Berlin 2024 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 15: Poster IIb

BP 15.16: Poster

Dienstag, 19. März 2024, 18:00–20:30, Poster F

Motility of Salmonella Typhimurium above and within mucus — •Kevin Diestelhorst¹, Fereshteh Ghazisaeedi², Anton Klimek³, Sebastian Braetz², Karsten Tedin², Marie Weinhart^1,4, Roland Netz³, Marcus Fulde², and Stephan Block¹ — ¹Institute of Chemistry and Biochemistry, Freie Universität Berlin — ²Institute of Microbiology and Epizootics, Freie Universität Berlin — ³Department of Physics, Freie Universität Berlin — ⁴Institute of Physical Chemistry and Electrochemistry, Leibnitz Universität Hannover

How do infectious agents like bacteria overcome protecting biohydrogels, such as the glycoalix or mucus? To address this question, the motion of GFP-labeled Salmonella Typhimurium in bulk solution and within hydrogels was recorded by fluorescence microscopy. A method is presented, which enables to correct the strong fragmentation of raw bacterial trajectories (caused by broad bacterial size distributions). In line with previous studies, random as well as ballistic bacterial motility is observed, the extent of which depends on the expression of key proteins. Analyzing random and deterministic features of the ballistic trajectories indicates that flagella-generated propulsion force is on the order of 100 fN per bacterium. To extend these investigations to 3D motion of bacteria across mucus, epithelial cells were cultured, leading to the formation of a native mucus layer on their apical side. The dynamics of bacterial penetration through mucus was followed by continuously recording fast 3D stacks of the cell culture. The experiments indicated that the invasion proceeded via tunnel-like structures.

Keywords: Salmonella Typhimurium; Mucus; Motility; Active motion; Propulsion force