[HN Gopher] Newly discovered deep-sea enzyme breaks down PET pla...
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Newly discovered deep-sea enzyme breaks down PET plastic
Author : hanniabu
Score : 145 points
Date : 2023-09-26 13:52 UTC (9 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| dzdt wrote:
| The way to understand the origin of fossil fuel deposits is that
| hundreds of millions of years ago trees were made of plastic.
|
| Thats not quite literally true but it gives the right sense. In
| the Carboniferous period trees grew abundently but there were not
| yet bacteria that could break down the lignins composing the
| woody structure. Its very similar to what you'd get with plastic
| trees today: they would fall and pile up like junk in a landfill.
| Then eventually this would be buried and result in the many-
| meters-thick coal deposits we find today.
|
| Lessons? I don't know. But piles of un-decomposable hydrocarbons
| is not a new thing for the planet.
| morsch wrote:
| When I searched for this, I found there to be some debate on it
| (isn't there always?):
| https://www.pnas.org/doi/10.1073/pnas.1517943113
| https://arstechnica.com/science/2016/01/why-was-most-of-the-...
| dzdt wrote:
| Thanks! Your newer research is pretty convincing. Makes me a
| bit sad: I really like the 'plastic tree' analogy. Ah, well.
| bno1 wrote:
| I wonder what forests looked back then. Trees going through and
| on piles of dead trees?
| m463 wrote:
| It's interesting to read about thomas gold's theories about
| hydrocarbons.
|
| https://en.wikipedia.org/wiki/Abiogenic_petroleum_origin
|
| To me it makes sense that some or all hydrocarbons are or at
| least started like the hydrocarbons found on other planets in
| our solar system.
| zellyn wrote:
| I love the idea of finding enzymes that break down plastics. I
| also like to imagine the post-apocalyptic Sci-Fi short story
| possibilities of accidentally releasing something that breaks
| down _all_ plastic!
|
| Imagine my delight in reading this: At the
| molecular level, PET46 is very similar to another enzyme, ferulic
| acid esterase. This degrades the natural polymer lignin in plant
| cell walls by breaking down lignin polymers to release
| sugars from woody plant parts. Lignin and PET have many
| structural similarities, so the PET-degrading enzymes
| found in nature may be important for composting wood in forest
| soils, for example.
|
| Now, join me in imagining the post-apocalyptic Sci-Fi short story
| possibilities of accidentally releasing something that breaks
| down all plastic _and_ all plants! I mean, until some of them
| finally adapt.
| lanstin wrote:
| Unlike the plastic substrate of modern technological society,
| plants have survived hundreds of millions of years of efforts
| by the rest of the biosphere to eat them.
| zellyn wrote:
| True, although I believe dredging up unusual enzymes from the
| stygian depths facilitates new and exciting dystopian
| storylines.
| aftbit wrote:
| You might enjoy the Rifters trilogy by Peter Watts.
| multiplegeorges wrote:
| So dumping all our plastic in the sea will work out! /s
|
| It seems like these discoveries are coming quickly and in higher
| numbers. Maybe there's hope in recycling/processing plastics down
| simpler molecules after all. Currently, recycling plastic is a
| bit of a lie -- very little of it is actually recycled.
| titzer wrote:
| I recognize the sarcasm in your first sentence, but I am not
| super hopeful. The question is always, "so now it breaks
| down...into what? And what happens to that?". If that gives
| rise to the equivalent of some kind of algal bloom that then
| kills off other life, it might actually be worse than the
| microplastics themselves.
|
| I for one do not hold out hope for recycling plastics. We had
| more sustainable materials in the past, and in places we still
| do that. For example, reusing beer bottles with the Pfand
| system in Germany, or milk bottles, crates, durable packaging.
| We're still going backwards with this consumerist throwaway
| culture.
| EGreg wrote:
| Here here.
|
| Unfortunately the government has teamed up with the
| corporations to continue to push it for decades:
|
| https://magarshak.com/blog/?p=362
|
| The recycling was a scam to keep the public distracted so
| their impulse to "do something" would lead to individuan
| action rather than lead to organizing to demand reforms!
| kzrdude wrote:
| I'm fearing that degradable plastics is also a lie.. is it just
| turning it into microplastics small enough that the problem
| visually disappears?
