Project C1: The formation of biofilms as a collective process - experiments.

In this project, we will perform a quantitative analysis of bacterial motion during
the early stages of biofilm formation. We will focus on bacteria of the genus
Pseudomonas, a popular model organism for the study of biofilms. Microfluidic
techniques will be an essential part of our experimental setup. In such devices,
experimental conditions can be precisely tuned and controlled. We will concentrate
on two sets of experiments.
First, we will image the recruitment of bacteria from the bulk fluid to the surface
(reversible attachment) under various flow conditions and in different micro-geometries.
A particularly challenging part is the application of in-line holographic imaging to
obtain the full three-dimensional trajectories of swimming bacteria prior to surface
attachment. From the dependence of swimming patterns on flow geometry, surface
structure, and chemical environment we expect new insight into the initiation of biofilm
growth.
Second, we will investigate the stage of surface movement, cluster formation, and
proliferation of bacteria that follows reversible attachment. We will use light microscopy
to gather large image sequence data sets of these processes. Imaging will be performed
both at the level of individual cells and at the more coarse grained level of cell densities.
In our microfluidic flow chambers, we can systematically tune the experimental conditions
such as the initial seeding density of bacteria, the ambient fluid flow, or the concentration
of chemical factors. This high level of control will allow us to map the dynamical variables
of biofilm formation as a function of various environmental parameters. A thorough statistical
analysis will be performed on this data.

Project leaders: Prof. Dr.  C. Beta [1],  Prof.Dr.  H. Stark [2],  Dr.  V. Zaburdaev