Researchers accidentally engineer plastic-eating enzyme

A boy stands near a whale-shaped art installation that is made of plastic and trash made by environmental activist group Greenpeace Philippines, lying along the shore in Naic, Cavite in the Philippines, in this May 12, 2017 file photo. (REUTERS)
Updated 17 April 2018
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Researchers accidentally engineer plastic-eating enzyme

  • Despite recycling efforts, most plastic can persist for hundreds of years in the environment
  • Researchers say they are now working on further improvements to the enzyme

TAMPA: Researchers in the US and Britain have accidentally engineered an enzyme which eats plastic and may eventually help solve the growing problem of plastic pollution, a study said Monday.
More than eight million tons of plastic are dumped into the world’s oceans every year, and concern is mounting over this petroleum-derived product’s toxic legacy on human health and the environment.
Despite recycling efforts, most plastic can persist for hundreds of years in the environment, so researchers are searching for better ways to eliminate it.
Scientists at the University of Portsmouth and the US Energy Department’s National Renewable Energy Laboratory decided to focus on a naturally occurring bacterium discovered in Japan a few years ago.
Japanese researchers believe the bacterium evolved fairly recently in a waste recycling center, since plastics were not invented until the 1940s.
Known as Ideonella sakaiensis, it appears to feed exclusively on a type of plastic known as polyethylene terephthalate (PET), used widely in plastic bottles.

The researchers’ goal was to understand how one of its enzymes — called PETase — worked, by figuring out its structure.
“But they ended up going a step further and accidentally engineered an enzyme which was even better at breaking down PET plastics,” said the report in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.
Using a super-powerful X-ray, 10 billion times brighter than the Sun, they were able to make an ultra-high-resolution three-dimensional model of the enzyme.
Scientists from the University of South Florida and the University of Campinas in Brazil did computer modeling which showed PETase looked similar to another enzyme, cutinase, found in fungus and bacteria.
One area of the PETase was a bit different, though, and researchers hypothesized that this was the part that allowed it to degrade man-made plastic.
So they mutated the PETase active site to make it more like cutinase, and unexpectedly found that this mutant enzyme was even better than the natural PETase at breaking down PET.
Researchers say they are now working on further improvements to the enzyme, with the hope of eventually scaling it up for industrial use in breaking down plastics.
“Serendipity often plays a significant role in fundamental scientific research, and our discovery here is no exception,” said study author John McGeehan, professor in the School of Biological Sciences at Portsmouth.
“Although the improvement is modest, 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.”
 


Massive diamond cache detected beneath Earth’s surface

Updated 18 July 2018
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Massive diamond cache detected beneath Earth’s surface

  • “This shows that diamond is not perhaps this exotic mineral..."
  • These naturally occurring precious minerals are located far deeper than any drilling expedition has ever reached

WASHINGTON: There’s a load of bling buried in the Earth.
More than a quadrillion tons of diamonds to be exact — or one thousand times more than one trillion — US researchers at the Massachusetts Institute of Technology reported this week.
But don’t expect a diamond rush. These naturally occurring precious minerals are located far deeper than any drilling expedition has ever reached, about 90 to 150 miles (145 to 240 kilometers) below the surface of our planet.
“We can’t get at them, but still, there is much more diamond there than we have ever thought before,” said Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences.
“This shows that diamond is not perhaps this exotic mineral, but on the scale of things, it’s relatively common.”
Using seismic technology to analyze how sound waves pass through the Earth, scientists detected the treasure trove in rocks called cratonic roots, which are shaped like inverted mountains that stretch through the Earth’s crust and into the mantle.
These are “the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates,” explained MIT in a statement.
The project to uncover deep Earth diamonds began because scientists were puzzled by observations that sound waves would speed up significantly when passing through the roots of ancient cratons.
So they assembled virtual rocks, made from various combinations of minerals, to calculate how fast sound waves would travel through them.
“Diamond in many ways is special,” Faul said.
“One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.”
They found that the only type of rock that matched the speeds they were detecting in craton would contain one to two percent diamond.
Scientists now believe the Earth’s ancient underground rocks contain at least 1,000 times more diamond than previously expected.
Still, very few of these gems are expected to make their way to the jewelry store.
Diamonds are made from carbon, and are formed under high-pressure and extreme temperatures deep in the Earth.
They emerge near the surface only through volcanic eruptions that occur rarely — on the order of every few tens of millions of years.