Comment by autoexec | Hacker News Reader

Comment by autoexec | Hacker News Reader

> The researchers took PET plastic, discarded corn plant stalks and leaves, and other biomass and put it through a proprietary process called oxidative hydrothermal dissolution. Created by SIU Carbondale Geology Professor Ken Anderson, this method uses water and oxygen at high temperatures and pressures to break down tough material into microbe-accessible pieces. Then, those pieces are fed to the programmed yeasts, which transform them into a variety of new food ingredients, including proteins, fats and acids. Finally, the researchers add fiber, starch and sweetener to the mix and extrude it through a 3D printer, forming protein-rich cookies dubbed µBites (pronounced "microbites"). [https://phys.org/news/2026-08-yeasts-pet-plastic-crop-protei...]

It kind of sounds like they made food out of corn plant stalks and leaves and "other biomass", added fiber, starch, and sweetener, but then just polluted the product with processed waste plastic as an additive. If this really is just using trash as a filler in actual food that's pretty dystopian. I'm sure companies would happily line up to sell their industrial waste products to food companies as an additive, but I'm not seeing the appeal in this for consumers.

Then, those pieces are fed to the programmed yeasts, which transform them into a variety of new food ingredients, including proteins, fats and acids

PET consists of repeating C10H8O4 monomers. Glucose is C6H12O6 and starch is a natural polymer containing it. It's not surprising that reactions can turn one into the other, along with other compounds containing hydrogen, carbon, and oxygen.

Just because two substances are made of a similar distribution of atoms it doesn't mean much in terms of how one can be transformed effectively into the other...

> transformed effectively

Well that's where the yeast comes in, it does the work for us. And we desperately need ways to convert plastics into something that is not as durable, and ideally something we (or if that's too icky, farm animals) can eat afterwards.

Short answer: No

Long answer: Starch and cellulose are just chains of glucose connected in a slightly different way. But they have very different properties, you can split starch and get energy from it, but you can't split cellulose (unless you are a bacteria or fungus).

As far as I know, no life form can transform starch directly into cellulose, they have to split it and reconnect the glucose later. (And the reverse path is even harder.)

There are a few cases where the cells can transform the monomers inside the chains, in particular to make collagen, but the change is to replace some -H by -OH. Changing the Carbon structure is harder, almost impossible.

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Back to the article: The yeast just split the plastic back into monomers (or probably short chains) and use the chains to build carotene (similar to vitamin A). It's quite similar to splinting starch or cellulose and using later the monomers. There is no polimer to polimer transformation.

Vegetables grown in shit, garbage, and pesticides are fine as long as the levels of harmful residues are low enough by the time they reach people's mouths. Not appealing, but also not that "dystopian"

Good luck actually doing that, however.

Plenty of folks wishing to pretend though.

Using manure and compost as fertilizer is likely as old as agriculture (though i disagree using pesticides is fine). What did you mean?

Plenty of substances bio accumulate, and being less than careful with animal waste as fertilizer causes outbreaks and disease.

Ha yes of course, this is obvious to anyone in the field but always a good idea to repeat. For example, do not use human feces as fertilizer for food you'll eat (at least not directly).

Ack, yeah it's one of those 'well duh', until people who have no idea blindly copy the idea and then plague, or prions, or arsenic poisoning, or whatever.

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