Scientists have once again announced a new way of plastic decomposition

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Scientists accidentally found a substance that decomposes plastic in a few days. They plan to focus their efforts on further improvements - they already have ideas on how to speed up the decomposition by a factor of 100.

Scientists have created an enzyme that can destroy plastic, and it works especially well with plastic bottles. This achievement will help tackle the huge amount of plastic that pollutes the planet. They reported the results in the journal Proceedings of the National Academy of Sciences.

In 2016, bacteria capable of absorbing plastic were found in a landfill in Japan. The process, which usually takes centuries, took them a few days. Now scientists have managed to determine the structure of the enzyme that they use for this, and synthesize it. When the team tested the enzyme, it turned out to be able to handle the polyethylene terephthalate (PET) used in beverage bottles even better than the original.

“It turned out that we improved the enzyme. We were a little shocked,”says Professor John McGehan of the University of Portsmouth in the UK. "This is a real discovery."

In doing so, the researchers hope that they will be able to improve it, making it work even faster.

“We hope to use this enzyme to break down plastic into its constituents and then use them again to make plastic. This means that there will be no more oil to be produced and that the amount of plastic in the environment can be reduced,”McGeehan notes.

About a million plastic bottles are sold every minute in the world. Only 14% of them are processed. Many of the rest end up in the oceans, polluting even the most remote corners, harming marine life and - potentially - seafood consumers.

“The plastic is extremely resistant to degradation,” McGehan explains.

Today, bottles that have been recycled are used to produce opaque fibers that become material for clothing and carpets. But thanks to the use of an enzyme, they can be used to make new plastic bottles, eliminating the need to produce more plastic.

“We have to live with the fact that oil costs little, which is why PET production is cheap,” McGehan said. "It is easier for manufacturers to create more plastic than to try to recycle it."

To begin with, the researchers identified the structure of an enzyme produced by bacteria from Japan. To do this, they used the Diamond synchrotron, which is capable of producing powerful X-rays, which makes it possible to see the structure of individual atoms. The enzyme was found to be similar to the one bacteria commonly use to break down the natural polymer cutin, the wax that often covers the skin of the fruit. The manipulation of the enzyme while studying its work inadvertently resulted in an improvement in its ability to degrade plastic.

"It's a modest 20% improvement, but that's not the point," McGehan says. - What happened shows that the enzyme has not yet been optimized. This gives us the opportunity to use all the technologies that have been used in the development of other enzymes over the years and create an enzyme that works ultra-fast.”

One of the possible improvements is to transplant the enzyme to extremophile bacteria that can withstand temperatures above 70 ° C - it melts PET, and in molten form it decomposes 10-100 times faster. Certain fungi can also contribute to plastic degradation, but bacteria are easier to use for industrial purposes.

Bacteria that are currently evolving in the environment could be used to kill other types of plastic, McGehan said. Although most of the plastic is in the ocean, the researchers hope it will be possible to transport plastic-eating bacteria to these debris piles.

“I think this is a very interesting piece of work that shows that there is potential for using enzymes to combat the growing waste problem,” said chemist Oliver Jones. "Enzymes are non-toxic, biodegradable and can be obtained with the help of microorganisms in large quantities."

Wax moth larvae can compete with bacteria - they have recently been shown to be able to absorb plastic at an impressive rate. The discovery was made by accident - one of the researchers, Federica Bertochini, an amateur beekeeper, was engaged in removing parasites from the honeycomb of her hives. Bertochini temporarily put the extracted caterpillars in a regular garbage bag and after a while discovered that there were no larvae.

Bertochini, a researcher at the Spanish Institute of Biomedicine and Biotechnology, became interested in the phenomenon and conducted a scientific experiment with biochemists from Cambridge. About a hundred larvae were taken, placed in an ordinary plastic bag bought in a British store, and waited for the holes to appear. As it turned out, a hundred caterpillars are able to deal with 92 mg of polyethylene in 12 hours.