Many drug-resistant infections are the result of bacterial biofilms, structured aggregates of bacteria that live on surfaces and that are extremely resistant to environmental stresses. These biofilms impact human health in many ways cystic fibrosis, for example, is a disease in which patients die from airway bacterial biofilm infections that are invulnerable to even the most potent antibiotics.
Now, UCLA researchers and their colleagues have found that during the initial stages of biofilm formation, bacteria can actually stand upright and "walk" as part of their adaptation to a surface.
"Bacteria exist in two physiological states: the free-swimming, single-celled planktonic state and the surface-mounted biofilm state, a dense, structured, community of cells governed by their own sociology," said Gerard Wong, a professor of bioengineering at the UCLA Henry Samueli School of Engineering and Applied Science and at the California NanoSystems Institute at UCLA.
"Bacteria in biofilms are phenotypically different from free-swimming bacteria even though they are genomically identical. As part of their adaptation to a surface and to the existence of a community, different genes are turned up and down for bacteria in biofilms, leading to drastically different behavior," he said.
In the study, which appears in the current issue of the journal Science, Wong and his research group describe the new surface adaptation the "walking" motility mechanism, which was observed in Pseudomonas aeruginosa, a biofilm-forming pathogen partly responsible for the lethal infections in cystic fibrosis.
What enables this upright walking are appendages called type IV pili, which function as the analog of legs. What's more, walking allows P. aeruginosa to move with trajectories optimized for surface exploration, so that they can forage more effectively. The upright orientation is also the first step in surface detachmen
|Contact: Wileen Wong Kromhout|
University of California -- Los Angeles