Scientists identify microbe that could help degrade polyurethane-based plastics | Hacker News Reader

Scientists identify microbe that could help degrade polyurethane-based plastics

phys.org

174 pointsdnetesn71 comments

These microbes are surprisingly hard to scale up i.e. to make them work on large amounts of product at a time. (My wife did research on such bugs for a while).

All sorts of things start happening once you have a lot of them, and the process becomes incredibly tricky to keep going.

Do they get fat and lazy? [Maybe we should invent Netflix for microbes, then]

(Paraphrasing because of my limited understanding of what my wife did)

The biological pathway that makes them eat plastic is pretty card to keep activated. It's not a very profitable pathway, so the bugs tend to try eating other stuff if there is even a little available, or they are even a little outside the optimal range for eating plastic.

Interesting stuff, would love to hear more intuition about why this is difficult. Is it just that we haven't found an economical pathway for metabolizing plastics, or is there a fundamental reason why one should not exist?

Hydrocarbons have an energy density 2-3x higher than glucose, so naively it seems like there should be a profitable metabolic pathway!

Hydrocarbons are extremely stable, which means it requires a large energy input to break them up.

The article doesn't go into a lot of detail, but my guess is that the bacteria can break up the carbamate links.

As a basic analogy, think of it like human metabolism burning fat vs. carbohydrates. Fat is much more energy dense, but until you starve the body of carbohydrates, your body won't burn it. This pathway likely exists as a "backup" metabolic system so that in the absence of easy-to-digest feedstocks, the microbe can still live, but at an energetic cost.

Wonder if CRISPR or similar could be used to knock out regular metabolism pathways. Seems like they'd be understood enough to do so effectively.

Once those microbes become efficient, say goodbye to specific plastics as a durable material for regular use. The microbes wouldn't know the difference between trash and in-use material.

Unless the metabolic pathway requires some super-specific and limited resource, thus garbage facilities could supply the catalyst and the microbes would begin consuming the plastics.

Essentially none would survive outside designated plastic eating situations.

Until ... life finds a way ...

Given that this pathway is inefficient and plastics aren’t an inefficient food mechanism it seems likely even without a specific limiter it’d be hard for the bacteria to spread widely. Similar to the bacteria that termites host which decompose cellulose. But then again maybe plastic eating termites would co-evolve with such a bacteria. That’s creepy to think about. “My tv got eaten by plastic termites”... As you say life often finds a way.

> Until ... life finds a way ...

In particular, a mutation that drops the need for catalyst turns out to be metabolically beneficial.

Pretty sure they alude to that in Ringworld

Plastics are very chemically difficult to degrade. The nearest biological polymer is probably lignin, and even though it's part of a very porous matrix, it still takes years to break down.

I'm not too worried about PE, PET, PU, or nylon "rotting"

In a sense. They're highly specialized organisms with relatively inefficient metabolisms. They do great in an environment filled with just them and their food. But in an environment filled with other organic material (like their own bodies) they get outcompeted pretty badly by more conventional microbes.

Is anyone else concerned about the effects this could have if it managed to get out of containment and into the wild? A self-replicating bacteria that eats plastics sounds like a potentially catastrophic event, considering how much we use them in day to day life.

Yup. The whole reason we use plastic for everything is because it's cheap and mostly inert (i.e. doesn't break down in the environment). If plastic starts rotting we are going to be in for a really bad time. It's difficult to even imagine the cost of all the damage. Seems like we're a decently far way off from that point though.

It pains me to think about all the plastic items I’ve bought over the years that weren’t up to the task; degraded in the sun to the point of failure; or otherwise ended up in landfill.

Ideally any bacteria, or other microbes, would only breakdown plastics under certain conditions, probably in some kind of bioreactor.

I used to think about that, but there really isn't that much plastic to sustain something like that. I know it might seem like there is tons and tons of plastic around and blowing in the wind and in our oceans, but the amount needed for a "infection" of this microbe to take hold would need to be many orders of magnitude higher.

It's not the mass of plastic, but the surface area. Microplastics have very high surface area to mass ratio, so large numbers of microbes have access to them. I expect to see rotting plastics in my lifetime. But this isn't necessarily a disaster. Many uses (e.g. food packaging) are still possible with biodegradable plastics, and for critical things like medical equipment we have fluorinated plastics, which are very resistant to anything a microbe could do. For everything else we'll just have to revert to wood and metal. This will mean paying more attention to repair and maintenance, and less disposable products.

You don't have to see it, for microbes to find it. We are aware that those tiny spheres of plastic made for facial scrubs, are now everywhere including Antarctica, right? So a microbe that can eat that, will find ready food everywhere, on every continent?

Just wash your hands before touching your AirPods :)

Wood is easily degradable under the right conditions, but that isn’t a major problem for us. I’m almost certain, for example, that 99% of plastic in use today is in environments that are too dry for bacteria.

