Mutant enzyme that eats plastic bottles
Scientists have increased the efficiency of PETase, an enzyme, to degrade PET (polyethylene terephthalate). It was found in a bacterium that had naturally evolved to eat plastic, at a waste dump in Japan in 2016. By revealing the detailed crystallographic structure of the crucial enzyme produced by the bug and the researchers tweaked it to more closely resemble cutinase, an enzyme that degrades the polymer surface of leaves – but tests showed they had inadvertently made it even 20% faster at breaking down the PET plastic used for soft drink bottles.
To usefully implement this innovation, the team must engineer the enzyme to function higher than 70°C, when PET is rubbery and more digestible, and implement it in bacteria adapted to industrial scaleup.