Microorganisms play a key role in the bioeconomy – from sustainable energy production to the development of new materials. It is therefore essential to understand and further optimise their metabolism. Researchers at Friedrich Schiller University and the Leibniz Institutes in Jena have discovered the extent to which the green alga Chlamydomonas reinhardtii can adapt its metabolism – simply through new cultivation conditions, without the need to intervene in the genetic material.

The algae, which is ten micrometres in size, is at home in the wet soil of rice fields. The researchers recreated this environment in their study, which was recently published in the journal New Phytologist. Using 3D printing technology, they imitated the structure- and acetate-rich environment of rice fields and observed how the algae changed under these conditions.

Adaptability without genetic changes

According to the study, the algae's cell wall thickened under the simulated conditions, while the cell became smaller and the flagella shorter. The 'eyespot', with which the alga perceives light, increased in size and the alga was even able to adjust the number of its light-sensitive receptors. In addition to these external changes, the research team found that the algae produced more carbohydrates in the form of starch, which indicates a change in metabolism. According to the study, these adaptations would ‘facilitate the survival of the alga in the complex, microorganism-rich and partly anaerobic environment’ and thus help it to cope with stress factors such as oxygen deficiency and competition with other microorganisms.

However, the researchers were surprised that all of these adaptations came about without interfering with the protozoa's genetic material. ‘Our study shows how important it is to investigate microorganisms not only under laboratory conditions, but also in environments that resemble their natural habitat,’ says Maria Mittag, Professor of General Botany at the University of Jena.

Excellent research in an interdisciplinary team

For the study, researchers from various disciplines combined their expertise in microbiology, botany, photonics and bioinformatics. They were brought together by the Cluster of Excellence ‘Balance of the Microverse’ in Jena. Together with Pierre Stallforth, Professor of Bioorganic Chemistry and Palaeobiotechnology at the University of Jena, the team created the complex, structured 3D environment for the study. Researchers with expertise in biophysics and microscopy then captured the changed external shape of the algae in images, while the teams led by Jürgen Popp and Maria Mittag visualised the metabolic processes within the cell.

‘The combination of innovative optical technologies and interdisciplinary approaches has enabled us to gain a comprehensive insight into the biological adaptations of Chlamydomonas reinhardtii,’ explains Jürgen Popp from the Leibniz Institute of Photonic Technology.

Biotechnological potential

The researchers hope that the findings can be applied in areas of biotechnology, for example for the production of sustainable biofuels.

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