A plastic particle (red) being colonized by Parengyodontium album, a fungus found in the Great Pacfiic Garbage Patch. Photo: Annika Vaksmaaa//NIOZ
A newly published study has identified a fungus living in the sea that can break down plastic. The marine microbe, called Parengyodontium album was found on plastic debris floating in the Great Pacific Garbage Patch. When scientists later isolated the fungus in a laboratory, they found it was capable of breaking down the plastic polyethylene after it had first been exposed to UV radiation from sunlight.
The discovery was made by marine microbiologists from the Royal Netherlands Institute for Sea Research (NIOZ) who cooperated with colleagues from Utrecht University, the Ocean Cleanup Copenhagen and St. Gallen, Switzerland. They were able to isolate the fungus from floating plastic debris found in the North Pacific Subtropical Gyre, colloquially known as the Great Pacific Garbage Patch. They were then able to grow the fungus in a laboratory on special plastics that contain labeled carbon, which allowed them to calculate the rate at which it broke down polyethylene.
“What makes this research scientifically outstanding, is that we can quantify the degradation process,” said lead author Annika Vaksmaa to Phys.org. Valsmaa and her team observed that the breakdown of PE by P. album occurs at a rate of about 0.05 percent per day. She continued, “Our measurements also showed that the fungus doesn’t use much of the carbon coming from the PE when breaking it down. Most of the PE that P. album uses is converted into carbon dioxide, which the fungus excretes again.”
However, one caveat is that P. album needs sunlight as an energy source, in order to carry out this process. “In the lab, P. album only breaks down PE that has been exposed to UV-light at least for a short period of time. That means that in the ocean, the fungus can only degrade plastic that has been floating near the surface initially,” explained Vaksmaa.
P. album joins a short list of fungi known to break down plastic. Only four species of plastic-degrading fungus have been discovered to date. There are, however, a larger number of bacteria known to be able to degrade plastic.
Hopefully the new discovery will aid efforts to control the alarming amount of plastic pollution in our oceans. “Large amounts of plastics end up in subtropical gyres, ring-shaped currents in oceans in which seawater is almost stationary,” said Vaksmaa, “That means once the plastic has been carried there, it gets trapped there. Some 80-million kilograms of floating plastic have already accumulated in the North Pacific Subtropical Gyre in the Pacific Ocean alone, which is only one of the six large gyres worldwide.”
