7 May 2025
When two organisms live together so closely that they merge into a functional unit, this is known as symbiosis. In the "1+1=1" project, an international, interdisciplinary research team is investigating how synthetic symbiosis between microorganisms can be created in a targeted manner - and what this reveals about the formation of complex cell structures. Researchers and engineers from Forschungszentrum Jülich's Institute of Bio- and Geosciences are involved in the project. As part of the project, the researchers draw on insights from the evolution of the plant world. Using experimental methods, they aim to gain unprecedented insights into synthetic symbiosis in living organisms, thus opening up new perspectives for biotechnology and medicine.
The project is being provided with $ 1.2 million in funding by the Human Frontier Science Program. Alongside Forschungszentrum Jülich, Michigan State University (USA) and the CNRS in Grenoble (France) are also involved in the project.
Plants - the product of an ancient symbiosis
Around one billion years ago, a single-celled organism with a cell nucleus absorbed a cyanobacterium - a bacterium capable of photosynthesis. Instead of digesting it, the two began to live in close cooperation. The small partner supplied sugar and oxygen, while the large host cell provided protection and nutrients. Over the course of evolution, the cyanobacterium became an integral part of the cell: the chloroplast. One plus one became one again - a new, more complex whole. This is how the first plants came into being - and with them the basis of all life that depends on oxygen.
Recreating symbiosis in the lab
The "1+1=1" project is now putting this fundamental step under the microscope. The aim is to observe under controlled conditions how one organism enters into a symbiotic relationship with another cell. Paramecium bursaria, which forms a natural symbiosis with the alga Chlorella vulgaris in nature, serves as the host cell. The researchers now want to investigate whether the paramecium can also fuse or cooperate with cyanobacteria. To this end, they have genetically modified the cyanobacteria in a targeted manner. The cyanobacteria are then able to excrete sugar molecules - a capability they do not normally possess - in order to "attract" the paramecium into symbiosis.
Video: A Paramecium | Copyrights: Forschungszentrum Jülich
High tech for an age-old question
The experiments are being conducted in microchips specially developed at Forschungszentrum Jülich - they allow light, temperature, and nutrient availability to be precisely controlled. The scientists deliberately put the paramecia under stress in the hope that they will take up the artificial symbionts. Using high-resolution, automated microscopy, the researchers can document thousands of these interactions and analyse them using self-developed AI image analysis methods. Particularly promising cases are then examined using state-of-the-art 3D electron microscopy to reveal the subtle architectural changes in the cell.
Video: The cultivation of cyanobacteria in microchips shown here was a necessary preliminary development for the IBG-1. | Copyrights: Reproduced from Witting et al., Lab Chip, 2025, 25, 319 DOI: 10.1039/D4LC00567H with permission from the Royal Society of Chemistry.
"I am constantly fascinated by the complexity of biological and biochemical processes that evolution has produced - and by how little we understand about them. The fact that an American, a Frenchman, and a German are joining forces to recreate an evolutionary process that may have only occurred once around a billion years ago almost sounds like the start of a joke. And yet there is real science behind it - with great potential for new discoveries," says project manager Dr. Dietrich Kohlheyer from Forschungszentrum Jülich.
More than basic research
Although this is basic research, the potential applications are far-reaching. Microbial interactions, and symbioses in particular, play a key role in almost all habitats. New findings and technologies could lead to numerous developments in medicine and biotechnology - for example, for the microbiome and intestinal health, for new antimicrobial agents, or for the industrial circular economy through the microbial production of substances, as well as for plant health. In the long term, findings from the project could help to develop new therapies, establish sustainable production processes, or improve plant protection strategies.
Contact Person
Dr. Dietrich Kohlheyer
Head of Microscale Bioengineering
- Institute of Bio- and Geosciences (IBG)
- Biotechnology (IBG-1)
