Ocean plastic pollution is a severe environmental problem, but most of the plastic that has been released to the ocean since the 1950s is unaccounted for. Although fungal degradation of marine plastics has been suggested as a potential sink mechanism, the unambiguous proof is scarce. We isolated a marine fungus, the yeast Rhodotorula mucilaginosa from the marine environment and tested the capability of R. mucilaginosa to degrade plastic by applying stable isotope tracing assays with UV-irradiated 13C-labelled polyethylene (PE) as a sole energy and carbon source. Accumulation of excess 13C in the CO2 pool during the 5-day incubation experiments with R. mucilaginosa and the 13C labelled PE translates to degradation rates of 3% yr-1 of the added substrate. Further nanoSIMS measurements allowing to measure the isotopic composition of individual cells revealed substantial incorporation of PE-derived carbon into fungal biomass. Our results demonstrate the potential of R. mucilaginosa to mineralize and assimilate carbon from plastics and suggest that fungal plastic degradation may be an important sink for polyethylene litter in the marine environment. 

Primary Presenter: Annika Vaksmaa, NIOZ (annika.vaksmaa@gmail.com)

Authors:

Annika Vaksmaa, NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, the Netherlands  (annika.vaksmaa@nioz.nl)

Lubos Polerecky, Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, the Netherlands  (l.polerecky@uu.nl)

Nina Dombrowski, NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, the Netherlands  (nina.dombrowski@nioz.nl)

Michiel Kienhuis, Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, the Netherlands  (m.v.m.kienhuis@uu.nl)

Ilsa Posthuma, NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, the Netherlands  (ilsa.posthuma@nioz.nl)

Jan Gerritse, Deltares, Unit Subsurface and Groundwater Systems, Utrecht, the Netherlands  (jan.gerritse@deltares.nl)

Teun Boekhout, Westerdijk Fungal Biodiversity Institute, the Netherlands, Institute of Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, the Netherlands  (t.boekhout@wi.knaw.nl)

Helge Niemann, NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, the Netherlands  (helge.niemann@nioz.nl)