by weight, and 3.0% by weight, respectively. , Example 18, and Example 19.
Furthermore, Comparative Example 9 and Reference Example 6 were prepared using liquid media containing Glomerella filamentous fungi with sucrose concentrations of 0% by weight, 0.03% by weight, 0.3% by weight, and 3.0% by weight, respectively. , Example 20, and Example 21.

After standing still for 16 days at 25° C. in the dark, the cultured cells and the culture filtrate were separated and collected, and the culture filtrate was used as a crude enzyme solution for an esterase activity measurement test.
Esterase activity in the crude enzyme solution was measured using p-Nitrophenyl butylate (pNPB, C4) as a substrate. The esterase hydrolyzes pNPB to produce 4-nitrophenol, which can be measured spectrophotometrically at 405-410 nm. A pNPB substrate solution was prepared by mixing pNPB in isopropanol to a concentration of 10 mM. After mixing 890 μl of buffer solution (50 mM Tris-HCL, pH 7.5) and 100 μl of crude enzyme solution, 10 μl of pNPB substrate solution was added. Thereafter, the mixture was allowed to stand for 60 minutes, and the absorbance of 1 ml of the reaction solution at 405 nm was measured at room temperature using a spectrophotometer (Nanodrop 2000C, manufactured by Thermo Fisher Scientific Co., Ltd.).

FIG. 7 shows the results of decomposition inhibition test 3-1 using filamentous fungi of the genus Fusarium (Fusarium oxysporum (NBRC9971)).
The respective esterase activities were 3.565 for Comparative Example 7 (0% sucrose), 3.095 for Reference Example 4 (0.03% sucrose), 0.805 for Example 16 (0.3% sucrose), and 0.805 for Example 17 (3.0% sucrose). ) was 0.88.

That is, the esterase activity of Example 16 was suppressed by 77.4% compared to Comparative Example 7, and the esterase activity of Example 17 was suppressed by 75.3% compared to Comparative Example 7.
Therefore, from these results, it is clear that the decomposition of biodegradable plastics can be suitably suppressed by adding sugars to biodegradable plastics at a concentration of 0.3 to 3.0% by weight. Ta.

FIG. 8 shows the results of the degradation inhibition test 3-2 using filamentous fungi of the genus Aspergillus (NBRC6343).
The respective esterase activities were 3.355 for Comparative Example 8 (0% sucrose), 2.99 for Reference Example 5 (0.03% sucrose), 0.665 for Example 18 (0.3% sucrose), and 0.665 for Example 19 (3.0% sucrose). ) was 1.105.

That is, the esterase activity of Example 18 was suppressed by 80.2% compared to Comparative Example 8, and the esterase activity of Example 19 was suppressed by 67.1% compared to Comparative Example 8.
Therefore, from these results, it is clear that the decomposition of biodegradable plastics can be suitably suppressed by adding sugars to biodegradable plastics at a concentration of 0.3 to 3.0% by weight. Ta.

FIG. 9 shows the results of the degradation inhibition test 3-3 using filamentous fungi of the genus Glomerella (NBRC107004).
The respective esterase activities were 10.535 for Comparative Example 9 (0% sucrose), 9.935 for Reference Example 6 (0.03% sucrose), 1.985 for Example 20 (0.3% sucrose), and 1.985 for Example 21 (3.0% sucrose). ) was 1.495.

That is, the esterase activity of Example 20 was suppressed by 81.2% compared to Comparative Example 9, and the esterase activity of Example 21 was suppressed by 85.8% compared to Comparative Example 9.
Therefore, from these results, it is clear that the decomposition of biodegradable plastics can be suitably suppressed by adding sugars to biodegradable plastics at a concentration of 0.3 to 3.0% by weight. Ta.

[Test 4]
A test was conducted to confirm by esterase activity that adding nutrients to biodegradable plastics can promote the decomposition of biodegradable plastics.
First, an artificial seawater medium was prepared as a medium. As the artificial seawater medium, the following Daigo artificial seawater SP formulation (mg/1000ml) was used.

This artificial seawater medium was divided into four types: artificial seawater medium only, artificial seawater medium with phosphorus (P) added, artificial seawater medium with nitrogen (N) added, and artificial seawater medium with nitrogen (N) added. A seawater medium to which both phosphorus (P) and nitrogen (N) were added was prepared.
As phosphorus, dipotassium hydrogen phosphate (K ₂ HPO ₄ ) was added at a concentration of 0.1% by weight. Further, as nitrogen, sodium nitrate (NaNO ₃ ) was added at a concentration of 0.3% by weight.

