from Hacker News

Scientists create artificial protein that can degrade PET plastics in bottles

by rose_ann_ on 11/5/23, 3:11 PM with 108 comments

by lysozyme on 11/6/23, 3:51 PM
As cool as this is, the word “microplastics” is a little misleading. There are dozens of types of plastic in common use, each made from a different monomer with a different chemical linkage, of which PET is only one. The engineered protein in TFA will only work on PET and we’ll need to design new proteins for the other types of plastic. (I can help with that.)
The problem with enzymes eating plastic is that enzymes are small Pacman-shaped protein blobs that are maybe 10 nanometers in diameter, whereas things made of plastic like bottles or even microplastics are huge in comparison. How do you get the little Pacman jaws around the bottle to start breaking it down?
The research paper [1] describes the authors’ effective innovation. They make a protein where one end is a pore-forming shape, and the other end is a PET cutting (called a PETase in the jargon of the field). This way, their protein can access nooks and crannies in the macroplastic shapes, allowing tons of copies of this small enzyme to fully degrade a bottle.
Without this, a great deal of physical agitation is required to break down the plastics into small enough chunks that earlier Pacman enzymes could work on, increasing the time and the cost.
I hope we’ll see the idea of linking the enzymatic “scissors” to a protein pore be used to engineer enzymes to degrade other types of plastics in the future, as the general idea of getting the catalytic machinery into physical contact with every bit of the bottle is broadly applicable to all plastics, not just PET (which is great news)
1. https://phys.org/news/2023-10-scientists-artificial-protein-...
by CptFribble on 11/6/23, 7:39 PM
Another story about waste "solutions," another opportunity to remind the gentle readers about plasma gasification. A re-post of an earlier comment of mine on the topic follows:
---
Why are we still not talking about plasma gasification? https://en.wikipedia.org/wiki/Plasma_gasification
As far as I can tell, the only real "disadvantages" if you can call them that, are:
1. more expensive than throwing the garbage in a big pile somewhere
2. need to clean it from time to time
3. not necessarily a profitable business
Other than that, it can handle just about anything that's not radioactive, can be designed to produce 0 toxic byproducts, and can run at or at least only slightly below energy neutral. Plasma gasifiers can also consume a huge amount of garbage for their size, so much so that the US Navy is starting to put them on the latest generation of aircraft carriers.
Not building out more gasifiers seems to me a failure of the free market. Because it's hard to make it profitable, no one is doing it - when really we should just be building one or two near every major city and funneling all our garbage there.
In theory, we could build out enough to start working through all the landfills too.
by lucb1e on 11/6/23, 5:04 PM
With these articles I always wonder what they're turned into, since headlines and introductory paragraphs always conveniently omit that. These seem to be the relevant parts of the article:
> degrading PET [particles] and reducing them to their essential components, which would allow them to be broken down or recycled
> "One variant breaks down the PET particles more thoroughly, so it could be used for degradation in sewage treatment plants. The other gives rise to the initial components needed for recycling. In this way we can purify or recycle, depending on the needs," explains Laura Fernández López
Hmm, so that sounds like it's a step forwards (working the problem), but not yet a solution that can recycle PET into something anyone can use
Edit: this is why I'm asking...
Article: "... the bacterium Idionella sakaiensis, which is capable of degrading this type of plastic and was discovered in 2016 in a packaging recycling plant in Japan."
Wikipedia on Ideonella sakaiensis: "[they] mineralize 75% of the degraded PET into carbon dioxide" (to be fair, it also produces a "MHETase enzyme" which "could also be optimized and used in recycling or bioremediation applications") https://en.wikipedia.org/wiki/Ideonella_sakaiensis
by gilleain on 11/6/23, 1:51 PM
Nice. A few points:
* This protein acts as a PETase - see also <https://news.ycombinator.com/item?id=37659327> - but may work at room temperature, and more efficiently
* The term 'artificial protein' is a bit awkward - it's a modified version of an existing protein from an anemone (see : <https://www.rcsb.org/structure/4tsy>)
* The scaffold protein is a pore-forming structure - where multiple trans-membrane helices come together, like melittin in bee venom - so they claim it could work as part of a membrane-bound complex
by citrin_ru on 11/6/23, 2:35 PM
