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BP: Fachverband Biologische Physik

BP 14: Poster Session II

BP 14.18: Poster

Dienstag, 10. März 2026, 18:00–21:00, P2

Exploring Chemotaxis in Magnetotactic Bacteria: A Biophysical Approach — •Diego Roesch — nstitut de Biosciences et Biotechnologies d’Aix-Marseille, Aix en Provence, France

Magnetotactic bacteria (MTB) navigate complex microenvironments by integrating magnetic, chemical, and physical cues. Although magnetotaxis and aerotaxis have been extensively studied, the mechanisms governing chemotaxis in MTB remain largely unexplored, particularly at the level of the bacterial flagellar motor. This work aims to establish a quantitative steady-state model of motor dynamics in Magnetospirillum gryphiswaldense (MSR-1) as a foundation for studying how the motor adapts to and integrates chemical stimuli.

Using tethered-cell assays, high-speed recording, and a custom Python analysis pipeline, individual MSR-1 motors were characterized, revealing three well-defined rotational states: counterclockwise (CCW), clockwise (CW), and pausing. MSR-1 motors exhibited frequent directional reversals and extensive time spent in transient failed-switch pauses, whereas genuine long pauses formed rare but highly persistent states following lognormal distributions, likely reflecting regulatory or mechanistic resets of the motor.

Switching intervals, long pauses, and most run durations follow non-Poissonian, lognormal-like statistics, suggesting structured rather than memoryless regulation. Since MSR-1 possesses two polar flagella, this framework also opens the way to investigate the synchronicity and coordinated behavior of both motors under chemical stimulation.

Keywords: Magnetotactic; Flagella; Motor; Chemotaxis