Plastic-eating sea fungus found in Great Pacific Garbage Patch

According to National GeographicThe Great Pacific Garbage Patch is a collection of marine debris in the North Pacific Ocean. Also called the Pacific Debris Vortex, it consists of two distinct collections of debris bounded by the vast subtropical gyre in the North Pacific Ocean.

Now scientists have examined plastic waste floating in the Great Pacific Garbage Patch and stumbled upon a sea fungus known as Parengyodontium album.

This discovery fascinated scientists because of the fungus’ unique ability to break down polyethylene, a common form of marine plastic pollution.

Sea mold could reduce plastic pollution in the oceans

This fungus adds to a small list of fungi known to break down plastic, offering a potential biological solution to combat plastic pollution in the oceans.

Scientists separated the fungus from plastic waste collected at the Great Pacific Garbage Patch and examined it in the laboratory. They demonstrated the fungus’ plastic-degrading ability by subjecting it to polyethylene (PE), a common type of plastic.

The PE was treated with UV radiation to simulate exposure to sunlight, because plastic often undergoes photodegradation in the ocean. The researchers then monitored the degradation of the plastic by P. album for some time.

They quantified the rate of plastic degradation and analyzed the conversion of polyethylene into carbon dioxide.

Furthermore, they used advanced methods, such as stable isotope assays and nanoSIMS analysis, to track the incorporation of plastic-derived carbon into fungal biomass, further confirming the plastic-degrading properties of P. album.

These experiments provided concrete evidence of the fungus’ ability to break down polyethylene, marking an important step in understanding and potentially reducing plastic pollution in the oceans.

Quantifying the degradation process

“What makes this research scientifically excellent is that we can quantify the degradation process,” says lead author Annika Vaksmaa in the paper.

The team noted that the distribution of PE per P. album appears to be approximately 0.05 percent per day.

“Our measurements also showed that the fungus does not use much of the carbon from the PE during decomposition. Most of the PE used by P. album is converted into carbon dioxide, which the fungus excretes,” says Vaksmaa.

The discovery of the sea fungus marks a significant step forward in the race to mitigate climate change and reduce plastic pollution accumulating in the marine environment.

Referring to the P. album, Vaksmaa explains: “In the laboratory, P. album only breaks down PE that has been exposed to UV light for at least a short period of time. This means that the fungus in the ocean can only break down plastic that initially floated on the surface.”

So far, only four other species are known to possess plastic-degrading fungi, but significant numbers of bacteria that break down plastic have been identified.

“Large amounts of plastic end up in subtropical gyres, ring-shaped currents in oceans in which the seawater is virtually stagnant,” says Vaksmaa.

“That means once the plastic is transported there, it gets stuck there. In the Pacific Ocean alone, around 80 million kilos of floating plastic has already accumulated in the North Pacific Subtropical Gyre, which is just one of six major gyres in the world.”

The research was carried out by marine microbiologists from the Royal Netherlands Institute for Sea Research (NIOZ), in collaboration with scientists from Utrecht University, the Ocean Cleanup Copenhagen and St. Gallen, Switzerland.

The research was published in the journal – Science of the total environment.

Study abstract:

Plastic pollution in the marine world is a serious environmental problem. Nevertheless, plastic can also serve as a potential carbon and energy source for microbes, but the contribution of marine microbes, especially marine fungi, to plastic degradation is not well constrained. We have isolated the fungus Parengyodontium album of floating plastic debris in the North Pacific subtropical gyre and measured fungal-mediated mineralization rates (conversion to CO₂) of polyethylene (PE) by applying stable isotope research tests ¹³C-PE for 9 days of incubation. When the PE was pretreated with UV light, the biodegradation rate of the initially added PE was 0.044%/day. Furthermore, we traced the incorporation of PE-derived ¹³C carbon in P. album biomass using nanoSIMS and fatty acid analysis. Despite the high mineralization rate of the UV-treated ¹³C-PE, integration of PE derivative ¹³C in fungal cells was low, and ¹³C uptake was undetectable for the untreated PE. Together, our results reveal the potential of P. album to break down PE in the marine environment and mineralize it into CO₂. However, the initial photodegradation of PE is crucial P. album to metabolize the carbon derived from PE.