World Ocean Day 丨 Plastic can also \"eat\"?The appetite of this marine microorganism

Produced: Science Popularization China
Author: Liu Rui, Feifan Institute of Chinese Academy of Sciences

Preparation: Chinese Science Popularization Expo

If you turn around and see your surroundings, you may find it to find Is it out of plastic items? In daily life, we can't do without plastic -small to shopping bags, plastic bottles, large to car, home decoration, and mobile phones and computers to participate in plastic participation. Large -scale plastic production has brought convenience to people, but it also brings natural problems -ordinary plastic degradation takes decades or even hundreds of years. According to the production rate and degradation rate, the earth will become huge plastic after a long time. Landfill.

A variety of plastic pictures Source: Veer Gallery

So how to degrade plastic faster and better becomes a problem that scientists need to solve. In 2021, scientists first discovered the marine microbial flora that can effectively degrade plastic garbage; now, they once again discovered and cultivated the 'upgraded version' marine microorganism, which can effectively degrade multiple types of plastics. You can degrade some plastic into fragments.

What is the magical microorganism? How did they shatter and digest in such a solid plastic? With them, does it mean that humans can use plastic with peace of mind?

Members of Sun Chaoyi team are studying the marine microorganisms of \"eating\" fragments

Picture Source: Chinese Academy of Sciences Marine Research

Pollution has become an epidemic

Knowing and knowing that he has been fighting. Before understanding how to degrade plastic, we need to know what plastic is. Plastic is a high -molecular polymer with an artificial synthetic synthetic type. Its synthetic raw materials are mainly oil, that is, oil -based plastic, which has gradually emerged in recent years, is mainly oil. Each year, about 35-4 billion tons of synthetic plastics can be produced worldwide. The main economic varieties include polypropylene, polyethylene, polystyrene, polyvinyl chloride, and polyurethane.

Like many inventions, plastic itself is not \"bad substances\", but due to the lack of disposal measures corresponding to huge output, plastic waste is not controlled in the environment and has become a global pollution problem. Essence Some plastic products from land were even wrapped into the ocean, causing severe damage to the marine ecosystem.

Statistics provided by the United Nations Environmental Planning Department showed that the world's plastic output soared from 2 million tons in 1950 to 348 million tons in 2017, and its production capacity will be doubled by 2040. About 11 million tons of plastic garbage flow into the ocean each year. By 2040, this number may be doubled. Plastic production and pollution are on the planet of the earth, the planet that humans live on the earth, causing a \"triple crisis\" in terms of climate change, natural losses and pollution.disaster. A large amount of plastic production and abandonment are \"triple crisis\" in terms of climate change, natural losses and pollution.

Land picture sources accumulated plastic garbage Source: Pixabay gallery

In order to cope with this problem that has troubled human society for many years, scientists put their eyes on their eyes on There are many types of microorganisms. These \"inconspicuous\" biological groups are among the various ecological environments of the earth, and have strong adaptability and diverse functional characteristics.

As a result, in places and environments with more plastic garbage and long -lasting duration, is there possible microorganisms that may be able to use plastic and \"eat\" plastic? Based on this guess, the researchers collected hundreds of plastic waste samples of various materials from the beach tide belt with frequent human activities. Through the broad -spectrum screening, it finally successfully distributed a plant that can effectively fix and degrade polyethylene. Plastic marine fungi.

2. What will happen when fungal and plastic are 逅?

When this fungus and plastic film are incubated together, the fungal mycelium will be tightly adhered to the plastic surface. This actually solves a major problem of plastic degradation -the plastic surface is highly hydrophobic, and generally microorganisms are difficult to absorb.

The hydrophobicity here can be simply understood as the ability to wet the surface of the material. If we immerse a piece of paper and a piece of plastic in the water at the same time, the paper is easily moistened by the water, and a large amount of water molecules remain on the surface. , But plastic is almost dripping. Because of this, it is difficult to stay on the surface of the plastic, so it is difficult for ordinary microorganisms to stop here. As soon as the waves are washed, they moved them.

The difference between this fungus is that it has the ability to secrete hydrophobic protein, and forms two lord membranes in hydrophobic/hydrophilic interface, increasing the contact area of \u200b\u200bthe same plastic, in the first first, in the first place Step won other microorganisms!

