Marine fungi degrade plastic and can be conditioned to do it faster

Plastics are a prevalent and persistent pollutant in the environment. As plastic production increases, finding ways to degrade these recalcitrant polymers is paramount. Many terrestrial fungi, across the kingdom, degrade various types of plastic. Plastics are the fastest-growing habitat in the oceans, and we hypothesized that fungi isolated from the ocean would demonstrate high success rates in degrading polyurethane (PU). To test this, visual degradation assays were performed by inoculating 1% PU medium with 68 different fungal strains cultured from marine habitats. The area of clearance of the fungus was measured periodically, to determine a relative degradation rate. Of the 68 fungal strains, 42 demonstrated the ability to degrade PU. We conditioned the nine fastest PU degraders through serial inoculations into liquid media with increasing concentrations of PU, starting at 1% and going up to 12%. The growth rates of the original and conditioned fungi were then compared in new inoculation trials, and results show that three of the nine conditioned fungi demonstrate higher PU degradation rates than their unconditioned counterparts. Marine fungi, coupled with conditioning, show promise for developing novel mycoremediation technologies.