Forest fungi can eat and dissolve plastics, much like they do with bark

The researchers investigated 50 fungal samples from decaying hardwoods found in the Dimbulagala dry zone forest reserve in central Sri Lanka. They then exposed the fungi to two “meals”: a dish with low-density polyethylene (a type of plastic) and a dish with both plastic and wood. 

They found that although the fungi overall preferred wood to plastic, they still broke down the polyethylene. 

"We think that these organisms are metabolically flexible, I would say, and this may be an evolutionary advantage," Attanayake told Live Science. "[The fungi] had to survive in the environment utilizing whatever available."

More research is needed to establish the fungi's chemical pathways that change when they eat polyethylene. However, the researchers report that the white rot used some oxidizing enzymes to break down the wood and the plastic. 

Removing plastics

Now, scientists hope that by pinpointing the enzymes these organisms secrete to degrade plastic and replicating them could aid in the removal of the 400 million tons of plastic waste produced each year around the planet. This waste can be found in landfills and great patches in the ocean and results in microplastics polluting even as far as the Antarctic. 

Attanayake told Live Science the new work is a "tiny baby step" toward possibly using fungi to deal with plastic pollution. Before these fungi are released into plastic dumps, scientists must establish how they perform in different conditions and whether they threaten much-needed trees. However, "under restricted conditions we may be able to utilize this thing one day, but a lot more research has to be done before that," she noted.

Study abstract:

The involvement of microorganisms in low-density polyethylene (LDPE) degradation is widely studied across the globe. Even though soil, landfills, and garbage dumps are reported to be promising niches for such organisms, recently the involvement of wood decay fungi in polyethylene degradation is highlighted. In light of this, 50 fungal samples isolated from decaying hardwoods were assessed for their wood degradation ability and for their depolymerization enzymatic activities. For the LDPE deterioration assay, 22 fungal isolates having wood decay ability and de-polymerization enzymatic activities were selected. Fungal cultures with LDPE sheets (2 cm x 10 cm x 37.5 μm) were incubated in the presence and in the absence of wood as the carbon source (C) for 45 days. Degradation was measured by weight loss, changes in tensile properties, reduction in contact angle, changes of functional groups in Fourier-transform infrared spectroscopy, Scanning electron microscopic imaging, and CO2 evolution by strum test. Among the isolates incubated in the absence of wood, Phlebiopsis flavidoalba out-performed the other fungal species showing the highest percentage of weight reduction (23.68 ± 0.34%), and the lowest contact angle (64.28° ± 5.01). Biodegradation of LDPE by P. flavidoalba was further supported by 46.79 ± 0.67% of the mass loss, and 3.07 ± 0.13% of CO2 emission (mg/L) in the strum test. The most striking feature of the experiment was that all the isolates showed elevated degradation of LDPE in the absence of wood than that in the presence of wood. It is clear that in the absence of a preferred C source, wood decay fungi thrive to utilize any available C source (LDPE in this case) showing the metabolic adaptability of fungi to survive under stressful conditions. A potential mechanism for LDPE degradation is also proposed.