For years the idea that a bacterium could nibble apart a plastic bottle sounded like a lab‑bench oddity. That story began to change after 2016, when researchers identified an enzyme called PETase that hydrolyzes polyethylene terephthalate (PET), the polyester used in millions of bottles and textile fibers. In the past three years protein engineers, computational chemists and industrial partners have taken that first finding and turned it into a suite of practical tools aimed at closing the loop on PET.
Scientists have improved PET‑hydrolyzing enzymes in multiple, complementary ways. Groups working with metagenome discoveries and compost‑derived cutinases have raised enzyme activity and thermostability so that engineered variants now depolymerize high‑crystallinity PET far faster than the original PETase. Detailed biochemical and structural work has produced variants that retain activity across a broader temperature range and perform under industrial solids loadings—an important step because thick, crystalline plastics are the hardest to break down. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC12767270/?utm_source=openai))
Other teams focused on making enzymes that work where plastic waste actually accumulates. Researchers reported engineered IsPETase variants that retain activity in seawater at near‑ambient temperatures, a promising proof‑of‑concept for processing PET contaminated by salt and environmental fouling rather than pristine lab samples. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC13083688/?utm_source=openai))
Those advances have not come from one trick but from many: directed evolution and rational mutation to stabilize flexible loops; introduction of disulfide bonds and salt bridges to raise melting points; and computational redesign to optimize substrate binding and catalysis. Generative models and AI‑assisted sequence mining have also accelerated the hunt for new polyester hydrolases in environmental sequence databases, producing candidate enzymes that outperform earlier designs in lab benchmarks. Taken together, the field now routinely reports PET hydrolases with orders‑of‑magnitude higher activity and far greater thermostability than the enzymes first described a decade ago. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC13179365/?utm_source=openai))
Bioprocess engineers have translated enzyme chemistry into two practical pathways. One is purified‑enzyme depolymerization, where enzyme cocktails break PET into its monomers—terephthalic acid and ethylene glycol—that can be purified and repolymerized into virgin‑quality PET. The other approach is whole‑cell biocatalysis, where microbes are engineered to secrete and sometimes even metabolize PET fragments, simplifying downstream handling. Laboratories have reported proof‑of‑concept whole‑cell systems engineered for stable, continuous expression of PETase genes without antibiotic selection—an important industrial consideration for large‑scale fermentations. ([sciencedirect.com](https://www.sciencedirect.com/science/article/abs/pii/S0304389426001482?utm_source=openai))
Those laboratory gains have begun to attract industrial partners and investment. One company that has been widely cited as attempting to bridge lab scale and commercial production is Carbios, which has operated a demonstration enzymatic biorecycling facility and is working with partners to deploy a larger industrial plant in Longlaville, France. The company reports that its demonstration unit has been operational since 2021 and that it remains committed to building an industrial plant—even as the project timeline has been adjusted and financing steps proceed. Recent updates from the company project a target of starting production at an industrial Longlaville site in the first half of 2028, while noting that financing and scheduling milestones continue to evolve. ([carbios.com](https://www.carbios.com/wp-content/uploads/2024/06/CARBIOS_DEU%202023_EN_WEB.pdf?utm_source=openai))
The case for industrial enzymatic recycling is practical as well as scientific. Current mechanical recycling streams for PET lose material quality and are sensitive to contamination; global and regional recycling rates remain far below total production. Industry data show that collection and closed‑loop bottle‑to‑bottle rates leave a large gap between the plastic produced each year and the material recovered for food‑grade reuse, creating a demand for chemical or enzymatic routes that can return contaminated or dyed PET to monomers. ([napcor.com](https://napcor.com/news/2022-pet-recycling-report/?utm_source=openai))
That does not mean the path ahead is free of challenges. Enzymes can be inactivated at interfaces, and industrial processes need robust formulations, reliable enzyme supply chains and efficient separation steps to recover monomers at commercial yields. Pilot projects and multi‑partner consortia are actively working through those scale‑up problems—optimizing enzyme formulations, testing local feedstock compatibility and negotiating offtake for the rPET that would be produced. The combination of faster, tougher enzymes with growing industrial commitment makes enzymatic recycling one of the most tangible routes toward chemically circular polyesters. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/42245522/?utm_source=openai))
For consumers and policy makers, enzymatic recycling is not a silver bullet: better collection, simpler packaging design and stronger reuse systems are still necessary to reduce waste. But in the laboratories and pilot plants where chemists and biotechnologists meet industry, the last few years have shown something important: a class of chemistry once relegated to academic curiosity has reached a level of maturity that makes industrial deployment credible. If the remaining engineering, financing and logistics milestones are met, enzymatic PET recycling could help turn millions of tonnes of used polyester from a disposal problem into feedstock for next‑generation packaging—closing a loop that until recently felt aspirational.
What to watch next
- Reports from industrial scale‑up projects about enzyme supply, process yields and proof of food‑grade rPET; these will be the clearest signal that lab enzyme performance translates to commercial economics. ([carbios.com](https://www.carbios.com/en/carbios-reports-first-half-2026-results/?utm_source=openai))
- Independent life‑cycle analyses comparing enzymatic routes to mechanical recycling and to advanced chemical recycling for greenhouse‑gas emissions and resource use. (Several groups are publishing such studies as pilot data appear.)
- New enzyme sequences from environmental and AI‑guided discovery campaigns that combine high activity with low production cost—an enzyme that needs less purification or lower dosing rates would change the business case. ([doi.org](https://doi.org/10.1016/j.nbt.2026.03.010?utm_source=openai))
In the convergence of chemistry, computation and industrial engineering, the story of PETase has moved from “can it be done?” to “how fast and how cheaply?”—a shift that, in industrial chemistry, is the most meaningful kind of progress.