| Kerb_ wrote:
| It breaks them down into their atomic components and enables
| bacteria that can straight up digest plastic. The issue from
| this is that we rely on plastics not being degradable for a
| lot of the properties we use it for. Imagine if bugs got this
| enzyme in their gut bacteria, and started eating the food
| wrappers instead of just nibbling through them. Plastic used
| to seal sterile equipment in medical settings or for
| implants? Useless. The plastic waste would only last a few
| years relative to the decades+ now, but it would also ruin
| plastic's ability to seal stuff, which is why we use it.
|
| Overall, probably a good thing to reduce our reliance on
| plastic, but it will come at a cost, it's not just "we can
| dump plastic in the ocean now"
| coffeebeqn wrote:
| It would still be difficult for bugs to gnaw on solid
| plastic
| hutzlibu wrote:
| "Currently, recycling plastic is a bit of a lie -- very little
| of it is actually recycled."
|
| Depends where you live and what you consider recycling. If you
| mean, making new plastics out of the old, than the challenge
| is, that there are many, many different plastics you cannot
| just melt in and reuse if mixed together. A annoying, but
| working solution here in germany is a mandated bottle bill.
| Meaning you pay 25 cent extra per bottle, and get it back, if
| you return that bottle into a machine: but this results in
| actual reusable plastics as they are all of the same kind.
|
| And for the rest, the most pragmatic solution is burning it for
| energy. If you use filters, it is not so bad and it is
| recycling, but it is the same as burning fossil fuels, so not a
| good long term solution.
| gruez wrote:
| >And for the rest, the most pragmatic solution is burning it
| for energy.
|
| No, burying is better because it sequesters the carbon rather
| than releasing it into the atmosphere.
| hutzlibu wrote:
| If it means not burning coal, oil or gas instead and there
| are good filters, I think burning plastic makes sense. But
| if you can actually get all the needed energy from non
| fossil sources, then yes, burying makes more sense. But I
| think only some rare places on earth are that far.
| digging wrote:
| > And for the rest, the most pragmatic solution is burning it
| for energy.
|
| I really wish we'd do more of this. I know it's not ideal,
| but we in the US need to treat plastic like the trash that it
| (mostly) is. And trash is just fuel. Instead we have
| convenient single-stream recycling which means all our actual
| recyclables also end up in the trash and/or oceans.
| ZeWaka wrote:
| We actually do a fair amount of this in the US. Marion
| County in Oregon burns 90% of their trash. It's much better
| than landfills, anyways.
| gruez wrote:
| How is burning better than landfilling it? If the
| landfill is lined the garbage isn't going anywhere, and
| leaving the plastic in the ground is much better than
| releasing its co2 into the atmosphere. Land use might be
| an issue in some places, but I doubt that's the case in
| Oregon.
| kwhitefoot wrote:
| Why do we want to break down PET? Why not just re-use it?
| Intralexical wrote:
| Heat, stress, and light will probably break it down
| mechanically over time no matter how diligent you are about
| reusing or recycling it.
|
| At the very least, this should hopefully mean that all those
| scary endocrine-disrupting and bioaccumulating microplastic and
| nanoplastic particles that are apparently being shed by the
| millions every time you heat or handle anything plastic aren't
| necessarily going to keep building up forever.
| wahnfrieden wrote:
| Most is not reused, or only reused with limited capacity
| ginko wrote:
| Now splice this into the genome of black mold and release it in a
| coca-cola bottling plant.
| tabtab wrote:
| Don't laugh, someday a terrorist or hacker may engineer a fast-
| eating critter, and half our stuff will become useless in a
| year. Termites learned to work with gut microbes to speed up
| wood munching, a home-owner's biggest nightmare.
| izzydata wrote:
| That's still kind of funny in a existential hysteria kind of
| way.
| hansvm wrote:
| Humans are pretty adaptable. If half our stuff did become
| useless do you think that might put a damper on rampant
| consumerism?
| hanniabu wrote:
| It would increase consumerism since everything would need
| to be replaced on a periodic basis
| digging wrote:
| Everything? I think instead, we'll just stop making most
| things out of plastics. We have longer-lasting, more
| durable materials than plastics already, for when you
| want something that will actually survive decades or
| generations. They're metals and woods and stones.
|
| Some things, like wire coatings, will still likely need
| to be plastic and will become disposable. But most uses
| of plastic for long-lasting goods will just stop using
| plastics. Goods will get much heavier, but more durable.
