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A team of biophysicists has published a step-by-step guide for the reliable cultivation of the unicellular green alga Chlamydomonas reinhardtii. The guide will support researchers worldwide in the fields of life sciences, biophysics, and bioengineering in their investigations of biological, biophysical, and biotechnological principles. These reliable cultivation methods are in Nature Protocols.

The unicellular green alga Chlamydomonas reinhardtii is a so-called model organism—an organism that is studied particularly frequently to understand general biological principles. Well-known examples include fruit flies used in genetics or mice employed in medical research as models for humans. C. reinhardtii is an established model organism, particularly in fields such as molecular biology, photosynthesis and light receptor research in living cells, cell metabolism, and protein transport.

Scientific studies require the reliable preparation of viable cell cultures in which the individual cells exhibit consistent properties. For this, researchers need dependable cultivation methods.

C. reinhardtii is a light-sensitive green alga whose use has recently extended beyond the life sciences into further research fields such as biophysics, statistical physics, fluid dynamics, and bioengineering. While some technical aspects of cultivating C. reinhardtii align with standard microbiological procedures, growing and reproducing this green alga requires tailored cultivation protocols due to its light sensitivity and simultaneous motility.

Unlike other model organisms in biology, C. reinhardtii not only requires specific temperature and atmospheric conditions but also a specialized lighting environment adapted to its circadian rhythm.

"Thanks to our many years of experience, colleagues from around the world frequently reach out to us with problems and questions regarding their cell cultivation. This encouraged us to document our expertise in a detailed and accessible way, and to make it available to the scientific community in the form of a comprehensive methods manual," says Prof. Dr. Oliver Bäumchen, Chair of Experimental Â鶹ÒùÔºics V at the University of Bayreuth.

The verification of successful cultivation is based on precise characterization of cell shape, population growth, and cell motility. For this, the researchers use microscopic techniques in combination with specially developed computer-based image analysis tools. Alongside the step-by-step protocol, the team is also making the algorithms and computer code freely available as open-source software.

Additionally, the protocol includes troubleshooting sections that describe common problems and sources of error, along with guidance on how these issues can be resolved in the laboratory. Finally, the methods paper includes a list of related microorganisms and genetically modified strains that can also be successfully cultivated and analyzed using the described methods.

"The Culture Collection of Algae at Göttingen University provides its living strains for research, teaching, and biotechnology worldwide. Our Chlamydomonas strains are particularly in demand. In this new, very detailed guide, we have compiled our extensive knowledge of how to cultivate them. With it, we particularly support researchers who are working with this fascinating model organism for the first time," adds Dr. Maike Lorenz, from the Department of Experimental Phycology and Culture Collection of Algae at the University of Göttingen.