Bioplastics from blue-green algae for the climate

Projects, Research |

Climate-friendly and rapidly degradable: Researchers at the Technical University of Munich (TUM) use blue-green algae and the soil bacterium Pseudomonas putida to produce bioplastics

Franziska Kratzl and her colleague conduct research with cyanobacteria
Franziska Kratzl and her colleague conduct research with cyanobacteria
Light and carbon dioxide are thus transformed into a sugar for the production of bioplastics
Light and carbon dioxide are thus transformed into a sugar for the production of bioplastics

Franziska Kratzl uses blue-green algae, sunlight and CO2 to produce sugar for bioplastics. With this fundamental research, she is making an important contribution to avoiding petroleum-based plastic waste and addressing the climate crisis.

ED: You have already completed the Bachelor Molecular Biotechnology and Master Industrial Biotechnology at TUM. What do you find particularly exciting about biotechnology?
Franziska Kratzl: Basically, we encounter biotechnology everywhere. With the pandemic, we saw how important this scientific discipline is.  But I am also attracted by the fact that it is a very interdisciplinary science. I don't just enjoy biology and chemistry, but also process engineering and mathematical models.

You can produce bioplastics from cyanobacteria - more commonly known as blue-green algae - sunlight and CO2, and the addition of the bacterium Pseudomonas putida. How can a person unfamiliar with the subject imagine the process?
The cyanobacterium can photosynthesize, just like plants on land. In the process of photosynthesis, CO2 is fixed. It is made usable for important biological processes. If the bacterium experiences salt stress, it forms a sugar, more precisely sucrose (table sugar), to compensate for this. The cyanobacterium used is modified in such a way that it can channel the formed sugar out of the cell. Here, the sucrose serves as a carbon source for a modified variant of the soil bacterium Pseudomonas putida, which is a natural producer of bioplastics. If the soil bacterium experiences an external limitation, for example of nitrogen, it accumulates the bioplastic as a storage and energy substance.  

The climate crisis shows us that sustainability is becoming increasingly important in all aspects of life. How can you contribute to this with your research?
First of all, our research with genetically modified microorganisms in a co-culture is fundamental research. In fact, it is precisely the co-culture that is exciting in our approach. This does not necessarily only apply to the production of bioplastics. Bioplastics can be produced by many other microorganisms. For our co-culture, we have the vision to develop a platform process that allows us to produce many interesting products from CO2 and light.
Further, it is not yet possible, for example, to use "dirty" CO2 from industrial plants for the mixed culture we are researching. Nevertheless, any research concerning a CO2 fixation is an important contribution to tackle the climate crisis.

Bioplastics are repeatedly criticized because the raw materials used, such as corn, sugar cane or wheat, compete with the food supply or contribute to deforestation. How does your approach differ from previous biotechnological approaches?
In the co-culture approach, CO2 is used that is not in direct competition with our food supply. In the long term, this would be an advantage of bioplastics produced with cyanobacteria or algae. Waste products such as molasses can also be used to produce bioplastics.

What other products can be produced from it? What potential do you see in plastics made from algae?
Blue-green algae, but also many other bacteria, bring enormous potential to our planet. This is currently being researched in many scientific fields. Since the blue-green bacteria only need water, CO2 and sunlight, they are an optimal player for climate-friendly and sustainable plastic production. There are no limits to research and development. For example, there are initial prototypes for algae facades. Wouldn't it be practical to be able to produce bioplastics on site as well? Unfortunately, microalgae biotechnology in particular is often not yet profitable on an industrial scale. The construction of demonstration plants could help to identify the potential "bottelnecks" from such processes on a larger scale.

About Franziska Kratzl:
Prior to her studies, Franziska Kratzl already completed an apprenticeship as a biology lab technician at TUM. She then studied the TUM bachelor's degree program in Molecular Biotechnology and the TUM master's degree program in Industrial Biotechnology. Since 2020, she has been a research associate at the Professorship for Systems Biotechnology in the Department of Energy and Process Engineering at the TUM School of Engineering and Design. As a doctoral candidate, she conducts fundamental research with genetically modified microorganisms.

Profile of Franziska Kratzl: https://www.epe.ed.tum.de/en/sbt/staff/franziska-kratzl/

More about the research project: "CoConut: Cell-cell interaction in a synthetic co-culture, PHA production from sunlight and CO2 in an artifical co-culture between Synechococcus elongatus and Pseudomonas putida": https://www.epe.ed.tum.de/en/sbt/research/coconut/