I read about this and tried testing something related. Testing Whether Fungi Can Grow on and Break Down Plastic
I used a small piece of plastic and exposed it to a damp environment where I had some fungal growth (not sure what species).
After about a week, I didn’t see the plastic break down, but I did notice growth forming on the surface.
Does the fungus actually break the plastic down directly, or is it a much slower process than that?