We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Identification and Characterization of a Polyethylene-Degrading Fungus Aspergillus sydowii Isolated from Soils of Waste Disposal Sites
Summary
Researchers isolated a new fungal strain, Aspergillus sydowii W144, from landfill soil and found it degrades untreated low-density polyethylene under solid-state conditions—achieving 6.4% weight loss and a 51% reduction in molecular weight in 30 days—then identified laccase as the key initiating enzyme through genomic analysis and heterologous expression.
Petrochemical-based plastics are widely used due to their convenience and low cost, with polyethylene (PE) being the most produced globally. However, the lack of efficient and sustainable treatment methods for conventional plastic wastes has led to severe environmental pollution. A new fungus strain capable of degrading PE was isolated from soil samples collected at a waste disposal site in Henan province and identified as Aspergillus sydowii W144. After 30 days of incubation under solid-state culture conditions, the strain demonstrated significant depolymerization and degradation of low-density polyethylene (LDPE). FTIR results revealed a substantial increase in the carbonyl index of the LDPE film, while differential scanning calorimetry (DSC) analysis detected an enhanced crystallinity in the LDPE film. Notably, distinct pitting and erosion marks was observed on the surface of LDPE film by scanning electron microscopy (SEM). Quantitative analysis showed a weight loss rate of 6.39% and a reduction in Weight-Average Molecular Weight (Mw) by 50.93%. Among currently identified PE-degrading strains polyethylene, A. Sydowii W144 exhibits particularly outstanding degradation efficiency, especially on untreated PE. Based on the whole-genome data of A. sydowii W144, a preliminary model of the putative polyethylene degradation pathway in A. sydowii W144 was constructed through homology-based sequence analysis and by referencing previously reported polyethylene degradation pathways. Laccase/multicopper oxidases plays a key role in the initial oxidation of PE. Heterologous expression of the candidate gene laccase4 in Pichia pastoris yielded an active enzyme (~56 kDa) with a laccase activity of 460 U/L, confirming its functionality. This study provides a novel microbial resource and potential enzymatic tools for PE biodegradation. The strain exhibits a promising application in complex ecosystems for PE pollution. IMPORTANCE: The polyethylene-degrading strain A. sydowii W144 isolated in this study exhibits highly efficient degradation capabilities, particularly under solid-state culture conditions. Genomic sequencing analysis enabled the construction of a potential polyethylene (PE) degradation pathway and facilitated the identification of key laccase and polyphenol oxidase genes involved in this process. he isolation of this novel strain enriches the microbial resources available for PE waste treatment and offers new insights into the mechanisms of plastic biodegradation.