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An enzyme that digests plastic could boost recycling (economist.com)
251 points by dberhane 8 months ago | hide | past | web | favorite | 122 comments



I'm fascinated by this. It took 60 million years after trees evolved for microbes to evolve that could digest them[1]. The resulting strata of undigested tree are now most of our coal. Now of course, if a tree dies and is left where it fell, it is usually digested entirely in a number of years by microbial life.

What would happen if a microbe evolved that could feed itself from plastic? And what if it got out of the lab? Imagine all the plastic items in the World suddenly as susceptible to rot as wood. It would fundamentally change almost every aspect our existence, in a very short amount of time.

[1]: http://phenomena.nationalgeographic.com/2016/01/07/the-fanta...


> Imagine all the plastic items in the World suddenly as susceptible to rot as wood. It would fundamentally change almost every aspect our existence, in a very short amount of time.

Hardly. Some usages of plastic would need to be altered, but most would be fine. The conditions in which wood will rot are very specific (the forest floor, basically) and reasonably easy to avoid, surely something similar will be true for rotting plastic. Pre plastics, practically anything, including all kinds of liquids, was stored in wooden barrels.


To be fair, wooden things—were they barrels, ships, or houses—absolutely require protection and maintenance to prevent them from rotting. We became pretty good at that because wood was a crucial raw material for millennia. We haven’t thought about how to protect plastics because we’ve accustomed to plastics not needing protection.


Plastics need protection from a lot of things, cold, heat, sun not to mention physical wear. Some older, cheaper plastics just crubles to dust when you touch them.


Is crumbled plastic part of the micro-plastics we hear about polluting the ocean?


Yes! In fact most plastic is relative susceptible to UV radiation, which facilitates that "crumbliness" in the ocean.


The conditions under which wood rots: untreated + outdoors.


That depends on the species of wood. White oak will survive a lot longer than Red Oak outdoors as an example. There are many others.


Hardwoods are too valuable to waste on outdoor projects, though.


and properly aged cedar won't rot for a hundred years.


Um, the article does actually explicitly mention such a microbe, as that is the origin of the titular enzyme! Do I misunderstand something, or you didn't read the article? It's hard for me to understand the "What would happen if a microbe evolved..." question when the article literally says:

"[The] PETase [enzyme] is secreted by a plastic-munching bacterium called Ideonella sakaiensis 201-F6. This bug was discovered in 2016 at a PET-bottle recycling plant in Sakai, Japan."


I think a more charitable interpretation of the parent comment was that of a doomsday thought experiment/rhetorical question: What would happen if these bacteria evolved to really be able to cause damage one day? The article only briefly remarks:

> If these hurdles can be surmounted, though, PETase might make a dent in the scourge of plastic waste.


FWIW, this 'doomsday scenario' is roughly the plot of a 1979 Judge Dredd episode (which I remember fondly) - featuring a world in which support bridges were made of 'plasteen' under attack from a novel bacterium: SOMETHING'S EATING IT AWAY

The Great Plasteen Disaster https://dreddalert.blogspot.co.uk/2014/01/judge-dredd-great-...


Also (sort of) the crux of one of my favorite horror manga, Biomeat: Nectar, which is about a genetically engineered animal that eats "garbage" (basically anything but metal, glass, and stone IIRC) and can be harvested for food, but escapes from the garbage plants and starts going after people. They're not microbes though, but more like nightmare fuel looking bugs about the size of a face, with the mouth on the bottom, and they reproduce via budding (like a hydra).


Also, a book published in 1972, _Mutant 59: The Plastic Eaters_.

https://www.goodreads.com/book/show/2368220.Mutant_59


> This bug

Is it just me, or is "bug" a weird choice of words here? To me, a "bug" is an insect, and I don't think that a bacterium would have six legs. :)


“Bug” is sometimes used to refer to an illness caused by a bacterium or virus, as in “I can’t come into work today; I must have caught that [flu/stomach] bug that’s going around”. It’s not such a stretch to use it colloquially to refer to the microorganism itself.


'Bugs' is also slang for 'germs'.


https://www.merriam-webster.com/dictionary/bug

Third definition. Using "bug" here is hardly a stretch.


