Enhanced degradation of microplastics by laccase under ambient conditions: Analysis of underlying molecular...

Microplastics (MPs) present a significant environmental challenge due to their widespread contamination and inherent resistance to biodegradation. Enzyme-driven biodegradation has emerged as a promising and environmentally friendly approach to mitigate microplastic pollution, yet the underlying molecular mechanisms remain poorly understood. This study systematically explored the laccase-mediated degradation of aliphatic (polyethylene, PE), aromatic (polyethylene terephthalate, PET), and biodegradable (polylactic acid, PLA) MPs, aiming to uncover the molecular-level mechanisms driving these processes. Our results demonstrated that laccase selectively degraded these MPs into low-molecular-weight products through polymer chain scission and functional group transformation. Notably, PLA exhibited the highest degradation efficiency, evidenced by significant surface modifications and molecular weight reduction. Reactive oxygen species (ROS) generation and electron-transfer processes were found to facilitate polymer chain cleavage and functional group evolution. Molecular dynamics simulations revealed distinct binding modes of laccase with different MPs: hydrophobic interactions dominated with PE, while hydrogen bonding and electrostatic forces played crucial roles with PET and PLA. These findings provide molecular-level insights into laccase-mediated MP degradation and offer valuable guidance for developing sustainable enzymatic strategies to tackle plastic pollution.