Extracellular DNA required for bacterial biofilm formation

Bacterial biofilms are structured communities of cells enclosed in self-produced hydrated poly-meric matrix adherent to an inert or living sur-face (1). Formation of these sessile communities and their inherent resistance to antibiotics and host immune attack are at the root of many persistent and chronic bacterial infections (1), including those caused by Pseudo-monas aeruginosa, which has been intensively studied as a model for biofilm formation (2, 3). The ma-trix, which holds bacterial biofilms together, is a complex mixture of macromolecules including exopo-lysaccharides, proteins, and DN