Would these microbes be kin to oil-eating microbes?
Probably same concept, but different class of bacteria.
Crude is a mix of hydrocarbon (about C1- C50) mix of paraffinic, aromatic, asphalitc, and PNA's. The carbon bonds are mostly aliphatic in nature, and lend themselves easier to microbiological digestion.
PP, PET, PE ect., are polymers that are generally produced by olefinic feedstocks that are made in high temperatures and pressures which create very very long chain polymers that my nature are very stable and difficult to degrade.
Would have to be a whole different animal.