Recycling Breakthrough, Microbes Digest Plastic at 15C

Recently discovered Arctic microbes can digest Plastic at low temperatures

The majority of plastic products we use are meant to be used once and then thrown away, however, these plastics stick around for hundreds of years. These plastics should be recycled or destroyed in a way that doesn’t hurt the environment. So for many years we have been depending on microbes that eat and digest plastic, however, they usually only work at hot temperatures (~30C) which costs the recyclers for heating facilities, and thus is not as environmentally friendly as needed.

A team of scientists from the Swiss Federal Institute WSL has discovered a species of microbes in the Alps and the Arctic which can eat and digest plastic at just 15C. The team sampled 19 bacteria strains and 15 fungi strains which they grew on free-lying plastic and buried plastic in Greenland, Svalbard, and Switzerland. 

19 strains from the sample (56%) which include 11 fungi and 8 bacteria were able to digest polyester-polyurethane (PUR) at 15C, whereas 17 strains (50%) which include 14 fungi and 3 bacteria were able to digest two commercially available biodegradable mixtures of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA). Unfortunately, none of the strains were able to digest the non-biodegradable polyethylene (PE) even after 126 days.

Dr. Joel Rüthi from the WSL team noted his surprise that a large fraction of the tested microbes could degrade even one of the plastics tested. These microbes can help the “enzymatic recycling process” for plastic by making it cheaper and more environmentally friendly.

The best performers of these 34 strains were 2 uncharacterized fungi species in the genera Neodevriesia and Lachnellula which digested all types of plastic tested except for PE.

The reason these microbes can digest plastic is that polymers resemble structures found in the cells of plants. The enzymes these microbes produce to degrade polymer are the same enzymes they use to break down plant cell walls.

These microbes were only tested at one temperature (15C) so the best microbe strain to use has not yet been found. However, we know that these strains of bacteria and fungi can grow well between temperatures of 4c and 20C. The next step in research also involves identifying the specific enzyme which degrades plastic. These enzymes might be in need of modification to improve protein stability, which may open doors to cost-effective and environmentally friendly plastic recycling.

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