Enzymatic recycling represents one of the most promising innovations in the field of sustainable plastic waste management, particularly for the packaging sector. This technology uses specific enzymes—biological catalysts—capable of breaking down plastics such as PET, which is widely used for bottles and packaging, into their original monomers, such as terephthalic acid and ethylene glycol.
Unlike traditional methods, enzymatic recycling makes it possible to obtain recycled materials with a quality equal to that of virgin plastic, even when starting from colored or complex plastic waste. It enables true reintegration into a circular production cycle. Recent scientific and industrial advancements—driven by companies like Carbios and major brands in the sector—have led to the production of the first bottles made from enzymatically recycled PET, demonstrating the feasibility and speed of the process: up to 97% of the plastic can be broken down in just 16 hours, with significantly higher efficiency than traditional organic recycling systems.
In addition to reducing energy consumption compared to thermal recycling, this technology offers a concrete solution for recovering valuable resources and reducing plastic pollution. It stands out as a key element in moving toward more sustainable packaging and a truly circular economy. In the case of more easily degradable polymers like PET, these enzymes have already been optimized and industrialized, whereas for polyolefins, research is still underway to identify effective enzymes, due to their more resistant chemical structure.
Enzymes attack the polymer chains, breaking them down into simpler molecules (monomers or oligomers). This process, called depolymerization, makes it possible to recover the basic building blocks of plastic, which can then be purified and reused to produce new materials. The resulting monomers are separated from the rest of the material and purified. They can then be used to synthesize new polyolefins or other chemical products, thus ensuring a true closed-loop process and the possibility of obtaining materials with virgin-like quality.
The main advantages of enzymatic recycling are as follows:
- The process generally occurs at lower temperatures compared to thermal recycling, resulting in lower energy consumption and reduced greenhouse gas emissions.
- It allows for the treatment of mixed, colored, or contaminated plastics, which are difficult to recycle using traditional mechanical methods.
- Enzymatic recycling avoids the loss of performance typical of mechanical recycling, enabling the production of materials suitable even for food-contact applications.
Enzymatic recycling of PET is much more advanced than that of polyolefins. In recent years, research on PET has made significant progress thanks to the discovery of natural enzymes, such as those produced by the bacterium Ideonella sakaiensis, capable of depolymerizing PET rapidly and efficiently. Today, there are already demonstrative industrial processes: for example, Carbios’ C-Zyme technology is able to recycle post-consumer PET on a ton-scale, producing new bottles with quality comparable to virgin material. The achieved efficiency allows for the breakdown of up to 98% of PET plastic within 48 hours, and ongoing research continues to optimize both enzymes and processes, also through the use of artificial intelligence and synthetic biology.
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Chemo-enzymatic depolymerization of low-molecular-weight functionalized polyethylene.
Polyethylene (PE) is the most widely used type of plastic in the world and contributes significantly to the plastic waste crisis. Microbial degradation of PE in natural environments is unlikely due to its chemical structure, which consists of saturated and inert carbon–carbon bonds that are difficult for enzymes to break. This makes it challenging to develop a biocatalytic recycling method for PE waste.
In this study, we demonstrated the depolymerization of low-molecular-weight polyethylene (LMW-PE) using an enzymatic cascade composed of catalase-peroxidase, alcohol dehydrogenase, Baeyer–Villiger monooxygenase, and lipase, following a chemical pretreatment of the polymer with m-chloroperoxybenzoic acid (mCPBA) and ultrasound. In a preparative experiment conducted on a gram scale with pretreated polymers, GC-MS analyses and weight loss measurements confirmed a polymer conversion of approximately 27%, with the formation of medium-sized functionalized molecules such as ω-hydroxycarboxylic acids and α,ω-dicarboxylic acids.
Further analyses conducted on LMW-PE nanoparticles using AFM microscopy showed that enzymatic depolymerization reduced the size of particles treated with mCPBA and enzymes. This multi-enzymatic catalytic concept, which integrates distinct chemical steps, represents an innovative starting point for the future development of bio-based recycling methods for polyolefin waste.
https://onlinelibrary.wiley.com/doi/full/10.1002/anie.202415012
Design of polyethylene-like polyesters degradable in natural environments and recyclable in an environmentally friendly way using commercial enzymes.
Polyethylene-like polyesters (PE-like) represent a potential alternative to the most commonly produced polyethylene materials, but they exhibit limited degradation rates and a recycling pathway that is not environmentally sustainable. However, “green” enzymatic recycling, which allows for the recovery of the original monomer, is often hindered by the crystalline structure of the materials and the limited hydrolytic activity of the enzymes.
