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Monday, October 18, 2010

Bacteria walk to infection site

Gerard Wong and his colleagues from UCLA, the University of Houston, the University of Illinois and University of Notre Dame have discovered one method bacteria use to move to a new site of infection. They ‘walk’ there.

The microbiologists studied Pseudomonas aeruginosa, a leading cause of death in patients with cystic fibrosis. These bacteria can exist as free-swimming individual bacteria, a state in which they do relatively little harm, or as part of a biofilm. Not only do these biofilms form an impenetrable coating, but the bacteria within them often excrete completely new and toxic substances. But how do bacteria transition between the two states?

Wong and his teammates made a breakthrough in answering this question when they discovered that P. aeruginosa can effectively walk upright. Each rod-shaped bacterium orients itself vertically and uses its type IV pili (tiny hairlike projections) to propel it across a surface. The bacterium hasn’t become part of a biofilm, nor is it free-swimming. It is, however, in the unique position of being able to forage over a surface, or to detach completely. In other words, a 'walking' bacterium appears to be in a transitional state between the free-swimming and biofilm phases.

The scientists expect this new data to answer questions not only about biofilms, but also about infectivity in general.

Walking bacterium
Artists representation of a bacterium "walking."