Regensburg 2025 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 17: Poster Session II

BP 17.4: Poster

Dienstag, 18. März 2025, 18:00–20:30, P4

Light-switchable adhesion and clustering of C. noctigama at liquid-air interfaces — •Gustav Nolte, Alexandros Fragkopoulos, and Oliver Bäumchen — University of Bayreuth, Experimental Physics V, 95447 Bayreuth, Germany

Microalgae are unicellular photoactive organisms that are ubiquitous in liquid-infused natural environments. The biciliated microalga Chlamydomonas reinhardtii shows light-switchable adhesion and clustering at surfaces, a process so far exclusively observed for solid-liquid interfaces [1,2,3]. Here we report on the light-switchable formation of clusters by Chlamydomonas noctigama, a related species with increasing relevance in the field of optogenetics, at liquid-air interfaces. The morphology and dynamics of these clusters differ significantly from the clusters formed by C. reinhardtii. Apart from the average cluster size and polydispersity, the growth dynamics of individual clusters are studied for a wide range of cell densities. We find a critical cell density above which the number of clusters decreases over time. For the underlying principles of cluster formation and dynamics, we address potential mechanisms like preferential attachment and Ostwald ripening. Reversible clustering may provide an advantage for C. noctigama by allowing the cells to accumulate in locations optimal for photosynthesis while also increasing resilience to environmental stress within the cluster.

[1] S. Till, et al., Phy. Rev. Res. 4, L042046 (2022).

[2] R. E. Catalán, et al., Soft Matter 19, 306 (2023).

[3] C. T. Kreis, et al., Nat. Phys. 14, 45 (2018).

Keywords: Chlamydomonas; cell clustering; cell-cell interactions