A fungus that lives within the ocean can break down the plastic polyethylene, provided it’s first exposed to UV rays from sunlight. NIOZ researchers, amongst others, publish their findings in a scientific journal, anticipating that plastic-destroying fungi could also be living within the deep ocean.
The fungus lives in thin layers on plastic litter within the ocean, together with other marine microbes. Marine microbiologists on the Royal Netherlands Institute for Sea Research (NIOZ) discovered that fungi are able to breaking down particles of the plastic polyethylene (PE), which is probably the most abundant of all plastics ending up within the ocean. . NIOZ researchers collaborated with colleagues from Utrecht University, the Ocean Cleanup Foundation and research institutes in Paris, Copenhagen and St. Gallen, Switzerland. The finding allows the fungus to hitch a really short list of plastic-destroying marine fungi: only 4 species have been found up to now. A lot of bacteria were already known to find a way to degrade plastics.
Follow the degradation process appropriately.
Researchers went to plastic pollution hotspots within the North Pacific to search for plastic-degrading microbes. From the collected plastic waste, they isolated marine fungi by growing them within the laboratory, on special plastic labeled with carbon. Waksma: “This so-called 13C isotopes remain detectable within the food chain. It's like a tag that allows us to see where the carbon goes. Then we are able to find it within the degradation products.”
Waksma could be very excited concerning the latest finding: “What makes this research scientifically significant is that we can quantify the degradation process.” In the laboratory, Waksma and his team observed that PE deteriorates at a rate of about 0.05 percent per day. “Our measurements also showed that the fungus does not use much of the carbon coming from PE when breaking it down. Most of the PE it does use is converted to carbon dioxide, which the fungus re-releases. ” Although CO2 is a greenhouse gas, this process just isn’t something that might cause a brand new problem: the quantity emitted by fungi is similar as that released when humans breathe.
Only under the influence of UV
The researchers found that the presence of sunlight is important for the fungus to make use of PE as an energy source. Waksma: “In the laboratory, only PE that has been exposed to UV light for the shortest amount of time breaks down. This means that in the ocean, the fungus can only degrade the plastic that is initially near the surface. Floating,” explains Waxma. “It was already known that UV-light mechanically breaks down plastic itself, but our results show that it also facilitates the breakdown of bioplastics by marine fungi.”
Other fungi there
Because many alternative plastics sink into deeper layers before being exposed to sunlight, not all of them will break down. Waksma expects that there are other, as-yet-unknown, fungi within the deep ocean which might be breaking down the plastic. “Marine fungi can break down complex materials made of carbon. Marine fungi are abundant, so it is likely that, in addition to the four species identified so far, other species also contribute to plastic degradation. In deeper layers The dynamics of how plastic degrades,” says Waksma.
Plastic soup
The seek for organisms that destroy plastic is urgent. Each 12 months, humans produce greater than 400 billion kilograms of plastic, and this is anticipated to not less than triple by 2060. Most plastic waste results in the ocean: from the poles to the tropics, it floats on the surface. The water reaches deeper into the ocean and eventually falls to the ocean floor.
NIOZ lead creator Annika Waksma: “Large amounts of plastic end up in the oceans in subtropical gyres, ring-shaped currents in which the ocean water is almost still. This means that once the plastic is transported there, It gets stuck there. About 80 million kilograms of floating plastic has already accumulated in the subtropical gyre of the North Pacific Ocean, just one of the six major gyres around the world.”