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BP: Fachverband Biologische Physik

BP 1: Cell migration

BP 1.11: Vortrag

Montag, 11. März 2013, 12:30–12:45, H43

Analyzing the mechanics and energetics of motile bacteria with object-adapted optical traps — •Julian Roth, Matthias Koch, and Alexander Rohrbach — Lab for Bio- and Nano-Photonics, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany

The spread of bacterial diseases and their pathogenicity can often be directly linked to their ability to move under different environmental conditions. In order to understand the basic locomotion principles of single helical bacteria, we use the recently developed object-adapted optical trapping and shape-tracking technique [1] to analyze their complex movements. In particular, we investigate Spiroplasma melliferum and the Spirochetes Borrelia japonica. Spiroplasma belong to the smallest and simplest forms of life, they cause tremendous agricultural damage, but their motility is not completely understood so far. As we show, Spiroplasma can rapidly undergo continuous transitions between different states of mechanical energy during motility. These transitions are related to conformational changes of the molecular subunits of their unique fibril-like cytoskeleton. We track their shape with nm precision at rates up to 1 kHz and estimate the energetics and forces involved in this process. In this project, we develop a model describing the potential landscape of the cytoskeletal ribbon and try to link it to different environmental influences, which we control by the addition of drugs, changes of the viscosity or the pH value of the surrounding medium. First experimental and computational results are presented.

[1] Koch, M. & A. Rohrbach (2012). Nature Photonics 6(10): 680-686