Reddit: Bacteria That Ingest Digest Plastics.

§ It actually digests one of the byproducts of nylon manufacture#They convert nylon byproducts into an🔍AminoAcid*(lysine)🔍🔎, which they can then use for energy.
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Could there be bacteria in landfills right now evolving to digest plastics?

u/jovialplutonium

We've all heard the facts about plastic water bottles, that they take many thousands of years to degrade, etc. But given that the ability to metabolize ubiquitous plastic products would confer a distinct evolutionary advantage to any organism that could do so, is it possible that such a bacterium could evolve to do so within a shorter amount of time than the physical degradation rate of plastics?

Similarly, could scientists direct the evolution of these organisms by, for example, placing a bacteria culture in a dish in the presence of polymers with enough natural media to get a sufficiently large level of variation, so that once the natural nutrients are expended the bacteria will have to evolve to digest the polymers to survive?

EDIT: Is this process akin to what happened when plants first started producing cellulose? And if this evolutionary feature does not happen, will the plastics that make their way into the earth's crust turn back into oil?

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danby Structural Bioinformatics • 2y

There are already bacteria which can eat some plastics. A nylon eating bacteria was discovered in 1975 and is one of the best examples of evolution in action Edit: It actually digests one of the byproducts of nylon manufacture

https://en.wikipedia.org/wiki/Nylon-eating_bacteria

And there is good evidence of polyethylene digestion by bacteria too.

http://pubs.acs.org/doi/abs/10.1021/es504038a

So it's quite probable that more microbes will evolve plastic digesting abilities for a wider range of plastics. Possibly some of these already exist at the bottom of landfills.

Personally I don't doubt that we could direct the evolution of microbes to digest further plastics. The difficulty comes identifying which plastic will be amenable to enzymatic digestion and which microbes already have enzymes which with a little evolution will be able to accomplish such a task.

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jovialplutonium • 2y

So the nylon eating bacteria can only metabolize the monomer unit, not the polymer?

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nate1212 Cortical Electrophysiology • 2y

No, they can digest short polymers (oligomers)! At least pentamers (chains of 5) can be digested, and very likely even longer chains (source).

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Hidden_Bomb • 2y

A 5 chain polymer, or anything close to that length would be essentially useless for any sort of polymer type. Why does this really matter?

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Vironomics • 2y

Firstly, digesting byproducts of manufacture is still potentially useful, even if the bacteria are unable to digest to manufactured product itself.

Secondly, it may be possible to tweak the bacteria's enzymatic machinery such that longer chains can be digested. Researchers can't really design enzymes from scratch right now, but we can modify existing enzymes via a couple of different processes. If we want to create a strain of bacteria that can digest new polymers, we're going to need a jumping-off point, which these bacteria provide.

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Hidden_Bomb • 2y

Thank you for answering my question. That does seem very useful. I suppose I was thinking to narrowly.

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pbatoon Grad Student|Analytical and Physical Chemistry|Mass Spectrometry • 2y

My best guess would be that those polymers buried underneath are exposed to "harsh" environments that cause the massive polymers to break down into smaller oligomers. For example, nylon is easily subject to hydrolysis in the presence of acidic conditions. And at the depth at which polymer-eating bacteria thrive you can bet some acid from the surface has seeped through to create a perfect environment to thrive.

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feared_rear_admiral • 2y

The conditions at the bottom of the landfill aren't really all that harsh, chemically speaking. Sure it's disgusting and very likely toxic but I doubt it's highly acidic or oxidising there. Or hot.

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shenye • 2y

There are usually still bits of organic matter left in landfills, whether it be the drops of milk left in milk cartons or unwanted bread crusts. Bacteria and fungi will digest these in anaerobic conditions which will produce acids such as lactic acid and acetic acid. When rain washes it down, it will certainly hydrolyze polypeptides like nylon. Not massively or quickly, but the reaction would definitely occur.

