Scientists have discovered microorganisms that can degrade polyurethane at low temperatures

Scientists at the Swiss Federal Institute of Research WSL have discovered microbes that can do this at 15°C, which could lead to a breakthrough in microbial recycling. Their findings were published in the journal Frontiers in Microbiology.

Dr. Joel Rüthi from WSL and his colleagues collected 19 bacterial strains and 15 fungi in Greenland, Svalbard and Switzerland that grew on freely placed or intentionally buried plastic products that were kept underground for a year. They had these microbes grow in the lab as single-strain cultures in the dark at 15°C and tested whether they could digest different types of plastics.

The results showed that the strains belonged to 13 genera of the phylum Actinomycetes and Proteobacteria, and the fungi belonged to 10 genera of the phylum Ascomycetes and the phylum Mucormycetes.

The plastics tested include non-biodegradable polyethylene (PE) and biodegradable polyurethane (PUR), as well as two commercially available biodegradable mixtures of polybutylene terephthalate-butylene adipate (PBAT) and polylactic acid (PLA).

Even after 126 days of incubation on these plastics, all strains were unable to digest PE. But 19 strains (56%), including 11 fungi and 8 bacteria, were able to digest PUR at 15°C, while 14 fungi and 3 bacteria were able to digest a plastic mixture of PBAT and PLA.

PUR hot melt adhesives are a type of adhesive that is commonly used in industrial applications. PUR stands for polyurethane reactive, which refers to the chemical composition of the adhesive.

These adhesives are typically applied in a molten state and then solidify as they cool.