Generally people will use "bug" to refer to any arthropod or, more loosely, to several classes of small thing including bacteria that seem animal-like but not bacteria that seem plant-like. Generally all of these usages have connotations of being bad but also not very important. For instance someone might refer to the common cold as a "bug" but generally not to Ebola.


Disappointing that you got downvoted for what appears to be an honest question, but as others are saying, "bug" is often used in slang for microbes (especially disease-causing ones).


> Imagine all the plastic items in the World suddenly as susceptible to rot as wood. It would fundamentally change almost every aspect our existence, in a very short amount of time.

Absolutely! The first thing came to my mind is the usage of polymers in construction industry (epoxy for joining material, coating for anti-corrosion measures) and the predominant PVC underground sewer lines and plumbing pipes. If those aren't as durable as we previously assumed, the rebuild/replacement is going to be catastrophic. (PS: I had almost had to replace the underground clay/cast iron sewer lines that's been there for 50 years and reaching the end of life for the material at our new home last year. The cost was astronomical and requires many town permits and time to even start the project. Thankfully we didn't have to!)


The article only mentions the enzyme breaking down polyethylene terephthalate (PET), not other kinds of plastics. So those would be safe from the enzyme.

Of course, the enzyme could be engineered to break down all kinds of plastics but I doubt that is biologically possible. It would become like the old joke of the 'acid that can dissolve anything', at which point the question becomes, "So what do you use to contain the acid?" :-)


Thanks for saying what kind of "plastic" is being referred to!

According to Wikipedia, PET (polyethylene terephthalate) is about 18% of world polymer production and is the fourth-most-produced polymer; 60% of PET is used for clothing and 30% for bottles. The bottles are frequently recycled into clothing, I've been told, so perhaps an even greater proportion of it ends up as clothing.

The most-produced polymer is, of course, PE (polyethylene), which is also used for bottles, but not for carbonated beverages, I think, which always seems to be PET round here.


> According to Wikipedia, PET (polyethylene terephthalate) is about 18% of world polymer production and is the fourth-most-produced polymer; 60% of PET is used for clothing

As fibre, it's known as dacron OR terylene. I had no idea there was that much dacron/terylene clothing about these days! What gets made out of it?


Synthetic fleece is typically PET.


And a major source of microplastic waste.


Correct me if I'm wrong, but I read that this happens particularly from washing synthetic clothing in washing machines where the waste water carries the microplastics into the water supply where they can't (yet) be filtered out.


I believe so, yes. Hopefully better filtering solutions will be devised.


Around here (Northern Europe) almost all soft drink bottles are recycled/recyclable PET nowadays.


> It would become like the old joke of the 'acid that can dissolve anything', at which point the question becomes, "So what do you use to contain the acid?" :-)

Tangential: not an acid, but antimatter has similar properties, and you contain it in a magnetic trap ;).


I think not. Magnetic traps can only contain anti-matter ions, not neutral anti-matter atoms or molecules.


You can actually use multipole magnets to capture neutral anti-hydrogen. Not that they're trapping a lot of neutral anti-hydrogen, but some.

[1] https://en.wikipedia.org/wiki/Antihydrogen#Low-energy_antihy...


Thanks for that. I forgot about the spin magnetic moment. Whether this works on other atoms or molecules depends, of course, on how strong this field is.


Just a shorthand. Ions are good enough to... dissolve regular matter. Into gamma rays.


It’s not quite the same though because all/most plastics are relatively simple organic polymers that have similarities in their chemical structure, which might in principle be exploited by an enzyme (or, more realistically, a class of enzymes) to digest them all. — So, what do you use to contain this enzyme? A glass bottle. ;-)


> relatively simple organic polymers

Sure, they contain carbon backbones. But structurally that's about the only thing they have in common.

Compare PU[0] and Teflon[1]. The former is marginally bio-degradeable. The latter boasts resistance to many otherwise extremely reactive substances.

[0] https://upload.wikimedia.org/wikipedia/commons/c/ca/Polyuret... [1] https://upload.wikimedia.org/wikipedia/commons/1/17/Teflon_s...


> But structurally that's about the only thing they have in common.

Sure, but it’s — at least in principle — enough: the whole point of my answer was to highlight that the same fundamental catalytic reaction can attack the bonds of the backbone without caring too much about the identity of the side chains/unit monomers. The main constraints then are sterical: the monomers of the polymer have to fit into the active site of the enzyme. This is by no means a given, but it’s not an insurmountable problem either.

