Comment by userbinator

Then, those pieces are fed to the programmed yeasts, which transform them into a variety of new food ingredients, including proteins, fats and acids

PET consists of repeating C10H8O4 monomers. Glucose is C6H12O6 and starch is a natural polymer containing it. It's not surprising that reactions can turn one into the other, along with other compounds containing hydrogen, carbon, and oxygen.