Séminaire de Nelly Henry

Séminaire de Nelly Henry

Bacterial biofilms : From lab to river
When Apr 20, 2018
from 11:00 to 01:00
Where Site Valrose
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Communities of bacteria adhering to surfaces and interfaces form three-dimensional materials so-called biofilms. The cells are embedded in an extracellular matrix of polymeric substances that protects them and promotes their development. In this confined environment, bacteria divide, interact and acquire specific properties that distinguish them from planktonic bacteria. These living organizations are very widespread and have a considerable impact on the human activities. Whereas molecular biology has revealed the multiplicity of the genes the expression of which is altered in the biofilm compared to planktonic cells, the mechanisms underlying the specific properties of these bacterial systems remain poorly understood. In this context, our laboratory* is working to clarify the causal relationships linking the special physicochemical conditions experimented by the biofilm-dwelling cells and the alteration of the biological functions. This task requires relevant working models and specific tools to bring out measurements of quantitative and reliable parameters within these heterogeneous and living materials.
We will see, in this seminar, the experimental strategies we have chosen to study biofilm properties and their development kinetics. Based on growing biofilms in millifluidic channels, these strategies aim at collecting in situoptical video-microscopy data with sufficient spatial and temporal resolutions under controlled conditions. We will focus on 3 biological models of increasing complexity: an E. coli biofilm, a 4 -species composite biofilm and a natural biofilm. We will see how the simple model studies give grounds for devising appropriate tools and understanding some general properties of the biofilm - such as biofilm physical properties bases or hydrodynamics impact on biofilm development.  Meanwhile, the more complex systems pose new methodological challenges and  we will show here our first moves into the issue of the biofilm fluorescent markers and into natural biofilm phenotypic analysis. 

Keywords: bacterial biofilms, microfabrication, imaging, video-microscopy, physical properties

Related bibliographic references:

1.Thomen, P., Robert, J., Monmeyran, A., Bitbol, A. F., Douarche, C., and Henry, N. (2017) Bacterial biofilm under flow: First a physical struggle to stay, then a matter of breathing, PLoS ONE12, e0175197.

2. Galy, O., Zrelli, K., Latour- Lambert, P., Kirwan, P. L., and Henry, N. (2014) Remote magnetic actuation of micrometric probes for in situ 3D mapping of bacterial biofilm physical properties, Journal of Visualized Experiments87, e50857.

3. Geng, J., Beloin, C., Ghigo, J. M., and Henry, N. (2014) Bacteria Hold Their Breath upon Surface Contact as Shown in a Strain of Escherichia coli, Using Dispersed Surfaces and Flow Cytometry Analysis, PLoS ONE9, e102049.

4. Galy, O., Latour-Lambert, P., Zrelli, K., Beloin, C., Ghigo, J. M., and Henry, N. (2012) Mapping of bacterial biofilm local mechanics by magnetic microparticle actuation, Biophysical journal5, 1400-1408.