My point is, unlike the hypothetical, universal acid that dissolves everything from biopolymers over monoatomic crystal lattices to amorphous silicates, a plastic-eating enzyme doesn’t have to be universal. It can in fact be very specific.

In fact, the cell has tons of such machinery. A good example is the ribosome, which manages to construct a peptide biopolymer by catalysing peptide bond formation regardless of amino acid side chain. And there’s a class of enzymes that do the inverse: proteases hydrolyse peptide bonds. This comes conceptually close to a universal plastic-eating enzyme.


It would be awesome if we could unleash something like this in our oceans without doing harm to the ecosystem (would be hard to do more harm that what we are already doing with plastic, but still).


About 20 years ago, I did a one week internship as a teenager in some lab that worked exactly on this. They were trying to grow and select enzymes that could process different types of oil that frequently occurred in spills.

The tricky part was to make sure they only targeted what was in the ocean. You didn't want them to start propagating into the oil tanks in boats, or start processing all the random plastics that make up boats or various infrastructure.

I remember on my last day, they had some really good results with some samples that processed some oil really well and were quite excited. I then left, and have no idea if they managed to reproduce the results or not.


This reminds me of a fun bit of soft sci-fi that I liked in the Uglies series by Scott Westerfeld: the “Rusties” (pre-apocalyptic) society was taken down in part by a bacterium that digested gasoline and other petroleum products into some unspecified volatile substance that would then explode and destroy vehicles, also spreading the organism further.


Meh, make them eat all the oil. Civilization could use the kick in the ass to switch to electrics.


When they eat the oil, how do they metabolize it? If they end up producing CO2 like ICEs do, that would not be a productive measure against climate change at all.


Given it was going to be burned, that's six of one and half a dozen of the other, except that if the bugs eat it, the humans have to change their behaviour.


Plastic pollution has tons of drawbacks but at least it doesn't contribute to global warming since it effectively stores carbon. Having all the plastic in the world start rotting away and releasing carbon into the atmosphere might to a lot of harm. Especially if other petrol byproducts like the bitumen of our roads are concerned.

You're right however that if these products start becoming effectively unusable (or less usable) because they now rot it would make alternative solutions a lot more attractive, but we already have so much petrol byproducts in the wild that the transition would be pretty nasty.


This I agree with and it's unfortunate. But I'd rather it was gotten rid of because the alternative is that it just sits there getting pulverized ever smaller and bioaccumulating.


We want humans to change their behavior because their behavior is releasing a lot of CO2 into the atmosphere.

If microbes proceeed to do it unconditionally, how is that better? Shall we then get them to change THEIR behavior?


The most they will release is what we've already dug up and turned into plastic litter, fuel, roads, etc. And by changing the viability of behaviour, they would prevent us continuing with status quo behaviour and replenishing the supply of litter.


If the environmental damage is simply stipulated to occur, then why would humans have to change their behavior? If it's either bacteria or us putting the carbon into the atmosphere, it might as well be us.

I think you're losing sight of the forest for the cynical trees here. At least nominally, "changing human behavior" is not the end goal in and of itself; it is supposed to be serving a purpose. If simply changing human behavior is your goal because you find it personally distasteful that people are living their lives a certain way, and that's it, you have no other environmental reason (because you stipulated it away), it's merely your opinion now, and a rather anti-social or misanthropic one not particularly deserving of praise or recognition as being especially moral or anything like that.


"why would humans have to change their behavior?"

Because the oil fed the bugs not the machine.

So the machine didn't work.


That is not the sense of the question I asked. The question is, if the pollution is stipulated either way, why do you desire the outcome?

You are hypothesizing a choice between a world in which pollution is 134 units (done by the human machines) and humans have machinery, and one in which pollution is 134 units (done by bacteria) and humans do not. You do not seem to have any non-misanthropic or non-Puritan reason to prefer the latter.


I'm a little surprised it isn't obvious. No, they aren't equivalent when iterated. Because the humans stop trying to use machines that use oil, so the oil stays in the ground.


I had the same exciting thought before it dawned on me that we usually choose plastics for a reason. Imagine water bottles breaking down in the store. Imagine protective coatings of ships breaking down. While I'd be happy for the mess we created in the oceans, I'm unsure if this would just trigger another arms race for more indestructible materials — that would clog the oceans once again.


