breaking down

Plastic Eating Fungus | Earth Wise

May 26, 2023 By EarthWise Leave a Comment

More than five billion tons of plastic have accumulated on land and sea including the most remote regions of the planet as well as in the bodies of animals and humans. There is a compelling need to recycle as much plastic as possible but doing so is a major challenge. Plastic comes in many varieties and breaking it down for reuse requires different methods for each.

Polypropylene is one of the biggest challenges for recycling. It is a very common plastic used for all sorts of products including food containers, coat hangers, plastic wrap, toys, and much more. It accounts for roughly 28% of the world’s plastic waste, but only 1% of it is recycled.

Polypropylene is seldom recycled because it generally has a short life as a packaging material, and it often becomes contaminated by other materials and plastics. Thus, it generally ends up in landfills.

Researchers at the University of Sydney in Australia have discovered that two common strains of fungi were able to successfully biodegrade polypropylene. The fungi species – with unavoidable Latin names of Aspergillus terreus and Engyodontium album – are typically found in soil and plants.

The researchers found that the fungi were able to break down polypropylene after it had been pre-treated with either UV light or heat, by 21% over 30 days, and by 25-27% over 90 days. This seems rather slow but compared with the nearly endless life of polypropylene in landfills, it is a major improvement.

The hope is that methods like this could ultimately reduce the amount of plastic polluting the environment by encouraging plastic to biodegrade naturally under the appropriate conditions.

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Fungi makes meal of hard to recycle plastic

Photo, posted March 5, 2010, courtesy of Kevin Krejci via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A New Super-Enzyme For Breaking Down Plastic | Earth Wise

November 13, 2020 By EarthWise Leave a Comment

The problems caused by plastic waste continue to grow. Plastic pollution is everywhere, from the Arctic to the depths of the ocean. We consume microplastics in our food and breathe them in the air. It is very difficult to break down plastic bottles into their chemical constituents in order to make new ones from old ones. Therefore, we continue to produce billions of single-use plastic bottles, creating more and more new plastic from oil each year.

Scientists at the University of Portsmouth in the UK have developed a new super-enzyme that degrades plastic bottles six times faster than before. They believe that the new enzyme could be used for plastic recycling within a year or two.

The super-enzyme was derived from bacteria that naturally have the ability to eat plastic. The researchers engineered it by linking two separate enzymes, both of which were found in a plastic-eating bug discovered in a Japanese waste site in 2016. They revealed an engineered version of the first enzyme in 2018, which started breaking down plastic in a few days. They had the idea that connecting two enzymes together would speed up the breakdown of plastic. Such linkage could not happen naturally in a bacterium.

Carbios, a French company, announced a different enzyme in April that can degrade plastic bottles within 10 hours but requires heating above 160 degrees Fahrenheit. The new super-enzyme works at room temperature.

The team is now examining how the enzymes can be tweaked to make them work even faster. Meanwhile, they plan to work in partnership with companies like Carbios, to bring super-enzymes for breaking down plastics into commercial use.

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New Super-Enzyme Can Break Down Plastic at Rapid Pace

Photo, posted March 24, 2017, courtesy of the USFWS – Pacific Region via Flickr. Photo credit: Holly Richards/USFWS.

Earth Wise is a production of WAMC Northeast Public Radio.

Breaking Down Forever Chemicals

October 25, 2019 By EarthWise Leave a Comment

One of the toughest classes of pollutants are per- and polyfluoralkyl substances, or PFAS, as they are known. PFAS are often called “forever chemicals” because they are extremely long-lasting and difficult to clean up. They are found in household products including non-stick pans, dental floss, water-repellent fabrics, and many others. They can be found extensively in U.S. waterways and soil.

PFAS move through the food chain, accumulating in humans at levels that scientists say can cause adverse health effects. While these have not been definitively proven, there is evidence that higher cholesterol levels, cancer, thyroid disruption, and low infant birth rates are all associated with PFAS ingestion.

PFAS are difficult to get rid of because their carbon-fluorine covalent bonds are some of the strongest in organic chemistry. Researchers at Princeton University have been studying a process known as Feammox in which ammonium breaks down in acidic, iron-rich soils in New Jersey wetlands and similar locations. They found that this reaction takes place when a bacterium called Acidimicrobium A6 is present.

Using gene-sequencing techniques, they found that the microbe has characteristics that could help break down carbon-fluorine bonds, and therefore break down PFAS. In tests using microbe-loaded soil samples, they found that the bacterium removed 60% of PFAS pollutants within 60 days.

The research has been published in the journal Environmental Science and Technology and the team is now testing the bacterium’s effectiveness over different time-spans in lab conditions before testing it in the field.

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New Jersey Soil Microbe Shown to Break Down ‘Forever Chemicals’

Photo, posted November 9, 2017, courtesy of the Department of Environmental Quality via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Where Does The Plastic Go?

October 15, 2018 By EarthWise Leave a Comment

The glut of plastic in the oceans is a global problem. About 9 million tons of plastic enter the oceans each year. Much of it is discarded fishing gear, plastic bags, and other macroscopic objects. But a great deal of it is in the form of microplastics or small particles. Some microplastics come from cosmetics and other products containing them but a lot of them are the result of larger plastic objects breaking down into small particles.