As global plastic waste increases, science turns to specialized microbes to degrade previously non-degradable plastics. A bacterial species found growing in a plastic recycling plant, Ideonella sakaiensis 201-F6, exhibits an incredible and rarely seen ability to use the common plastic, PET, as its major energy source.
While there are 7 official codes to distinguish between plastics, set by the Society of Plastic Industries, there really are only 2 types that regularly get recycled: polyethylene terephthalate (PET, code 1) and high density polyethylene (HDPE, code 2). PET is the most common polymer of the polyester family; it is used in a variety of materials including fibers for clothing production, containers for liquid storage, in custom forms for manufacturing processes and in combination with glass fibre for producing resins used in engineering. The monomeric structure is bis(2-hydroxyethyl) terephthalate (see Figure 2) and can be easily made into a polymer through an esterification process.
More than 60% of the PET manufactured globally is used in the production of synthetic fibers (also called polyester), and 30% is used in the manufacture of bottles, often used for soft drink distribution. The remainder of PET is used in varying products such as solar cells, liners in gas cylinders, and even as a 3D-printing material. Though incredibly useful for multiple uses, PET is highly resistant to biodegradation, and has even been implicated in endocrine disorders due to the leaching of hormone-mimicking compounds such as phthalates and antimony into the water or soda PET bottles are often manufactured to hold.