Microbial Degradation of Microplastics and Its Environmental Implications
الكلمات المفتاحية:
microplastics، biodegradation، PETase، MHETase، composting، respirometry، Raman، pyrolysis GC/MS، environmental riskالملخص
Plastic pollution in the form of microplastics (MPs) is a growing environmental threat. Unlike physical fragmentation, true biodegradation requires mineralization to CO₂ (and H₂O) or complete depolymerization to monomers. This study outlines a comprehensive approach to quantify and mechanistically dissect microbial MP degradation in composting and aquatic conditions. We will test a range of polymers (PET, LDPE/HDPE, PP, PS) with PLA as a positive control. Weathered and unweathered MPs will be characterized (FTIR, Raman, SEM, Py‑GC/MS) and exposed to mixed microbial consortia or purified enzymes. In compost assays (ISO 14855/ASTM D5338), we expect rapid mineralization of PLA, partial mineralization of PET, and negligible PE/PP degradation unless pre-oxidized. In aquatic assays, slow CO₂ evolution and loss of particle mass will be monitored. Purified PETase±MHETase will be applied to PET films and particles to quantify TPA/MHET release. Biofilm assays on PE/PP/PET will examine colonization and surface erosion (SEM, confocal, AFM). Enriched consortia will be profiled (16S/ITS, shotgun metagenomics) to link taxa with hydrolase genes. Environmental risk will be assessed by leachate toxicity (algal, Daphnia, Vibrio tests) and by-product analysis (LC-HRMS of oligomers, GHG monitoring). Community and kinetic analyses (first-order decay, Michaelis-Menten, ANOVA) will yield rates and half-lives. Engineered PETase+MHETase systems are expected to outperform wild-type enzymes in PET depolymerization. Overall, we aim to clarify polymer-specific degradation pathways, avoid overestimation of biodegradation, and inform waste management and enzyme engineering strategies.