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BP: Fachverband Biologische Physik
BP 22: Bacterial Biophysics II
BP 22.8: Vortrag
Mittwoch, 20. März 2024, 17:00–17:15, H 0112
Photokinesis and phototaxis in light-driven E. coli — •Giacomo Frangipane1,2, Claudio Maggi2, Maria Cristina Cannarsa1, and Roberto Di Leonardo1,2 — 1Department of Physics, Sapienza University of Rome, Italy — 2NANOTEC-CNR, Soft and Living Matter Laboratory, Institute of Nanotechnology, Italy
Bacteria inherently possess signal-detection capabilities, altering their movement patterns accordingly. Today synthetic biology techniques allow us to engineer bacteria by introducing heterologous receptors so that they respond to new stimuli. In this work, we expressed the light-driven proton-pump proteorhodopsin in E. coli cells to control their flagellar motors with light. In this modified bacteria, light affects both speed (photokinesis) and tumbling rate (phototaxis). We study the phenomenology emerging from the interplay between these two effects and observe that, if we apply a sinusoidal light pattern, its spatial frequency affects the fate of the cells' density profile. For slowly changing patterns bacteria tend to behave as if photophilic, while for high spatial frequency modulation, the photokinetic mechanism is dominant and results in an higher concentration in dark regions. We develop a run-and-tumble model that includes both phototaxis and photokinesis and provides a robust description and aligns well with the observed experimental data. Furthermore, for small modulation of light, this organism behaves as microswimmer whose tumbling rate can be controlled with light. This represents a way to control the tumbling rate of microorganisms with light and thus a significant step forward in achieving comprehensive control over the motility of at the microscale.
Keywords: motility; taxis; light; active matter; synthetic biology