| ars wrote:
| Woods? If wood can survive so can plastic in this
| hypothetical world. Just keep water away from the
| plastic.
| BizarroLand wrote:
| With new plastics full of chemicals that the bugs won't
| eat.
| Metacelsus wrote:
| Sounds like "Mutant 59"
| monocasa wrote:
| Less fun, PET is heavily used in medical devices including
| implants. There's a huge cut to life expectancy if it becomes a
| secondary food source for something like an engineered MSRA
| strain.
| digging wrote:
| More reason to be furious at plastic peddling billionaires.
| They made us hostages. We still have to stop them, but it's
| going to hurt even more.
| Intralexical wrote:
| Eh. Thinking plastic would last forever was probably a
| reasonable assumption at the time. I doubt it was the
| billionaires making that design call. Though in hindsight
| maybe we should have known better, given the history of
| lignin and natural waxes.
|
| Though especially given the history of lignin, we probably
| have millions of years before medical devices being eaten
| by microbes becomes a widespread problem that anyone
| seriously needs to worry about. There's bigger fish to fry
| right now.
| digging wrote:
| > Thinking plastic would last forever was probably a
| reasonable assumption at the time
|
| That's... not what I'm mad about at all.
| [deleted]
| walnutclosefarm wrote:
| The Andromeda Strain!
| mattkrause wrote:
| Or Peter Watts' _Starfish_ , since it's from the deep sea
| digging wrote:
| There's one significant detail about Behemoth missing...
| rand0mx1 wrote:
| AMP-Free link
|
| https://phys.org/news/2023-09-newly-deep-sea-enzyme-pet-plas...
| dang wrote:
| Changed from https://phys.org/news/2023-09-newly-deep-sea-
| enzyme-pet-plas.... Thanks!
| sproketboy wrote:
| [dead]
| perlgeek wrote:
| Thank you phys.org for putting an actual link to the scientific
| publication, something that is missing far too often these days.
| gilleain wrote:
| Slightly misleading headline, as PET (polyethylene terephthalate)
| hydrolases were already known - see
| https://www.chm.bris.ac.uk/motm/PETase/PETaseh.htm
|
| This is a study of an archaeal enzyme (from the deep-sea) that
| can degrade both long-chain and short-chain polymers that is more
| efficient at 70 deg C than other enzymes.
|
| The details are that this is a feruloyl esterase with a conserved
| alpha/beta-hydrolase fold but with an additional flexible 'lid'
| domain that covers the active site. The authors suggest this lid
| domain replaces the conserved Trp that is an Ala in the archaeal
| enzyme.
| hanniabu wrote:
| > Slightly misleading headline, as PET (polyethylene
| terephthalate) hydrolases were already known
|
| It doesn't say it was the only one, just a newly discovered one
| gilleain wrote:
| Sure, fair enough. I just thought people might read it as
| "Enzyme with new ability (to break down PET) discovered", but
| maybe I was being pessimistic.
| capableweb wrote:
| It's also mentioned in the article body:
|
| > Until now, about 80 different PET-degrading enzymes were
| known, most of which were found in bacteria or fungi.
| digging wrote:
| Most of us aren't reading the body though.
| pneumic wrote:
| Yeah, it's not bad news at all but it appears to be one of many
| that still require considerable heat, industrial infra, etc.
|
| Has anyone attempted to put these enzymes to the test in at
| some scale in an industrial setting, I wonder?
| hanniabu wrote:
| Should work well in landfills since there's heat buildup
| jamesjuicy55 wrote:
| https://www.purecycle.com/who-we-are. ?
| hinkley wrote:
| I mean my processor hits 70deg and has for a decade or more,
| and my car engine thinks 87deg is the happy temperature.
|
| 70deg is maybe a little out of the reach of a home system but
| nothing for a municipal system. Right?
| gilleain wrote:
| No idea. From skimming some university press releases, I see
| a lot of "potential for!" and similar wording.
|
| This https://news.utexas.edu/2022/04/27/plastic-eating-
| enzyme-cou... has "Up next, the team plans to work on scaling
| up enzyme production to prepare for industrial and
| environmental application. " which is more promising.
|
| As far as I understand, yes it is a very different challenge
| to make a bioreactor for actually using some random new
| enzyme than the (also hard) problem of getting the structure
| in the first place. How to immobilize it on some surface, how
| to pre-process the material to pass it through the reactor
| (?) I guess ...
