Bacteria can organize into structured communities, called biofilms, that protect them from antibiotics and from immune attack by the host. The biofilms are embedded in a matrix containing a complex mixture of macromolecules including exopolysaccharides and proteins. In the February 22 Science, Cynthia Whitchurch and colleagues reported that extracellular DNA is a major component of the biofilms of Pseudomonas aeruginosa (Science 2002, 295:1487).

Whitchurch et al. demonstrated that adding DNase I to P. aeruginosa cultures inhibited biofilm formation and bacterial colonization. The enzyme could also dissolve established biofilms. The extracellular DNA is thought to be derived from membrane vesicles.

They propose that DNase I treatment may be beneficial to prevent biofilm formation in infection-linked diseases such as cystic fibrosis.

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