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Scientists Accidentally Develop 'Mutant' Enzyme That Eats Plastic

Science

Researchers in the UK and the U.S. have inadvertently engineered an enzyme that eats up plastic.

The enzyme is able to digest PET (polyethylene terephthalate)—the same material used in the ubiquitous plastic bottle that's clogging up landfills, coastlines and oceans around the world.


Amazingly, this discovery only happened by chance. Scientists from the University of Portsmouth in the UK and the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) were examining the structure of a natural enzyme, Ideonella sakaiensis, found in 2016 at a Japanese waste recycling center. This enzyme could already break down PET plastic—it just doesn't do it very quickly.

To understand how Ideonella sakaiensis evolved, the research team "tweaked" the structure of the enzyme by adding some amino acids, according to John McGeehan, a Portsmouth professor who co-led the work. They ended up creating an enzyme that worked even faster than the natural one.

"Surprisingly, we found that the PETase mutant outperforms the wild-type PETase in degrading PET," said NREL materials scientist Nic Rorrer.

McGeehan added, "Serendipity often plays a significant role in fundamental scientific research and our discovery here is no exception."

The modified enzyme, called PETase, can break down PET in just a few days—a stunning discovery that could help fight the world's escalating plastic crisis.

Electron microscope image of enzyme degrading PET plastic Dennis Schroeder / NREL

"After just 96 hours you can see clearly via electron microscopy that the PETase is degrading PET," said NREL structural biologist Bryon Donohoe.

"And this test is using real examples of what is found in the oceans and landfills."

As BBC News explained, PETase works by reversing the manufacturing process by reducing polyesters back to their building blocks so it can be used again.

When you drink soda, water or juice from a plastic bottle, those bottles are almost never made from recycled plastic. Additionally, as the Guardian noted, the plastic bottles that do get recycled can only be turned into polyester fibers for carpet or fabric.

But this new finding suggests a way to turn plastic bottles back into plastic bottles.

"They could be used to make more plastic and that would avoid using any more oil ... Then basically we'd close the loop. We'd actually have proper recycling," McGeehan told BBC News.

The team's finding was published Monday in the journal Proceedings of the National Academy of Sciences.

The researchers are now working to improve PETase to see if it can work on an industrial scale. About one million plastic bottles are purchased around the world every minute, with that number predicted to increase another 20 percent by 2021.

"This unanticipated discovery suggests that there is room to further improve these enzymes, moving us closer to a recycling solution for the ever-growing mountain of discarded plastics," McGeehan said.

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Aerial view of Ruropolis, Para state, northen Brazil, on Sept. 6, 2019. Tthe world's biggest rainforest is under threat from wildfires and rampant deforestation. JOHANNES MYBURGH / AFP via Getty Images

By Kate Martyr

Deforestation in Brazil's Amazon rainforest last month jumped to the highest level since records began in 2015, according to government data.

A total of 563 square kilometers (217.38 square miles) of the world's largest rainforest was destroyed in November, 103% more than in the same month last year, according to Brazil's space research agency.

From January to November this year an area almost the size of the Caribbean island of Puerto Rico was destroyed — an 83% overall increase in destruction when compared with the same period last year.

The figures were released on Friday by the National Institute for Space Research (INPE), and collected through the DETER database, which uses satellite images to monitor forest fires, forest destruction and other developments affecting the rainforest.

What's Behind the Rise?

Overall, deforestation in 2019 has jumped 30% compared to last year — 9,762 square kilometers (approximately 3769 square miles) have been destroyed, despite deforestation usually slowing during November and December.

Environmental groups, researchers and activists blamed the policies of Brazil's president Jair Bolsonaro for the increase.

They say that Bolosonaro's calls for the Amazon to be developed and his weakening support for Ibama, the government's environmental agency, have led to loggers and ranchers feeling safer and braver in destroying the expansive rainforest.

His government hit back at these claims, pointing out that previous governments also cut budgets to environment agencies such as Ibama.

The report comes as Brazil came to loggerheads with the Association of Small Island States (AOSIS) over climate goals during the UN climate conference in Madrid.

AOSIS blasted Brazil, among other nations, for "a lack of ambition that also undermines ours."

Last month, a group of Brazilian lawyers called for Bolsonaro to be investigated by the International Criminal Court over his environmental policies.

Reposted with permission from DW.

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