Polyethylene Terephthalate (PET) is a widely used polymer in consumer goods like plastic bottles and is highly accepted for recycling due to its lightweight, durability, and low oxygen permeability, which helps keep foods fresh. PET can be recycled mechanically or depolymerized into its chemical components, but only 9% of the 35.7 million tons of plastic waste generated in 2018 was recycled. Recycled plastics often suffer from lower quality due to contamination and physical damage, and they can be more expensive than virgin plastics, as seen with Coca-Cola's reduction in recycled plastic usage. Upcycling plastics with engineered microorganisms offers potential cost and environmental benefits, though it has not yet been proven viable on an industrial scale.
University inventors have developed genetically-engineered Pseudomonas putida strains that synergistically degrade polyethylene terephthalate (PET) plastic into building blocks that can be used to create new materials. The use of multiple strains of bacteria instead of a single one allows for the use of a greater number of degradation pathways. This alleviates the metabolic pressure on the strains and reduces the effects of toxic starting materials and degradation products, increasing efficiency.