Mutant Enzyme Could Vastly Improve Recycling of Plastic Bottles (sciencemag.org) 35
sciencehabit writes: Recycling isn't as guilt-free as it seems. Only about 30% of the plastic that goes into soda bottles gets turned into new plastic, and it often ends up as a lower strength version. Now, researchers report they've engineered an enzyme that can convert 90% of that same plastic back to its pristine starting materials. Work is underway to scale up the technology and open a demonstration plant next year.
The researchers generated hundreds of mutant enzymes changing amino acids as they went. They then mass produced the mutants in bacteria and screened them to find efficient breakers of plastic bonds. After repeating this process for several rounds, they isolated a mutant enzyme that's 10,000 times more efficient at breaking down an important bond that allows plastic to be recycled.
The team is currently building a demonstration plant that is expected to recycle hundreds of tons of plastic per year. The enzyme can't recycle other major types of plastics, such as polyethylene and polystyrene, which have bonds between building blocks that are harder to break. But if successful, it could make it help society deal with one of the most challenging plastic problems we face.
John McGeehan, who directs the center for enzyme innovation at the University of Portsmouth, also tells Science that now recycling companies typically melt plastics together to make carpets or other low-grade plastic fibers that will eventually end up in a landfill or get incinerated.
"It's not really recycling at all."
The researchers generated hundreds of mutant enzymes changing amino acids as they went. They then mass produced the mutants in bacteria and screened them to find efficient breakers of plastic bonds. After repeating this process for several rounds, they isolated a mutant enzyme that's 10,000 times more efficient at breaking down an important bond that allows plastic to be recycled.
The team is currently building a demonstration plant that is expected to recycle hundreds of tons of plastic per year. The enzyme can't recycle other major types of plastics, such as polyethylene and polystyrene, which have bonds between building blocks that are harder to break. But if successful, it could make it help society deal with one of the most challenging plastic problems we face.
John McGeehan, who directs the center for enzyme innovation at the University of Portsmouth, also tells Science that now recycling companies typically melt plastics together to make carpets or other low-grade plastic fibers that will eventually end up in a landfill or get incinerated.
"It's not really recycling at all."
It's gonna escape and mutate some more (Score:1)
Then it will eat all our fancy new plastic plumbing.
Re:It's gonna escape and mutate some more (Score:5, Informative)
Mutant 59: The Plastic-Eaters Pedler and Davis, 1973.
Not a particularly good book - it is "SF product", an technical gimmick, a plot built around the gimmick, and on to market.
Re: It's gonna escape and mutate some more (Score:2)
Damn, beat me to it by 20 minutes.
A cautionary tale. Despite its mediocrity, I always enjoyed it.
it's leaking into the turtle sanctuary! (Score:2)
it's leaking into the turtle sanctuary!
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Then it will eat all our fancy new plastic plumbing.
Drink bottles are made of PET. Plumbing is PVC.
To most people, they are both "plastic", but they are really two very different substances.
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Your about 20 years behind there gramp's.
Look up what PEX pipe is made out of (here's a hint polyethylene).
Pex and there couple of competitors have taken over the top spot in new home construction (in the USA at least) and remodel projects over the last decade mostly just for the speed and ease of installation.
Only old people use PVC pipe.
Polyethylene Terephthalate (Score:5, Informative)
To help the average slashdotter here (who just reads the summary), the plastic this enzyme digest is the popular bottle plastic PET or polyethylene terephthalate, also used (in vastly smaller amounts) in 3D printing. It converts the PET back into its starting materials - terephthalate and ethylene glycol - which can be obtained from the reaction mixture in pure form.
And no, we won't have microbes eating plastic. They just make the enzyme which is used in a reactor at a temperature well above the survival temperature of any engineered production microbe (72 C).
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Just adding some extra info to your previous comment, because Slashdot summary states that the enzyme doesn't work on polyethylene alone:
and apparently Google doesn't help people easily understand the difference between Polyethylene (PE) and Poly(Ethylene Terephthalate). So, I found in some very old book of mine some good info:
Polyethylene (PE)
Po [wikipedia.org]
Re: Polyethylene Terephthalate (Score:4, Funny)
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I think some way to try to explain this matter is: Every kind of enzyme are used to be very specific in what they can "cut", e. g..: some specific chemical bond. So this enzyme will be able to degrade some kind of plastics because they have this specific region for docking (and subsequent cleavage), but with other kind of polymers this enzyme will be able to do nothing.
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First.. thank you (all the people providing useful information here) for breaking the normal Slashdot mold and being so informative.
I'm not able to read the paper as I believe it's several degrees above my level of chemistry and materials.
When I read these "too good to be true" articles, my initial knee jerk reaction is to wonder "what's the catch?". And the first thing that comes to mind is that while i
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You are welcome.
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I'm not sure what more I can say other than just thanks!
fuel? (Score:2)
Re:fuel? (Score:5, Informative)
They mean terephthalate (terephthalic acid) and ethylene glycol, the actual chemicals from which the PET is made. The former needs an aromatic nucleus as a starting point, p-xylene usually, which would be obtained from petroleum (plant based production is possible though). Ethylene glycol though only needs carbon monoxide and hydrogen, and so various raw materials can be used with existing industrial methods.
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Silver bullets (Score:1)
silver bullets,
silver bullets, one and all.
If only
silver bullets
would do anything at all.
Great, this will get out... (Score:4, Funny)
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There already is plastic 'rust' .
The automotive and white goods industry learned long ago to make critical parts out of 'greener' plastics that wear out and force people to buy parts or replace the whole car or appliance more often.
Most big companies have 'continuation engineeing' teams on staff to drive costs down and design products to wear out soon after the warranty period ends.
No True Scotsman (Score:2)
"It's not really recycling at all."
Yes, it is recycling. It's not endless recycling but there are very few things which are.
Biodegradable (Score:2)
Plastics are biodegradable. It seems to be taking a long time for people to recognize this. First, it was ocean archaea. Now, lab-grown bacteria.
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Nothing is so clueless as citing red dwarf [wikipedia.org]—and not even knowing it. Only not even red dwarf recycles plastic all the way back to hydrogen. For that particular fly in the ointment, I think the blame falls on Slartibartfast.
Or we could... (Score:1)
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It's truly horrifying to shine a black light over the common public water fountain.
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Yeah, that. If you're going to mandate drinking fountains you also have to mandate regular sanitization of them. They are frequently disgusting.
It would be great if they can do something similar (Score:2)
that will break down old tires.
How about plastic to oil? (Score:2)
https://interestingengineering... [interestin...eering.com]
Anyone want to debunk this?
why does (Score:2)
why does the original movie version of The Andromeda Strain come to mind?
The problem isn't recycling per se (Score:2)
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The process of burying plastics can only lead to create an impermeable layer underground, that will block the rain water from being filtered and safely return to the groundwater in its natural renewable cycle. This can cause a lot of environmental problems.
On the contrary, if you have to create a s