Enzyme that eats plastic could change the world
Thursday, April 19, 2018
Scientists have discovered what might be one of the most important organic compounds ever discovered, if research, tests and time bear out the results as true. Per a new report published by the BBC, a "naturally occurring enzyme" can digest some of mankind's most common plastics known as polyethylene terephthalate (PET), the strong plastic typically used in bottles that takes hundreds of years to break down in the environment.
The enzyme, originally discovered in Japan, has been modified and is known as PETase. Based on the findings, PETase can start breaking down PET in just a few days. This breakthrough could have enormous, potentially world-altering effects on waste management and the environment.
Per the BBC, this discovery could "revolutionize the recycling process, allowing plastics to be reused more effectively."
Americans use more than 22 billion water bottles per year; U.K. consumers use about 13 billion plastic drinks bottles a year.
The enzyme is produced by a bacterium that eats PET; the enzyme ideonella sakaiensis uses the plastic as its major energy source. Researchers reported in 2016 that they had found the strain living in sediments at a bottle recycling site in the port city of Sakai.
"[PET] has only been around in vast quantities over the last 50 years, so it's actually not a very long timescale for a bacteria to have evolved to eat something so man-made," said Professor John McGeehan, who was involved in the current study.
Once the enzyme is better understood, scientists say they can improve the performance of PETase by adjusting a few residues on its surface and making it more effective at its job. PETase also was tested on PEF plastic, a plant-based alternative to PET that also is slow to degrade in nature.
"We were absolutely stunned when we did that experiment because it actually works better on PEF than PET," McGeehan told BBC News.
Challenges remain to bringing the enzyme to market and releasing it into the world, of course. For example, developing a technique for producing the enzyme cheaply may be a problem; producing it on an industrial scale could be tricky and costly; and ensuring that such a wide-scale release would be safe for the environment is essential.
Such plastics are industrially produced from petroleum and are widely used in drink bottles and clothing. However, even when these materials are recycled, they "follow a downward quality spiral, losing some of their properties each time they go through the cycle. Bottles become fleeces, then carpets, after which they often end up in landfill."
PETase reverses the manufacturing process, reducing polyesters to their building blocks, ready to be used again, the BBC reports. "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."
For some perspective, only one 1 of 5 plastic bottles is estimated to be recycled. The rest just become trash. PET plastic bottles can take more than 700 years to start decomposing; more than 100 million plastic bottles are used worldwide every day, per the World Counts. Finally, an estimated 1,500 plastic bottles end up as waste in landfills or thrown in the ocean every second.
McGeehan is hopeful that this marks the beginning of a shift in the management of plastics: "There is an urgent need to reduce the amount of plastic that ends up in landfill and the environment, and I think if we can adopt these technologies we actually have a potential solution in the future to doing that."
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