Controversy continues between activists who call for a reduction in the use of plastic and consider it essential, and those who work on recycling who argue that strong and lightweight materials such as plastic are very useful, and that true recycling is part of the solution to the pollution problem.
As part of this, scientists have created a super enzyme that breaks down plastic bottles 6 times faster than before, and can be used for recycling within a year or two.
According to a report by Damian Carrington, environmental editor of the Guardian newspaper on September 28, the super enzyme derived from bacteria that naturally developed the ability to ingest plastic allows for the complete recycling of bottles.
Scientists believe that combining this enzyme with the enzymes that break down cotton could also allow mixed clothing to be recycled, as today millions of tons of these clothes are disposed of in landfill or incinerated.
Plastic pollution has polluted the entire planet, from the Arctic to the deep oceans, and people are now known to consume and breathe microplastics.
Currently, it is extremely difficult to break down plastic bottles into their chemical components in order to make old new bottles, which means creating more new plastic from oil every year.
The super enzyme was engineered by linking two separate enzymes, both of which were found in a plastic-eating insect discovered at a Japanese waste site in 2016.
The researchers unveiled an engineered version of the first enzyme in 2018, which was breaking down plastic in a few days, but the super enzyme works 6 times faster.
In turn, says Professor John McGeehan of the Center for Enzyme Innovation at the University of Portsmouth in the United Kingdom, “When we linked the enzymes we got an unexpectedly large increase in activity. This is a path toward trying to produce enzymes faster and more relevant to the industry, but Also one of the stories of learning from nature, then entering it into the laboratory. “
The French company, Carbios, revealed a different enzyme last April, originally discovered in a pile to convert tree leaves into fertilizer, that analyzes 90% of the plastic bottles within 10 hours, but it requires heating above 70 degrees Celsius. The new super enzyme works at room temperature.
Increase in speed
The combination of different approaches could accelerate progress toward commercial use, says McGeehan. “If we can make better and faster enzymes by binding them together and providing them to companies like Carpius and working in partnership then we could start doing that within the next year or two.”
A 2018 discovery determined that the structure of a single enzyme called PETase could attack the hard, crystal surface of plastic bottles, and scientists found by chance that a mutant version ran 20% faster.
The new study analyzed a second enzyme, also present in Japanese bacteria, that doubles the speed of dissociation of chemical groups released by the first enzyme.
Bacteria that break down natural polymers like cellulose have evolved this dual approach over millions of years, and scientists believe that by binding the two enzymes together, this could increase the speed of degradation, enabling them to work more closely together.
And it would be impossible for the bacteria to form the bound super-enzyme, because the molecule would be so large, so the scientists connected the two enzymes in the lab and saw another 3-fold increase in velocity.
The new research, conducted by scientists from the University of Portsmouth and four US institutions, has been published in the Proceedings of the National Academy of Sciences.
Around the corner
The team is now examining how to modify the enzymes to make them work faster, and “there is huge potential,” McGeehan said.
A £ 1 million test center is being built in Portsmouth, and Carpius is currently building a plant in Lyon.
“Combining the plastic-eating enzymes with the existing enzymes that break down the natural fibers can allow mixed materials to be completely recycled,” said McGeehan, adding that “mixed fabrics (polyester and cotton) are really difficult to recycle, and we have spoken to some of the major fashion companies that produce.” These textiles, because they are really struggling at the moment. “
Researchers have also succeeded in finding insects that eat other plastic materials such as polyurethane that is widely used but rarely recycled. When polyurethane decomposes it can release toxic chemicals that kill most bacteria, but the defect that has been identified is actually using the material as food to run. the operation.