CiQUS and CRETUS teams develop a new technology to recycle plastic using reusable enzymes

A study conducted by researchers at CiQUS, in collaboration with CRETUS—both distinguished research centres at the University of Santiago de Compostela and members of the CIGUS Network, an initiative promoted by the Xunta de Galicia that brings together centres recognised for their scientific excellence—presents a new technology that uses reusable enzymes for plastic recycling.

In recent years, enzymes have emerged as a sustainable alternative to traditional mechanical and chemical recycling methods. These biotechnological tools are capable of breaking down polymers such as PET—commonly found in bottles and packaging—into their basic building blocks in a clean and efficient way.

The study introduces an innovative strategy for encapsulating enzymes within tiny protein spheres produced by bacteria. This system not only simplifies production and recovery but also extends enzyme lifespan, enables multiple reuses, and can break down over 90% of household plastic waste without the need for pre-treatment.

The strategy addresses some of the major challenges that have so far limited the large-scale application of enzymes in plastic waste management—such as high production costs and limited reusability in industrial processes. Unlike conventional methods, which require separate production of the enzyme and its support structure, this new approach integrates both in a single step, significantly reducing operational and technical costs.

The system builds on IC-Tagging technology, previously developed by the research group led by Prof. José Manuel Martínez Costas at CiQUS. This technology allows proteins of interest to be immobilised within protein nanocompartments generated by the viral protein muNS-Mi. This protein self-assembles into nanoscale spheres inside Escherichia coli cells and attracts any enzyme carrying a small tag (the “IC-tag”). In effect, the bacteria themselves act as microfactories, producing the enzyme already immobilised in a functional, reusable structure. Although this method has previously been applied to other industrial enzymes, this is the first time it has been used with a benchmark enzyme for plastic degradation—opening up new possibilities in the field of environmental biotechnology.

The study forms part of the PETzyme project, funded by NextGeneration EU, and coordinated by Gemma Eibes (CRETUS) and José Martínez Costas (CiQUS). According to the authors, the results surpass those of other enzyme immobilisation strategies tested in the lab so far, marking a significant step toward the practical application of enzyme-based plastic recycling solutions: “Our system shows great promise in supporting the industrial rollout of new enzymes being developed to break down PET and other polymers—making a meaningful contribution to the circular economy of plastics,” says to CiQUS Adrián López Teijeiro, first author of the study