Fungi are an essential component of marine ecosystems, although little is known about their global distribution and underwater diversity, especially in sediments. Microplastics (MPs) are widespread contaminants worldwide and threaten the organisms present in the oceans. In this study, we investigated the fungal abundance and diversity in sediments, as well as the MPs, of three sites with different anthropogenic impacts in the Mediterranean Sea: the harbor of Livorno, the marine protected area “Secche della Meloria”; and an intermediate point, respectively. A total of 1526 isolates were cultured and identified using a polyphasic approach. For many of the fungal species this is the first record in a marine environment. A comparison with the mycobiota associated with the sediments and MPs underlined a “substrate specificity”, highlighting the complexity of MP-associated fungal assemblages, potentially leading to altered microbial activities and hence changes in ecosystem functions. A further driving force that acts on the fungal communities associated with sediments and MPs is sampling sites with different anthropogenic impacts.

The harbour's sediments are among the biotypes most affected by contamination by pollutants due to anthropogenic activities. The porpoise of this work is to perform a preliminary screening on 74 fungi previously isolated in the polluted sediments of the harbour of Livorno, to identify those endowed with oxidative capabilities and to evaluate the potential producers of metabolites or enzymes of interest, for potential applications in future environmental bioremediation. The results have shown that 26 (35.1%) out of 74 tested fungi produced positive oxidation signal on at least one media