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Many chromosomal genes have now been shown to be involved in different stages of biofilm development. By contrast, the contribution of the extra-chromosomal plasmid gene pool (representing as much as 10-20 % of total bacterial DNA) to biofilm biology is poorly understood. As a consequence, with the exception of biotechnology application and antibiotic resistance spread, the role of plasmids in bacterial ecology has been largely overlooked.

Role of natural conjugative plasmids in bacterial biofilm formation

We and others have shown that conjugative plasmids contribute directly to the capacity of E. coli to form a biofilm through the expression of conjugative pili (Reisner et al., 2003). We demonstrated that this properties is linked to the expression of the F pilus expressed by cells harboring the F factor and a further analysis showed that this capacity is not restricted to the F factor but, rather, is a general feature of Gram-negative bacterial conjugative plasmids. This work suggests that conjugative plasmids express adhesion factors that drive their host cells into biofilms where horizontal transfer of genetic material of diverse origins can be exchange at high rates through conjugation.

 Ghigo, J.M. (2001). “Natural conjugative plasmids induce bacterial biofilm development.” Nature 412(6845): 442-5.

Caracterization of plasmid-borne aggregative adherence factors in an atypical Enteroaggregative Escherichia coli strain.

E. G. Dudley, C. Abe, J. M. Ghigo, P. Latour-Lambert, J. C. Hormazabal and J. P. Nataro. (2006) An IncI1 Plasmid Contributes to the Adherence of the Atypical Enteroaggregative Escherichia coli Strain C1096 to Cultured Cells and Abiotic Surfaces Infect Immun.74:2102-14.