Manufacturers don't really choose plastic for longevity, they choose it because it's cheap and easy to work with (ie plastic [adjective]).

There are already biodegradable alternatives for almost everything but they add a few pence to the cost of a happy meal, say, and aren't a strong enough differentiator at the point of sale for profit-driven companies to care about it. The alternatives don't instantaneously degrade, they usually need proper composting to quickly degrade (high temperatures, aerobic).

We've used compostable nappies that when properly composted can degrade fully in a year - they're similar in use (save not releasing "gel balls"), don't appear to have a significantly depleted shelf-life. I don't know why such things aren't mandated TBH.


The main reason is not having to account for externalities. As long as someone else has to pay for cleaning up, why bother thinking about it when you can keep the short-term profits?


We chose plastics because it was cheaper. Yes, there are other benefits. Unfortunately, no one asked, "If this stuff doesn't decompose, then what?" to assess that risk vs the benefits.

Without that answer the use of plastics should have been mitigated a la nuclear fission. Instead, micro bits of plastics are everywhere; the oceans and their ecoayatem are compromised. Etc.

For what? Convenience and a few cents?


I ask myself the same question about our current techno-commercial landscape.


My favourite what if: What if we engineer such bacteria to survive in our gut?


The best way to unleash it in our system without doing harm to the ecosystem is to be patient. There is energy content in the plastic and over 100-200 million years the chance is extremely high Earth’s ecosystem will adapt to the abundance of plastic.


The issue has never been whether the ecosystem will adapt. It has been how well we will.

If plastic in the ocean kills/renders toxic all the fish, that will be an issue for us. The ecosystem? It will be fine.


The idea that ecosystems are self balacning and always bounce back is discredited science. It’s still a popular idea in mainstream discussion, though.


Is it really discredited? What are your sources? I tend to believe (with no actual evidence, since there is none), that the ecosystem will adapt to whatever damage we do to it using the tried-and-tested method of natural selection.

Most mainstream conversations about this are entirely anthropocentric and assume we have to be part of that equation. They always assume we're the top of the food chain. But whereas most of us will never be eaten by a tiger, pretty much all of us will be eaten by bacteria one day. Microbial life has been around for far longer, and is far more abundant than we can ever hope to be. I don't think much we can do will fundamentally alter that balance.


We tend to imagine that the ecosystem that will bounce back is the current one, or something much like the current one.

Of course it's possible that the current ecosystem could be completely destabilized and die off, to be replaced by something radically different. It's happened many times in Earth's history.

https://en.wikipedia.org/wiki/Extinction_event#List_of_extin...

https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extin...


I would generally consider the current ecosphere being replaced by something totally different as a variant of "The ecosphere recovering" as long as the successor has as much complexity as the predecessor - and exactly what the GP is talking about.

But of course there are far worse things than that sort of disaster. Earth turned into a snowball several times but geologic processes producing CO2 managed to fix the problem. The Sun is continuously getting brighter so that wouldn't be a problem nowadays. But eventually, in a billion years, the increasing brightness of the sun will cause the oceans to evaporate and complex life on Earth will probably never recover.


It's a hyperbolic example, but I doubt life on Earth would adapt to being engulfed by the sun, for one


Sure, but that's not the debate.


Is there a term to distinguish this idea of damage to human habitat vs damage to actual ecosystem? Also how could we know whether something was going to be damaging to the ecosystem in a fundamental/longterm way as opposed to simply changing the balance within it?


> The ecosystem? It will be fine.

It will be greatly impoverished, so not really 'fine'. Its possible that in several 10s of million of years the sheer level of diversity of the ecosystem may have rebounded. But not a given


The preference for diversity is just a human bias. Nature doesn't care.


This is just old fashioned nihilism. The Earth could be vaporized tomorrow and "nature" wouldn't "care", but I think we can all agree that it would be bad by any standard meaningful to us. 'Human bias' is the only way we have of judging anything as good or bad.


And the word "fine" is a human word. If you're saying an ecosystem containing one kind of alga is in any way as fine as an ecosystem comprising billions of organisms and interdependencies, then what can I say.


You're right, 'nature' doesn't care if life on Earth ends. Most humans do.


