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)
I don't really see why there is a problem with degrading whole bottles. If you have separated from the waste stream, you can incinerate or even landfill them (it's not like you'd be wasting any resources). It's the microplastics that form when the bottles are dumped into the oceans or waterways and broken up by Nature which need a novel solution for removal.
I think what lysozyme said holds even if you do not consider "whole" bottles at all. According to wikipedia the biggest microplastics are 5mm, whereas the enzyme is 10nm, that is 5 orders of magnitude of difference, but just in lenght! To process the entire volume you need to cube the units and you get 15 orders of magnitude in difference (1 mm^3 to 10 nm^3).
To get an idea I asked wolfram alpha what is the volume of the average human, and apparently that is around 66 liters. Then I looked up the estimated water volume of the Baltic sea, and wikipedia says it is 21,700 km^3 of water, soo
$ units
586 units, 56 prefixes
You have: 21.7E3 km3
You want: 66 liters
* 3.2878788e+14
/ 3.0414747e-15
if you could somehow fill your entire body with water, then make 30 copies of yourself, and you (30 of you) drink an entire Baltic sea (one for each), that is a very very rough analogy of the task we are giving to that poor enzyme. And this is for a single speck of microplastic! Of course the enzyme is not alone, there are a few other billions (trillions?) others with it, but there are also a few million specks of microplastic at any point in the sea. This is a very difficult task.
Plastic aren't simply plastics, they have lots of additives to give them different properties. Incinerating is transforming these additives into other chemicals maybe making more toxic molecules escape to the environment in ashes, dust, smoke. And landfilling is storing trash for future generations to solve the problem.
The most plausible reason they might need to dig them up is to remediate them. Landfills require maintenance in perpetuity, which costs a considerable amount of money. The biggest expense is maintaining the top cap—if it leaks, big problems can result.
After several centuries, it’s hard to imagine that most landfills will still be doing regular maintenance and fighting off entropy maintaining the cap. At some point, with the right technology, it becomes more sensible to reprocess the waste in a more permanent manner.
I think plasma gasification is likely the best idea, but it still needs work.
I would agree. Burying our post-nuclear family waste worldwide for the last 60 years will come back to haunt us. I also agree that we’ll have the tech to address it then into a more sustainable solution and possibly extract energy from it.
Looks like the title was edited to accommodate your clarification.
Unfortunately, that makes your comment a bit confusing, since the context of the title change is not present. I think the best solution would have been the title, "Scientists create artificial protein capable of degrading [PET] microplastics in bottles".
It was never about precision, truth, nor actual science. It was always about "plastics=bad" ideological virtue signaling, just like "chemicals=bad" and "(non-ionising) radiation=bad" before it.
> It was never about precision, truth, nor actual science. It was always about "plastics=bad" ideological virtue signaling
Microplastics were not a concept created for ideological virtue signaling. I don't know who manipulated you into thinking that was true, but you may wish to re-evaluate where you've been getting your information. The good news is that you don't have to depend on some invented sinister backstory for microplastics, you can instead read the paper where the phrase was coined for yourself (https://www.researchgate.net/publication/8575062_Lost_at_Sea...) and see that it was just a lot of typical boring science like searching through sediment and plankton samples, and keeping track of what lugworms eat. A paper that concludes with "we'd need more research to determine if there are any environmental consequences" is about as far from ideological virtue signaling as it gets. Take your own advice and "Beware those who distort the truth and exploit fear for their own gains."
As far as precision goes, currently microplastics are for plastic bits smaller than 5mm. We even have primary and secondary categories for them. Nanoplastics are for bits smaller than 100 nm. Do we really need a better classification system at this stage? I imagine that shortly after we do, we'll get one. Science loves to come up with boxes to put things in.
Regardless what the origin was, it should be clear to see that the term has become associated with ideological virtue signaling and used to promote all manner of junk science and taken up by the engagement-chasing paranoia-spreading media.
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-...