Of course the places where plastic is used specifically because it doesn't rot in damp environments probably include some of its more critical deployments.

We use too much plastic, too casually, wastefully, with eventual results of microplastic and carbon release into the atmosphere. I would not weep in the least if this stuff blew around world-over and forced us to change our behaviour.

I think you generalize it too much. There are many different plastics with many different properties. Some will degrade in a few years, others take a thousand years. Some degrade to micro particles floating in our seas for a long time. Others do not and can be even eaten.

Some usages of plastics are essential. What about in medicine for example?

Right, exactly. A runaway bacterium that ate medical equipment, electronic equipment, industrial equipment, vehicles, food packaging... that would be a Bad Thing. It would mean an end to much of the modern world.

I'm reminded of a reddit discussion on how awful it would be if a coronal mass ejection event destroyed all electronics on Earth. They were lamenting how tragic the loss of Netflix would be given the current lock-down, oblivious to that it would presumably result in society collapsing, with millions or billions dying in the ensuing famine.

Bacteria fail to eat our organic wooden houses.

What's your point? We're talking about a hypothetical.

Sure they do, it's a major repair bill for many people. If we wind up with critical infrastructure that was previously stable randomly rotting, it will likely disrupt our current uptime rates, require expensive preventative measures and repairs, and in the end limit access to services due to the added costs. The dangers of hidden rot to electrical lines in buildings is one of the scariest possibilities.

Thats because the wood is treated with lots of chemicals. We would need to start treating plastics with these chemicals, creating potentially toxic plastics, which is not a good thing because it is very hard to test chemicals for toxicity and much of our food is stored in plastics.

Most of the wood used in house construction is not treated with anything. Only the stuff that touches soil, foundations, or is exposed to elements is. Unless you use real wood siding, that’ll be less than 5% of all lumber used. It doesnt decay, because it’s kept dry, and microorganisms arent very good at decomposing dry wood.

On the one hand I understand what you are saying, but on the other hand we've only had good plastics for a couple decades.

That's not relevant. We know it's possible to build a society with no plastics, but the question is how much harm it would do if plastics suddenly started to rapidly decay.

We've only had widespread electronics for a handful of decades, but if we lost it overnight, we'd be unable to produce and distribute food at the necessary scale. Restoring the global economy wouldn't even be on the horizon, we'd be too busy dying of famine.

We've only had the internal combustion engine for a handful of decades, but if we lost it overnight we'd be similarly ruined.

If the bacteria only slowly ate plastics, we wouldn't be doomed, it would just make things more costly, as with way rust and rot.

Water, gas, sewage, electricity and telecom lines are conducted/coated with PET.

You would weep.

you sir have won the understatement of the thread award.

i'd literally be flooded with shit if something ate my plumbing, which likely means dead. that is, unless the isolation of electric cabling wouldn't burn me alive first.

weep isn't really on the TODO list in that scenario. covid is peanuts in comparison.

It would be wasteful to have to replace almost all vehicles, appliances, computers, and so on.

A bactery that eat oil and you have the movie mad max

There are cureently bacteria that eat diesel/gasoline, which is why if you leave either in your vehicle tank for a long period (1-6 months) , you shoud to siphon it out and replace it.

No.

Gasoline and diesel go bad because they are solutions of many hydrocarbons, and the lighter hydrocarbons are the first to evaporate, leaving a heavier-than-intended slurry of what's left plus accrued moisture from atmosphere.

It has little to nothing to do with bacterial growth.

'Fuel Stabilizer', additives that are intended to be added to tanks of vehicles which must have fuel sitting in them for prolonged periods, are oils which are designed to prevent the evaporation of the lighter hydrocarbons and prevent water infiltration; usually through the use of molecules that either bond with water readily, or by layering oil atop the fuel mass to encapsulate it from evaporation to atmosphere.

leaving a heavier-than-intended slurry of what's left plus accrued moisture from atmosphere

You didn't mention ethanol but that's what you mean. Normal gasoline is very stable, it's just the federally-mandated corn ethanol added to it that turns into sludge after a few months. Fuel stabilizer keeps that ethanol from degrading.

I would advise anyone with small engines, like lawnmowers or snowblowers, to seek out ethanol-free gasoline and use that exclusively in those engines.

Another possibility: the bacteria could be engineered to switch to a different metabolic mechansim, like the use of the lac operon to digest lactose instead of glucose whenever there's a scarcity of glucose. Although this envisages stably engineered bacteria that switch between plastic and regular metabolic process, which I'm not sure about the current feasibility/precision.

The article implies that this microbe was found in the wild, rather than engineered in a laboratory. The paper confirms it - https://www.frontiersin.org/articles/10.3389/fmicb.2020.0040...

