Comparison between Observation and Boundary Element Analysis of Bacterium Swimming Motion

Abstract

In the present study, we observed the motion of the bacterium, Vibrio alginolysicus, which swims by rotating a single helically shaped flagellum, by means of a dark-field microscope with a CCD camera system. We took measurements of the speed and the rotation rate as well as the size of individual bacteria. Next, we predicted the swimming speed by means of the boundary element method to analyse the bacterium’s motion and compared the calculated speed with the observed one. There was a close correlation between them not only qualitatively but also qauntitatively. Furthermore, we evaluated the torque of the flagellar motor, by coupling the computational and the experimental results. The torque was estimated to be of the order of 0.1-1 pNμm.