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Project C.1: From trajectories to an understanding of chemotactic response: experiments
It is our aim to develop a
generalized data-driven description of bacterial chemotaxis. We will
pursue this goal in close collaboration with project C.2. While the
underlying theoretical concepts will be developed in C.2, project C.1
will provide the experimental data as a basis for this joint effort.
Our experiments will focus on two bacterial model organisms. As E.
coli is the generally accepted and most widely studied paradigm
of bacterial chemotaxis, it will serve as a benchmark for the
generalized descriptions developed here. As a first step, we will thus
consider chemotactic trajectories of E. coli. We will perform
a stochastic data analysis to obtain a quantitative description of the
chemotactic motion, relying on the approach that has been initially
developed for eukaryotic chemotaxis. We will then advance this
description by applying the methods developed in C.2 to extract, for
example, the chemotactic response function R from the experimental
motion patterns. Besides experiments in stationary gradient fields, we
will also provide data for periodically changing input signals to
compare with the respective modeling predictions. Furthermore, cell
density dependent collective effects will be included. In a second
step, we will exemplify our approach with the soil bacterium
Pseudomonas putida, a bacterial system for which we have only
little quantitative knowledge of its chemotactic performance. The work
with P. putida as a model for bacterial swimming has been
well established in our laboratory during the previous funding period
of this Research Training Group, where we have studied swimming
patterns and wall interactions in complex micro-geometries.
Our experiments will be performed in microfluidic setups that have been an integral part of our previous research for years. Cell trajectories will be recorded by light microscopy. The necessary high-speed imaging setup has been established during the previous funding period and is available for both bright-field and fluorescence imaging. Furthermore, our setup is equipped with a piezo-driven objective mount that allows three-dimensional tracking of moving objects and automated z-stacking.
Project leaders: Prof. Dr. C. Beta , Prof. Dr. H. Stark