Quorum Sensing-Based Long-Term Biodegradation of Polyethylene Terephthalate in Contaminated Soil by Engineered <i>Escherichia coli</i> and <i>Pseudomonas putida</i>

Long-term biodegradation of soil microplastics such as polyethylene terephthalate (PET) in situ remains inadequately addressed due to the limited expression of efficient PET degrading enzymes in engineered bacteria. Here, we developed a quorum-sensing (QS)-based protein expression system (XylS-LuxI/LuxR) that enhanced reporter green fluorescent protein (GFP) expression by 44-fold in Escherichia coli ( E. coli ). Using this system, we constructed whole-cell PET biodegraders expressing PET hydrolases (FASTPETase-MHETase) and leaf-branch compost cutinase (LCC ICCG ) in E. coli and Pseudomonas putida ( P. putida ). Soil-based assays using crude enzymes and E. coli XylS-QS-LCC ICCG cells showed >80% degradation of bis(2-hydroxyethyl) terephthalate (BHET) within 30 min. Furthermore, Agde-LCC ICCG was identified as the most effective signal peptide (SP) for protein secretion in E. coli, whereas LCC ICCG without a SP performed best in P. putida . Engineered E. coli achieved up to 63% PET nanoparticle degradation over 30 days, while P. putida reached 42.3% within 20 days in nonsterilized soil, substantially outperforming wild-type controls and indicating synergistic interactions with native microbiota. These results demonstrate that XylS-QS-based systems enable efficient, self-regulated whole-cell PET biodegradation in soil environments, providing new insights for the development of efficient biodegradation strategies of environmental plastic waste.