Biodegradation of low-density polyethylene microplastics by Fusarium and Penicillium strains isolated from agricultural soil mulched with polyethylene film

The presence of low-density polyethylene (LDPE) in agricultural soils poses significant ecological risks due to its resistance to biodegradation. Despite the widespread use of polyethylene mulch, the potential of soil microorganisms to degrade LDPE microplastic particles (MPPs) remains underexplored. This study represents one of the first attempts to isolate and evaluate the LDPE MPP degradation potential of fungal strains isolated from agricultural soils exposed to polyethylene mulch. Four LDPE MPP-degrading fungal strains (Fusarium oxysporum, F. solani, Penicillium sp., and P. olsonii) were isolated from polyethylene-mulched agricultural soil. After 30 d of incubation in mineral salt medium, F. oxysporum, F. solani, Penicillium sp., and P. olsonii degraded 2.40, 2.36, 5.25, and 2.94 % (w/w) of the LDPE MPPs, respectively. This represents the first report of P. olsonii as an LDPE degrader. Scanning electron microscopy revealed extensive microbial colonization and morphological changes on treated LDPE surfaces, indicating fungal colonization and surface degradation. Enzyme activity assays demonstrated the contribution of laccase and manganese peroxidase to LDPE degradation. This study provides valuable insights into the biodegradation potential of soil plastisphere-derived Fusarium and Penicillium strains and highlights their potential as promising agents for the bioremediation of LDPE-contaminated agricultural soils. However, further research is needed to address the effects of environmental variability and microbial competition and to improve the scalability of fungal-based biodegradation strategies.