New enzyme-embedded plastic degrades rapidly, overcoming current obstacles

Plastic production reached a staggering 400 million tons in 2022, with packaging and single-use items making up a significant portion. The resulting waste often ends up in landfills, incinerators, or the environment, contributing to the growing crisis of plastic pollution.

Due to this situation, there is a burgeoning interest in biodegradable and compostable plastics as more sustainable alternatives. Polylactide (PLA) is the most widely used biosourced polymer, however, PLA degrades very slowly in home compost and soil.

Now scientists led by the company Carbios and the Toulouse Biotechnology Institute (TBI), in France, have developed a PLA-based plastic embedded with a specially optimized enzyme that ensures rapid biodegradation and compostability at room temperature through a scalable industrial process.

The encapsulated enzyme CARBIOS Active, in granule form, when integrated directly into PLA-based packaging or products at the production phase, enables compostability at room temperature. Credits: Carbios.

They optimised the process used to achieve an engineered enzyme able to withstand the 170°C temperature required to introduce it in molten state PLA during the plastic production process. The new enzyme-embedded material, containing just 0.02% enzyme by weight, fully disintegrated under home compost conditions within 20–24 weeks, meeting all home composting standards. It also helped produce more biomethane, another source of waste recovery. Part of this research required the structure determination of the enzyme, which the scientists acquired using the ESRF structural biology beamlines.

This is the second Nature publication led by Carbios with data from the ESRF. Alain Marty, Chief Scientific Officer of Carbios, explains the long-term collaboration with the ESRF: “Since the early days of Carbios, TBI (Toulouse Biotechnology Institute), IPBS (The Institute of Pharmacology and Structural Biology) and Carbios have collaborated with the ESRF as synchrotron radiation plays an important role in this research.

In particular, in this article diffraction data helped us unveil the structure of the enzyme to understand better the relation between the structure of the enzyme and its function.

The resulting enzyme engineering work leads to an efficient enzyme that allows the plastic to self-biodegrade at room temperature.”

Applications in packaging

In addition, the material remains intact over long-term storage, as the enzyme is only activated under composting or methanization conditions, ensuring compatibility with commercial PLA-based applications, such as flexible packaging (such as sauce packets and wrappers) and short-life items (such as food containers, yogurt pots and coffee capsules).

“As CARBIOS expands its portfolio of enzymatic solutions beyond PET, enzyme-embedded PLA represents a major leap forward, addressing a critical gap in the market for compostable plastic”, concludes Emmanuel Ladent, CEO of CARBIOS.

Reference: Guicherd, M., et al. Nature 631, 884–890 (2024). https://doi.org/10.1038/s41586-024-07709-1

Text by Montserrat Capellas Espuny