Microbiologists are testing bacteria from soil, seawater, and wastewater for plastic-degrading properties.
In a laboratory at DTU, microbiologist Eva Sonnenschein and a group of MSc students are searching for halos, also called zones of inhibition, which are clear, circular areas in Petri dishes.
A halo is a good sign, because it means that the bacterium has ‘eaten’ some of the carbon-rich substrate inside the Petri dish. This is good news when looking for bacteria that can break down carbon, which is one of the key ingredients in plastic.
“The field of research into bacteria’s ability to break down plastic is only a few years old. There is much to explore, and we also need to invent the methods for it,” says Eva Sonnenschein, who has a PhD in marine microbiology from Germany and works as an Assistant Professor at DTU Bioengineering.
The research group are investigating bacteria sourced from soil, wastewater, and sea water—including samples from the Galathea expedition.
Bacterial colonies
The DTU microbiologists are currently working with a narrowed field of 20 to 30 interesting bacteria to be explored further.
In addition to observing the bacterial growth in Petri dishes, the researchers are also comparing the bacterial genes with databases of known genes that play a role in microorganisms’ ability to degrade plastic. But according to Eva Sonnenschein, the challenge is not only finding isolated bacteria:
“In nature, bacteria never live alone. They live in colonies and communicate and interact with each other and other microorganisms, but this interaction hasn’t been fully explored yet. Perhaps we will learn that entire colonies are more effective at breaking down plastic than a single bacterium or a single enzyme.”
One of the possible future prospects for plastic-degrading bacteria is to use them in water treatment plants for removing microplastics.