Extracellular DNA

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, Whitchurch et al. report that extracellular DNA is a major component of the biofilms of Pseudomonas aeruginosa (Science 2002(Science , 295:1487)).They demonstrate 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.Whitchurch et al.propose that DNase I treatment may be beneficial to prevent biofilm formation in infection-linked diseases such as cystic fibrosis.