Engineering environmental bacteria for whole-cell PET hydrolysis and assimilation

Poly(ethylene terephthalate) (PET) is one of the most widely used plastics in food and textile applications, yet post-consumer PET waste persists and accumulates in the environment as macro- and microplastics with adverse health and ecological impacts. Although PET-hydrolysing enzymes have been extensively studied in vitro, whole-cell microbial systems capable of using PET as a growth substrate remain limited, particularly for difficult-to-collect waste. Here, we engineer an environmental bacterium to directly assimilate PET. A strain of Pseudomonas umsongensis capable of metabolising the PET monomer terephthalic acid was isolated and engineered to secrete the high-activity PET hydrolase polyester hydrolase Leipzig 7 via a recombinant twin-arginine translocation motif signal peptide. PET bioavailability was further enhanced through solvent-based pretreatment to generate an amorphous, macroporous substrate. The engineered strain demonstrated direct PET utilisation and hydrolysis, supporting self-sustaining microbial growth. Additionally, in non-sterile wastewater the strain survived and hydrolysed PET microplastics, highlighting its potential for bioremediation and sustainable upcycling applications.