In addition, polycaprolactone was added to each medium at a concentration of 0.5% by weight, stirred with heat using a heat stirrer (set at around 280°C), suspended while crushing the pellets with a spatula, and then autoclaved to form a liquid. A medium was obtained. The liquid medium was dispensed into 24 flasks in total, 6 flasks for each of the above four mediums.

In addition, filamentous fungi of the genus Fusarium (NBRC9971), Aspergillus flavus (NBRC6343), and Glomerella cingulata (NBRC107004) were cultured in PDA medium, and the grown colonies were cultured with a diameter of 5 mm. A bacterial disk punched out with a cork borer was prepared. These bacterial disks were then placed in each liquid medium.

Comparative Example 10 is a liquid medium containing only artificial seawater containing Fusarium fungi, Example 22 is a liquid culture medium in which P is added to artificial seawater, and Example 23 is an artificial seawater in which N is added. In Example 24, P and N were added.
In addition, Comparative Example 11 used a liquid medium containing filamentous fungi of the Aspergillus genus and consisted only of artificial seawater, Example 25 added P to artificial seawater, Example 26 added N to artificial seawater, Example 27 was prepared by adding P and N to artificial seawater.
Furthermore, Comparative Example 12 used a liquid medium containing Glomerella filamentous fungi and consisted only of artificial seawater, Example 28 added P to artificial seawater, Example 29 added N to artificial seawater, Example 30 was prepared by adding P and N to artificial seawater.

After static culture at 25°C in the dark for 21 days, the cultured cells and the culture filtrate were separated and collected, and the culture filtrate was used as a crude enzyme solution and subjected to the esterase activity measurement test in the same manner as Test 3.

FIG. 10 shows the results of the degradation acceleration test 4-1 using filamentous fungi of the genus Fusarium (Fusarium oxysporum (NBRC9971)).
The respective esterase activities were 0.275 for Comparative Example 10 (artificial seawater), 0.655 for Example 22 (artificial seawater + P), 1.22 for Example 23 (artificial seawater + N), and 11.785 for Example 24 (artificial seawater + P + N). Ta.

That is, the esterase activity of Example 22 was promoted by 138.2% compared to Comparative Example 10, and the esterase activity of Example 23 was promoted by 342.6% compared to Comparative Example 10.
Moreover, the esterase activity of Example 24 was promoted by 4185.5% compared to Comparative Example 10.

Here, the theoretical value based on Colby's formula can be calculated using the formula "(actual value of A + actual value of B) - (actual value of A x actual value of B)/100", and the actual value is It is said that there is a synergistic effect when the value exceeds the theoretical value.
As shown in FIG. 13, the theoretical value of the esterase activity in Example 24 is 1.8, and the actual value is 11.8. Therefore, in the biodegradable plastic decomposition control method of this embodiment, as nutrients, It is considered that when both phosphorus and nitrogen are used together, a synergistic effect is obtained compared to when either phosphorus or nitrogen is used.

As described above, it has been revealed that the decomposition of biodegradable plastics can be promoted by adding nutrient salts to the biodegradable plastics. Furthermore, it has been found that by using both nitrogen and phosphorus as nutritional salts, an excellent effect of promoting the decomposition of biodegradable plastics can be obtained.

FIG. 11 shows the results of the degradation acceleration test 4-2 using filamentous fungi of the genus Aspergillus (NBRC6343).
The respective esterase activities were 1.125 for Comparative Example 11 (artificial seawater), 1.5 for Example 25 (artificial seawater + P), 0.505 for Example 26 (artificial seawater + N), and 2.24 for Example 27 (artificial seawater + P + N). Ta.

That is, the esterase activity of Example 25 was promoted by 33.3% compared to Comparative Example 11.
Moreover, the esterase activity of Example 27 was promoted by 99.1% compared to Comparative Example 11.
As shown in FIG. 13, the theoretical value of the esterase activity in Example 27 is 2.0, and the actual value is 2.2. Therefore, in the biodegradable plastic decomposition control method of this embodiment, as nutrients, It is considered that when both phosphorus and nitrogen are used together, a synergistic effect is obtained compared to when either phosphorus or nitrogen is used.

The above results also revealed that the decomposition of biodegradable plastics can be promoted by adding nutrient salts to the biodegradable plastics. Furthermore, it has been found that by using both nitrogen and phosphorus as nutritional salts, an excellent effect of promoting the decomposition of biodegradable plastics can be obtained.

