About Bacterial Biofilms

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A. Utada and N. Obana from Nomura Lab (U. Tsukuba, Japan), will give a combined seminar about bacterial biofilms.



#1 : Role in Surface Motility in Biofilm Formation in Motile and non-Motile bacteria

Andrew S. Utada


In the environment, bacteria can exist as solitary individuals or as members of surface-adhered social communities, called biofilms. These communities provide protection from harsh environmental conditions, predation, enable resource sharing, and facilitate intracellular communication. Depending on the local conditions bacteria will transition between these two states and this interplay is fundamental to the ecology and biology of bacteria. To begin to understand bacterial behavior and biofilm formation we analyze the initial stages of surface engagement in two species of bacteria: one which is motile, the other non-motile. We analyze surface attachment strategies using aggregation assays, deletion mutants, tracking algorithms and microfluidics.


#2 : Biofilm formation and heterogeneity in Clostridium perfringens 

Nozomu Obana


Most microbes live in microbial communities called biofilms in natural environments. Cells in biofilms are enclosed in self-produced extracellular polymeric substances (EPS). Biofilms exhibit increased tolerance to disinfectant chemicals, antibiotics, and immune systems and thus are widely recognized as causative agents of infectious diseases and environmental contaminants. Clostridium perfringens is a Gram-positive spore-forming anaerobic pathogen, which causes gas gangrene and food poisoning. Biofilm formation and/or sporulation confer increased resistance to various environmental stresses. C. perfringens forms biofilms with different structures in response to different growth temperatures. At 37°C, cells adhere densely to surfaces, forming thin biofilms. In contrast, at 25°C cells produce a threadlike EPS that facilitates the formation of a thick, elastic, pellicle-like biofilm. Here we found heterogeneous expression of the EPS gene within a population determines cell fate in C. perfringens; cells may either attach to surfaces or produce extracellular matrix. This heterogeneity is further modulated by temperature, which greatly affects biofilm morphology. The spatial distribution of matrix-producing cells within the biofilms suggests that the EPS protects the whole population in the biofilm. C. perfringens may modulate EPS gene expression to induce morphological changes in the biofilm structure as a strategy for adapting to the inter-host and external environments.


IPGG, 6 rue Jean Calvin 75005 Paris

Mercredi 20 Septembre 2017 10:30
Séminaire Thématique
Unité de rattachement: 
UMR 8640
Equipe de rattachement 8640: