Monday October 22, 2018

Plastics Can Be Eaten By Enzymes And Reduce Pollution

The enzyme is able to digest polyethylene terephthalate

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Packs of flattened polyethylene terephthalate (or PET) bottles are carried into a depot before being pulverized as part of a recycling process at Tokyo PET Bottle Recycle Co. in Tokyo, Aug. 13, 2002. Researchers in Britain and the United States have engineered an enzyme that breaks down such plastics.
Packs of flattened polyethylene terephthalate (or PET) bottles are carried.VOA
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Scientists in Britain and the United States say they have engineered a plastic-eating enzyme that could help in the fight against pollution.

The enzyme is able to digest polyethylene terephthalate, or PET — a form of plastic patented in the 1940s and now used in millions of tons of plastic bottles. PET plastics can persist for hundreds of years in the environment and currently pollute large areas of land and sea worldwide.

Researchers from Britain’s University of Portsmouth and the U.S. Department of Energy’s National Renewable Energy Laboratory made the discovery while examining the structure of a natural enzyme thought to have evolved in a waste-recycling center in Japan.

Finding that this enzyme was helping a bacteria to break down, or digest, PET plastic, the researchers decided to “tweak” its structure by adding some amino acids, said John McGeehan, a professor at Portsmouth who co-led the work.

This led to a serendipitous change in the enzyme’s actions — allowing its plastic-eating abilities to work faster.

“We’ve made an improved version of the enzyme better than the natural one already,” McGeehan told Reuters in an interview.

“That’s really exciting because that means that there’s potential to optimize the enzyme even further.”

The team, whose finding was published Monday in the Proceedings of the National Academy of Sciences journal, is now working on improving the enzyme further to see if it could be capable of breaking down PET plastics on an industrial scale.

Plastic pollution
Plastic pollution, Pixabay

“It’s well within the possibility that in the coming years we will see an industrially viable process to turn PET, and potentially other [plastics], back into their original building blocks so that they can be sustainably recycled,” McGeehan said.

‘Strong potential’

Independent scientists not directly involved with the research said it was exciting, but cautioned that the enzyme’s development as a potential solution for pollution was still at an early stage.

“Enzymes are non-toxic, biodegradable and can be produced in large amounts by microorganisms,” said Oliver Jones, a Melbourne University chemistry expert. “There is strong potential to use enzyme technology to help with society’s growing waste problem by breaking down some of the most commonly used plastics.”

Douglas Kell, a professor of bioanalytical science at Manchester University, said further rounds of work “should be expected to improve the enzyme yet further.”

Also read: Ayushmann Khurana speaks against plastic pollution

“All told, this advance brings the goal of sustainably recyclable polymers significantly closer,” he added. (VOA)

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Invasive Species May Not Be All Bad: Scientists

An active debate among biologists about the role of invasive species in a changing world is going on

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Invasive Species
The invasive European green crab is tearing down ecosystems in Newfoundland and building them up on Cape Cod. VOA

Off the shores of Newfoundland, Canada, an ecosystem is unraveling at the hands (or pincers) of an invasive crab.

Some 1,500 kilometers (930 miles) to the south, the same invasive crab — the European green crab — is helping New England marshes rebuild.

Both cases are featured in a new study that shows how the impacts of these alien invaders are not always straightforward.

Around the world, invasive species are a major threat to many coastal ecosystems and the benefits they provide, from food to clean water. Attitudes among scientists are evolving, however, as more research demonstrates that they occasionally carry a hidden upside.

“It’s complicated,” said Christina Simkanin, a biologist at the Smithsonian Environmental Research Center, “which isn’t a super-satisfying answer if you want a direct, should we keep it or should we not? But it’s the reality.”

Simkanin co-authored a new study showing that on the whole, coastal ecosystems store more carbon when they are overrun by invasive species.

Good news, crab news

Take the contradictory case of the European green crab. These invaders were first spotted in Newfoundland in 2007. Since then, they have devastated eelgrass habitats, digging up native vegetation as they burrow for shelter or dig for prey. Eelgrass is down 50 percent in places the crabs have moved into. Some sites have suffered total collapse.

That’s been devastating for fish that spend their juvenile days among the seagrass. Where the invasive crabs have moved in, the total weight of fish is down tenfold.

The loss of eelgrass also means these underwater meadows soak up less planet-warming carbon dioxide from the atmosphere.

In Cape Cod, Massachusetts, the same crab is having the opposite impact.

Off the coast of New England, fishermen have caught too many striped bass and blue crabs. These species used to keep native crab populations in check. Without predators to hold them back, native crabs are devouring the marshes.

But the invasive European green crab pushes native crabs out of their burrows. Under pressure from the invader, native crabs are eating less marsh grass. Marshes are recovering, and their carbon storage capacity is growing with them.

Invasive species
In this May 8, 2016 photo, eelgrass grows in sediment at Lowell’s Cove in Harpswell, Maine. VOA

Carbon repositories

Simkanin and colleagues compiled these studies and more than 100 others to see whether the net impact on carbon storage has been positive or negative.

They found that the ones overtaken by invasive species held about 40 percent more carbon than intact habitats.

They were taken by surprise, she said, because “non-native species are thought of as being negative so often. And they do have detrimental impacts. But in this case, they seem to be storing carbon quicker.”

At the Smithsonian Environmental Research Center where she works, the invasive reed Phragmites has been steadily overtaking a marsh scientists are studying.

Phragmites grows much taller, denser and with deeper roots than the native marsh grass it overruns.

But those same traits that make it a powerful invader also mean it stores more carbon than native species.

“Phragmites has been referred to as a Jekyll and Hyde species,” she said.

Not all invaded ecosystems stored more carbon. Invaded seagrass habitats generally lost carbon, and mangroves were basically unchanged. But on balance, gains from marsh invaders outweighed the others.

Invasive species
Phragmites plants growing on Staten Island draft in a breeze in the Oakwood Beach neighborhood of Staten Island. VOA

Not a lot of generalities

To be clear, Simkanin said the study is not suggesting it’s always better to let the invaders take over; but, it reflects an active debate among biologists about the role of invasive species in a changing world.

“One of the difficult things in the field of invasion biology is, there aren’t a lot of generalities,” said Brown University conservation biologist Dov Sax, who was not involved with the research. “There’s a lot of nuance.”

The prevailing view among biologists is that non-native species should be presumed to be destructive unless proven otherwise.

When 19 biologists wrote an article in 2011 challenging that view, titled, “Don’t judge species on their origins,” it drew a forceful rebuke from 141 other experts.

Sax said the argument is likely to become more complicated in the future.

Also Read: Climate Change Not A Hoax: Trump

“In a changing world, with a rapidly changing climate, we do expect there to be lots of cases where natives will no longer be as successful in a region. And some of the non-natives might actually step in and play some of those ecosystem services roles that we might want,” he said.

“In that context, what do we do? I definitely don’t have all the answers.” (VOA)