Following their successful collaboration on the enzymatic depolymerization of PET polyester which is now rapidly being commercialised, Carbios and the Toulouse Biotechnology Institute (TBI) are jointly developing another engineered enzyme that can be embedded into PLA (polylactic acid) to make it also self-biodegradable.

A study published in the joural Nature in July describes the engineering strategies deployed to ensure the development of the enzyme which is capable of biologically depolymerizing PLA materials over a wide temperature and pH range, reflecting the natural variations found in the life cycle of domestic compost.

The study also describes the methodologies and challenges involved in obtaining a homogeneous incorporation of the enzyme into PLA films at high temperatures of 170°C, while retaining sufficient activity to enable the polymer produced to degrade completely and rapidly under domestic and industrial composting conditions, as well as in anaerobic digestion (methanization).

The optimisation process used to obtain an enzyme capable of withstanding the 170°C required to melt it into PLA by extrusion is also described.

The new enzymatic material has been shown to disintegrate and biodegrade at a much faster rate than the 26 weeks required for certification for use in home composting, and also to help produce more biomethane, another source of waste recovery. It remains intact during long-term storage and use and its degradation is only activated when transferred to composting or methanization conditions, guaranteeing its compatibility with PLA-based commercial applications, including nonwoven fabrics as well as plastics.

www.toulouse-biotechnology-institute.fr

www.carbios.com