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Bull_Saw • 2y

Actually, the inside and bottoms of landfills can be hot. In the same way a compost generates and holds heat, landfill can have the same effect. Here is some pictures of compost being flipped.https://www.google.com/search?q=flipping+a+compost&safe=off&client=ms-android-att-us&source=univ&tbm=isch&tbo=u&sa=X&ei=PAgfVZz7D_iMsQSLzIFY&ved=0CDIQ7Ak&biw=360&bih=640

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nate1212 Cortical Electrophysiology • 2y

6-aminocaproate oligomers are a normal byproduct of nylon industrial synthesis

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Trailmagic • 2y

What about polystyrene?

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Hidden_Bomb • 2y

It varies from process to process, but typically polystyrene has a chain length of a few thousand monomers. Also, nylon's monomer and polymer forms are extremely different from styrene based polymers.

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nate1212 Cortical Electrophysiology • 2y

Non full-length polymers are a common byproduct of nylon manufacture, and have been present in industrial waste since the 1930s (source).

I'm not sure what you mean by 'useless'... in the end, the bacteria are able tometabolize (that is, get energy from) a set of molecules that have suddenly started to build up in the environment that no other plants, animals, fungi, bacteria, etc, have the ability to utilize. I'd say that's pretty useful.

These organisms spontaneously evolved the ability to metabolize an industrial waste product. They convert nylon byproducts into an amino acid (lysine), which they can then use for energy. There is no further toxic byproduct produced in this process. Not only are they actually getting rid of industrial waste that has accumulated, but they serve as a model to study for things like directed evolution of other waste-consuming bacterial enzyme systems (this is an active, promising research area). I'm not sure how else to demonstrate the present and potential utility of something like this.

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danby Structural Bioinformatics • 2y

Yeah, I should have made that clearer.

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inawordno • 2y

Could that potentially lead to plastic being biodegradable and would the upshot of this make plastics less useful?

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danby Structural Bioinformatics • 2y

ha, ha. Yeah, perhaps there will one day be a world where bacteria eat all our plastics!

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strawberrykoff • 2y

That would be a great sci-fi novel! A world that has become completely dependent on plastics, suddenly being unable to use them...

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mangeek • 2y

In Andromeda Strain the 'space virus' evolves to start digesting a certain kind of rubber.

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AleXndrTheGr8st • 2y

You're really not doing the book any favours by calling it a virus. It's a suspected extraterrestrial micro-organism that mutates to be able to eat through rubber and plastic. Great book, definitely worth the read, like a lot of Crichton's others.

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mangeek • 2y

That's why I put it in quotes... I just didn't want to explain too much.

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nrj • 2y

Wait, was it really a virus? That somehow evolves to... What? Infect rubber? Viruses can't "eat" anything, AFAIK. That seems a bit far-fetched, even for soft sci-fi.

Edit: Thanks for the replies. I haven't read the book or watched the movie and I was confused by the use of "virus".

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tim_mcdaniel • 2y

That seems a bit far-fetched, even for soft sci-fi.

To remind, The Andromeda Strainwas written by Michael Crichton, the same guy who wrote Jurassic Park.

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•	Zargyboy • 2y

It also kind of sounds a bit like the nanobots in his book Prey as well.

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Hagu_TL • 2y

It wasn't a virus, but then, as an extraterrestrial microorganism it somehow lacked DNA, RNA, proteins, and amino acids.

So, still kind of far-fetched.

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•	Fusilero • 2y

True, but tell a microbiologist in the first half of the 20th Century about prions and viroids and you'd be told your ideas were kind of far-fetched.

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mangeek • 2y

No, it wasn't. In the book and film, it was a crystalline thing that grew and spread. It fed on radiation (light, radio, x-ray, etc.) and coagulated people's blood. In the end, I think it mutates to eat the kind of rubber used in the gaskets they were containing it with, but no longer poses a threat to people.

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•	TimeToSackUp • 2y

Actually, it wasnt rubber but a new type of plastic.“Well, no rubber was used in this airplane. It was all a synthetic plastic compound. Newly developed by Ancro; they’re quite proud of it. It’s a polymer that has some of the same characteristics as human tissue. Very flexible, lots of applications.”

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Tenthyr • 2y

It was a crystalline form of life that had an ability to convert radiation it absorbed into new mass. It was also horrendously mutagenic. There was no biological analogue on earth and virus was just the best word they had for it. A far fetched form of life, but a cool exploration of it.

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