Poly(ethylene terephthalate) – PET - is used extensively worldwide in plastic products: Because it’s difficult to degrade it is the major contaminant in many ecosystems. One approach to solve this problem is the synthesis of degradable products from renewable resource. However, this approach provides solutions for the feature. A recent publication in Science by Japanese researchers (Yoshida et all) can be game changer for the current situation of plastic recycling. Yoshida et al. address this problem by using an organism that can fully degrade and assimilate PET.
The ability to enzymatically degrade PET has been thought to be limited to a few fungal species, biodegradation is not yet a viable remediation or recycling strategy. The approach followed by Yoshida et al. was screening natural microbial communities exposed to PET in the environment, so they isolated a novel bacterium (Ideonella sakaiensis 201-F6) that is able to use PET as its major energy and carbon source. When grown on PET, this strain produces two enzymes capable of hydrolyzing PET and the reaction intermediate, mono(2-hydroxyethyl) terephthalic acid. Both enzymes are required to enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol.
This brand-new discovery opens a whole different approach to plastic recycling and decontamination. At present, most plastic bottles are not truly recycled. Instead they are melted and reformed into other hard plastic products. Packaging companies normally opt for freshly made “virgin” plastics that are created from chemical starting materials that are usually derived from oil. The PET-digesting enzymes offer an alternative path to the current circular economy business models for plastic recycling. By adding PET-digesting enzymes to vats of waste, breaking all the bottles or other plastic items down into easy-to-handle chemicals. These could then be used to make fresh plastics, producing a true recycling system.
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