In this study, a bio-based pyrrolidone dicarboxylic acid was selected as a central building block to promote both accelerated hydrolysis and improved substrate–enzyme binding in the design of PBTDP copolyesters. The resulting PBTDP copolymers showed high crystallinity and rapid crystallization, comparable to that of commercial HDPE. They also demonstrated remarkable mechanical strength, with elongation exceeding 1000%.
Moreover, these copolymers were able to hydrolyze in aqueous conditions at 37 °C, degrading rapidly in the presence of the commercial enzyme Candida antarctica lipase B within just 10 days. The role of the pyrrolidone units as hydrophilic sites and the hydrolytic mechanism were further clarified through Fukui function analysis and density functional theory (DFT) calculations. Molecular dynamics (MD) simulations showed that the pyrrolidone units engage in non-covalent interactions with the enzyme, increasing the occurrence of pre-reaction conformations favorable to nucleophilic attack.
Notably, the rapid enzymatic degradation of the PBTDP20 copolymer enabled the recovery of over 92% of the 1,14-tetradecanedioic acid, which can be reused under mild conditions, thus achieving true closed-loop recycling of the copolyesters.
Overall, the advanced performance, environmental degradability, and actual enzymatic recyclability make PBTDP copolymers a promising sustainable alternative to polyethylene-like materials.
https://pubs.rsc.org/en/content/articlelanding/2025/gc/d4gc06604a
Life cycle assessment of enzymatic recycling of polyethylene terephthalate (PET).
Enzymatic hydrolysis of polyethylene terephthalate (PET) is a chemical recycling method designed to promote a circular economy for polyesters. To quantitatively compare this technology with other PET recycling and synthesis approaches, it is essential to conduct rigorous and transparent process analyses.
We have recently developed a detailed process model used to analyze the economic aspects, energy consumption, and greenhouse gas emissions of enzymatic PET recycling. In this study, we expand on previous work by conducting a life cycle assessment (LCA) based on the same enzymatic hydrolysis system, aimed at producing terephthalic acid (TPA) and ethylene glycol (EG), to be reused in a closed-loop PET recycling system.
The LCA shows that, in its current state, enzymatic hydrolysis performs worse—by a factor of 1.2 to 17—compared to the production of virgin TPA and PET in almost all environmental impact categories, except for ecotoxicity and fossil resource depletion. The main contributors to these impacts are the collection and treatment of post-consumer PET, the use of sodium hydroxide, and electricity consumption.
Sensitivity analysis indicates that by improving yields throughout the recycling process and eliminating certain steps (such as the amorphization pretreatment and pH control during the reaction), the overall environmental impact of enzymatic PET recycling could be reduced to the point of being statistically equivalent to virgin TPA and PET production. This highlights key areas for further research and innovation.
Halloysite nanotubes treated in an alkaline environment (aHal) were incorporated into a poly(butylene succinate) (PBS) matrix using melt mixing and solvent casting techniques to enhance its functional properties. The resulting films were characterized in terms of morphology, thermal behavior, mechanical strength, antibacterial activity, barrier properties, and ethylene absorption capacity, for application in fresh food packaging.
The ethylene absorption properties were attributed to the increased lumen diameter of the aHal nanotubes. The best performance was achieved with a 5% by weight concentration of aHal (5-aHal) for both production methods. In sealed containers, ethylene levels were reduced by 80% and 75% using extruded and solvent-cast films, respectively.
PBS/aHal films displayed mechanical properties comparable to other materials recommended for food packaging, with the extruded films being more flexible and resistant. Furthermore, the extruded films provided a more effective water vapor barrier. A packaging test with slices of tomatoes and apples stored at room temperature for 7 days showed that 5-aHal films were the most effective in extending the shelf life of the fruit.
Considering all results, films produced via melt mixing offered superior performance. These bio-based PBS/aHal films therefore demonstrate significant potential for improving food safety, serving as active and environmentally friendly packaging materials.
https://pubs.rsc.org/en/content/articlehtml/2022/gc/d2gc02162
Enzymatic recycling and microbial upcycling for a circular plastic bioeconomy.
Since the 1950s, plastic has become a common material, present in virtually every aspect of our daily lives. However, the current economic model governing the production and use of plastics is fundamentally linear: less than 10% of plastic materials are actually reintroduced into the value chain at the end of their life cycle.
In recent years, efforts have intensified to develop new technologies capable of transforming this model into a circular plastic economy. Among these, enzymatic recycling and biological upcycling into high value-added products represent promising approaches.
This article reviews the most recent advances in this rapidly evolving field and discusses how further development of these technologies could help reduce the share of post-consumer plastic waste destined for landfilling or incineration.
https://www.sciencedirect.com/science/article/pii/S0958166925000515