The biodegradation process of the polymer

Picture source: Magnin A, Pollet E, Phalip V, et al. Evaluation of biological degradation of polyurethanes [j ]. BIOTECHNOLOGY Advances, 2020, 39

After the adsorption, the fungal mycelium structure can secrete multiple extracellular enzymes and act on plastic. Just like the saliva amylase in saliva can hydrolyze the long chain starch in the rice, making it smaller and easier to be absorbed by the human body. Microbial can also synthesize its own enzyme system to gradually degrade large molecular substances located outside the microorganism. Interrupt their long -chain structure, make the molecules of these substances smaller, and then start \"a meal for a beautiful meal.\"

Plastic is also a long chain of a complex structure,And this fungus can secrete the enzymes of these macromolecules, and achieve an important step in plastic degradation, degeneration and solving.

In addition to the characteristics of the fungus itself, it has also evolved with the plastic piles, or the ability to decompose and use plastic, thereby gradually evolving some groups that can effectively degrade plastic.

For many microorganisms, if they eat bread and rice, they will live well, but if they do not have such a good living environment, such as microorganisms around plastic garbage for a long time, in order to survive, They will slowly \"evolve\" and \"eat\" plastic by secreting enzymes to obtain additional energy sources. This also reflects the characteristics of the interaction, interaction, and adaptation of microorganisms and the environment.

After incubation with fungi, the polyethylene plastic surface produced obvious shrinkage and cracks. The observation results of scanning electronic microscope showed that the micro -surface of the plastic surface was densely holes, indicating that the fungus that attached to the plastic Silk has penetrated the plastic surface and exerts the degradation effect.

Fixed colonization and degradation of fungus to polyethylene plastic. Electronic microscope observes the degradation of fungal to polyethylene plastic

Picture Source: Institute of Chinese Academy of Sciences

3. The fungus shows a broad -spectrum degradation ability

in the It was found in subsequent experiments that the ability of this bacteria is not limited to this. It seems to have a degradation effect on more plastic substrates, such as polyurethane, polyvinyl chloride, polystyrene, polypropylene, etc.

Among them, polyurethane plastic is widely used in industries such as electrical manufacturing, automobiles, buildings, clothing, etc., such as muffle materials and insulation materials. Its market share is also second only to 4 polyolefin plastics.

Since its introduction in the 1930s, a lot of polyurethane waste waste has been accumulated in the environment. This fungus can degrade polyurethane products with a speed visible speed visible to the naked eye. After 2 weeks of fungal treatment, the surface of polyurethane film can occur. After the processing time was extended to 5 weeks, the membrane showed obvious fragmentation and the degradation effect was good.

Since the face of ordinary plastics can have a good degradation effect, if the object to be processed is degradable plastic, can it improve the degradation efficiency and shorten the degradation cycle on the basis of the original basis? The answer is yes.

When this degradable plastic and fungal incubation was only one week, obvious cracks appeared on the surface, and the color was yellow, which was the manifestation of oxidation and erosion. The area of \u200b\u200berosion has increased significantly, and even a large area of \u200b\u200bholes appear; after the timeline is extended to three weeks, there are very few plastic residues.For a period of time, degradable plastic will be fully used by fungi.

The decomposable plastic bag containing PBAT+PLA+ST ingredients was degraded by marine fungi within 4 weeks

Picture Source: Chinese Academy of Sciences Marine Research

4. Recommended use of degradable plastic

Compared with traditional plastic products in the natural environment for hundreds of years, the degradable plastic can be shortened to several months. A major progress in the history of human synthetic plastic. It is recommended to use degradable plastics and recognize the \"degradable plastic\" logo. This identification is a pattern made of arrow circular ring, dual \"J\" (degradable pinyin's first letter), material abbreviation (such as PBAT, PLA, etc.), national standards and product names.

\"Degradable Plastic\" logo Example Picture Source: National Standard GB/T 41010-2021

The corresponding national standard is GB/T 41010-2021 It was implemented on June 1, 2022. Products that meet the national standard certification have passed the corresponding degradation rate, heavy metal content, and toxicity experiments of degradation products, and have high environmental safety.

It is worth noting that the degradable plastic used in life cannot completely degrade in the simple wind and sun, and the degradation rate is also very low. It is very likely to block the digestive tract and cause death.

By using degradable plastic, we can also protect the environment while allowing us to achieve convenient life. Of course, we should develop the consciousness of using plastic products -such as carrying shopping bags by ourselves to reduce the use of disposable supplies. As long as everyone can maintain good green habits in their own lives, I believe our environment will welcome Different from coming.

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