Degradation of PET plastic with engineered environmental bacteria

Polyethylene terephthalate (PET) is one of the most widely used plastic materials in the food and textile industry. Consequently, post-consumer PET waste is a common environmental pollutant that leaks into the environment in the form of macro and microplastics with concerning health impacts. There is a pressing need to identify novel and sustainable solutions to process the abundance of PET waste contributing to this pollution. While there is extensive research into enzymes able to hydrolyse PET in vitro, a similar solution for discarded or difficult-to-collect PET based on whole-cell microbial catalysts is missing. In this work we report the engineering of environmental bacteria to use PET as a growth substrate. This was achieved by isolating a strain of Pseudomonas umsongensis able to use the PET monomer terephthalate as carbon source, engineering the strain to effectively secrete the high-activity PET hydrolase PHL7 through the addition of a recombinant TAT secretion leader sequence, and enhancing the bioavailability of PET by transforming it into an amorphous and macroporous structure by pre-treatment with an organic solvent. Our findings demonstrate the direct microbial consumption of PET, which could lead to improved and more sustainable upcycling strategies for this plastic.