In 2011, a group of Yale University students, during a bioprospecting expedition in the Ecuadorian Amazon, isolated an endophytic fungus capable of growing using synthetic polyurethane as its sole carbon source—and doing so even without oxygen. The discovery opened a line of research that today seeks fungi capable of breaking down some of the most persistent polymers ever manufactured.
The fungus that grows inside anaerobic landfills
Pestalotiopsis microspora, isolated as an endophyte from Amazonian plants, demonstrated a unique ability among the organisms analyzed: to grow on polyester polyurethane under both aerobic and anaerobic conditions, using plastic as its sole carbon source. Molecular analysis suggests that a serine hydrolase enzyme is responsible for this degradation—a relevant fact because landfills are, precisely, environments with very little available oxygen.
From urban landfill to laboratory
A second discovery, this time at a waste disposal site in Islamabad, Pakistan, identified Aspergillus tubingensis as responsible for measurable degradation of polyester polyurethane. Scanning electron microscopy confirmed that the mycelium physically colonized the material, causing visible surface degradation, and after two months in liquid culture, the polyurethane film completely fragmented.
The limits of hope
None of these findings imply an immediate solution to the global plastic waste crisis: the documented processes occur on timescales and under laboratory conditions that are far from a real landfill. But they identify specific enzymatic mechanisms—and specific organisms—on which to build applied bioremediation strategies.
References
- Russell JR, Huang J, Anand P, et al. Biodegradation of polyester polyurethane by endophytic fungi. Appl Environ Microbiol. 2011;77(17):6076-6084. PMID: 21764951. DOI: 10.1128/AEM.00521-11
- Khan S, Nadir S, Shah ZU, et al. Biodegradation of polyester polyurethane by Aspergillus tubingensis. Environ Pollut. 2017;225:469-480. PMID: 28318785. DOI: 10.1016/j.envpol.2017.03.012