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Dreaming of micro-plastics-free vegetables

published by Julia Hinz
Dr. Harald Seitz forscht daran, Mikroplastik in Pflanzen nachzuweisen. © Fraunhofer IZI-BB

For many decades, micro-plastics remained a scarcely researched issue. But awareness is growing, as is the realization that we, too, ingest plastic particles through food and water. Hardly anyone can estimate the consequences. PD Dr. Harald Seitz from Fraunhofer IZI-BB and Dr. Susanne Baldermann from the IGZ dare to take a closer look. They research methods with which micro- and nano-plastics can be detected in plants. In doing so, they are doing real pioneering work – and pursuing a great goal.

Sometimes, a normal meeting room, cushioned chairs, and switched-off laptops are all you need to promote bit ideas. That was exactly the starting point in 2018, when a professor of food chemistry and a Doctor in biochemistry sat together and did something that scientists don’t necessarily do very often: dream. They let their minds wander, talked a lot and furthered each other’s thoughts. They dreamed of labels like “plastic-free food” and imagined what it would be like to detect micro- and nano-plastics in food and water – and how to remove them. Some initial ideas were born, from which the EMINA project emerged in 2019, on which PD Dr. Harald Seitz from the Fraunhofer Institute for Cell Therapy and Immunology, Bioanalytics and Bioprocesses (IZI-BB), and Dr. Susanne Baldermann from the Leibniz Institute for Vegetable and Ornamental Plant Production (IGZ) are currently doing research. The abbreviation stands for: Proof of Entry and Migration of Nano-plastics in plants.

How much micro- and nano-plastic is present in our environment?

With a focus on micro-plastics, the scientists began working on a subject that is talked about a lot but is often less well researched when it comes to plants, as plastic particles are microscopic and difficult to detect on smaller surfaces. In August 2020, a study by the National Oceanography Center (NOC) from England estimated the total amount of micro-plastic in the Atlantic to be at about 12 to 21 million tons. But the amount of micro-plastic in our environment – especially proportions in plants – remains to be explored in any extensive studies so far. This is where EMINA comes in. “The basic question that we ask ourselves is: what happens to plastic when it gets smaller and smaller? How is it absorbed by plants? There is still a lot to be explored in this field. And since we ingest a lot of plants and, therefore, potential micro-plastic particles with our food, this is something that should definitely be looked at,” explains Dr. Seitz. Professor Susanne Baldermann remembers how difficult it was at the beginning to get the necessary funding: “In 2019, at the start of the project, there were still many discussions about whether plants would even absorb micro- and nano-plastics”

Prof.'in Susanne Baldermann vom Leibniz-Institut für Gemüse- und Zierpflanzenbau (IGZ) forscht mit Dr. Harald Seitz an Möglichkeiten, Mikroplastik in Pflanzen nachzuweisen

Prof. Susanne Baldermann of the Leibniz Institute of Vegetable and Ornamental Crops (IGZ) is working with Dr. Harald Seitz on ways to detect microplastics in plants.

The challenge of demonstrating amounts of micro- and nano-plastics

After initial difficulties, the two began their work. First, they had to find methods with which they could detect particles of micro- and nano-plastics in plants, raising. the question which stems or shoots of the native flora to use for analyses. Taking any green plant from any field was out of the question. “It might sound simple to laymen, who might think that all one has to do is pick a random plant and look at it under the microscope to see which micro- and nano-plastic particles are to be found there. But not all plastic is the same. Car tires, for example, consist of different particles than a plastic bag. And the particles have to be detected in different ways. In addition, there are environmental influences that change the surface properties and, therefore, make detection more difficult,” says biochemist Dr. Harald Seitz. That is why they decided to use cultivated organisms that were as unaffected by the environment as possible for their experiments. They found them directly on site, at Fraunhofer IZI-BB: the algae strains from Dr. Thomas Leya. Their basic idea was to mix the algae with plastic particles of a single plastic, such as polystyrene or polyethylene, and then watch how they absorb the foreign matter.