FIG. 12 shows the results of the degradation acceleration test 4-3 using filamentous fungi of the genus Glomerella (NBRC107004).
The respective esterase activities were 0.315 for Comparative Example 12 (artificial seawater), 1.68 for Example 28 (artificial seawater + P), 0.575 for Example 29 (artificial seawater + N), and 2.69 for Example 30 (artificial seawater + P + N). Ta.

That is, the esterase activity of Example 28 was promoted by 433.3% compared to Comparative Example 12, and the esterase activity of Example 29 was promoted by 82.5% compared to Comparative Example 12.
Moreover, the esterase activity of Example 30 was promoted by 754.0% compared to Comparative Example 12.

As shown in FIG. 13, the theoretical value of the esterase activity in Example 30 is 2.3, and the actual value is 2.7. Therefore, in the biodegradable plastic decomposition control method of this embodiment, as nutrients, It is considered that when both phosphorus and nitrogen are used together, a synergistic effect is obtained compared to when either phosphorus or nitrogen is used.

The above results also revealed that the decomposition of biodegradable plastics can be promoted by adding nutrient salts to the biodegradable plastics. Furthermore, it has been found that by using both nitrogen and phosphorus as nutritional salts, an excellent effect of promoting the decomposition of biodegradable plastics can be obtained.

[Test 5]
A test was conducted to confirm that the decomposition of biodegradable plastics can be promoted by adding nutrients to them.
First, as in Test 4, an artificial seawater medium was prepared as a medium.

Next, this artificial seawater medium was divided into four types: one with only artificial seawater, one with phosphorus (P) added to the artificial seawater medium, and one with nitrogen (N) added to the artificial seawater medium. , and an artificial seawater culture medium to which both phosphorus (P) and nitrogen (N) were added.
As phosphorus, dipotassium hydrogen phosphate (K ₂ HPO ₄ ) was added at a concentration of 0.1% by weight. Further, as nitrogen, sodium nitrate (NaNO ₃ ) was added at a concentration of 0.3% by weight.

In addition, polycaprolactone was added to each medium at a concentration of 0.5% by weight, and the liquid medium was stirred with heat using a heat stirrer (set at around 280°C) and suspended while crushing the pellets with a spatula. Obtained.
Then, agar was added to the liquid medium at a concentration of 1.5% by weight, autoclaved, and dispensed into petri dishes with a diameter of 90 mm and solidified at room temperature to obtain an agar medium. Each agar medium obtained contained biodegradable plastic lumps with a size of 0.1 mm to 1 mm.

Next, filamentous fungi of the genus Fusarium (NBRC9971) and filamentous fungi of the genus Aspergillus (Aspergillus flavus (NBRC6343)) were cultured in PDA medium, and the grown colonies were punched out using a cork borer with a diameter of 5 mm. A bacterial disk was prepared.
Then, a bacterial disk was brought into contact with each agar medium, static culture was started in the dark at 30°C, and the state of the biodegradable plastic was observed with a microscope over time. The results are shown in Figures 14-15.

Figure 14 shows the results of the decomposition acceleration test 5-1 using filamentous fungi of the genus Fusarium (NBRC9971). Example 31 is the one in which phosphorus is added to artificial seawater, Example 32 is in which phosphorus is added to artificial seawater, and Example 33 is one in which nitrogen and phosphorus are added to artificial seawater.

In FIG. 14, photographs showing the state of the biodegradable plastic on the 7th day of culture, the 9th day of culture, the 14th day of culture, the 28th day of culture, and the 38th day of culture are shown. In addition, the seventh day of culture is the state just before the mycelium reaches the biodegradable plastic, and the number of days after the mycelium reaches the biodegradable plastic of the comparative example and each example is the same on the ninth day of culture. 0-2 days, 5-7 days on the 14th day of culture, 19-21 days on the 28th day of culture, and 29-31 days on the 38th day of culture.

As shown in FIG. 14, in Comparative Example 13 (artificial seawater), about half of the biodegradable plastic lumps were decomposed on the 28th day of culture.
On the other hand, in Example 31 (artificial seawater + N), the biodegradable plastic lump was decomposed on the 28th day of culture, and the biodegradable plastic lump was decomposed to some extent on the 14th day of culture.
Furthermore, in Example 32 (artificial seawater + P) and Example 33 (artificial seawater + N + P), the biodegradable plastic lumps were decomposed on the 14th day of culture.