Exactly... And nature itself is a construct of humans. We're certainly anthropocentric in our ways, but that is only problematic if we view ourselves as separate from our environment somehow.

Unfortunately, many do.


> And nature itself is a construct of humans.

What does this even mean?


> over 100-200 million years

Wow that is patient!


It would be awesome if we ourselves could interact with the ocean without doing harm to the ecosystem.


Yes, yes it would. Systems thinking is hard. (Eco)Systems thinking is nearly maddening. Even if one could account for many variables (for an acceptable value of many), one would still have to deal with everything else, which often includes stupidity, irrationality, politics, emotion, villains... Nature makes many errors, but at least it isn't stupid; those errors result in the adaptations that make the world work. This process involves a lot of death, but it works. Or, it did. I am somewhat familiar with ecosystems and environmental restoration, and I don't mean to discourage anyone from positive thinking; in this case, however, I really think people need to try to comprehend the mechanisms before experimenting.

I reiterate: systems thinking is hard.


The organisms would probably need micronutrients as well, such as iron or copper.

Advantage: We can control their spread—target them at the Garbage Patches

Disadvantage: More expensive to deploy, since you have to also sprinkle fertilizer for the cleanup to be effective.


We build lots of durable structures out of wood. I don't think it would be a very serious problem.


Lots of modern construction wood is laminated together with plastic. I'm sure people would adapt though.


I expect this would also make the material scientists happy for being given a new challenge.


This could be a great plot for a sci-fi novel.



See also Larry Niven's Ringworld

https://en.wikipedia.org/wiki/Ringworld


I've tried to write some short stories on the theme but I'm no writer, I could never get something I was happy with.


>I could never get something I was happy with

You sound like a writer! Keep going


Possibly a slight spoiler, but Andromeda Strain does exactly this.

https://en.wikipedia.org/wiki/The_Andromeda_Strain


Clots blood and eats rubber, but ok.


It's an interesting thought, but perhaps we should consider how susceptible we would actually be. We still build houses from wood, which can rot and be digested, but generally doesn't with a reasonable amount of maintenance. Even if an hyper effective microbe were to spread, the manner of spread is unlikely to be any more effective with respect to dispersion than others that e.g. attack wood.


That's a cute story, but the evidence is lacking.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780611/

The Carboniferous−Permian marks the greatest coal-forming interval in Earth’s history, contributing to glaciation and uniquely high oxygen concentrations at the time and fueling the modern Industrial Revolution. This peak in coal deposition is frequently attributed to an evolutionary lag between plant synthesis of the recalcitrant biopolymer lignin and fungal capacities for lignin degradation, resulting in massive accumulation of plant debris. Here, we demonstrate that lignin was of secondary importance in many floras and that shifts in lignin abundance had no obvious impact on coal formation. Evidence for lignin degradation—including fungal—was ubiquitous, and absence of lignin decay would have profoundly disrupted the carbon cycle. Instead, coal accumulation patterns implicate a unique combination of climate and tectonics during Pangea formation.

from another article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780642/

There is a long-invoked but incorrect (9) perception that lycopsid-dominated forests were the main source vegetation of Carboniferous coals because of the abundance and resistance to decomposition of lycopsid periderm (bark) (e.g., refs. 1, 4, and 5). Thus, lycopsid dominance supposedly was essential for formation of the economically important Carboniferous coals. In what initially appears to support this perception, Nelsen et al. (8) use spatiotemporal trends in Phanerozoic organic-rich terrestrial sediments to demonstrate peak North American coal production during intervals when lycopsids dominated Euramerican tropical forests. Most dominant Carboniferous wetland plants, however, produced little wood, and the arborescent lycopsids were no exception (10). The towering lycopsid stature was made possible by unlignified periderm rather than lignin-rich wood. Therefore, they contributed less lignin to peat accumulations than woody plants, which were episodically abundant, although rarely dominant, in Pennsylvanian–early Permian tropical lowland basins (9, 11). Nelsen et al.’s (8) scientific twist to the hypothesized lycopsid–lignin–coal linkage—that is, documenting coincidence in peak coal production and lycopsid dominance, when lignin would have contributed minimally to peat accumulation—weakens the argument that the emergence of lignin synthesis was one criteria for intensified terrestrial organic carbon sequestration in the Carboniferous.

