Biorecycling of polylactide: From enzymatic depolymerization to biotransformation of released products

Polylactic acid (PLA) is a polymer that can replace several petroleum-based polymers due to its properties and bio-sourced nature. However, sustainable recycling processes of PLA avoiding the creation of waste and enabling it to be used as a raw material must be implemented. Enzymatic hydrolysis seems to be a promising way to recycle PLA. The different approaches that have led to the discovery of new PLA depolymerizing enzymes are reviewed here. Moreover, an overview of the various factors affecting enzymatic depolymerization of PLA have been done as well as the contribution of enzyme engineering in understanding the essential residues of these enzymes and improving their properties (e.g., thermostability and activity). Finally, enzymatic polymerization and biosynthesis of PLA from lactide or lactic acid have been reviewed to provide an overview of the various biotechnological approaches that could enable PLA to be completely recycled and remade.