A bacterial treadmill
Yann Chemla and Ido Golding in the Department of Physics at the University of Illinois, Urbana-Champaign have recently developed a new method to study this process (Nature Methods 6 (11):831-835, 2009). Using optical “tweezers”, or focused laser light, they immobilized individual E. coli cells in water without impeding their swimming motion. In essence, this generated a “bacterial treadmill” in which a cell swims but remains in place. This technique allowed the team to follow bacterial swimming over long durations and with a resolution hitherto unachievable. The figure above is an artist's rendering of a bacterium held in the light of the optical tweezers (depicted by the red cones).
For more information see: http://news.illinois.edu/news/09/1005bacteria.html