No iron, no biofilms

Biofilm bacteria are extremely resistant to antibiotic treatments and can occur on many medical implants and in the lungs of cystic fibrosis patients. In 30 May Nature, Pradeep Singh and colleagues from University of Iowa College of Medicine, Iowa City, Iowa, show that lactoferrin, a component of innate immunity, prevents bacterial biofilm development (Nature 2002, 417:552-555).

Singh et al. used a continuous culture-flow of Pseudomonas aeruginosa cells expressing a green fluorescent protein and observed that lactoferrin blocks bio-film development of the bacteria. This effect occurred at lactoferrin concentrations below those that kill or prevent bacterial growth. Lactoferrin sequestrates iron and they showed that this stimulates twitching — a specialized form of surface motility — causing the bacteria to roam across the surface instead of forming cell clusters and biofilms.

"These findings reveal a specific anti-biofilm defense mechanism acting at a critical juncture in biofilm development, the time bacteria stop roaming ...