Microorganisms are great hope for the development of a circular economy for plastics. Some species produce enzymes, i.e. catalysts made of proteins, which accelerate the degradation of plastic into smaller, reusable components. However, the enzymes known so far require temperatures above 30°C for industrial application. This type of recycling therefore consumes a lot of energy and money. Now, as part of his doctoral thesis in the research group led by Dr. Beat Frey at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Joel Rüthi has found microbes that can decompose certain types of plastic even at 15°C. The study was published on Wednesday in the scientific journal "Frontiers in Microbiology".
The researchers buried plastic in soil from the Alps and Greenland and examined the bacteria and fungi that grew on it over the course of several months. They also isolated microbes from plastic buried for one year in Greenland and from plastic waste collected on Svalbard. Then they tested their ability to degrade different types of plastic in the laboratory under controlled conditions. Nineteen strains were able to break down biodegradable plastics, but none were able to break down the "normal" plastic polyethylene (PE).
Before the new findings can actually be applied in the recycling of biodegradable plastic, the researchers still have to tackle some issues: "The next big challenge will be to identify the plastic-degrading enzymes produced by the microbes and to optimize the process to obtain large amounts of enzymes. In addition, further modification of the enzymes might be needed to optimize properties such as their stability." says Beat Frey, co-author of the study.