SKM 2023 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 53: Active Matter V (joint session BP/CPP/DY)

DY 53.2: Vortrag

Freitag, 31. März 2023, 10:00–10:15, TOE 317

Filamentous Cyanobacteria Aggregate at Light Boundaries — •Maximilian Kurjahn1, Leila Abbaspour1, Philip Bittihn1, Ramin Golestanian1,2, Benoît Mahault1, and Stefan Karpitschka11Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Rudolf Peierls Centre for Theoretical Physics, University of Oxford, OX1 3PU, Oxford, UK

Filamentous cyanobacteria are among the oldest, yet still most abundant phototrophic prokaryotes on Earth, fixing vast amounts of atmospheric carbon by photosynthesis. Gliding motility, coupled to photophobic responses (direction reversals in response to light intensity gradients), are believed to drive accumulation in suitable light conditions. Here, we demonstrate that photosensitivity goes beyond simple accumulation: Super-filamentous aggregates, capable of collective mechanical action, form at the boundaries of illuminated regions and may, for instance, contract and detach from the substrate, once grown to a critical mass. We explore how the light pattern, in particular its boundary curvature, impacts aggregation. A minimal model of active rods captures the behavior qualitatively. The ecological impact of such behavior is still unclear, but may enable colonies to escape from saturated habitats by switching to a planktonic state.

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