Ancestral hydrocarbon metabolism enables PET degradation by a natural bacterial consortium.

Plastic biodegradation in natural environments is increasingly recognized as a multi-organism process; however, the mechanisms enabling coordinated depolymerization and metabolism of polyethylene terephthalate (PET) remain poorly understood. Previously, we demonstrated that a full consortium containing three IMPORTANCE: Environmental plastic degradation is rarely accomplished by a single organism; however, the microbial mechanisms enabling community-level polyethylene terephthalate (PET) plastic breakdown remain poorly understood. This study shows that a bacterial consortium isolated from crude petroleum-contaminated coastal soils degrades PET by coordinating older hydrocarbon, aromatic, stress-response, and redox-associated metabolisms rather than by acquiring a dedicated PET pathway. Predicted horizontal gene transfer events were linked mainly to survival, biofilm formation, and metabolic flexibility, not PET depolymerization itself. These findings shift the focus from searching for single PET-degrading organisms toward understanding how microbial communities combine pre-existing metabolic tools to process synthetic polymers and manage the chemical stress created during biodegradation.