Triggering the polyurethane and polyethylene-degrading potential of filamentous fungi secretomes

In the present study, we screened various fungi for their ability to degrade intact polymers, such as ether-based PU and LDPE, using Impranil and a mixture of long-chain alkanes, not only as sole carbon sources but also as enzyme indicators for polymer degradation. The agar plate screening revealed 3 fungal strains belonging to Fusarium and Aspergillus genera, which were further cultured in presence of the same carbon sources, and their secretome was utilized for polymer degradation. Especially for ether-based PU, the secreted proteins of a Fusarium species reduced the weight and the molecular weight of the sample by 24.5 and 20.4%, respectively, while at the same time the secretome of an Aspergillus species caused changes in the molecular structure of LDPE. The proteomic analysis followed proved that the enzymes induced in presence of Impranil can selectively degrade the urethane bond of ether-based PU, a discovery that offers a new alternative in PU waste treatment. Meanwhile, the mechanism of LDPE degradation was not completely understood, although the presence of oxidative enzymes probably accompanied by reactive oxygen species, could be the main factors contributing to polymer functionalization.