How fluorescent markings make plastic particles visible

With the right plants and the right plastic as a basis, what remained was the question of a suitable method for detecting micro- and nano-plastics. “This is a big analytical challenge, as particles from micro- and nano-plastics have certain properties that other particles can also have,” explains Professor Susanne Baldermann. So, they started testing different methods. In order to recognize the microscopic plastic particles, it has proven useful, for example, to work with markings. In practice, this process works something like this: researchers receive plastics from a company that contain fluorescent markings. They mix these with nutrient solutions in which the algae and plants are cultivated. “We can then use special light to make the fluorescent markings visible. If we look at the algae or plants under the microscope, we see, to put it simply, small plastic pieces that shine brightly,” says Dr. Seitz.

Proving the concentration of micro-plastics? “Unfortunately, this does not work without destructive processes.”

However, the detection of micro- and nano-plastic particles is only a small part of this complex field of research. Microscopy may allow researchers to detect particles, but it does not allow them to estimate its concentration. As of the project’s current status (November 2021), fully established method to do so still remains to be found. Until then, researchers combine different approaches and models in order to “understand the means of absorption and the quantity”, as is the technical term. To estimate concentration, they use a detector, for example. “This is a specialized device that can record the concentration of the plastics. We can concretely specify that the device records, for example, polystyrene or polyethylene. But this only works with substances in a gaseous state. So, we have to heat the alga or plant with the plastic particles, which causes the plastics to decompose. But this method also has its disadvantages: “Unfortunately, it cannot be done without destructive processes. It’s a shame because then, we won’t get all the information we’d like. This includes, for example, the question of what effects the plastic particles have on the DNA and RNA of the plant. Are metabolic processes changing, for example? Are the division processes of cells slowing down?” These are questions that Seitz asks.

Plastic-free drinking water?

All in all, there is still a lot of research ahead for Dr. Seitz from Fraunhofer IZI-BB and Professor Baldermann from the IGZ. If you will, their research is still in its infancy. But at least the two are working to ensure that things start to get up and running. When the dream of plastic-free vegetables or drinking water will come true is a question of time – and of determination as well as industry’s and municipalities’ willingness to invest. “If politics and business make more efforts to support companies and our research accordingly, a period of five years is realistic, for example, for detecting and solving the issue of micro-plastics in water treatment plants,” says Dr. Seitz. With Professor Baldermann’s main focus, it becomes much more difficult to remove plastic products from food. “Unfortunately, the circumstances are a bit more complex here,” explains Professor Baldermann. “Plants for the food industry are grown in greenhouses, for example. They are covered with foil to promote quick growth. This means that you have a higher possibility of plastic absorption,” says the chemist. That is why it will probably take ten years or more before a “plastic-free” label would be realistic.

EMINA – a prime example of co-operation in the Berlin-Brandenburg metropolitan region

The collaboration between the two organizations is astonishing. This is because Dr. Seitz works at the Fraunhofer IZI-BB in the Potsdam Science Park and Professor Baldermann conducts research at the Leibniz Institute for Vegetable and Ornamental Plant Production (IGZ) in Großbeeren, south of Berlin. Although the two locations are about 30 km apart, they make an effort to exchange information regularly. Both have three employees each, who work a lot in the laboratory; there, especially, short communication channels are essential. Both benefit from very good research conditions at their locations. According to Dr. Seitz, “working in the Potsdam Science Park has many advantages. With the university, the two Max Planck institutes and the two Fraunhofer institutes, we have an excellent position in the field of natural sciences. But working together with the many research institutions in the Berlin-Brandenburg metropolitan region is also possible.” He has been working at the site since 2014 and also draws a positive conclusion when it comes to development and change: “The campus has developed very well,” says Dr. Seitz. “The station has been expanded, and there are shops and a day-care center for children. This growth also brings people into contact with other institutes, and individuals can work together quickly and positively.”

This blog and the projects of Standortmanagement Golm GmbH in the Potsdam Science Park are funded by the European Regional Development Fund (ERDF) and the state of Brandenburg.

Image Credits: Dr. Harald Seitz ©Fraunhofer IZI-BB;
Prof. Susanne Baldermann © Jürgen Rennecke (Photographer)-University Bayreuth