Potential of Fusarium and Penicillium species from soil for polyethylene microplastic degradation

Polyethylene (PE) products are commonly used plastics all throughout the world. However, due to its high resistance to degradation, PE plastic waste can accumulate in the environment over long periods, posing a significant ecological threat. Mycoremediation is considered to be an effective and environmentally friendly plastic degradation strategy. Therefore, the present study focuses on the degradation of PE microplastic particles (PE MPP) by soil fungi. Four fungal strains were isolated from field soil with the potential to biodegrade pristine PE MPP (≤125 µm) and were identified as Fusarium oxysporum, Fusarium solani, Penicillium sp., and Penicillium olsonii based on morphological and ITS region analyses. For biodegradation studies, PE MPP were incubated with the fungal strains in mineral salt medium for 30 d at 28oC and 150 rpm. The PE MPP cultured with F. oxysporum, F. solani, Penicillium sp., and P. olsonii showed weight losses of 2.40%, 2.36%, 5.25%, and 2.94%, respectively, after 30 d of incubation. Also, surface cracks and perforations were observed in the biodegraded PE MPP under a scanning electron microscope and the FTIR analysis further revealed surface structural changes. Furthermore, two PE-degrading enzymes, laccase and manganese peroxidase were detected in the PE MPP culture media by spectrophotometric assay. These results demonstrate that the fungal genera, Fusarium and Penicillium can be promising candidates for PE bioremediation.