Elucidating polyethylene and polypropylene microplastics degradation mechanisms and metabolic pathways via...

The contamination of water bodies by polyethylene (PE) and polypropylene (PP) microplastics (MPs) represents a growing environmental concern worldwide. Biodegradation offers a sustainable solution for mitigating this pollution, but is often hindered by slow degradation rates. This study investigates the combined use of novel fungal consortia QMFC1 and QMFC2 [comprising Aspergillus niger, Cunninghamella elegans (reported here for the first time for MPs degradation), and Aspergillus flavus] and pectin-biochar beads (PBBs) to enhance the degradation of PE and PP in contaminated water. Over 30 days, treatments integrating fungal consortia with PBBs achieved significant weight loss of 56 % for PE and 44 % for PP, exceeding the degradation observed with fungal consortia alone. The synergistic effect of fungal consortia and PBBs enhanced fungal biomass production and enzymatic efficiency. The enzymatic activities of lipase, laccase, and manganese peroxidase increased substantially in these treatments, promoting polymer breakdown. Morphological changes such as cracks and pits on MPs' surfaces were confirmed by scanning electron microscopy. At the same time, chemical modifications including the formation of hydroxyl (-OH), carbonyl (CO), and ether (C-O) groups were detected via Fourier transform infrared spectroscopy and supported by reductions in crystallinity from X-ray diffraction analysis. Gas chromatography-mass spectrometry revealed the presence of shorter-chain degradation byproducts, indicating effective polymer depolymerization and transformation into less harmful compounds. This integrated biotechnological approach represents a promising, eco-friendly solution for MPs pollution in aquatic environments. Our findings provide valuable insights into the degradation mechanisms and metabolic pathways, paving the way for scalable and effective bioremediation strategies against MPs in water systems.