Bacteria that eats nylon was first found in the wild: https://en.wikipedia.org/wiki/Nylon-eating_bacteria

With this in mind, it may be worth considering that plastic-eating bacteria that currently exist in the wild do not appear to present any significant threat of a catastrophic event. I'm sure it's just an oversight on my part, but can you help me understand why this newly identified strain would pose a threat?

By selectively breeding them to be more efficient at breaking down plastics faster, one might be increasing the risk of a runaway 'plastic-rot'.

I'm not concerned yet though, since current landfill sites are effectively perfect selective breeding grounds for 'plastic rot', yet so far we haven't detected any significant increase in the breakdown speeds of plastics in the environment.

I once read a sci-fi book that featured a metal eating organism that was released as a weapon.

Yeah, whenever humans engineer something to fix something else we've broken in the complex system that is earth, it seems like there's a high chance of it messing other stuff up and itself becoming a problem.

grey goo scenario :)

a plastic eating pathogen is a prominent actor in 'The Andromeda Strain'

[0]: https://en.wikipedia.org/wiki/The_Andromeda_Strain

My first thought. My second thought was a terrorist releasing this in a hospital.

My friends and I played a card game in which the point was to write a short story. Our story was like so:

Planet Earth had been evacuated, and all that was left was little robots. All of different types, performing different jobs, but with one major function: to rid the world of a microbe that turned all organic matter into crude oil. Initially this microbe was developed for plastics, but it got out of hand really quickly.

Now, given the world was entirely covered, clean up was an impossible task, so most of the robots just gave up and "zenned out." They'd go into an infinite loop of impossibility and stay there. Our robots were a bit different and instead decided to just pretend to work.

Eventually a catastrophic change happened wherin a small comet hit the Earth. Then growing from that point, all of the sludge began to crystalize. These crystals grew like plague, so any robot that became even an little bit glinty was sure to be a goner soon.

The story ended with all our robots dying, having learned that humanity had sent the crystalizing thing, but also having seen greenery grow once again where the crystals had cleaned up.

I doubt this will ever compete with power generation from incineration. Most plastics are recycled into power and smoke. https://www.nationalgeographic.com/environment/2019/03/shoul...

How is this different from the products currently developed by companies like Carbios[1] ?

I'm a totally ignorant in physics and chemistry (except from what I've studied at school) so excuse my genuine question.

[1] https://carbios.fr/en/

Carbios looks like a product. This is essentially a microorganism that feeds on plastics.

So this is the same as what is talked about in the post?

It seems there is a ritual of articles every 6 months for finding a microbe to degrade plastic for past 5 years now. I wonder what is the real story.

Guess they haven't read some science fiction classics :)

Mutant 59 The Plastic Eater Book by Gerry Davis and Kit Pedler

I prefer we not engineer bugs to rot our plastics. The problem is not that plastics are durable. The problem is humans are shortsighted and have not developed systematic thinking and processes to prevent waste.

We need plastics. Durable, rot-resistant, waterproof, light, strong, malleable, easy to cast into different shapes.

But we as a species do not reuse and recycle enough, and even throw plastics into the ocean or into compost bins.

How about we get to the root of the problem, instead of apply bandaid atop of bandaid?

Reduce, reuse, recycle. Repair, repurpose, reclaim (put money into cleaning up our oceans?), rethink (do we need individually wrapped produce?) etc.

There are also caterpillars that eat plastic: https://www.nature.com/articles/d41586-017-00593-y

I've always been curious about the balance here.

Breaking down plastic waste sounds great, except it almost certainly releases CO2. Leaving it in a landfill is probably the better option.

Granted, if they could turn these plastics into some sort of biofuel it would be a much different story. Better to convert the waste we already have then pump more oil. It's unclear whether that is a byproduct of this microbe.

It's interesting, because pretty much for anything you want to do chemically these days:

"There's a bacteria for that..."

Perhaps Marc Andreessen should have said "Bacteria are eating the world" (quite literally!) -- instead of "software"...

In the next century, things very well might be that way! <g>

Have there been studies about the dangers of these types of microbes spreading out into the "wild"?

The article talks about a microbe that already exists in the wild.

I'm not referring to this article - I'm referring to the general case of plastic-eating microbes. Plastic eating organisms are not new. Even certain types of mealworms will eat styrofoam...

Articles like these are published several times a year, but I don't think I've seen any studies on the potential impact.

This article mentions it, but there are no accompanying references.

http://theconversation.com/how-plastic-eating-bacteria-actua...

They are probably as dangerous as silverfish to your book collection.

As a lay person, I currently get the distinct impression that polymer-digesting microbes are not currently considered dangerous, with the current impacts being negligible.

What kind of dangers and impacts would you like to see studied?

> I currently get the distinct impression that polymer-digesting microbes are not currently considered dangerous, with the current impacts being negligible.

Well, you've just answered it. I would like to know the scientific rationale for this or an opposing belief. I currently have no opinion on the matter because I haven't read any material to think about in any way other than "these things exist".

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