A recent article in Science by Gibiansky et al. (2010) reports that Pseudomonas aeruginosa can actually stand upright and use type IV pili (a motility structure we discussed in class the other day) to "walk". They used a novel method of computational microscopy to track the progress of individual P. aeruginosa cells as they moved across a solid surface within a biofilm.
This research builds upon earlier research by Orans et al. (2009) who elucidated the crystal structure of the P. aeruginosa type IV pilus in hopes of learning more about how to disrupt twitching motility over solid surfaces.
Biofilm formation and twitching motility are both essential for the ability of P. aeruginosa to establish infections. These types of infections are the most common cause of death for people afflicted with cystic fibrosis and they can cause a variety of other problems, such as ear, skin, and eye infections.
The Rowland Institute at Harvard University collects videos of bacterial motility in action, including a video of twitching by P. aeruginosa from a paper by Skerker and Berg (2001).
References:
M. L. Gibiansky, J. C. Conrad, F. Jin, V. D. Gordon, D. A. Motto, M. A. Mathewson, W. G. Stopka, D. C. Zelasko, J. D. Shrout, G. C. L. Wong. Bacteria Use Type IV Pili to Walk Upright and Detach from Surfaces. Science, 2010; 330 (6001): 197 DOI: 10.1126/science.1194238
Jillian Orans, Michael D. L. Johnson, Kimberly A. Coggan, Justin R. Sperlazza, Ryan W. Heiniger, Matthew C. Wolfgang, and Matthew R. Redinbo. Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0911616107
Skerker, J.M. and Berg, H.C. Direct observation of extension and retraction of type IV pili. Proc Natl. Acad. Sci. USA, 98, 6901-6904 (2001).
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