Researchers Parengiodontium album It breaks down polyethylene in the ocean under the influence of UV rays, suggesting that similar fungi can also break down plastic in deeper waters.

Researchers, including those from NIOZ, discovered that marine fungi can break down plastic polyethylene after exposure to ultraviolet radiation from sunlight. Their findings were published in the journal Total Environmental ScienceIt shows that many other fungi that can break down plastic probably live in deeper parts of the ocean.

Mushroom Parengiodontium album It lives together with other marine microbes in thin layers on plastic debris in the ocean. Marine microbiologists from the Royal Netherlands Institute for Marine Research (NIOZ) have discovered that a fungus can break down plastic polyethylene (PE) particles, the most common type of plastic found in the ocean. NIOZ researchers are from the University of Utrecht, the Ocean Cleanup Foundation, and researchers from Paris, Copenhagen, and St. Louis, Switzerland. He collaborated with colleagues from research institutes in the city of St. Gallen. This discovery allows the fungus to join a very short list of plastic-degrading marine fungi: only four species have been found to date. It is already known that large numbers of bacteria can decompose plastic.

Monitor the degradation process carefully

Researchers set out to find microbes that break down plastic in plastic pollution hotspots in the North Pacific. They isolated a marine fungus from collected plastic waste and grew it in the laboratory on special plastic containing labeled carbon. Waksmaa: “These so-called 13C isotopes are traceable in the food chain. It’s like a tag that allows us to track where the carbon is going. We can then track it in the degradation products.”

Waksmaa is excited about the new discovery: “What makes this study scientifically extraordinary is that we were able to measure the degradation process.” Waksmaa and his team observed destruction of PE in the laboratory. album It occurs at a rate of about 0.05 percent per day. “Our measurements also showed that the fungus does not use much of the carbon that comes when polyethylene breaks down. Most of the PE used is P.album, turns into carbon dioxide, which the fungus releases again.” Although CO₂ is a greenhouse gas, this process is not something that would create a new problem: The amount released by fungi is the same as the small amount that humans release when breathing.

Only under the influence of UV

The researchers found that the presence of sunlight is necessary for the fungus to use PE as an energy source. Vaksmaa: “In the laboratory album It only degrades PE exposed to UV light for at least a short period of time. This means that the fungus can only break down plastic floating near the surface in the ocean,” explains Waksmaa. “Ultraviolet light was already known to mechanically break down plastic, but our results show that it also promotes the biodegradation of plastic by marine fungi.”

There are other mushrooms too

Because many different plastics sink into deeper layers before being exposed to sunlight. album It will not be possible to break them all. Waksmaa speculates that there are other, as yet unknown, fungi that break down plastic in the deep ocean. “Marine fungi can decompose complex carbon materials. Since there are a large number of marine fungi present, it is likely that other species, in addition to the four species already identified, contribute to the decomposition of plastic. There are still many questions about the dynamics of how plastic decomposes in deeper layers,” says Waksmaa.

plastic soup

Research into organisms that break down plastic is urgent. Humans produce more than 400 billion kilograms of plastic every year, and this figure is expected to at least triple by 2060. Most plastic waste ends up in the sea; floating on the surface from the poles to the tropics. the water reaches deeper into the sea and eventually falls to the seafloor.

Annika Waksmaa, lead author of NIOZ, said: “Large amounts of plastic end up in subtropical gyres, ring-shaped currents in the oceans where seawater is almost constant. This means that once the plastic is transported there, it becomes trapped. There are about 80 in the North Pacific Subtropical Gyre in the Pacific Ocean alone.” Millions of kilograms of floating plastic have accumulated, and this is just one of six major vortices around the world.”