Mineralization of photodegraded polyethylene by the marine-derived fungus Aspergillus terreus

• A. terreus degrades UV-treated PE but does not degrade untreated PE. • Degradation of UV-treated PE by A. terreus occurred at a rate of 0.3% per month. • Minor assimilation of 13 C-PE derived carbon into the A. terreus biomass. The microbial processes and kinetics involved in plastic biodegradation in marine environments remain largely unexplored. In particular, the role of marine fungi in this context is largely unconstrained. In this study, we incubated the marine-derived fungus Aspergillus terreus in microcosms with 13 C-labelled polyethylene (PE) to trace mineralization and assimilation of plastic-derived carbon. Our assays provide evidence that A. terreus mineralizes UV-treated PE. Over the 22-day period of incubation, fungal-mediated mineralization of photodegraded PE amounted to 0.24% of the initially added PE. NanoSIMS imaging and isotopic analysis of fatty acids demonstrated the limited incorporation of UV-treated PE-derived carbon into fungal biomass. In contrast, incubations with A. terreus and untreated PE for up to 102 days showed no measurable evidence of biotic degradation. These findings underscore the critical role of photodegradation in facilitating subsequent biotic degradation of PE by A. terreus in marine environments.