…T. Those tests, it turned out, inadvertantly made the enzyme, PETase, even better at degrading PET. The resulting mutant PETase now takes just a few days to break down PET, compared to the 4…T. Those tests, it turned out, inadvertantly made the enzyme, PETase, even better at degrading PET. The resulting mutant PETase now takes just a few days to break down PET, compared to the 450 years it takes for the stuff to degrade naturally.