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.
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/superfamily/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.
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?).
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.
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 ...
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.
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.
Wood doesn’t spontaneously rot at a rate that is problematic. This new enzyme requires temperatures of around 70C to operate. Any microbe that does evolve to eat plastic will probably need some specific living conditions. They are unlikely to be so efficient and universal that we see plastic rotting while we are using it.
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?
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.
"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.
> 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.
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.
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!
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"
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.
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.
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.
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.
Readit News
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.
As educated as I think I am, it is always humbling to read a hacker news comment that I cannot understand.
ELI5?
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/superfamily/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.
Has anyone attempted to put these enzymes to the test in at some scale in an industrial setting, I wonder?
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 ...
70° is maybe a little out of the reach of a home system but nothing for a municipal system. Right?
It doesn't say it was the only one, just a newly discovered one
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.
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.
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.
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.
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.
No, burying is better because it sequesters the carbon rather than releasing it into the atmosphere.
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.
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.
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!
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"
https://phys.org/news/2023-09-newly-deep-sea-enzyme-pet-plas...
Imagine my delight in reading this:
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.Deleted Comment