Author Topic: Polyurethane eating bacteria; should we be concerned?  (Read 501 times)

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Offline splin

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Polyurethane eating bacteria; should we be concerned?
« on: March 28, 2020, 02:26:21 pm »
https://amp.theguardian.com/environment/2020/mar/27/scientists-find-bug-that-feasts-on-toxic-plastic

Quote
A bacterium that feeds on toxic plastic has been discovered by scientists. The bug not only breaks the plastic down but uses it as food to power the process.

The bacterium, which was found at a waste site where plastic had been dumped, is the first that is known to attack polyurethane.
...
While the research has identified the bug and some of its key characteristics, much work remains to be done before it can be used to treat large amounts of waste plastic.

Good: A potential solution to toxic plastic waste.

Bad: If this strain of bacteria is successful and spreads in the environment, would we be in danger of losing much of the polyurethane insulation used in modern homes? Or furniture foams etc?

Potentially worse,  what if the bacterial decomposition process releases toxic chemicals, (such as cyanates perhaps?) into the home?
Or just more nano-grey-goo fear mongering?


[EDIT] likely the conditions for the bacteria to flourish would have to be just right. In particular I would guess they would require a certain amount of moisture which would keep most of the 'wanted' polyurethane safe. In which case it wouldn't be much different to many other building materials which need to be kept free of damp to avoid rot.
« Last Edit: March 28, 2020, 02:37:26 pm by splin »
 

Offline Stray Electron

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #1 on: March 28, 2020, 02:51:35 pm »
   PLEASE, just one crisis at a time.
 

Online Zero999

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #2 on: March 28, 2020, 03:06:55 pm »
It's just a matter of time before some life form evolves to use all man made polymers has a food source. Plastics are very energy dense and any bacteria or fungus which can live off them will do very well. The is analogous to trees evolving before the bacteria and fungi to decompose them, resulting in huge coal deposits, which stopped being formed, when bacteria and fungi evolved to decompose them.
 

Offline kosine

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #3 on: March 28, 2020, 03:39:05 pm »
The article mentions high temperatures and acidic conditions, so your cables will be safe. Polyurethanes are not very resistant to acids and will also oxidize over time, especially at higher temperatures. The bacteria are probably making use of this process and speeding it up with enzymes. Clear PU (such as tubing) tends to yellow noticeably over time as a result of the oxidation, and certain types of PU are also known to disintegrate after a few years, though we generally use the stuff that doesn't.

Article doesn't say what type of PU we're dealing with either. It's a broad church. There's cast PU resins, foam, and thermoplastics - both rigid and elastomeric. The commonest are made from esters, though ether and ketone variants are also available for more demanding applications, albeit at a higher cost. As a copolymer there's also a wide variation in the number "hard" and "soft" segments that are strung together. The bacteria will probably favour one or the other, so I'd expect only certain PUs to be significantly affected.

There's also no isocyanates in the finished material, though thermal decomposition releases all sorts of stuff - as does burning wood to be fair. Chemically, the simplest PUs are very similar to nylon, and it was actually developed by Otto Bayer in the later 1930s as a direct response to the tight patents Du Pont had on their nylons.

As far as recycling goes, thermoplastic PUs (as used on cable sleeving) is compatible with PVC, so when that stuff gets reprocessed there is often some amount of PU mixed in the recycled PVC. The companies that recycle cables are only after the copper, and a lot of the sleeving goes to waste. It sells for less than $100/tonne and they generate spoil heaps of the stuff. Need something that eats PVC. It lasts much longer and we use a heck of a lot more of it.
 
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Offline jogri

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #4 on: March 28, 2020, 04:49:06 pm »
Seems like the headline just doesn't stand up to the actual research...

Quote
The strain, identified as Pseudomonas sp. by 16S rRNA gene sequencing and membrane fatty acid profile, was able to grow on a PU-diol solution, a polyurethane oligomer, as the sole source of carbon and energy. In addition, the strain was able to use 2,4-diaminotoluene

Well, Sigma lists an avg Mn of 320 for this "oligomer"... Nothing even close to Polyurethane, that stuff is basically just a few isocyanates and alcohols slapped together. I didn't read the entire article, but it doesn't seem like they let the colonies grow until they died of starvation, so they just proved that this strain can probably attack the isocyanate/alcohol endgroups and use them as food, but they didn't prove that it can actually attack a polymere and therefore eat plastic.

Same thing with the toluene, i'm not that surprised that a bacteria can attack it, but that stuff just doesn't exist in the polymer (it isn't even a monomer of PU as it has to be converted to its isocyanate form before using it). It's kinda cool that they found something that can degrade an aminotoluene, but proofing that something can degrade an amino compound in a lab experiments where all conditions were optimized for its growth (temperature, growth medium, nutrition etc) and claiming that this group has found a bacteria that "feasts on toxic plastics" are just not the same thing...

So i guess this is another article by a person who just doesn't care to check if their claims are actually backed up by their sources before publishing...
 
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Offline splin

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #5 on: March 28, 2020, 10:51:39 pm »
Great responses. I'm always impressed by the depth and extent of knowledge of posters here. So for the time being nothing to worry about - the press as usual over-egging the pudding.

I have to agree with Zero999 that it's only a matter of time before something evolves the ability to digest plastics - natural selection is a powerful mechanism (process?). We are conducting a massive experiment, especially in the oceans, to give nature a good chance of suceeding. We may or may not regret the eventual outcome!
 

Offline CatalinaWOW

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #6 on: March 28, 2020, 11:00:55 pm »
Great responses. I'm always impressed by the depth and extent of knowledge of posters here. So for the time being nothing to worry about - the press as usual over-egging the pudding.

I have to agree with Zero999 that it's only a matter of time before something evolves the ability to digest plastics - natural selection is a powerful mechanism (process?). We are conducting a massive experiment, especially in the oceans, to give nature a good chance of suceeding. We may or may not regret the eventual outcome!

An organism that can digest a plastic ground to fine bits in a salt water environment is still a long way from a threat to your home unless you live in salt spray range of a coast.  There are probably several more crises before this one ripens.
 

Offline splin

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Re: Polyurethane eating bacteria; should we be concerned?
« Reply #7 on: March 28, 2020, 11:11:07 pm »
An organism that can digest a plastic ground to fine bits in a salt water environment is still a long way from a threat to your home unless you live in salt spray range of a coast.  There are probably several more crises before this one ripens.

Don't you watch the movies? If evolution has manged to produce 5 and 6-headed sharks, a few plastic munching micro-organisms should be a doddle (Brit term for easy-peasy) in comparison!  :-DD
 


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