| justaskme wrote:
| Feels like it's always "potential for"... _sigh_
| eindiran wrote:
| I was recently at a party and spent some time talking with
| someone who has a stealth startup working on this exact
| problem. He said that they aren't the first, but getting the
| scale right (in an industrial setting) and finances right
| enough that someone is willing to spend the money to set it
| up is far harder than just finding an enzyme that can break
| down PET / similar polymers.
| testfoobar wrote:
| "this is a feruloyl esterase with a conserved alpha/beta-
| hydrolase fold but with an additional flexible 'lid' domain
| that covers the active site"
|
| As educated as I think I am, it is always humbling to read a
| hacker news comment that I cannot understand.
|
| ELI5?
| gilleain wrote:
| Apologies, that was meant for the specialists :) It is mostly
| just technical jargon so do not feel too humble ...
|
| So I'll break it down:
|
| - "feruloyl esterase" : an 'esterase' is an enzyme that makes
| or breaks ester bonds. In this case, 'feruloyl' which I've
| never heard of but apparently is some small molecule that is
| normally attached to a sugar.
| https://en.wikipedia.org/wiki/Feruloyl_esterase
|
| - "conserved alpha/beta-hydrolase fold" : a structural
| pattern (fold) that is shared (conserved) between a set of
| structures. In other words, these enzymes all have roughly
| the same shape. https://www.cathdb.info/version/v4_3_0/superf
| amily/3.40.50.1...
|
| - "additional flexible 'lid' domain that covers the active
| site" : a 'domain' is just a compact part of a protein,
| without going into too much detail. They are calling it a
| 'flexible lid' as the idea is that it moves out of the way to
| bind the substrate to the active site (where the reaction is
| carried out) and back again when fully bound.
| testfoobar wrote:
| Thank you.
| neftaly wrote:
| Enzymes are kind of like a tool for breaking apart lego
| blocks, or a jig for assembling them. This sounds like a
| moving part that covers the "teeth" and makes it more
| effective (or less likely to get jammed by the wrong
| molecules?).
| Gibbon1 wrote:
| Two things.
|
| Lot of reactions are energetically favorable. But the
| reactants are stuck in a local minima. So either doesn't
| happen or is too slow. Enzymes mediate the reaction so it
| can happen or happen faster.
|
| Lot of reactions there are side reactions that produce
| stuff you don't want. Resulting a terrible yield or maybe
| none. Enzymes can promote the reaction you want increasing
| the yield.
|
| Interesting thing to watch for is eletrocatalysts. Where
| you use electricity and a catalist to push a reaction that
| is energetically unfavorable. Like CO2 + H2O --> methanol.
| These may become very important as we stop pumping oil and
| gas out of the ground.
| anon84873628 wrote:
| I don't think there's much to say besides "slightly different
| chemical structure makes it better". At some point you hit
| jargon rock bottom.
| FredPret wrote:
| It's really awesome that all our plastic will one day rot.
|
| But we have lots of pipes and cables underground that will need
| to be replaced - with what I wonder.
| Max-q wrote:
| As much plastic as we dump into nature now, we increase the
| chance for a mutation of a microbe being able to digest it.
|
| If that microbe manage to multiply and spread, plastic can start
| to rot, just like wood is doing now. On a long term basis, that
| might be a good thing, but in the short term it would be a
| catastrophy. We are using plastic as a long lasting material,
| often with no surface treatment. Imagine if wire insulation,
| waterproof encapsulation, gaskets and other important parts of
| our infrastructure starts to rapidly degrade!
|
| That alone should be motivation for cleaning up and stop
| spreading plastic waste in nature.
| geoelectric wrote:
| IIRC, "plastic eater" was one of the mutations of The Andromeda
| Strain in the eponymous Crichton novel.
| vagab0nd wrote:
| Not to undermine your point about cleaning up plastic, but
| following your logic: isn't this similar to the antibiotics
| situation, just maybe on a longer time scale? The more you use
| it the less effective it is. What's the ultimate solution?
| yukkuri wrote:
| Walls and ladders. There isn't a solution to evolution, you
| just have to keep adapting.
| Intralexical wrote:
| Is it feasible for something like, e.g., teflon to be
| decomposed biologically?
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