Is there any benefits to degrading plastic (using proteins or bacteria) if BPA/BPS will stay not degraded? From what I recon health harm comes not from plastic itself but from additives like BPA, BPS e. t. c.
by bcardarella on 11/6/23, 2:21 PM
I see similar articles or research like twice a year. And nothing ever comes of it.
by lasermike026 on 11/6/23, 3:47 PM
While that nice the goal is to significantly reduce the use of plastics and petrochemical in general. What we are talking about is a reengining of modern tools and products. These efforts will be aggressive.
by passwordoops on 11/6/23, 5:29 PM
Plastic eating enzymes have been a thing since the 90s. There's a breathless headline every 3-6 months. None get out of the lab
by monista on 11/6/23, 9:41 PM
It's good news, but reminded me at once Mutant 59: The Plastic Eaters (1971) by Kit Pedler and Gerry Davis, where a bacteria made to utilize plastic went wild and started destroying wire isolation everywhere, causing multiple crashes etc.
by zackmorris on 11/6/23, 5:46 PM
I'd like to know who originally put incompatible types of plastic under the same number, which contaminates recycling runs. Like PET/PETE under "1" and injection-molded/blow-molded HDPE under "2":
https://www.warwickri.gov/sanitation-recycling/faq/why-cant-...
Many cities have banned recycling the most commonly used plastics, like plastic water bottles made of 1 (PET). Where I live, 1 and 2 get recycled, 3 (PVC) gets thrown in a landfill and 4-7 get sent to a separate refinery which converts them to diesel fuel.
Not to mention that there seems to be no standard on the legibility of the number.
How many people reading this have thought about automating recycling by having machine learning sort the types? Yet I've never seen "recycling engineer" as a job title. Nor have I seen any grants for improving recycling. Nor any corporations/billionaires making recycling a priority. There have even been TV shows by prominent celebrities pushing propaganda against recycling, like the Penn & Teller: Bullsh*t! episode from the post Dot Bomb luddite era of 2004:
https://www.imdb.com/title/tt0771119/
We're willing to drink a protein that can degrade plastic before we're willing to hold industry accountable for the waste it produces?
by larodi on 11/6/23, 8:57 PM
Nature created mycelium which eats microplastics (and all kinds of carbohydrates) for lunch and grows shrooms on top of it. Not sure why we need artificial proteins for that.
by EasyTiger_ on 11/7/23, 2:17 PM
The whole "microplastics" thing is terrifyging
by peakskill on 11/6/23, 2:07 PM
How about microplastics in the body? :^]
by TuringNYC on 11/7/23, 12:56 AM
```
  Reminded me of Ice-9
```
by bell-cot on 11/6/23, 2:04 PM
Major omitted-from-headline limitation: It only works on PET plastic. (AKA "PETE", or https://en.wikipedia.org/wiki/Polyethylene_terephthalate - recycling number "1" or "01")
Quibble: "microplastics in bottles" looks far more like keyword stuffing then a sensible description.
by asow92 on 11/6/23, 2:26 PM
Microplastics are the "lead/asbestos poisoning" of our generation, and the problem is actually far more dire than either of the former. Someday, we will look back on how we could have ever allowed microplastics into our lives with shock and awe.
by troupe on 11/6/23, 4:44 PM
This announcement sounds like something mentioned in the background on TV while the soon to be hero eats breakfast before heading to work in an underpaid thankless position. 15 minutes later the audience learns that the protein has escaped the lab, become sentient, and is assembling plastic into Godzilla.
by just_boost_it on 11/6/23, 5:41 PM
It would be an interesting world if all our plastics started to rot. Water and sewerage piping is mostly plastic, there's heavy uses of plastics in electrical infrastructure, the majority of our containers, many car parts, the bulk of the housings of our electronics, building weatherproofing, most of our clothing... It would be nice to use other materials, but plastics are used because they're cheap, easy to work with, and they work well.
Also, how much plastic has been produced over the last 100 years? It also would have been nice not to have just thrown it all into a landfill, but now that it's there do we really want to release all the CO2 that's been safely locked away underground in solid plastic?
by DrThunder on 11/6/23, 2:35 PM
How do you keep something like this from spreading and deteriorating plastics in things you don't want it to?
by jdawg777 on 11/6/23, 3:06 PM
We should stop focusing on recycling plastics and invest in garbage incinerators/power plants.
by jokoon on 11/6/23, 5:28 PM
I wish hacker news was only about computing and not fringe science news, because unless it's an innovative product and it shows it's a breakthrough, it's probably techno-optimism or it's click-baity.
This applies for everything about batteries, and environmental techs.
The supraconductor crystal news was also quite a revealing event of the problem.