Large-scale peat accumulation further requires suppression of organic matter decay, of which woody tissue, in the absence of efficient lignin-degrading fungi, has been considered the source (5). Nelsen et al. (8) challenge this view by documenting fungal and bacterial degradation of Paleozoic lignified tissues and, conversely, evidence for abundant unlignified organic matter in many peats. Nelson et al.’s study, building on decades of paleobotanical research, thus unequivocally demonstrates that pre-Permian lignin resistance to decay, and thus preferential biochemical composition of vegetation, was not the key to high rates of peat accumulation 325–300 Myr ago. Intriguingly, lignin’s legacy in Carboniferous peat accumulation may be moot: Nelsen et al. (8) point out that the evolution of Agaricomycetes fungi, based on reassessment of phylogenomic evidence (7), is permissible as far back as the Devonian (420–359 Myr), thus potentially closing the evolutionary lignin–fungal gap. If correct, then a closer temporal association between the onset of lignin biosynthesis and the evolution of lignin-degrading fungi suggests rapid evolutionary innovation in response to a novel resource. Nelsen et al.’s collective findings (8) further resolve a mass balance conundrum regarding the Carboniferous–Permian atmosphere. In a world with hypothesized abundant lignin, the absence of fungal-mediated degradation, in concert with widespread peat accumulation and burial, would have depleted atmospheric CO2 within a fraction of the proposed ∼120 Myr evolutionary gap. Large-magnitude CO2 degassing from volcanism, for which there is no clear evidence, would be needed to maintain the requisite long-term balance in total CO2 inputs and outputs to and from the atmosphere (1).


Interesting paradox. Either making cellulose is easier than breaking it up (even under the sun/rain/etc) or maybe bacteria "didn't see a reason" to tap that energy source (hence not evolving in that direction).


It's not so much the cellulose, it's the lignin that makes wood so hard to digest. Fungi resort to producing peroxides instead of attacking it directly with tailored enzymes


There is no paradox: Plastics have really only been around for less than a century. Modern plastics are all synthetic, and sufficiently distinct to all naturally occurring biopolymers. So bacteria only had ~100 years to evolve this capability. Compare this to the ~60 million years it took to evolve wood-digesting enzymes efficiently.

The situation isn’t entirely comparable, since these enzymes wouldn’t have to evolve “from scratch”. Hence why researchers may have found rudimentary capabilities in the wild. But evolving this from the basics to an efficient food source naturally would take a very long time indeed.


Cellulose was hard to break down, so when bacteria found a way to do it, they had no competition for that food source and millions of years worth of it just sitting around to feed on.


Or maybe it required a leap of evolution in a direction in which there was no other evolutionary pressure to take the first steps and make subsequent steps smaller and thus more likely? Complex mutations are probably more rare if the environment does not facilitate doing it bit by bit.


> It took 60 million years after trees evolved for microbes to evolve that could digest them

Go back further in time, and you'll discover that from the moment photosynthesis arrived on the scene and took over as an energy source, until a life-form evolved that could make use of the poisonous oxygen that was a byproduct of it, it took roughly 0.7 billion years[0]. Resulting in many, many cyanobacterial apocalypses in that time.

We may have to come up with new (old) material solutions to many things, but on the whole I think that plastic-eating microbes are probably more of an apocalypse-averting scenario than an apocalypse-causing one.

EDIT: to put that 0.7 billion years number into perspective, let's look at the age of life on Earth:

> The earliest time that life forms first appeared on Earth is unknown. They may have lived earlier than 3.77 billion years ago, possibly as early as 4.28 billion years ago, not long after the oceans formed 4.41 billion years ago, and not long after the formation of the Earth 4.54 billion years ago. The earliest direct evidence of life on Earth are fossils of microorganisms permineralized in 3.465-billion-year-old Australian Apex chert rocks.

Sticking to the confirmed existence of life, 0.7 billion years represents 20% of life's history on this planet. With conservative estimates 18%, and assuming it was there from very early on, 16%. Even if life has existed on this planet for as long as Earth itself has, then this still accounts for 15% of the history of life on this planet. Meanwhile, we likely split off from Chimpanzees around 12 million years ago, with modern humans not evolving until about 300-200 thousand years ago (which I still find mind-bogglingly recent), which is somewhere between 0.006 to 0.008%[3].