These results also revealed that adding nutrients to biodegradable plastics can promote the decomposition of biodegradable plastics. Furthermore, it has been found that by using both nitrogen and phosphorus as nutritional salts, an excellent effect of promoting the decomposition of biodegradable plastics can be obtained.

Figure 15 shows the results of the degradation acceleration test 5-2 using filamentous fungi of the genus Aspergillus (NBRC6343). In Example 34, nitrogen was added to artificial seawater, in Example 35, phosphorus was added to artificial seawater, and in Example 36, nitrogen and phosphorus were added to artificial seawater.

In FIG. 15, photographs showing the state of the biodegradable plastic on the 7th day of culture, the 9th day of culture, the 20th day of culture, the 38th day of culture, and the 51st day of culture are shown. The number of days after hyphae reached the biodegradable plastic in the comparative example and each example was 1-3 days on the 7th day of culture, 3-5 days on the 9th day of culture, and 14-16 days on the 20th day of culture. On the 38th day of culture, it was 32-34 days, and on the 51st day of culture, it was 45-47 days.

As shown in FIG. 15, in Comparative Example 14 (artificial seawater), the biodegradable plastic lump was not decomposed even on the 51st day of culture.
On the other hand, in Example 34 (artificial seawater + N), the biodegradable plastic lump was decomposed on the 20th day of culture.

Furthermore, in Example 35 (artificial seawater + P), the biodegradable plastic lumps were decomposed on the 51st day of culture.
Furthermore, in Example 36 (artificial seawater + N + P), the biodegradable plastic lump was decomposed on the 7th day of culture.

These results also revealed that adding nutrients to biodegradable plastics can promote the decomposition of biodegradable plastics. Furthermore, it has been found that by using both nitrogen and phosphorus as nutritional salts, an excellent effect of promoting the decomposition of biodegradable plastics can be obtained.

It goes without saying that the present invention is not limited to the above-described embodiments and examples, and that various modifications can be made within the scope of the present invention. For example, the saccharides are not limited to the above types, and other types of saccharides can be used as long as they can suppress the decomposition of biodegradable plastics.

The present invention can be used when it is desired to suppress or accelerate the decomposition of biodegradable plastics, depending on the situation.

Claims (15)

A method for controlling the decomposition of biodegradable plastics, comprising controlling the decomposition of the biodegradable plastics by adding sugars or nutritional salts to the biodegradable plastics. 2. The method for controlling the decomposition of biodegradable plastics according to claim 1, characterized in that plastic-degrading microorganisms and sugars or nutritional salts are added to the biodegradable plastics. 3. The biodegradable plastic decomposition control method according to claim 1, wherein decomposition of the biodegradable plastic is suppressed by adding sugars to the biodegradable plastic. 4. The biodegradable plastic decomposition control method according to claim 3, wherein a monosaccharide and/or a disaccharide is used as the saccharide. 5. The biodegradable plastic decomposition control method according to claim 4, wherein glucose or a sugar composition containing glucose is used as the saccharide. 3. The biodegradable plastic decomposition control method according to claim 1, wherein the decomposition of the biodegradable plastic is promoted by adding nutrient salts to the biodegradable plastic. 7. The biodegradable plastic decomposition control method according to claim 6, wherein nitrogen and/or phosphorus are used as the nutrient salts. A biodegradable plastic decomposition inhibitor characterized by containing sugars as an active ingredient. The biodegradable plastic decomposition inhibitor according to claim 8, characterized in that the active ingredients are saccharides and plastic-degrading microorganisms. A biodegradable plastic decomposition accelerator characterized by containing nutrient salts as an active ingredient. The biodegradable plastic decomposition promoter according to claim 10, characterized in that the active ingredients are nutrient salts and plastic-degrading microorganisms. A method for suppressing decomposition of biodegradable plastics, which comprises suppressing the decomposition of biodegradable plastics by adding sugars to the biodegradable plastics in a container or in the environment. A method for promoting the decomposition of biodegradable plastics, which comprises promoting the decomposition of biodegradable plastics by adding nutrients to the biodegradable plastics in a container, in the environment, in artificial seawater, or in natural seawater. A method for evaluating the decomposition of biodegradable plastics, which comprises evaluating the degradability of biodegradable plastics by adding sugars to the biodegradable plastics in a container or in the environment. A method for evaluating the decomposition of biodegradable plastics, which comprises evaluating the degradability of biodegradable plastics by adding nutrients to the biodegradable plastics in a container, in the environment, in artificial seawater, or in natural seawater.

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