Good news! Effective plastic waste management is coming! Once more, human ingenuity at its best! And this is only the beginning!
Dismiss most of the alarmism and hysteria about plastic! Plastic is one of the greatest inventions of modern times! Plastophobia is a serious disease, please get treated immediately! 😄
"A plastic-degrading enzyme enhanced by amino acid changes designed by a machine-learning algorithm can depolymerise polyethylene terephthalate (PET) at least twice as fast and at lower temperatures than the next best engineered enzyme. ...
Out of the millions of possible combinations, the researchers zeroed in on three suggested amino acid substitutions. Combined with two modifications from a previous PETase engineering effort, they designed an enzyme that is ‘highly, highly active, especially at lower temperatures, compared to anything else that’s out there’ ..."
Six years ago scientists sifting through debris of a plastic bottle recycling plant discovered a bacterium that can degrade PET. The organism has two enzymes that hydrolyse the polymer first into mono-(2-hydroxyethyl) terephthalate and then into ethylene glycol and terephthalic acid to use as an energy source.
One enzyme in particular, PETase, has become the target of protein engineering efforts to make it stable at higher temperatures and boost its catalytic activity. ...Out of the millions of possible combinations, the researchers zeroed in on three suggested amino acid substitutions. Combined with two modifications from a previous PETase engineering effort, they designed an enzyme that is ‘highly, highly active, especially at lower temperatures, compared to anything else that’s out there’ ..."
From the abstract:
"Plastic waste poses an ecological challenge and enzymatic degradation offers one, potentially green and scalable, route for polyesters waste recycling. Poly(ethylene terephthalate) (PET) accounts for 12% of global solid waste, and a circular carbon economy for PET is theoretically attainable through rapid enzymatic depolymerization followed by repolymerization or conversion/valorization into other products. Application of PET hydrolases, however, has been hampered by their lack of robustness to pH and temperature ranges, slow reaction rates and inability to directly use untreated postconsumer plastics. Here, we use a structure-based, machine learning algorithm to engineer a robust and active PET hydrolase. Our mutant and scaffold combination (FAST-PETase: functional, active, stable and tolerant PETase) contains five mutations compared to wild-type PETase (N233K/R224Q/S121E from prediction and D186H/R280A from scaffold) and shows superior PET-hydrolytic activity relative to both wild-type and engineered alternatives between 30 and 50 °C and a range of pH levels. We demonstrate that untreated, postconsumer-PET from 51 different thermoformed products can all be almost completely degraded by FAST-PETase in 1 week. FAST-PETase can also depolymerize untreated, amorphous portions of a commercial water bottle and an entire thermally pretreated water bottle at 50 ºC. Finally, we demonstrate a closed-loop PET recycling process by using FAST-PETase and resynthesizing PET from the recovered monomers. Collectively, our results demonstrate a viable route for enzymatic plastic recycling at the industrial scale."
(No public access, link to PDF file)
The engineered enzyme was able to break down an untreated plastic container within 48 hours
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