The present disclosure relates to the novel activity of the enzymatic composition containing lytic polysaccharide monooxygenases (LPMOs) that are bacterial (Auxiliary Activity 10, AA10) and/or fungal (Auxiliary Activity 9, AA9) for degrading polyethylene terephthalate (PET) and related plastic polymers. The genes that encode KpLPMO10A (AA10) and AfLPMO9A (AA9) were isolated from Kitasatospora papulosa and Aspergillus fischeri microorganisms, respectively. Methods such as atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) detected alterations in the superficial chemical composition and morphology of the PET found in liquid bottles when treated with LPMOs. The gentle temperature conditions used during the LPMO-PET reaction suit the use of these enzymes to help canonical enzymes (PETases) deconstruct plastics, which is beneficial for the circular economy for PET.