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.
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.
"[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."
> If these hurdles can be surmounted, though, PETase might make a dent in the scourge of plastic waste.
The Great Plasteen Disaster
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. :)
Third definition. Using "bug" here is hardly a stretch.
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!)
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?" :-)
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.
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?
Tangential: not an acid, but antimatter has similar properties, and you contain it in a magnetic trap ;).
Sure, they contain carbon backbones. But structurally that's about the only thing they have in common.
Compare PU and Teflon. The former is marginally bio-degradeable. The latter boasts resistance to many otherwise extremely reactive substances.
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.
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.
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.
If microbes proceeed to do it unconditionally, how is that better? Shall we then get them to change THEIR behavior?
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.
Because the oil fed the bugs not the machine.
So the machine didn't work.
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.
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.
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?
If plastic in the ocean kills/renders toxic all the fish, that will be an issue for us. The ecosystem? It will be fine.
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.
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.
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 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
Unfortunately, many do.
What does this even mean?
Wow that is patient!
I reiterate: systems thinking is hard.
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.
You sound like a writer! Keep going
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).
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.
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. 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%.
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.
also plastic degrades in UV light and due to weather so it probably wouldn't be that much different to now.
Still hasn't happened.
I wonder what byproduct of this digestion would be. I don't want to sound like a luddite but remember BPA?
Harry P. Austin el al., "Characterization and engineering of a plastic-degrading aromatic polyesterase," PNAS (2018)
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.
are we sure we want this?
It's actually an artificially engineered enzyme formerly discovered in certain bacteria which is able to break PET molecules. Lots of potential, moving on.