EDIT2: This makes me wonder if modern bacterial life-forms, if not all modern life-forms that we may consider simple and primitive, may not in fact be incredibly sophisticated compared to their ancestors of billions of years ago. I can imagine that they appear similar due to a particular solution already being stuck in a local optimum (say, shark body plans, or certain leaf shapes) but that on the genetic level the more recent life-forms might have evolved complicated systems of evolvability itself that lets them adapt much faster than before[4].

[0] http://www.patheos.com/blogs/daylightatheism/2009/02/bands-o...

[1] https://en.wikipedia.org/wiki/Earliest_known_life_forms

[2] https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_...

[3] https://en.wikipedia.org/wiki/Timeline_of_human_evolution#Ho...

[4] https://en.wikipedia.org/wiki/Evolvability


>What would happen if a microbe evolved that could feed itself from plastic?

it did.

also plastic degrades in UV light and due to weather so it probably wouldn't be that much different to now.


I have been seeing articles on this topic for at least 5 years. What is stopping this from becoming actual practical process than just PR release that keeps poping up every now and then? Is there any real article on technical problems in this area that are still unsolved?


The article states that a 100-fold increase in efficiency is required before it can be used.


I worked on this during my undergrad in 2004. DARPA grant back then. Basically the military has to haul trash where ever they go or burn it, they can save money by embedding these enzymes directly into the plastic and turning it into fuel.

Still hasn't happened.


Likely, the organisms that make it require other nutrients as well, that aren't found in plastic. So you can't just go drop a few on the Great Garbage Patch unless you also sprinkle fertilizer along with it.


Can't help be reminded of this (awesome) book [1] where a bacterium is engineered to eat PCBs and released in the wild without proper testing, leading to very interesting side-effects.

I wonder what byproduct of this digestion would be. I don't want to sound like a luddite but remember BPA?

[1] https://en.wikipedia.org/wiki/Zodiac_(novel)


Can someone link to a pdf of the actual paper?

Harry P. Austin el al., "Characterization and engineering of a plastic-degrading aromatic polyesterase," PNAS (2018)


> At the moment, a litre of a solution of even the improved enzyme would break down just a few milligrams of plastic per day. Its plastic-digesting ability must therefore be improved by a hundredfold or more to be commercially useful.

Good! The last thing we need right now is yet another source of CO2. I say bury the thing, it's that much carbon sequestered for a few hundred years.


What I have yet to understand is what happens in a few hundred years when all this sequestered CO2 becomes not sequestered, and how this is not more "kick the can".


It's pretty obvious what will happen; it will transform into CO2 into the atmosphere. But at least it will have given us a few hundred years to figure out instead of piling over the present mess.


I'm all optimistic about technological innovation, but I have a doubt regarding the will of the (at least politically) great and powerful. Is this where the Free Market comes in a la Musk's future ilk?


If our civilization survives another few hundred years, we’ll be incredibly lucky.


Don't forget the caterpillars that can do this as well: http://www.bbc.co.uk/news/science-environment-39694553


We should engineer this into slime mold and release it into the wild to eat litter.


Anyone remember Andromeda strain? A bug that digests plastic was responsible for the crash of a plane. Bacteria are too small to contain. They'll get out somehow - on the worker's clothes, etc. And then they'll wreak havoc (armageddon?) on this plastic world.


Does anyone remember the first Doomwatch episode, the Plastic Eaters?


Life has an awesome way of turning disaster into opportunity!


Life made the disaster.


There's a great song about that in the Lion King.

https://www.youtube.com/watch?v=GibiNy4d4gc


there was a judge dredd story way way back where the whole city was falling apart because of something airborne that was eating plastic.

are we sure we want this?




We get an article like this every week. Wake me up when any of these miracle solutions actually get put into practice. I'm still waiting for those graphite batteries btw.


"Digesting" enzymes? "Boost recycling"? That sound like a typical click bait.

It's actually an artificially engineered enzyme formerly discovered in certain bacteria which is able to break PET molecules. Lots of potential, moving on.


Nothing clickbaity there, that I can see. 'digest' is a very reasonable word for enzyme-mediated breakdown, and it does have lots of potential in terms of recycling, since the monomers can be reused.


Don’t have mission




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