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GENOMICS OF BIOFILM FORMATION

Global impact of mature biofilm lifestyle on Escherichia coli K12 gene expression

The formation of biofilm results in a major lifestyle switch that is thought to affect the expression of multiple genes and operons (Ghigo, 2003; Sauer, 2003). We compared on a genomic scale the expression profiles of free-floating and surface attached mature biofilm populations of E. coli K12. We showed that when biofilm formation is compared to planktonic growth phases, up to 10% of the E. coli genome is significantly differentially expressed. This analysis of the global transcriptional response triggered in mature E. coli biofilms led to the identification of new biofilm-related functions (see Figure).. This opens new prospects for the characterization of physiological pathways developed in sessile bacterial communities

• Beloin, C; J. Valle, P. Latour-Lambert, P. Faure, M.Kzreminski, D. Balestrino, J. Haagensen, S. Molin, G. Prensier, B. Arbeille and Ghigo. J.-M. (2004) Global impact of mature biofilm lifestyle on E. coli K12 gene expression. Mol Microbiol. 51 (3), 659–674

Molecular analysis of biofilm formation by the pathogenic yeast Candida albicans

Biofilm formation by pathogenic yeasts has been observed on different medical devices (prosthesis, catheters) and is associated to several forms of disease (e.g. stomatitis). Our objectives are to decipher the genetic basis of Candida albicans biofilm formation and, through a better understanding of its molecular mechanisms, to achieve a better management of Candida infections.

We performed transcript profiling of mature biofilms and planktonic cultures grown under a variety of physiological conditions.The main conclusion of this study is that biofilm formation represents a specific developmental event associated with the expression of a specific subset of genes. Interestingly, it appears that the transcriptome of C. albicans biofilms is in a particular state that is only modestly sensitive to variations in the environment.

García-Sánchez, S. , S.Aubert, I.Iraqui, G. Janbon, J-M.Ghigo and d'Enfert, C. (2004) Biofilms of Candida albicans: a developmental state associated with specific and stable gene expression patterns. Eukaryotic Cell. (3):536-45

Ghigo, J.M. (2003.) Are there biofilm-specific physiological pathways beyond a reasonable doubt? Res Microbiol.154:1-8.

Sauer, K. (2003) The genomics and proteomics of biofilm formation. Genome Biol 4: 219.

Characterization of functions involved in the establishment and maturation of Klebsiella pneumoniae in vitro biofilm

We used signature-tagged mutagenesis (STM) to screen for K. pneumoniae functions required for biofilm formation and competition within the biofilm environment. Our analysis reveals the involvement of several bacterial functions at early and late stages of biofilm formation. We demonstrate in particular that, depending on the biofilm stage, K. pneumoniae surface exopolysaccharides, (capsule and LPS), play opposite roles, either controlling proper spatial distribution of biofilm bacteria or modulating bacterial aggregation ability..

Balestrino, D., Ghigo, J. M., Charbonnel, N., Haagensen, J. A. and Forestier, C. (2008) The characterization of functions involved in the establishment and maturation of Klebsiella pneumoniae in vitro biofilm reveals dual roles for surface exopolysaccharides  Environ Microbiol.10:685-701.