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An engineered PET depolymerase to break down and recycle plastic bottles
- baq 6y agoi don't want this anywhere near my home please
- anonuser123456 6y agoBecause?
- phkahler 6y agoIt might be extremely toxic.
- thomas 6y agoIt’ll eat everything inside!
- greglindahl 6y agoI have a large number of plastic things inside my home that I hope do not become decomposed. Garbage, sure, decompose away.
- YetAnotherNick 6y agoIt does not multiply like you expect in a movie. So the amount it can decompose is limited by quantity of the enzyme.
- the8472 6y agoEnzymes are proteins. They're applied to powderized plastic in a bio-reactor. It's unlikely that they'd be able significantly attack bulk plastics before they themselves get broken down.
- lostmsu 6y agoWait until some organism eats them and learns to reproduce.
- deleted 6y ago[deleted]
- eloff 6y agoMy parents have a neighbor whose house is literally made of plastic, aside from a few structural supports. You could spray this on his house and 10 hours later, goodbye house ( assuming it is PET plastic, I have no idea.)
- cmrx64 6y agoDon't be histrionic, the PET they did this with wasn't in large chunks, it was processed into a powder (with particle sizes between 200-500 micrometers). This enzyme would be less harmful to their house than rubbing it with acetone.
- ScottBurson 6y agoWas it 3-D printed? I was going to say that it probably isn't PET, but a bit of Googling quickly turns up articles about people making houses out of recycled plastic. If that's what it is, it could well be PET.
- eloff 6y agoMore like big, hollow 2x4 beams of plastic arranged vertically and interlocked. Could be recycled, I don't know for sure.
- mattkrause 6y agoI suspect that your parents' neighbor would already be unhappy if someone smashed their house into micron-size particles, heated it to 155˚F and kept it there for many hours. At that point, not having the PET broken down into monomers is a pretty lousy silver lining. (Seriously though, it needs fairly particular conditions to work.)
- rsynnott 6y agoIf you're heating the whole house to 65 degrees, as required, that is probably the least of their worries. And it's not like the ability to dissolve plastic is new; there are plenty of solvents which will do this for various plastics.
- gus_massa 6y agoThe research article say they use the enzyme at 65°C/70°C (150°F/160°F). Also, usually the reaction speed decrease exponentially with the temperature. So your home items are probably fine.
- tandr 6y agoSay, at 18C - does it still work? Maybe 100 times slower, but still work? Or you have to reach 65C for it to evens start working?
- battery_cowboy 6y ago> An engineered PET depolymerase to break down and recycle plastic Wrong title, and it's not for all plastics. We all complain here about journalism taking the wrong conclusion and I'm just pointing out the factually wrong message in the title.
- eloff 6y agoI prefer this title, I clicked on it. I might not have with the original.
- battery_cowboy 6y agoBut it doesn't break down all plastics, just for PET. The title should match the article according to the HN rules.
- eloff 6y agoHow many people know what PET is? I'm not sure I would have got the reference. The original title has too much jargon.
- battery_cowboy 6y agoSo? It's not for all plastics, there are so many different kinds and they're all different! This is basically only used in food containers, not products like your TV or phone case. Also, that's a false argument. We shouldn't dumb things down to incorrectness just so people understand them. It's not hard to look up 'PET plastic', and I see enough complex article titles on HN that I don't think that applicable to our community.
- eloff 6y agoHow's that a false argument? It's reasonable to avoid jargon in communication where possible - if you want to communicate to a wider audience. In this case I don't think it adds much. Once you click through you get the details. But the mods seem to agree with you, so I'm in the minority opinion it seems.
- makapuf 6y agoFor a layman like me, what does this enzyme decompose the plastic into?
- Cerium 6y agoI think that it decomposes the plastic back into the monomers that it is made up of. At which point it could be polymerized again to create new plastic.
- battery_cowboy 6y agoMonomers, the basic building block of plastic. You can then re-polymerize them.
- chewymouse 6y agoFrom the abstract: Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging3. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties4. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units—which reduce chain mobility—PET is a polyester that is extremely difficult to hydrolyse5. Several PET hydrolase enzymes have been reported, but show limited productivity6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). Basically, plastics are polymers (many units) of repeating building block monomers (single unit). The single unit is terephthalate, a " dimethyl-ester that is a major starting material for polyester fibers and coatings." So you're breaking down the already formed polymers into the building blocks that can be redeployed.
- masnao 6y agothe article only says hydrolase. which means using water to break bonds. breaking bonds in plastic gives you smaller plastic.
- jkqwzsoo 6y ago
- stenlix 6y agoDon't have access to the full article so I've only read the abstract, but what's the feasibility of deployment here?
- lowdose 6y agohttps://sci-hub.tw/downloads-ii/2020-04-09/c8/10.1038@s41586-020-2149-4.pdf https://sci-hub.tw/downloads-ii/2020-04-09/c8/10.1038@s41586...
- avalys 6y agoThat’s alarming. Sounds like an effective way to destroy every modern manufactured good.
- ladberg 6y agoIt only destroys the goods if you let them soak in the solution for hours. How does that make it dangerous? If someone wanted to just destroy goods, fire is way more effective.
- temikus 6y agoIt’s a solution that needs controlled pressure and 60+C temperature in a bioreactor...
- ahsima1 6y agoThere are many more effective chemicals if your goal is just to destroy, chlorine trifluoride for example
- otterley 6y agoHow do you feel about gasoline and matches?
- jhoechtl 6y agoSounds like a weapon
- wdwvt1 6y agoThe exciting thing about this research is that the authors substantially exceeded the normal bar for publishing a scientific article (even one in Nature). They demonstrated industrial feasibility of their proposed enzymatic process by depolymerizing waste PET then repolymerizing it into a useful item (water bottle) that met industry standards for strength/ductility and coloration. I work in microbiology, and seeing research that connects basic biochemistry to actual industrial implementation (at the lab scale) is really impressive. There are pieces of their process that would need to be refined (and the cost of oil would have to rise) for this to be cost competitive with just manufacturing from virgin PET units, but it's a strong foundation. It's much closer to realization than most "researchers discover enzyme that does X and will revolutionize industry Y".
- snovv_crash 6y agoIt doesn't need to be cheaper than virgin PET, it just needs to be cheaper than virgin PET plus the cost of landfill/"recycling". With more countries now refusing to be dumping grounds the cost of getting rid of old bottles stands to rise considerably.
- piker 6y ago...to the extent that such cost of landfill/recycling is internalized to the producer.
- EGreg 6y agoCan’t plastic already be melted down and reshaped? Now the question is how to collect plastic in the wild
- stan_rogers 6y agoIt can be reshaped, but the plastic will not have the same mechanical and optical properties as "virgin" PET, so it can't be used for the same applications.
- barney54 6y agoYes, but for plastics like PET that downgrades the plastic. This process breaks it into monomers so the recycling can be truly circular.
- maxander 6y agoI don't have access to the article right now either, but I would like to note to the "this enzyme is going to eat all our stuff!" commenters that, in general, most enzymes don't work very effectively in ambient conditions. The abstract doesn't go into detail into how they acheived the "90% in 10h" metric, but I would assume this was in a precisely controlled solution, incubated at an optimal temperature, with fresh enzyme that hadn't had a chance to start denaturing. You aren't going to be able to spray this on the plastic siding of someone's house and watch it wither away (even if home siding was PET and not, IIRC, vinyl or something.) I guess I can't rule out at that some recombinant bacterium expressing this enzyme might escape the lab and start causing PET objects to get moldy or develop a patina if left out too long [0]. But that would require that this enzyme somehow benefits the bacterium enough that natural selection wouldn't favor dropping the gene for it. [0] Hrm, there's a thought - what if your refrigerator needed to be refrigerated?
- deleted 6y ago[deleted]
- perl4ever 6y agoThis all sounds sensible and reasonable, but just at this exact moment, it's hard to feel totally confident that something bioengineered can't possibly create a plague inadvertently. And I'm assuming that covid-19 isn't in fact an example. It made an impression on me, something I read on HN not too long ago, comparing an epidemic to a nuclear reaction - it's really hard to create a critical mass, and when it's dispersed that's it; the really acute problems are local and temporary, despite peoples' fears of invisible radiation and contamination. But once a global epidemic gets going, essentially the whole world may have reached critical mass and has to be diluted. Maybe obvious when stated, but presenting the comparison in the context of the fears people have of nuclear weapons/power is the point. The probability is low, but the stakes in the near future of biotech seem higher than anything else people can mess with.
- HarryHirsch 6y agoThe exciting thing is that there is real progress in increasing temperature stability of enzymes. That's the point of the article, engineering an enzyme that is still active above the glass transition temperature of the substrate. I remember a paper where they tried random mutations all over some enzyme, it was just mindless make-work for an army of graduate students. This one is different.
- dnautics 6y agoI can't read the article due to paywall. How did they achieve this thermostability? Supercharging the surface?
- HarryHirsch 6y agoSite-saturation mutagenesis in the active site followed by introduction of disulphide bridges.
- dnautics 6y agoMan. I would have guessed that adding disulfide bridges would decrease catalytic conversiom rates by making the protein too rigid.
- DavidPiper 6y agoWhat does this mean for PET already in landfills? Can we trawl through our landfills for old PET and bring it back to (perpetual) life with this process?
- mediaman 6y agoIt would not make economic sense. You'd spend far more money and CO2 output moving mountains of garbage and trying to sort than would ever be recovered by recycling some scraps of plastic. The supply chain of incoming recyclable material is very important to make any recycling process work well. But yes, it would be possible.
- tandr 6y agoWould spraying garbage or landfill with bacteria that could produce this enzyme work? At least at slowly reducing volumes of plastic in landfills into liquid-y form?
- jussij 6y agoA better place to start would be the Great Pacific garbage patch: https://en.wikipedia.org/wiki/Great_Pacific_garbage_patch#Size_estimates https://en.wikipedia.org/wiki/Great_Pacific_garbage_patch#Si... That's an above ground source for trillions of pieces of plastic.
- nikanj 6y ago"Most debris consists of small plastic particles suspended at or just below the surface, evading detection by aircraft or satellite." Collecting that is going to be a massive headache.
- kumarski 6y agoThere's complicated stuff for figuring out if it's useful: - Energy in vs energy out - The price fluctuation of the underlying feedstocks - Scalability - (chemistry is 1000x harder to scale things than comp sci.)
- econcon 6y agoIt's interesting, I've been helping plastic situation by buying shredded plastic scrap and turning it into filament for 3d printers, you need to mix it with virgin plastic (30-70 or 40-60) Here's the project details: https://medium.com/endless-filament/make-your-filament-at-home-for-cheap-6c908bb09922 https://medium.com/endless-filament/make-your-filament-at-ho... Communities can setup their own machines and create filament from scrap plastic, this is good enough for 3d printing where your life doesn't depend on it.
- Gatsky 6y agoSee the end of the article, patents were taken out starting 2017, and there is a company https://carbios.fr/en/profile/ https://carbios.fr/en/profile/
- JoeAltmaier 6y agoIts got to be cost-effective. That's the gold standard. Is it cheaper than not breaking the plastic down? E.g. other solutions - burning, burying... Not a moral argument. Just a practical one - the free market isn't going to use this unless it has a short payback period.