Carnivorous plants can decompose the polyesters poly(ethylene terephthalate) and poly(butylene adipate terephthalate)

Plants from the Nepenthes genus, which enumerates approximately 120 species, possess specialized pitchers enabling them to capture and digest various preys, mainly arthropods, from which the plants derive nutrients. The pitcher fluid contains many molecules of noteworthy importance, including antimicrobial compounds, traditionally used in medicine, as well as hydrolytic enzymes for prey digestion. In this study, polyesters films made from poly(ethylene terephthalate) (PET) and from poly(butylene adipate -co- terephthalate) (PBAT) were incubated in the pitcher of the carnivorous plants Nepenthes alata and Sarracenia purpurea. High performance liquid chromatography analysis revealed hydrolysis into their corresponding monomers, while hydrolysis efficiency was up to ten times higher in the presence of dried mealworm Tenebrio molitor and jasmonic acid. Proteomic analysis indicated the presence of the aspartic proteinase nepenthesin in most conditions, with high abundance in 70% of polyester-containing conditions compared to those without polyesters. Molecular docking simulations further suggested that nepenthesin has the potential to hydrolyze polyesters. While in contrast to cutinases there is only little information on hydrolysis of PET and PBAT by proteases in the literature, this work clearly demonstrates hydrolysis of both PET and PBAT by the recombinant protease nepenthesin, releasing similar amounts of TPA as the cutinase from Humicola insolens. These results suggest carnivorous plant fluids as a source for new enzymes for industrial applications such as for polyester hydrolysis.