Plastic has now been a fixed component of our packaging industry for more than fifty years. Plastic packaging is lightweight, durable and cheap to produce. However, if they are not disposed of properly, they pose risks to our biosphere, which has a hard time dealing with man-made plastics.
It seems all the more astonishing that within half a century - the blink of an eye in evolutionary history - microorganisms have been able to adapt to these materials. Many are known to co-degrade plastics as a so-called co-substrate, but only a few have adapted to the extent that they can completely metabolize plastic as a sole substrate. Ideonella sakaiensis, a bacterium that was isolated for the first time in a plastic recycling station in Sakai (Japan), is able to use PET as its sole carbon source.
In the course of a research project funded by the "Tiroler Wissenschaftsförderung", the biodegradation potential of this strain could be tested on two different, commercially available packaging materials.
In laboratory tests, Ideonella sakaiensis metabolized 64 % and up to 97 %, respectively, of the plastic originally used within seven weeks. These gravimetric results were confirmed by scanning electron images, which showed strong cracks and distortions on the surface of the plastic particles - caused by an enzyme produced by Ideonella, PETase - as well as by molecular biological investigations.
This research underlines the flexibility and biotechnological potential of microorganisms, which are often negatively associated only as "pathogenic". It also shows once again that nature finds solutions to deal with anthropogenic disturbances. Nevertheless, we must live up to our responsibility and avoid these disturbances or at least reduce them if possible.
This project was carried out in a research collaboration between the Departments of Biotechnology and Environmental, Process & Energy Engineering. MCI is part of the European University Ulysseus and represents the Innovation Hub “Food, Biotechnology and Circular Economy".
Biodegradation of PET through Ideonella sakaiensis (right to left: original PET, degradation within seven weeks) ©MCI
Bacterium Ideonella sakaiensis is able to completely metabolize the plastic polyethylene terephthalate. ©Unsplash
Nearly 400 million tons of plastic produced worldwide in 2021 ©Unsplash