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Microplastics promote conjugative transfer of antibiotic resistance genes via membrane protein interactions: Highlighting oxidative stress and energy supply
Summary
Researchers investigated how polyethylene, polystyrene, and polypropylene microplastics affect the transfer of antibiotic resistance genes between bacteria. Polyethylene at 5 mg/L showed the strongest effect, increasing conjugative gene transfer nearly 9-fold compared to controls, driven by enhanced cell contact, increased energy supply, and membrane interactions that lower barriers to plasmid transfer.
Microplastics (MPs) and antibiotic resistance genes (ARGs) are emerging global pollutants, but the impact of MPs on plasmid-mediated conjugative transfer (CTF) of ARGs remains poorly understood. This study investigates the impact of polyethylene (PE), polystyrene (PS), and polypropylene (PP) on the plasmid-mediated CTF of the RP4 plasmid in E. coli. PE (5 mg/L, 1000 nm) exhibited the highest CTF (5.96 × 10), which was 8.9-fold greater than that of the control. Exposure to MPs upregulated genes involved in ROS generation, energy metabolism, membrane integrity, stress responses, and various transcriptional regulatory genes critical for plasmid transfer. Among the MPs tested, PE showed the highest affinity for ARGs adsorption, which can be attributed to its hydrophobicity and negative surface charge, enhancing microbial adhesion and the spread of ARGs. Molecular docking and density functional theory analyses demonstrated that the flexible structure, charge distribution, and frontier orbital characteristics of PE stabilized interactions with membrane components and reduced the energy barrier (-3.626 kcal/mol) for plasmid translocation. Structural equation modeling identified cell contact (19.79-fold increase) and energy supply (11.5-fold increase) as key factors driving CTF. These findings offer mechanistic insights into MPs-facilitated ARGs propagation, highlighting the potential ecological and public health risks associated with MP contamination.