Novel Feruloyl Esterase for the Degradation of Polyethylene Terephthalate (PET) Screened from the Gut Microbiome of Plastic-Degrading Mealworms ( Tenebrio Molitor Larvae).

Mealworms ( Tenebrio molitor ) larvae can degrade both plastics and lignocellulose through synergistic biological activities of their gut microbiota because they share similarities in chemical and physical properties. Here, a total of 428 genes encoding lignocellulose-degrading enzymes were screened from the gut microbiome of T. molitor larvae to identify poly(ethylene terephthalate) (PET)-degrading activities. Five genes were successfully expressed in E. coli , among which a feruloyl esterase-like enzyme named Tm Fae-PETase demonstrated the highest PET degradation activity, converting PET into MHET (0.7 mg _MHETeq ·h ^-1 ·mg _enzyme ^-1 ) and TPA (0.2 mg _TPAeq ·h ^-1 ·mg _enzyme ^-1 ) at 50 °C. Tm Fae-PETase showed a preference for the hydrolysis of ferulic acid methyl ester (MFA) in the presence of both PET and MFA. Site-directed mutagenesis and molecular dynamics simulations of Tm Fae-PETase revealed similar catalytic mechanisms for both PET and MFA. Tm Fae-PETase effectively depolymerized commercial PET, making it a promising candidate for application. Additionally, the known PET hydrolases Is PETase, FsC, and LCC also hydrolyzed MFA, indicating a potential origin of PET hydrolytic activity from its lignocellulosic-degrading abilities. This study provides an innovative strategy for screening PET-degrading enzymes identified from lignocellulose degradation-related enzymes within the gut microbiome of plastic-degrading mealworms. This discovery expands the existing pool of plastic-degrading enzymes available for resource recovery and bioremediation applications.